Update readers to be memory pool friendly

mediadevices_test.go

@@ -201,11 +201,11 @@ type mockVideoCodec struct {
 	closed chan struct{}
 }
 
-func (m *mockVideoCodec) Read() ([]byte, error) {
+func (m *mockVideoCodec) Read() ([]byte, func(), error) {
-	if _, err := m.r.Read(); err != nil {
+	if _, _, err := m.r.Read(); err != nil {
-		return nil, err
+		return nil, func() {}, err
 	}
-	return make([]byte, 20), nil
+	return make([]byte, 20), func() {}, nil
 }
 
 func (m *mockVideoCodec) Close() error { return nil }
@@ -216,11 +216,11 @@ type mockAudioCodec struct {
 	closed chan struct{}
 }
 
-func (m *mockAudioCodec) Read() ([]byte, error) {
+func (m *mockAudioCodec) Read() ([]byte, func(), error) {
-	if _, err := m.r.Read(); err != nil {
+	if _, _, err := m.r.Read(); err != nil {
-		return nil, err
+		return nil, func() {}, err
 	}
-	return make([]byte, 20), nil
+	return make([]byte, 20), func() {}, nil
 }
 func (m *mockAudioCodec) Close() error { return nil }
 

meta.go

@@ -15,7 +15,7 @@ func detectCurrentVideoProp(broadcaster *video.Broadcaster) (prop.Media, error)
 	// in any case.
 	metaReader := broadcaster.NewReader(false)
 	metaReader = video.DetectChanges(0, func(p prop.Media) { currentProp = p })(metaReader)
-	_, err := metaReader.Read()
+	_, _, err := metaReader.Read()
 
 	return currentProp, err
 }
@@ -29,7 +29,7 @@ func detectCurrentAudioProp(broadcaster *audio.Broadcaster) (prop.Media, error)
 	// in any case.
 	metaReader := broadcaster.NewReader(false)
 	metaReader = audio.DetectChanges(0, func(p prop.Media) { currentProp = p })(metaReader)
-	_, err := metaReader.Read()
+	_, _, err := metaReader.Read()
 
 	return currentProp, err
 }

meta_test.go

@@ -17,12 +17,12 @@ func TestDetectCurrentVideoProp(t *testing.T) {
 	second.Pix[0] = 2
 
 	isFirst := true
-	source := video.ReaderFunc(func() (image.Image, error) {
+	source := video.ReaderFunc(func() (image.Image, func(), error) {
 		if isFirst {
 			isFirst = true
-			return first, nil
+			return first, func() {}, nil
 		} else {
-			return second, nil
+			return second, func() {}, nil
 		}
 	})
 
@@ -42,7 +42,7 @@ func TestDetectCurrentVideoProp(t *testing.T) {
 	}
 
 	reader := broadcaster.NewReader(false)
-	img, err := reader.Read()
+	img, _, err := reader.Read()
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -65,12 +65,12 @@ func TestDetectCurrentAudioProp(t *testing.T) {
 	second.Data[0] = 2
 
 	isFirst := true
-	source := audio.ReaderFunc(func() (wave.Audio, error) {
+	source := audio.ReaderFunc(func() (wave.Audio, func(), error) {
 		if isFirst {
 			isFirst = true
-			return first, nil
+			return first, func() {}, nil
 		} else {
-			return second, nil
+			return second, func() {}, nil
 		}
 	})
 
@@ -86,7 +86,7 @@ func TestDetectCurrentAudioProp(t *testing.T) {
 	}
 
 	reader := broadcaster.NewReader(false)
-	chunk, err := reader.Read()
+	chunk, _, err := reader.Read()
 	if err != nil {
 		t.Fatal(err)
 	}

pkg/avfoundation/avfoundation_darwin.go

@@ -110,12 +110,12 @@ func (rc *ReadCloser) dataCb(data []byte) {
 // Read reads raw data, the format is determined by the media type and property:
 //   - For video, each call will return a frame.
 //   - For audio, each call will return a chunk which its size configured by Latency
-func (rc *ReadCloser) Read() ([]byte, error) {
+func (rc *ReadCloser) Read() ([]byte, func(), error) {
 	data, ok := <-rc.dataChan
 	if !ok {
-		return nil, io.EOF
+		return nil, func() {}, io.EOF
 	}
-	return data, nil
+	return data, func() {}, nil
 }
 
 // Close closes the capturing session, and no data will flow anymore

pkg/codec/codec.go

@@ -58,7 +58,7 @@ type VideoEncoderBuilder interface {
 
 // ReadCloser is an io.ReadCloser with methods for rate limiting: SetBitRate and ForceKeyFrame
 type ReadCloser interface {
-	Read() ([]byte, error)
+	Read() (b []byte, release func(), err error)
 	Close() error
 	// SetBitRate sets current target bitrate, lower bitrate means smaller data will be transmitted
 	// but this also means that the quality will also be lower.

pkg/codec/mmal/mmal.go

@@ -55,17 +55,17 @@ func newEncoder(r video.Reader, p prop.Media, params Params) (codec.ReadCloser,
 	return &e, nil
 }
 
-func (e *encoder) Read() ([]byte, error) {
+func (e *encoder) Read() ([]byte, func(), error) {
 	e.mu.Lock()
 	defer e.mu.Unlock()
 
 	if e.closed {
-		return nil, io.EOF
+		return nil, func() {}, io.EOF
 	}
 
-	img, err := e.r.Read()
+	img, _, err := e.r.Read()
 	if err != nil {
-		return nil, err
+		return nil, func() {}, err
 	}
 	imgReal := img.(*image.YCbCr)
 	var y, cb, cr C.Slice
@@ -79,7 +79,7 @@ func (e *encoder) Read() ([]byte, error) {
 	var encodedBuffer *C.MMAL_BUFFER_HEADER_T
 	status := C.enc_encode(&e.engine, y, cb, cr, &encodedBuffer)
 	if status.code != 0 {
-		return nil, statusToErr(&status)
+		return nil, func() {}, statusToErr(&status)
 	}
 
 	// GoBytes copies the C array to Go slice. After this, it's safe to release the C array
@@ -87,7 +87,7 @@ func (e *encoder) Read() ([]byte, error) {
 	// Release the buffer so that mmal can reuse this memory
 	C.mmal_buffer_header_release(encodedBuffer)
 
-	return encoded, err
+	return encoded, func() {}, err
 }
 
 func (e *encoder) SetBitRate(b int) error {

pkg/codec/openh264/openh264.go

@@ -50,17 +50,17 @@ func newEncoder(r video.Reader, p prop.Media, params Params) (codec.ReadCloser,
 	}, nil
 }
 
-func (e *encoder) Read() ([]byte, error) {
+func (e *encoder) Read() ([]byte, func(), error) {
 	e.mu.Lock()
 	defer e.mu.Unlock()
 
 	if e.closed {
-		return nil, io.EOF
+		return nil, func() {}, io.EOF
 	}
 
-	img, err := e.r.Read()
+	img, _, err := e.r.Read()
 	if err != nil {
-		return nil, err
+		return nil, func() {}, err
 	}
 
 	yuvImg := img.(*image.YCbCr)
@@ -74,11 +74,11 @@ func (e *encoder) Read() ([]byte, error) {
 		width:  C.int(bounds.Max.X - bounds.Min.X),
 	}, &rv)
 	if err := errResult(rv); err != nil {
-		return nil, fmt.Errorf("failed in encoding: %v", err)
+		return nil, func() {}, fmt.Errorf("failed in encoding: %v", err)
 	}
 
 	encoded := C.GoBytes(unsafe.Pointer(s.data), s.data_len)
-	return encoded, nil
+	return encoded, func() {}, nil
 }
 
 func (e *encoder) SetBitRate(b int) error {

pkg/codec/opus/opus.go

@@ -72,22 +72,22 @@ func newEncoder(r audio.Reader, p prop.Media, params Params) (codec.ReadCloser,
 	return &e, nil
 }
 
-func (e *encoder) Read() ([]byte, error) {
+func (e *encoder) Read() ([]byte, func(), error) {
-	buff, err := e.reader.Read()
+	buff, _, err := e.reader.Read()
 	if err != nil {
-		return nil, err
+		return nil, func() {}, err
 	}
 
 	encoded := make([]byte, 1024)
 	switch b := buff.(type) {
 	case *wave.Int16Interleaved:
 		n, err := e.engine.Encode(b.Data, encoded)
-		return encoded[:n:n], err
+		return encoded[:n:n], func() {}, err
 	case *wave.Float32Interleaved:
 		n, err := e.engine.EncodeFloat32(b.Data, encoded)
-		return encoded[:n:n], err
+		return encoded[:n:n], func() {}, err
 	default:
-		return nil, errors.New("unknown type of audio buffer")
+		return nil, func() {}, errors.New("unknown type of audio buffer")
 	}
 }
 

pkg/codec/vaapi/vp8.go

@@ -64,7 +64,6 @@ import (
 	"unsafe"
 
