Implements RequireKeyFrame for VPX codec (#334)

pkg/codec/vpx/params.go

@@ -16,6 +16,7 @@ type Params struct {
 	RateControlOvershootPercent  uint
 	RateControlMinQuantizer      uint
 	RateControlMaxQuantizer      uint
+	LagInFrames                  uint
 	ErrorResilient               ErrorResilientMode
 }
 

pkg/codec/vpx/vpx.go

@@ -23,6 +23,9 @@ package vpx
 // int pktSz(vpx_codec_cx_pkt_t *pkt) {
 //   return pkt->data.frame.sz;
 // }
+// vpx_codec_frame_flags_t pktFrameFlags(vpx_codec_cx_pkt_t *pkt) {
+//   return pkt->data.frame.flags;
+// }
 //
 // // Alloc helpers
 // vpx_codec_ctx_t *newCtx() {
@@ -70,6 +73,8 @@ type encoder struct {
 	tLastFrame      int
 	frame           []byte
 	deadline        int
+	requireKeyFrame bool
+	isKeyFrame      bool
 
 	mu     sync.Mutex
 	closed bool
@@ -141,6 +146,7 @@ func newParams(codecIface *C.vpx_codec_iface_t) (Params, error) {
 		RateControlOvershootPercent:  uint(cfg.rc_overshoot_pct),
 		RateControlMinQuantizer:      uint(cfg.rc_min_quantizer),
 		RateControlMaxQuantizer:      uint(cfg.rc_max_quantizer),
+		LagInFrames:                  uint(cfg.g_lag_in_frames),
 		ErrorResilient:               ErrorResilientMode(cfg.g_error_resilient),
 	}, nil
 }
@@ -171,6 +177,7 @@ func newEncoder(r video.Reader, p prop.Media, params Params, codecIface *C.vpx_c
 	cfg.g_h = C.uint(p.Height)
 	cfg.g_timebase.num = 1
 	cfg.g_timebase.den = 1000
+	cfg.g_lag_in_frames = C.uint(params.LagInFrames)
 	cfg.rc_target_bitrate = C.uint(params.BitRate) / 1000
 	cfg.kf_max_dist = C.uint(params.KeyFrameInterval)
 
@@ -254,6 +261,9 @@ func (e *encoder) Read() ([]byte, func(), error) {
 		duration = 1
 	}
 	var flags int
+	if e.requireKeyFrame {
+		flags = flags | C.VPX_EFLAG_FORCE_KF
+	}
 	if ec := C.encode_wrapper(
 		e.codec, e.raw,
 		C.long(t-e.tStart), C.ulong(duration), C.long(flags), C.ulong(e.deadline),
@@ -262,6 +272,7 @@ func (e *encoder) Read() ([]byte, func(), error) {
 		return nil, func() {}, fmt.Errorf("vpx_codec_encode failed (%d)", ec)
 	}
 
+	e.requireKeyFrame = false
 	e.frameIndex++
 	e.tLastFrame = t
 
@@ -273,6 +284,7 @@ func (e *encoder) Read() ([]byte, func(), error) {
 			break
 		}
 		if pkt.kind == C.VPX_CODEC_CX_FRAME_PKT {
+			e.isKeyFrame = C.pktFrameFlags(pkt)&C.VPX_FRAME_IS_KEY == C.VPX_FRAME_IS_KEY
 			encoded := C.GoBytes(unsafe.Pointer(C.pktBuf(pkt)), C.pktSz(pkt))
 			e.frame = append(e.frame, encoded...)
 		}
@@ -288,7 +300,10 @@ func (e *encoder) SetBitRate(b int) error {
 }
 
 func (e *encoder) ForceKeyFrame() error {
-	panic("ForceKeyFrame is not implemented")
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	e.requireKeyFrame = true
+	return nil
 }
 
 func (e *encoder) Close() error {

pkg/codec/vpx/vpx_test.go

@@ -20,6 +20,8 @@ func TestImageSizeChange(t *testing.T) {
 		},
 		"VP9": func() (codec.VideoEncoderBuilder, error) {
 			p, err := NewVP9Params()
+			// Disable latency to ease test and begin to receive packets for each input frame
+			p.LagInFrames = 0
 			return &p, err
 		},
 	} {
@@ -87,3 +89,72 @@ func TestImageSizeChange(t *testing.T) {
 		})
 	}
 }
+
+func TestRequestKeyFrame(t *testing.T) {
+	for name, factory := range map[string]func() (codec.VideoEncoderBuilder, error){
+		"VP8": func() (codec.VideoEncoderBuilder, error) {
+			p, err := NewVP8Params()
+			return &p, err
+		},
+		"VP9": func() (codec.VideoEncoderBuilder, error) {
+			p, err := NewVP9Params()
+			// Disable latency to ease test and begin to receive packets for each input frame
+			p.LagInFrames = 0
+			return &p, err
+		},
+	} {
+		factory := factory
+		t.Run(name, func(t *testing.T) {
+			param, err := factory()
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			var initialWidth, initialHeight, width, height int = 320, 240, 320, 240
+
+			var cnt uint32
+			r, err := param.BuildVideoEncoder(
+				video.ReaderFunc(func() (image.Image, func(), error) {
+					i := atomic.AddUint32(&cnt, 1)
+					if i == 3 {
+						return nil, nil, io.EOF
+					}
+					return image.NewYCbCr(
+						image.Rect(0, 0, width, height),
+						image.YCbCrSubsampleRatio420,
+					), func() {}, nil
+				}),
+				prop.Media{
+					Video: prop.Video{
+						Width:       initialWidth,
+						Height:      initialHeight,
+						FrameRate:   1,
+						FrameFormat: frame.FormatI420,
+					},
+				},
+			)
+			if err != nil {
+				t.Fatal(err)
+			}
+			_, rel, err := r.Read()
+			if err != nil {
+				t.Fatal(err)
+			}
+			rel()
+			r.ForceKeyFrame()
+			_, rel, err = r.Read()
+			if err != nil {
+				t.Fatal(err)
+			}
+			if !r.(*encoder).isKeyFrame {
+				t.Fatal("Not a key frame")
+			}
+			rel()
+			_, _, err = r.Read()
+			if err != io.EOF {
+				t.Fatal(err)
+			}
+		})
+
+	}
+}