 	"github.com/pion/mediadevices/pkg/codec"
-	mio "github.com/pion/mediadevices/pkg/io"
 	"github.com/pion/mediadevices/pkg/io/video"
 	"github.com/pion/mediadevices/pkg/prop"
 )
@@ -296,17 +295,17 @@ func newVP8Encoder(r video.Reader, p prop.Media, params ParamsVP8) (codec.ReadCl
 	return e, nil
 }
 
-func (e *encoderVP8) Read() ([]byte, error) {
+func (e *encoderVP8) Read() ([]byte, func(), error) {
 	e.mu.Lock()
 	defer e.mu.Unlock()
 
 	if e.closed {
-		return nil, io.EOF
+		return nil, func() {}, io.EOF
 	}
 
-	img, err := e.r.Read()
+	img, _, err := e.r.Read()
 	if err != nil {
-		return nil, err
+		return nil, func() {}, err
 	}
 	yuvImg := img.(*image.YCbCr)
 
@@ -348,7 +347,7 @@ func (e *encoderVP8) Read() ([]byte, error) {
 			}
 		}
 		if e.picParam.reconstructed_frame == C.VA_INVALID_SURFACE {
-			return nil, errors.New("no available surface")
+			return nil, func() {}, errors.New("no available surface")
 		}
 
 		C.setForceKFFlagVP8(&e.picParam, 0)
@@ -416,7 +415,7 @@ func (e *encoderVP8) Read() ([]byte, error) {
 			C.size_t(uintptr(p.src)),
 			&id,
 		); s != C.VA_STATUS_SUCCESS {
-			return nil, fmt.Errorf("failed to create buffer: %s", C.GoString(C.vaErrorStr(s)))
+			return nil, func() {}, fmt.Errorf("failed to create buffer: %s", C.GoString(C.vaErrorStr(s)))
 		}
 		buffs = append(buffs, id)
 	}
@@ -426,17 +425,17 @@ func (e *encoderVP8) Read() ([]byte, error) {
 		e.display, e.ctxID,
 		e.surfs[surfaceVP8Input],
 	); s != C.VA_STATUS_SUCCESS {
-		return nil, fmt.Errorf("failed to begin picture: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to begin picture: %s", C.GoString(C.vaErrorStr(s)))
 	}
 
 	// Upload image
 	var vaImg C.VAImage
 	var rawBuf unsafe.Pointer
 	if s := C.vaDeriveImage(e.display, e.surfs[surfaceVP8Input], &vaImg); s != C.VA_STATUS_SUCCESS {
-		return nil, fmt.Errorf("failed to derive image: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to derive image: %s", C.GoString(C.vaErrorStr(s)))
 	}
 	if s := C.vaMapBuffer(e.display, vaImg.buf, &rawBuf); s != C.VA_STATUS_SUCCESS {
-		return nil, fmt.Errorf("failed to map buffer: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to map buffer: %s", C.GoString(C.vaErrorStr(s)))
 	}
 	// TODO: use vaImg.pitches to support padding
 	C.memcpy(
@@ -452,10 +451,10 @@ func (e *encoderVP8) Read() ([]byte, error) {
 		unsafe.Pointer(&yuvImg.Cr[0]), C.size_t(len(yuvImg.Cr)),
 	)
 	if s := C.vaUnmapBuffer(e.display, vaImg.buf); s != C.VA_STATUS_SUCCESS {
-		return nil, fmt.Errorf("failed to unmap buffer: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to unmap buffer: %s", C.GoString(C.vaErrorStr(s)))
 	}
 	if s := C.vaDestroyImage(e.display, vaImg.image_id); s != C.VA_STATUS_SUCCESS {
-		return nil, fmt.Errorf("failed to destroy image: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to destroy image: %s", C.GoString(C.vaErrorStr(s)))
 	}
 
 	if s := C.vaRenderPicture(
@@ -463,38 +462,38 @@ func (e *encoderVP8) Read() ([]byte, error) {
 		&buffs[1], // 0 is for ouput
 		C.int(len(buffs)-1),
 	); s != C.VA_STATUS_SUCCESS {
-		return nil, fmt.Errorf("failed to render picture: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to render picture: %s", C.GoString(C.vaErrorStr(s)))
 	}
 	if s := C.vaEndPicture(
 		e.display, e.ctxID,
 	); s != C.VA_STATUS_SUCCESS {
-		return nil, fmt.Errorf("failed to end picture: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to end picture: %s", C.GoString(C.vaErrorStr(s)))
 	}
 
 	// Load encoded data
 	for retry := 3; retry >= 0; retry-- {
 		if s := C.vaSyncSurface(e.display, e.picParam.reconstructed_frame); s != C.VA_STATUS_SUCCESS {
-			return nil, fmt.Errorf("failed to sync surface: %s", C.GoString(C.vaErrorStr(s)))
+			return nil, func() {}, fmt.Errorf("failed to sync surface: %s", C.GoString(C.vaErrorStr(s)))
 		}
 		var surfStat C.VASurfaceStatus
 		if s := C.vaQuerySurfaceStatus(
 			e.display, e.picParam.reconstructed_frame, &surfStat,
 		); s != C.VA_STATUS_SUCCESS {
-			return nil, fmt.Errorf("failed to query surface status: %s", C.GoString(C.vaErrorStr(s)))
+			return nil, func() {}, fmt.Errorf("failed to query surface status: %s", C.GoString(C.vaErrorStr(s)))
 		}
 		if surfStat == C.VASurfaceReady {
 			break
 		}
 		if retry == 0 {
-			return nil, fmt.Errorf("failed to sync surface: %d", surfStat)
+			return nil, func() {}, fmt.Errorf("failed to sync surface: %d", surfStat)
 		}
 	}
 	var seg *C.VACodedBufferSegment
 	if s := C.vaMapBufferSeg(e.display, buffs[0], &seg); s != C.VA_STATUS_SUCCESS {
-		return nil, fmt.Errorf("failed to map buffer: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to map buffer: %s", C.GoString(C.vaErrorStr(s)))
 	}
 	if seg.status&C.VA_CODED_BUF_STATUS_SLICE_OVERFLOW_MASK != 0 {
-		return nil, errors.New("buffer size too small")
+		return nil, func() {}, errors.New("buffer size too small")
 	}
 
 	if cap(e.frame) < int(seg.size) {
@@ -507,13 +506,13 @@ func (e *encoderVP8) Read() ([]byte, error) {
 	)
 
 	if s := C.vaUnmapBuffer(e.display, buffs[0]); s != C.VA_STATUS_SUCCESS {
-		return nil, fmt.Errorf("failed to unmap buffer: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to unmap buffer: %s", C.GoString(C.vaErrorStr(s)))
 	}
 
 	// Destroy buffers
 	for _, b := range buffs {
 		if s := C.vaDestroyBuffer(e.display, b); s != C.VA_STATUS_SUCCESS {
-			return nil, fmt.Errorf("failed to destroy buffer: %s", C.GoString(C.vaErrorStr(s)))
+			return nil, func() {}, fmt.Errorf("failed to destroy buffer: %s", C.GoString(C.vaErrorStr(s)))
 		}
 	}
 
@@ -538,7 +537,7 @@ func (e *encoderVP8) Read() ([]byte, error) {
 
 	encoded := make([]byte, len(e.frame))
 	copy(encoded, e.frame)
-	return encoded, err
+	return encoded, func() {}, err
 }
 
 func (e *encoderVP8) SetBitRate(b int) error {

pkg/codec/vaapi/vp9.go

@@ -47,7 +47,6 @@ import (
 	"unsafe"
 
 	"github.com/pion/mediadevices/pkg/codec"
-	mio "github.com/pion/mediadevices/pkg/io"
 	"github.com/pion/mediadevices/pkg/io/video"
 	"github.com/pion/mediadevices/pkg/prop"
 )
@@ -285,17 +284,17 @@ func newVP9Encoder(r video.Reader, p prop.Media, params ParamsVP9) (codec.ReadCl
 	return e, nil
 }
 
-func (e *encoderVP9) Read() ([]byte, error) {
+func (e *encoderVP9) Read() ([]byte, func(), error) {
 	e.mu.Lock()
 	defer e.mu.Unlock()
 
 	if e.closed {
-		return nil, io.EOF
+		return nil, func() {}, io.EOF
 	}
 
-	img, err := e.r.Read()
+	img, _, err := e.r.Read()
 	if err != nil {
-		return nil, err
+		return nil, func() {}, err
 	}
 	yuvImg := img.(*image.YCbCr)
 
@@ -379,7 +378,7 @@ func (e *encoderVP9) Read() ([]byte, error) {
 			C.size_t(uintptr(p.src)),
 			&id,
 		); s != C.VA_STATUS_SUCCESS {
-			return 0, fmt.Errorf("failed to create buffer: %s", C.GoString(C.vaErrorStr(s)))
+			return nil, func() {}, fmt.Errorf("failed to create buffer: %s", C.GoString(C.vaErrorStr(s)))
 		}
 		buffs = append(buffs, id)
 	}
@@ -389,17 +388,17 @@ func (e *encoderVP9) Read() ([]byte, error) {
 		e.display, e.ctxID,
 		e.surfs[surfaceVP9Input],
 	); s != C.VA_STATUS_SUCCESS {
-		return nil, fmt.Errorf("failed to begin picture: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to begin picture: %s", C.GoString(C.vaErrorStr(s)))
 	}
 
 	// Upload image
 	var vaImg C.VAImage
 	var rawBuf unsafe.Pointer
 	if s := C.vaDeriveImage(e.display, e.surfs[surfaceVP9Input], &vaImg); s != C.VA_STATUS_SUCCESS {
-		return nil, fmt.Errorf("failed to derive image: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to derive image: %s", C.GoString(C.vaErrorStr(s)))
 	}
 	if s := C.vaMapBuffer(e.display, vaImg.buf, &rawBuf); s != C.VA_STATUS_SUCCESS {
-		return nil, fmt.Errorf("failed to map buffer: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to map buffer: %s", C.GoString(C.vaErrorStr(s)))
 	}
 	// TODO: use vaImg.pitches to support padding
 	C.copyI420toNV12(
@@ -410,10 +409,10 @@ func (e *encoderVP9) Read() ([]byte, error) {
 		C.uint(len(yuvImg.Y)),
 	)
 	if s := C.vaUnmapBuffer(e.display, vaImg.buf); s != C.VA_STATUS_SUCCESS {
-		return nil, fmt.Errorf("failed to unmap buffer: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to unmap buffer: %s", C.GoString(C.vaErrorStr(s)))
 	}
 	if s := C.vaDestroyImage(e.display, vaImg.image_id); s != C.VA_STATUS_SUCCESS {
-		return nil, fmt.Errorf("failed to destroy image: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to destroy image: %s", C.GoString(C.vaErrorStr(s)))
 	}
 
 	if s := C.vaRenderPicture(
@@ -421,27 +420,27 @@ func (e *encoderVP9) Read() ([]byte, error) {
 		&buffs[1], // 0 is for ouput
 		C.int(len(buffs)-1),
 	); s != C.VA_STATUS_SUCCESS {
-		return nil, fmt.Errorf("failed to render picture: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to render picture: %s", C.GoString(C.vaErrorStr(s)))
 	}
 	if s := C.vaEndPicture(
 		e.display, e.ctxID,
 	); s != C.VA_STATUS_SUCCESS {
-		return nil, fmt.Errorf("failed to end picture: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to end picture: %s", C.GoString(C.vaErrorStr(s)))
 	}
 
 	// Load encoded data
 	if s := C.vaSyncSurface(e.display, e.picParam.reconstructed_frame); s != C.VA_STATUS_SUCCESS {
-		return nil, fmt.Errorf("failed to sync surface: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to sync surface: %s", C.GoString(C.vaErrorStr(s)))
 	}
 	var surfStat C.VASurfaceStatus
 	if s := C.vaQuerySurfaceStatus(
 		e.display, e.picParam.reconstructed_frame, &surfStat,
 	); s != C.VA_STATUS_SUCCESS {
-		return nil, fmt.Errorf("failed to query surface status: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to query surface status: %s", C.GoString(C.vaErrorStr(s)))
 	}
 	var seg *C.VACodedBufferSegment
 	if s := C.vaMapBufferSeg(e.display, buffs[0], &seg); s != C.VA_STATUS_SUCCESS {
-		return nil, fmt.Errorf("failed to map buffer: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to map buffer: %s", C.GoString(C.vaErrorStr(s)))
 	}
 	if cap(e.frame) < int(seg.size) {
 		e.frame = make([]byte, int(seg.size))
@@ -453,13 +452,13 @@ func (e *encoderVP9) Read() ([]byte, error) {
 	)
 
 	if s := C.vaUnmapBuffer(e.display, buffs[0]); s != C.VA_STATUS_SUCCESS {
-		return 0, fmt.Errorf("failed to unmap buffer: %s", C.GoString(C.vaErrorStr(s)))
+		return nil, func() {}, fmt.Errorf("failed to unmap buffer: %s", C.GoString(C.vaErrorStr(s)))
 	}
 
 	// Destroy buffers
 	for _, b := range buffs {
 		if s := C.vaDestroyBuffer(e.display, b); s != C.VA_STATUS_SUCCESS {
-			return 0, fmt.Errorf("failed to destroy buffer: %s", C.GoString(C.vaErrorStr(s)))
+			return nil, func() {}, fmt.Errorf("failed to destroy buffer: %s", C.GoString(C.vaErrorStr(s)))
 		}
 	}
 
@@ -473,7 +472,7 @@ func (e *encoderVP9) Read() ([]byte, error) {
 
 	encoded := make([]byte, len(e.frame))
 	copy(encoded, e.frame)
-	return encoded, err
+	return encoded, func() {}, err
 }
 
 func (e *encoderVP9) SetBitRate(b int) error {

pkg/codec/vpx/vpx.go

@@ -204,17 +204,17 @@ func newEncoder(r video.Reader, p prop.Media, params Params, codecIface *C.vpx_c
 	}, nil
 }
 
-func (e *encoder) Read() ([]byte, error) {
+func (e *encoder) Read() ([]byte, func(), error) {
 	e.mu.Lock()
 	defer e.mu.Unlock()
 
 	if e.closed {
-		return nil, io.EOF
+		return nil, func() {}, io.EOF
 	}
 
-	img, err := e.r.Read()
+	img, _, err := e.r.Read()
 	if err != nil {
-		return nil, err
+		return nil, func() {}, err
 	}
 	yuvImg := img.(*image.YCbCr)
 	bounds := yuvImg.Bounds()
@@ -230,7 +230,7 @@ func (e *encoder) Read() ([]byte, error) {
 	if e.cfg.g_w != C.uint(width) || e.cfg.g_h != C.uint(height) {
 		e.cfg.g_w, e.cfg.g_h = C.uint(width), C.uint(height)
 		if ec := C.vpx_codec_enc_config_set(e.codec, e.cfg); ec != C.VPX_CODEC_OK {
-			return nil, fmt.Errorf("vpx_codec_enc_config_set failed (%d)", ec)
+			return nil, func() {}, fmt.Errorf("vpx_codec_enc_config_set failed (%d)", ec)
 		}
 		e.raw.w, e.raw.h = C.uint(width), C.uint(height)
 		e.raw.r_w, e.raw.r_h = C.uint(width), C.uint(height)
@@ -243,7 +243,7 @@ func (e *encoder) Read() ([]byte, error) {
 		C.long(t-e.tStart), C.ulong(t-e.tLastFrame), C.long(flags), C.ulong(e.deadline),
 		(*C.uchar)(&yuvImg.Y[0]), (*C.uchar)(&yuvImg.Cb[0]), (*C.uchar)(&yuvImg.Cr[0]),
 	); ec != C.VPX_CODEC_OK {
-		return nil, fmt.Errorf("vpx_codec_encode failed (%d)", ec)
+		return nil, func() {}, fmt.Errorf("vpx_codec_encode failed (%d)", ec)
 	}
 
 	e.frameIndex++
@@ -264,7 +264,7 @@ func (e *encoder) Read() ([]byte, error) {
 
 	encoded := make([]byte, len(e.frame))
 	copy(encoded, e.frame)
-	return encoded, err
+	return encoded, func() {}, err
 }
 
 func (e *encoder) SetBitRate(b int) error {

pkg/codec/x264/x264.go

@@ -94,17 +94,17 @@ func newEncoder(r video.Reader, p prop.Media, params Params) (codec.ReadCloser,
 	return &e, nil
 }
 
-func (e *encoder) Read() ([]byte, error) {
+func (e *encoder) Read() ([]byte, func(), error) {
 	e.mu.Lock()
 	defer e.mu.Unlock()
 
 	if e.closed {
-		return nil, io.EOF
+		return nil, func() {}, io.EOF
 	}
 
-	img, err := e.r.Read()
+	img, _, err := e.r.Read()
 	if err != nil {
-		return nil, err
+		return nil, func() {}, err
 	}
 	yuvImg := img.(*image.YCbCr)
 
@@ -117,11 +117,11 @@ func (e *encoder) Read() ([]byte, error) {
 		&rc,
 	)
 	if err := errFromC(rc); err != nil {
-		return nil, err
+		return nil, func() {}, err
 	}
 
 	encoded := C.GoBytes(unsafe.Pointer(s.data), s.data_len)
-	return encoded, err
+	return encoded, func() {}, err
 }
 
 func (e *encoder) SetBitRate(b int) error {

pkg/driver/audiotest/dummy.go

@@ -52,10 +52,10 @@ func (d *dummy) AudioRecord(p prop.Media) (audio.Reader, error) {
 
 	closed := d.closed
 
-	reader := audio.ReaderFunc(func() (wave.Audio, error) {
+	reader := audio.ReaderFunc(func() (wave.Audio, func(), error) {
 		select {
 		case <-closed:
-			return nil, io.EOF
+			return nil, func() {}, io.EOF
 		default:
 		}
 
@@ -78,7 +78,7 @@ func (d *dummy) AudioRecord(p prop.Media) (audio.Reader, error) {
 				a.SetFloat32(i, ch, wave.Float32Sample(sin[phase]))
 			}
 		}
-		return a, nil
+		return a, func() {}, nil
 	})
 	return reader, nil
 }

pkg/driver/camera/camera_darwin.go

@@ -56,10 +56,10 @@ func (cam *camera) VideoRecord(property prop.Media) (video.Reader, error) {
 	if err != nil {
 		return nil, err
 	}
-	r := video.ReaderFunc(func() (image.Image, error) {
+	r := video.ReaderFunc(func() (image.Image, func(), error) {
-		frame, err := rc.Read()
+		frame, _, err := rc.Read()
 		if err != nil {
-			return nil, err
+			return nil, func() {}, err
 		}
 		return decoder.Decode(frame, property.Width, property.Height)
 	})

pkg/driver/camera/camera_linux.go

@@ -182,7 +182,7 @@ func (c *camera) VideoRecord(p prop.Media) (video.Reader, error) {
 	ctx, cancel := context.WithCancel(context.Background())
 	c.cancel = cancel
 	var buf []byte
-	r := video.ReaderFunc(func() (img image.Image, err error) {
+	r := video.ReaderFunc(func() (img image.Image, release func(), err error) {
 		// Lock to avoid accessing the buffer after StopStreaming()
 		c.mutex.Lock()
 		defer c.mutex.Unlock()
@@ -191,23 +191,23 @@ func (c *camera) VideoRecord(p prop.Media) (video.Reader, error) {
 		for i := 0; i < maxEmptyFrameCount; i++ {
 			if ctx.Err() != nil {
 				// Return EOF if the camera is already closed.
-				return nil, io.EOF
+				return nil, func() {}, io.EOF
 			}
 
 			err := cam.WaitForFrame(5) // 5 seconds
 			switch err.(type) {
 			case nil:
 			case *webcam.Timeout:
-				return nil, errReadTimeout
+				return nil, func() {}, errReadTimeout
 			default:
 				// Camera has been stopped.
-				return nil, err
+				return nil, func() {}, err
 			}
 
 			b, err := cam.ReadFrame()
 			if err != nil {
 				// Camera has been stopped.
-				return nil, err
+				return nil, func() {}, err
 			}
 
 			// Frame is empty.
@@ -227,7 +227,7 @@ func (c *camera) VideoRecord(p prop.Media) (video.Reader, error) {
 			n := copy(buf, b)
 			return decoder.Decode(buf[:n], p.Width, p.Height)
 		}
-		return nil, errEmptyFrame
+		return nil, func() {}, errEmptyFrame
 	})
 
 	return r, nil

pkg/driver/camera/camera_windows.go

@@ -116,10 +116,10 @@ func (c *camera) VideoRecord(p prop.Media) (video.Reader, error) {
 
 	img := &image.YCbCr{}
 
-	r := video.ReaderFunc(func() (image.Image, error) {
+	r := video.ReaderFunc(func() (image.Image, func(), error) {
 		b, ok := <-c.ch
 		if !ok {
-			return nil, io.EOF
+			return nil, func() {}, io.EOF
 		}
 		img.Y = b[:nPix]
 		img.Cb = b[nPix : nPix+nPix/2]
@@ -128,7 +128,7 @@ func (c *camera) VideoRecord(p prop.Media) (video.Reader, error) {
 		img.CStride = p.Width / 2
 		img.SubsampleRatio = image.YCbCrSubsampleRatio422
 		img.Rect = image.Rect(0, 0, p.Width, p.Height)
-		return img, nil
+		return img, func() {}, nil
 	})
 	return r, nil
 }

pkg/driver/microphone/microphone_linux.go

@@ -97,11 +97,11 @@ func (m *microphone) AudioRecord(p prop.Media) (audio.Reader, error) {
 		return nil, err
 	}
 
-	reader := audio.ReaderFunc(func() (wave.Audio, error) {
+	reader := audio.ReaderFunc(func() (wave.Audio, func(), error) {
 		buff, ok := <-samplesChan
 		if !ok {
 			stream.Close()
-			return nil, io.EOF
+			return nil, func() {}, io.EOF
 		}
 
 		a := wave.NewInt16Interleaved(
@@ -112,7 +112,7 @@ func (m *microphone) AudioRecord(p prop.Media) (audio.Reader, error) {
 		)
 		copy(a.Data, buff)
 
-		return a, nil
+		return a, func() {}, nil
 	})
 
 	stream.Start()

pkg/driver/microphone/microphone_windows.go

@@ -194,10 +194,10 @@ func (m *microphone) AudioRecord(p prop.Media) (audio.Reader, error) {
 
 	// TODO: detect microphone device disconnection and return EOF
 
-	reader := audio.ReaderFunc(func() (wave.Audio, error) {
+	reader := audio.ReaderFunc(func() (wave.Audio, func(), error) {
 		b, ok := <-m.chBuf
 		if !ok {
-			return nil, io.EOF
+			return nil, func() {}, io.EOF
 		}
 
 		select {
@@ -210,7 +210,7 @@ func (m *microphone) AudioRecord(p prop.Media) (audio.Reader, error) {
 				uintptr(unsafe.Sizeof(b.waveHdr)),
 			)
 			if err := errWinmm[ret]; err != nil {
-				return nil, err
+				return nil, func() {}, err
 			}
 		}
 
@@ -229,7 +229,7 @@ func (m *microphone) AudioRecord(p prop.Media) (audio.Reader, error) {
 			}
 		}
 
-		return a, nil
+		return a, func() {}, nil
 	})
 	return reader, nil
 }

pkg/driver/screen/x11_linux.go

@@ -68,9 +68,9 @@ func (s *screen) VideoRecord(p prop.Media) (video.Reader, error) {
 	var dst image.RGBA
 	reader := s.reader
 
-	r := video.ReaderFunc(func() (image.Image, error) {
+	r := video.ReaderFunc(func() (image.Image, func(), error) {
 		<-s.tick.C
-		return reader.Read().ToRGBA(&dst), nil
+		return reader.Read().ToRGBA(&dst), func() {}, nil
 	})
 	return r, nil
 }

pkg/driver/videotest/dummy.go

@@ -103,10 +103,10 @@ func (d *dummy) VideoRecord(p prop.Media) (video.Reader, error) {
 	d.tick = tick
 	closed := d.closed
 
-	r := video.ReaderFunc(func() (image.Image, error) {
+	r := video.ReaderFunc(func() (image.Image, func(), error) {
 		select {
 		case <-closed:
-			return nil, io.EOF
+			return nil, func() {}, io.EOF
 		default:
 		}
 
@@ -130,7 +130,7 @@ func (d *dummy) VideoRecord(p prop.Media) (video.Reader, error) {
 			CStride:        p.Width / 2,
 			SubsampleRatio: image.YCbCrSubsampleRatio422,
 			Rect:           image.Rect(0, 0, p.Width, p.Height),
-		}, nil
+		}, func() {}, nil
 	})
 
 	return r, nil

pkg/frame/compressed.go

@@ -6,6 +6,7 @@ import (
 	"image/jpeg"
 )
 
-func decodeMJPEG(frame []byte, width, height int) (image.Image, error) {
+func decodeMJPEG(frame []byte, width, height int) (image.Image, func(), error) {
-	return jpeg.Decode(bytes.NewReader(frame))
+	img, err := jpeg.Decode(bytes.NewReader(frame))
+	return img, func() {}, err
 }

pkg/frame/frame.go

@@ -3,12 +3,12 @@ package frame
 import "image"
 
 type Decoder interface {
-	Decode(frame []byte, width, height int) (image.Image, error)
+	Decode(frame []byte, width, height int) (image.Image, func(), error)
 }
 
 // DecoderFunc is a proxy type for Decoder
-type decoderFunc func(frame []byte, width, height int) (image.Image, error)
+type decoderFunc func(frame []byte, width, height int) (image.Image, func(), error)
 
-func (f decoderFunc) Decode(frame []byte, width, height int) (image.Image, error) {
+func (f decoderFunc) Decode(frame []byte, width, height int) (image.Image, func(), error) {
 	return f(frame, width, height)
 }

pkg/frame/yuv.go

@@ -5,13 +5,13 @@ import (
 	"image"
 )
 
-func decodeI420(frame []byte, width, height int) (image.Image, error) {
+func decodeI420(frame []byte, width, height int) (image.Image, func(), error) {
 	yi := width * height
 	cbi := yi + width*height/4
 	cri := cbi + width*height/4
 
 	if cri > len(frame) {
-		return nil, fmt.Errorf("frame length (%d) less than expected (%d)", len(frame), cri)
+		return nil, func() {}, fmt.Errorf("frame length (%d) less than expected (%d)", len(frame), cri)
 	}
 
 	return &image.YCbCr{
@@ -22,15 +22,15 @@ func decodeI420(frame []byte, width, height int) (image.Image, error) {
 		CStride:        width / 2,
 		SubsampleRatio: image.YCbCrSubsampleRatio420,
 		Rect:           image.Rect(0, 0, width, height),
-	}, nil
+	}, func() {}, nil
 }
 
-func decodeNV21(frame []byte, width, height int) (image.Image, error) {
+func decodeNV21(frame []byte, width, height int) (image.Image, func(), error) {
 	yi := width * height
 	ci := yi + width*height/2
 
 	if ci > len(frame) {
-		return nil, fmt.Errorf("frame length (%d) less than expected (%d)", len(frame), ci)
+		return nil, func() {}, fmt.Errorf("frame length (%d) less than expected (%d)", len(frame), ci)
 	}
 
 	var cb, cr []byte
@@ -47,5 +47,5 @@ func decodeNV21(frame []byte, width, height int) (image.Image, error) {
 		CStride:        width / 2,
 		SubsampleRatio: image.YCbCrSubsampleRatio420,
 		Rect:           image.Rect(0, 0, width, height),
-	}, nil
+	}, func() {}, nil
 }

pkg/frame/yuv_cgo.go

@@ -12,13 +12,13 @@ import (
 // void decodeUYVYCGO(uint8_t* y, uint8_t* cb, uint8_t* cr, uint8_t* uyvy, int width, int height);
 import "C"
 
-func decodeYUY2(frame []byte, width, height int) (image.Image, error) {
+func decodeYUY2(frame []byte, width, height int) (image.Image, func(), error) {
 	yi := width * height
 	ci := yi / 2
 	fi := yi + 2*ci
 
 	if len(frame) != fi {
-		return nil, fmt.Errorf("frame length (%d) less than expected (%d)", len(frame), fi)
+		return nil, func() {}, fmt.Errorf("frame length (%d) less than expected (%d)", len(frame), fi)
 	}
 
 	y := make([]byte, yi)
@@ -41,16 +41,16 @@ func decodeYUY2(frame []byte, width, height int) (image.Image, error) {
 		CStride:        width / 2,
 		SubsampleRatio: image.YCbCrSubsampleRatio422,
 		Rect:           image.Rect(0, 0, width, height),
-	}, nil
+	}, func() {}, nil
 }
 
-func decodeUYVY(frame []byte, width, height int) (image.Image, error) {
+func decodeUYVY(frame []byte, width, height int) (image.Image, func(), error) {
 	yi := width * height
 	ci := yi / 2
 	fi := yi + 2*ci
 
 	if len(frame) != fi {
-		return nil, fmt.Errorf("frame length (%d) less than expected (%d)", len(frame), fi)
+		return nil, func() {}, fmt.Errorf("frame length (%d) less than expected (%d)", len(frame), fi)
 	}
 
 	y := make([]byte, yi)
@@ -73,5 +73,5 @@ func decodeUYVY(frame []byte, width, height int) (image.Image, error) {
 		CStride:        width / 2,
 		SubsampleRatio: image.YCbCrSubsampleRatio422,
 		Rect:           image.Rect(0, 0, width, height),
-	}, nil
+	}, func() {}, nil
 }

pkg/frame/yuv_nocgo.go

@@ -7,13 +7,13 @@ import (
 	"image"
 )
 
-func decodeYUY2(frame []byte, width, height int) (image.Image, error) {
+func decodeYUY2(frame []byte, width, height int) (image.Image, func(), error) {
 	yi := width * height
 	ci := yi / 2
 	fi := yi + 2*ci
 
 	if len(frame) != fi {
-		return nil, fmt.Errorf("frame length (%d) less than expected (%d)", len(frame), fi)
+		return nil, func() {}, fmt.Errorf("frame length (%d) less than expected (%d)", len(frame), fi)
 	}
 
 	y := make([]byte, yi)
@@ -39,16 +39,16 @@ func decodeYUY2(frame []byte, width, height int) (image.Image, error) {
 		CStride:        width / 2,
 		SubsampleRatio: image.YCbCrSubsampleRatio422,
 		Rect:           image.Rect(0, 0, width, height),
-	}, nil
+	}, func() {}, nil
 }
 
-func decodeUYVY(frame []byte, width, height int) (image.Image, error) {
+func decodeUYVY(frame []byte, width, height int) (image.Image, func(), error) {
 	yi := width * height
 	ci := yi / 2
 	fi := yi + 2*ci
 
 	if len(frame) != fi {
-		return nil, fmt.Errorf("frame length (%d) less than expected (%d)", len(frame), fi)
+		return nil, func() {}, fmt.Errorf("frame length (%d) less than expected (%d)", len(frame), fi)
 	}
 
 	y := make([]byte, yi)
@@ -74,5 +74,5 @@ func decodeUYVY(frame []byte, width, height int) (image.Image, error) {
 		CStride:        width / 2,
 		SubsampleRatio: image.YCbCrSubsampleRatio422,
 		Rect:           image.Rect(0, 0, width, height),
-	}, nil
+	}, func() {}, nil
 }

pkg/frame/yuv_test.go

@@ -27,7 +27,7 @@ func TestDecodeYUY2(t *testing.T) {
 		Rect:           image.Rect(0, 0, width, height),
 	}
 
-	img, err := decodeYUY2(input, width, height)
+	img, _, err := decodeYUY2(input, width, height)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -56,7 +56,7 @@ func TestDecodeUYVY(t *testing.T) {
 		Rect:           image.Rect(0, 0, width, height),
 	}
 
-	img, err := decodeUYVY(input, width, height)
+	img, _, err := decodeUYVY(input, width, height)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -77,7 +77,7 @@ func BenchmarkDecodeYUY2(b *testing.B) {
 		b.Run(fmt.Sprintf("%dx%d", sz.width, sz.height), func(b *testing.B) {
 			input := make([]byte, sz.width*sz.height*2)
 			for i := 0; i < b.N; i++ {
-				_, err := decodeYUY2(input, sz.width, sz.height)
+				_, _, err := decodeYUY2(input, sz.width, sz.height)
 				if err != nil {
 					b.Fatal(err)
 				}

pkg/io/audio/audio.go

@@ -5,13 +5,14 @@ import (
 )
 
 type Reader interface {
-	Read() (wave.Audio, error)
+	Read() (chunk wave.Audio, release func(), err error)
 }
 
-type ReaderFunc func() (wave.Audio, error)
+type ReaderFunc func() (chunk wave.Audio, release func(), err error)
 
-func (rf ReaderFunc) Read() (wave.Audio, error) {
+func (rf ReaderFunc) Read() (chunk wave.Audio, release func(), err error) {
-	return rf()
+	chunk, release, err = rf()
+	return
 }
 
 // TransformFunc produces a new Reader that will produces a transformed audio

pkg/io/audio/broadcast.go

@@ -27,7 +27,7 @@ func NewBroadcaster(source Reader, config *BroadcasterConfig) *Broadcaster {
 		coreConfig = config.Core
 	}
 
-	broadcaster := io.NewBroadcaster(io.ReaderFunc(func() (interface{}, error) {
+	broadcaster := io.NewBroadcaster(io.ReaderFunc(func() (interface{}, func(), error) {
 		return source.Read()
 	}), coreConfig)
 
@@ -51,16 +51,16 @@ func (broadcaster *Broadcaster) NewReader(copyChunk bool) Reader {
 	}
 
 	reader := broadcaster.ioBroadcaster.NewReader(copyFn)
-	return ReaderFunc(func() (wave.Audio, error) {
+	return ReaderFunc(func() (wave.Audio, func(), error) {
-		data, err := reader.Read()
+		data, _, err := reader.Read()
 		chunk, _ := data.(wave.Audio)
-		return chunk, err
+		return chunk, func() {}, err
 	})
 }
 
 // ReplaceSource replaces the underlying source. This operation is thread safe.
 func (broadcaster *Broadcaster) ReplaceSource(source Reader) error {
-	return broadcaster.ioBroadcaster.ReplaceSource(io.ReaderFunc(func() (interface{}, error) {
+	return broadcaster.ioBroadcaster.ReplaceSource(io.ReaderFunc(func() (interface{}, func(), error) {
 		return source.Read()
 	}))
 }
@@ -68,9 +68,9 @@ func (broadcaster *Broadcaster) ReplaceSource(source Reader) error {
 // Source retrieves the underlying source. This operation is thread safe.
 func (broadcaster *Broadcaster) Source() Reader {
 	source := broadcaster.ioBroadcaster.Source()
-	return ReaderFunc(func() (wave.Audio, error) {
+	return ReaderFunc(func() (wave.Audio, func(), error) {
-		data, err := source.Read()
+		data, _, err := source.Read()
 		img, _ := data.(wave.Audio)
-		return img, err
+		return img, func() {}, err
 	})
 }

pkg/io/audio/broadcast_test.go

@@ -14,18 +14,18 @@ func TestBroadcast(t *testing.T) {
 		SamplingRate: 48000,
 	})
 
-	source := ReaderFunc(func() (wave.Audio, error) {
+	source := ReaderFunc(func() (wave.Audio, func(), error) {
-		return chunk, nil
+		return chunk, func() {}, nil
 	})
 
 	broadcaster := NewBroadcaster(source, nil)
 	readerWithoutCopy1 := broadcaster.NewReader(false)
 	readerWithoutCopy2 := broadcaster.NewReader(false)
-	actualWithoutCopy1, err := readerWithoutCopy1.Read()
+	actualWithoutCopy1, _, err := readerWithoutCopy1.Read()
 	if err != nil {
 		t.Fatal(err)
 	}
-	actualWithoutCopy2, err := readerWithoutCopy2.Read()
+	actualWithoutCopy2, _, err := readerWithoutCopy2.Read()
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -39,7 +39,7 @@ func TestBroadcast(t *testing.T) {
 	}
 
 	readerWithCopy := broadcaster.NewReader(true)
-	actualWithCopy, err := readerWithCopy.Read()
+	actualWithCopy, _, err := readerWithCopy.Read()
 	if err != nil {
 		t.Fatal(err)
 	}

pkg/io/audio/buffer.go

@@ -13,15 +13,15 @@ func NewBuffer(nSamples int) TransformFunc {
 	var inBuff wave.Audio
 
 	return func(r Reader) Reader {
-		return ReaderFunc(func() (wave.Audio, error) {
+		return ReaderFunc(func() (wave.Audio, func(), error) {
 			for {
 				if inBuff != nil && inBuff.ChunkInfo().Len >= nSamples {
 					break
 				}
 
-				buff, err := r.Read()
+				buff, _, err := r.Read()
 				if err != nil {
-					return nil, err
+					return nil, func() {}, err
 				}
 				switch b := buff.(type) {
 				case *wave.Float32Interleaved:
@@ -59,7 +59,7 @@ func NewBuffer(nSamples int) TransformFunc {
 					ib.Size.Len += b.Size.Len
 
 				default:
-					return nil, errUnsupported
+					return nil, func() {}, errUnsupported
 				}
 			}
 			switch ib := inBuff.(type) {
@@ -71,7 +71,7 @@ func NewBuffer(nSamples int) TransformFunc {
 				copy(ibCopy.Data, ib.Data)
 				ib.Data = ib.Data[n:]
 				ib.Size.Len -= nSamples
-				return &ibCopy, nil
+				return &ibCopy, func() {}, nil
 
 			case *wave.Float32Interleaved:
 				ibCopy := *ib
@@ -81,9 +81,9 @@ func NewBuffer(nSamples int) TransformFunc {
 				copy(ibCopy.Data, ib.Data)
 				ib.Data = ib.Data[n:]
 				ib.Size.Len -= nSamples
-				return &ibCopy, nil
+				return &ibCopy, func() {}, nil
 			}
-			return nil, errUnsupported
+			return nil, func() {}, errUnsupported
 		})
 	}
 }

pkg/io/audio/buffer_test.go

@@ -49,16 +49,16 @@ func TestBuffer(t *testing.T) {
 	trans := NewBuffer(3)
 
 	var iSent int
-	r := trans(ReaderFunc(func() (wave.Audio, error) {
+	r := trans(ReaderFunc(func() (wave.Audio, func(), error) {
 		if iSent < len(input) {
 			iSent++
-			return input[iSent-1], nil
+			return input[iSent-1], func() {}, nil
 		}
-		return nil, io.EOF
+		return nil, func() {}, io.EOF
 	}))
 
 	for i := 0; ; i++ {
-		a, err := r.Read()
+		a, _, err := r.Read()
 		if err != nil {
 			if err == io.EOF && i >= len(expected) {
 				break

pkg/io/audio/detect.go

@@ -13,12 +13,12 @@ func DetectChanges(interval time.Duration, onChange func(prop.Media)) TransformF
 	return func(r Reader) Reader {
 		var currentProp prop.Media
 		var chunkCount uint
-		return ReaderFunc(func() (wave.Audio, error) {
+		return ReaderFunc(func() (wave.Audio, func(), error) {
 			var dirty bool
 
-			chunk, err := r.Read()
+			chunk, _, err := r.Read()
 			if err != nil {
-				return nil, err
+				return nil, func() {}, err
 			}
 
 			info := chunk.ChunkInfo()
@@ -40,7 +40,7 @@ func DetectChanges(interval time.Duration, onChange func(prop.Media)) TransformF
 			}
 
 			chunkCount++
-			return chunk, nil
+			return chunk, func() {}, nil
 		})
 	}
 }

pkg/io/audio/detect_test.go

@@ -11,12 +11,12 @@ import (
 
 func TestDetectChanges(t *testing.T) {
 	buildSource := func(p prop.Media) (Reader, func(prop.Media)) {
-		return ReaderFunc(func() (wave.Audio, error) {
+		return ReaderFunc(func() (wave.Audio, func(), error) {
 				return wave.NewFloat32Interleaved(wave.ChunkInfo{
 					Len:          0,
 					Channels:     p.ChannelCount,
 					SamplingRate: p.SampleRate,
-				}), nil
+				}), func() {}, nil
 			}), func(newProp prop.Media) {
 				p = newProp
 			}
@@ -34,7 +34,7 @@ func TestDetectChanges(t *testing.T) {
 			detectBeforeFirstChunk = true
 		})(src)
 
-		_, err := src.Read()
+		_, _, err := src.Read()
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -63,7 +63,7 @@ func TestDetectChanges(t *testing.T) {
 				expected.ChannelCount = channelCount
 				expected.SampleRate = sampleRate
 				update(expected)
-				_, err := src.Read()
+				_, _, err := src.Read()
 				if err != nil {
 					t.Fatal(err)
 				}

pkg/io/audio/mixer.go

@@ -8,14 +8,14 @@ import (
 // NewChannelMixer creates audio transform to mix audio channels.
 func NewChannelMixer(channels int, mixer mixer.ChannelMixer) TransformFunc {
 	return func(r Reader) Reader {
-		return ReaderFunc(func() (wave.Audio, error) {
+		return ReaderFunc(func() (wave.Audio, func(), error) {
-			buff, err := r.Read()
+			buff, _, err := r.Read()
 			if err != nil {
-				return nil, err
+				return nil, func() {}, err
 			}
 			ci := buff.ChunkInfo()
 			if ci.Channels == channels {
-				return buff, nil
+				return buff, func() {}, nil
 			}
 
 			ci.Channels = channels
@@ -32,9 +32,9 @@ func NewChannelMixer(channels int, mixer mixer.ChannelMixer) TransformFunc {
 				mixed = wave.NewFloat32NonInterleaved(ci)
 			}
 			if err := mixer.Mix(mixed, buff); err != nil {
-				return nil, err
+				return nil, func() {}, err
 			}
-			return mixed, nil
+			return mixed, func() {}, nil
 		})
 	}
 }

pkg/io/audio/mixer_test.go

@@ -34,16 +34,16 @@ func TestMixer(t *testing.T) {
 	trans := NewChannelMixer(1, &mixer.MonoMixer{})
 
 	var iSent int
-	r := trans(ReaderFunc(func() (wave.Audio, error) {
+	r := trans(ReaderFunc(func() (wave.Audio, func(), error) {
 		if iSent < len(input) {
 			iSent++
-			return input[iSent-1], nil
+			return input[iSent-1], func() {}, nil
 		}
-		return nil, io.EOF
+		return nil, func() {}, io.EOF
 	}))
 
 	for i := 0; ; i++ {
-		a, err := r.Read()
+		a, _, err := r.Read()
 		if err != nil {
 			if err == io.EOF && i >= len(expected) {
 				break

pkg/io/broadcast.go

@@ -127,10 +127,10 @@ func NewBroadcaster(source Reader, config *BroadcasterConfig) *Broadcaster {
 func (broadcaster *Broadcaster) NewReader(copyFn func(interface{}) interface{}) Reader {
 	currentCount := broadcaster.buffer.lastCount()
 
-	return ReaderFunc(func() (data interface{}, err error) {
+	return ReaderFunc(func() (data interface{}, release func(), err error) {
 		currentCount++
 		if push := broadcaster.buffer.acquire(currentCount); push != nil {
-			data, err = broadcaster.source.Load().(Reader).Read()
+			data, _, err = broadcaster.source.Load().(Reader).Read()
 			push(&broadcasterData{
 				data:  data,
 				err:   err,

pkg/io/broadcast_test.go

@@ -57,7 +57,7 @@ func TestBroadcast(t *testing.T) {
 					frameCount := 0
 					frameSent := 0
 					lastSend := time.Now()
-					src = ReaderFunc(func() (interface{}, error) {
+					src = ReaderFunc(func() (interface{}, func(), error) {
 						if pauseCond.src && frameSent == 30 {
 							time.Sleep(time.Second)
 						}
@@ -74,7 +74,7 @@ func TestBroadcast(t *testing.T) {
 						frame := frames[frameCount]
 						frameCount++
 						frameSent++
-						return frame, nil
+						return frame, func() {}, nil
 					})
 					broadcaster := NewBroadcaster(src, nil)
 					var done uint32
@@ -95,7 +95,7 @@ func TestBroadcast(t *testing.T) {
 								if pauseCond.dst && count == 30 {
 									time.Sleep(time.Second)
 								}
-								frame, err := reader.Read()
+								frame, _, err := reader.Read()
 								if err != nil {
 									t.Error(err)
 								}

pkg/io/reader.go

@@ -3,12 +3,13 @@ package io
 // Reader is a generic data reader. In the future, interface{} should be replaced by a generic type
 // to provide strong type.
 type Reader interface {
-	Read() (interface{}, error)
+	Read() (data interface{}, release func(), err error)
 }
 
 // ReaderFunc is a proxy type for Reader
-type ReaderFunc func() (interface{}, error)
+type ReaderFunc func() (data interface{}, release func(), err error)
 
-func (f ReaderFunc) Read() (interface{}, error) {
+func (f ReaderFunc) Read() (data interface{}, release func(), err error) {
-	return f()
+	data, release, err = f()
+	return
 }

pkg/io/video/broadcast.go

@@ -27,7 +27,7 @@ func NewBroadcaster(source Reader, config *BroadcasterConfig) *Broadcaster {
 		coreConfig = config.Core
 	}
 
-	broadcaster := io.NewBroadcaster(io.ReaderFunc(func() (interface{}, error) {
+	broadcaster := io.NewBroadcaster(io.ReaderFunc(func() (interface{}, func(), error) {
 		return source.Read()
 	}), coreConfig)
 
@@ -51,16 +51,16 @@ func (broadcaster *Broadcaster) NewReader(copyFrame bool) Reader {
 	}
 
 	reader := broadcaster.ioBroadcaster.NewReader(copyFn)
-	return ReaderFunc(func() (image.Image, error) {
+	return ReaderFunc(func() (image.Image, func(), error) {
-		data, err := reader.Read()
+		data, _, err := reader.Read()
 		img, _ := data.(image.Image)
-		return img, err
+		return img, func() {}, err
 	})
 }
 
 // ReplaceSource replaces the underlying source. This operation is thread safe.
 func (broadcaster *Broadcaster) ReplaceSource(source Reader) error {
-	return broadcaster.ioBroadcaster.ReplaceSource(io.ReaderFunc(func() (interface{}, error) {
+	return broadcaster.ioBroadcaster.ReplaceSource(io.ReaderFunc(func() (interface{}, func(), error) {
 		return source.Read()
 	}))
 }
@@ -68,9 +68,9 @@ func (broadcaster *Broadcaster) ReplaceSource(source Reader) error {
 // Source retrieves the underlying source. This operation is thread safe.
 func (broadcaster *Broadcaster) Source() Reader {
 	source := broadcaster.ioBroadcaster.Source()
-	return ReaderFunc(func() (image.Image, error) {
+	return ReaderFunc(func() (image.Image, func(), error) {
-		data, err := source.Read()
+		data, _, err := source.Read()
 		img, _ := data.(image.Image)
-		return img, err
+		return img, func() {}, err
 	})
 }

pkg/io/video/broadcast_test.go

@@ -9,18 +9,18 @@ import (
 func TestBroadcast(t *testing.T) {
 	resolution := image.Rect(0, 0, 1920, 1080)
 	img := image.NewGray(resolution)
-	source := ReaderFunc(func() (image.Image, error) {
+	source := ReaderFunc(func() (image.Image, func(), error) {
-		return img, nil
+		return img, func() {}, nil
 	})
 
 	broadcaster := NewBroadcaster(source, nil)
 	readerWithoutCopy1 := broadcaster.NewReader(false)
 	readerWithoutCopy2 := broadcaster.NewReader(false)
-	actualWithoutCopy1, err := readerWithoutCopy1.Read()
+	actualWithoutCopy1, _, err := readerWithoutCopy1.Read()
 	if err != nil {
 		t.Fatal(err)
 	}
-	actualWithoutCopy2, err := readerWithoutCopy2.Read()
+	actualWithoutCopy2, _, err := readerWithoutCopy2.Read()
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -34,7 +34,7 @@ func TestBroadcast(t *testing.T) {
 	}
 
 	readerWithCopy := broadcaster.NewReader(true)
-	actualWithCopy, err := readerWithCopy.Read()
+	actualWithCopy, _, err := readerWithCopy.Read()
 	if err != nil {
 		t.Fatal(err)
 	}

pkg/io/video/convert.go

@@ -63,10 +63,10 @@ func imageToYCbCr(dst *image.YCbCr, src image.Image) {
 // ToI420 converts r to a new reader that will output images in I420 format
 func ToI420(r Reader) Reader {
 	var yuvImg image.YCbCr
-	return ReaderFunc(func() (image.Image, error) {
+	return ReaderFunc(func() (image.Image, func(), error) {
-		img, err := r.Read()
+		img, _, err := r.Read()
 		if err != nil {
-			return nil, err
+			return nil, func() {}, err
 		}
 
 		imageToYCbCr(&yuvImg, img)
@@ -79,11 +79,11 @@ func ToI420(r Reader) Reader {
 			i422ToI420(&yuvImg)
 		case image.YCbCrSubsampleRatio420:
 		default:
-			return nil, fmt.Errorf("unsupported pixel format: %s", yuvImg.SubsampleRatio)
+			return nil, func() {}, fmt.Errorf("unsupported pixel format: %s", yuvImg.SubsampleRatio)
 		}
 
 		yuvImg.SubsampleRatio = image.YCbCrSubsampleRatio420
-		return &yuvImg, nil
+		return &yuvImg, func() {}, nil
 	})
 }
 
@@ -130,13 +130,13 @@ func imageToRGBA(dst *image.RGBA, src image.Image) {
 // ToRGBA converts r to a new reader that will output images in RGBA format
 func ToRGBA(r Reader) Reader {
 	var dst image.RGBA
-	return ReaderFunc(func() (image.Image, error) {
+	return ReaderFunc(func() (image.Image, func(), error) {
-		img, err := r.Read()
+		img, _, err := r.Read()
 		if err != nil {
-			return nil, err
+			return nil, func() {}, err
 		}
 
 		imageToRGBA(&dst, img)
-		return &dst, nil
+		return &dst, func() {}, nil
 	})
 }

pkg/io/video/convert_test.go

@@ -144,10 +144,10 @@ func TestToI420(t *testing.T) {
 	for name, c := range cases {
 		c := c
 		t.Run(name, func(t *testing.T) {
-			r := ToI420(ReaderFunc(func() (image.Image, error) {
+			r := ToI420(ReaderFunc(func() (image.Image, func(), error) {
-				return c.src, nil
+				return c.src, func() {}, nil
 			}))
-			out, err := r.Read()
+			out, _, err := r.Read()
 			if err != nil {
 				t.Fatalf("Unexpected error: %v", err)
 			}
@@ -199,10 +199,10 @@ func TestToRGBA(t *testing.T) {
 	for name, c := range cases {
 		c := c
 		t.Run(name, func(t *testing.T) {
-			r := ToRGBA(ReaderFunc(func() (image.Image, error) {
+			r := ToRGBA(ReaderFunc(func() (image.Image, func(), error) {
-				return c.src, nil
+				return c.src, func() {}, nil
 			}))
-			out, err := r.Read()
+			out, _, err := r.Read()
 			if err != nil {
 				t.Fatalf("Unexpected error: %v", err)
 			}
@@ -225,12 +225,12 @@ func BenchmarkToI420(b *testing.B) {
 			for name, img := range cases {
 				img := img
 				b.Run(name, func(b *testing.B) {
-					r := ToI420(ReaderFunc(func() (image.Image, error) {
+					r := ToI420(ReaderFunc(func() (image.Image, func(), error) {
-						return img, nil
+						return img, func() {}, nil
 					}))
 
 					for i := 0; i < b.N; i++ {
-						_, err := r.Read()
+						_, _, err := r.Read()
 						if err != nil {
 							b.Fatalf("Unexpected error: %v", err)
 						}
@@ -253,12 +253,12 @@ func BenchmarkToRGBA(b *testing.B) {
 			for name, img := range cases {
 				img := img
 				b.Run(name, func(b *testing.B) {
-					r := ToRGBA(ReaderFunc(func() (image.Image, error) {
+					r := ToRGBA(ReaderFunc(func() (image.Image, func(), error) {
-						return img, nil
+						return img, func() {}, nil
 					}))
 
 					for i := 0; i < b.N; i++ {
-						_, err := r.Read()
+						_, _, err := r.Read()
 						if err != nil {
 							b.Fatalf("Unexpected error: %v", err)
 						}

pkg/io/video/detect.go

@@ -14,12 +14,12 @@ func DetectChanges(interval time.Duration, onChange func(prop.Media)) TransformF
 		var currentProp prop.Media
 		var lastTaken time.Time
 		var frames uint
-		return ReaderFunc(func() (image.Image, error) {
+		return ReaderFunc(func() (image.Image, func(), error) {
 			var dirty bool
 
-			img, err := r.Read()
+			img, _, err := r.Read()
 			if err != nil {
-				return nil, err
+				return nil, func() {}, err
 			}
 
 			bounds := img.Bounds()
@@ -52,7 +52,7 @@ func DetectChanges(interval time.Duration, onChange func(prop.Media)) TransformF
 			}
 
 			frames++
-			return img, nil
+			return img, func() {}, nil
 		})
 	}
 }

pkg/io/video/detect_test.go

@@ -12,8 +12,8 @@ import (
 
 func BenchmarkDetectChanges(b *testing.B) {
 	var src Reader
-	src = ReaderFunc(func() (image.Image, error) {
+	src = ReaderFunc(func() (image.Image, func(), error) {
-		return image.NewRGBA(image.Rect(0, 0, 1920, 1080)), nil
+		return image.NewRGBA(image.Rect(0, 0, 1920, 1080)), func() {}, nil
 	})
 
 	b.Run("WithoutDetectChanges", func(b *testing.B) {
@@ -40,8 +40,8 @@ func BenchmarkDetectChanges(b *testing.B) {
 
 func TestDetectChanges(t *testing.T) {
 	buildSource := func(p prop.Media) (Reader, func(prop.Media)) {
-		return ReaderFunc(func() (image.Image, error) {
+		return ReaderFunc(func() (image.Image, func(), error) {
-				return image.NewRGBA(image.Rect(0, 0, p.Width, p.Height)), nil
+				return image.NewRGBA(image.Rect(0, 0, p.Width, p.Height)), func() {}, nil
 			}), func(newProp prop.Media) {
 				p = newProp
 			}
@@ -86,7 +86,7 @@ func TestDetectChanges(t *testing.T) {
 			detectBeforeFirstFrame = true
 		})(src)
 
-		frame, err := src.Read()
+		frame, _, err := src.Read()
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -113,7 +113,7 @@ func TestDetectChanges(t *testing.T) {
 				expected.Width = width
 				expected.Height = height
 				update(expected)
-				frame, err := src.Read()
+				frame, _, err := src.Read()
 				if err != nil {
 					t.Fatal(err)
 				}
@@ -143,7 +143,7 @@ func TestDetectChanges(t *testing.T) {
 		})(src)
 
 		for count < 3 {
-			frame, err := src.Read()
+			frame, _, err := src.Read()
 			if err != nil {
 				t.Fatal(err)
 			}

pkg/io/video/scale.go

@@ -156,10 +156,10 @@ func Scale(width, height int, scaler Scaler) TransformFunc {
 			}
 		}
 
-		return ReaderFunc(func() (image.Image, error) {
+		return ReaderFunc(func() (image.Image, func(), error) {
-			img, err := r.Read()
+			img, _, err := r.Read()
 			if err != nil {
-				return nil, err
+				return nil, func() {}, err
 			}
 
 			switch v := img.(type) {
@@ -169,7 +169,7 @@ func Scale(width, height int, scaler Scaler) TransformFunc {
 				scalerCached.Scale(dst, rect, v, v.Rect, draw.Src, nil)
 
 				cloned := *dst // clone metadata
-				return &cloned, nil
+				return &cloned, func() {}, nil
 
 			case *image.YCbCr:
 				ycbcrRealloc(v)
@@ -184,10 +184,10 @@ func Scale(width, height int, scaler Scaler) TransformFunc {
 				scalerCached.Scale(dst, dst.Bounds(), src, src.Bounds(), draw.Src, nil)
 
 				cloned := *(imgScaled.(*image.YCbCr)) // clone metadata
-				return &cloned, nil
+				return &cloned, func() {}, nil
 
 			default:
-				return nil, errUnsupportedImageType
+				return nil, func() {}, errUnsupportedImageType
 			}
 		})
 	}

pkg/io/video/scale_test.go

@@ -215,11 +215,11 @@ func TestScale(t *testing.T) {
 				c := c
 				t.Run(name, func(t *testing.T) {
 					trans := Scale(c.width, c.height, algo)
-					r := trans(ReaderFunc(func() (image.Image, error) {
+					r := trans(ReaderFunc(func() (image.Image, func(), error) {
-						return c.src, nil
+						return c.src, func() {}, nil
 					}))
 					for i := 0; i < 4; i++ {
-						out, err := r.Read()
+						out, _, err := r.Read()
 						if err != nil {
 							t.Fatalf("Unexpected error: %v", err)
 						}
@@ -261,12 +261,12 @@ func BenchmarkScale(b *testing.B) {
 						img := img
 						b.Run(name, func(b *testing.B) {
 							trans := Scale(640, 360, algo)
-							r := trans(ReaderFunc(func() (image.Image, error) {
+							r := trans(ReaderFunc(func() (image.Image, func(), error) {
-								return img, nil
+								return img, func() {}, nil
 							}))
 
 							for i := 0; i < b.N; i++ {
-								_, err := r.Read()
+								_, _, err := r.Read()
 								if err != nil {
 									b.Fatalf("Unexpected error: %v", err)
 								}

pkg/io/video/throttle.go

@@ -10,16 +10,16 @@ import (
 func Throttle(rate float32) TransformFunc {
 	return func(r Reader) Reader {
 		ticker := time.NewTicker(time.Duration(int64(float64(time.Second) / float64(rate))))
-		return ReaderFunc(func() (image.Image, error) {
+		return ReaderFunc(func() (image.Image, func(), error) {
 			for {
-				img, err := r.Read()
+				img, _, err := r.Read()
 				if err != nil {
 					ticker.Stop()
-					return nil, err
+					return nil, func() {}, err
 				}
 				select {
 				case <-ticker.C:
-					return img, nil
+					return img, func() {}, nil
 				default:
 				}
 			}

pkg/io/video/throttle_test.go

@@ -19,14 +19,14 @@ func TestThrottle(t *testing.T) {
 
 	var cntPush int
 	trans := Throttle(50)
-	r := trans(ReaderFunc(func() (image.Image, error) {
+	r := trans(ReaderFunc(func() (image.Image, func(), error) {
 		<-ticker.C
 		cntPush++
-		return img, nil
+		return img, func() {}, nil
 	}))
 
 	for i := 0; i < 20; i++ {
-		_, err := r.Read()
+		_, _, err := r.Read()
 		if err != nil {
 			t.Fatalf("Unexpected error: %v", err)
 		}

pkg/io/video/video.go

@@ -5,13 +5,14 @@ import (
 )
 
 type Reader interface {
-	Read() (img image.Image, err error)
+	Read() (img image.Image, release func(), err error)
 }
 
-type ReaderFunc func() (img image.Image, err error)
+type ReaderFunc func() (img image.Image, release func(), err error)
 
-func (rf ReaderFunc) Read() (img image.Image, err error) {
+func (rf ReaderFunc) Read() (img image.Image, release func(), err error) {
-	return rf()
+	img, release, err = rf()
+	return
 }
 
 // TransformFunc produces a new Reader that will produces a transformed video

track.go

@@ -160,7 +160,7 @@ func (t *track) onError(err error) {
 // start starts the data flow from the driver all the way to the localTrack
 func (t *track) start() {
 	for {
-		buff, err := t.encoder.Read()
+		buff, _, err := t.encoder.Read()
 		if err != nil {
 			t.onError(err)
 			return