Update module pion/rtp to v1.6.2 (#265)

Generated by Renovate Bot

Co-authored-by: Renovate Bot <bot@renovateapp.com>

.gitattributes

@@ -1 +0,0 @@
-*.gif filter=lfs diff=lfs merge=lfs -text

.github/workflows/ci.yaml

@@ -11,6 +11,7 @@ jobs:
   build-linux:
     runs-on: ubuntu-latest
     strategy:
+      fail-fast: false
       matrix:
         go: [ '1.15', '1.14' ]
     name: Linux Go ${{ matrix.go }}
@@ -48,6 +49,7 @@ jobs:
   build-darwin:
     runs-on: macos-latest
     strategy:
+      fail-fast: false
       matrix:
         go: [ '1.15', '1.14' ]
     name: Darwin Go ${{ matrix.go }}

README.md

@@ -15,8 +15,6 @@
 
 `mediadevices` provides access to media input devices like cameras, microphones, and screen capture. It can also be used to encode your video/audio stream to various codec selections. `mediadevices` abstracts away the complexities of interacting with things like hardware and codecs allowing you to focus on building appilcations, interacting only with an amazingly simple, easy, and elegant API!
 
-![](img/demo.gif)
-
 ## Install
 
 `go get -u github.com/pion/mediadevices`
@@ -87,7 +85,7 @@ func main() {
 | :--------: | :---: | :-: | :-----: |
 |   Camera   |  ✔️   | ✔️  |   ✔️    |
 | Microphone |  ✔️   | ✔️  |   ✔️    |
-|   Screen   |  ✔️   | ✖️  |   ✖️    |
+|   Screen   |  ✔️   | ✔️  |   ✔️    |
 
 By default, there's no media input registered. This decision was made to allow you to pay what you need. Therefore, you need to import the associated packages for the media inputs. For example, if you want to use a camera, you need to import the camera package as a side effect:
 
@@ -146,8 +144,7 @@ A free software library and application for encoding video streams into the H.26
 A framework to enable H264 hardware encoding for Raspberry Pi or boards that use VideoCore GPUs.
 
 * Package: [github.com/pion/mediadevices/pkg/codec/mmal](https://pkg.go.dev/github.com/pion/mediadevices/pkg/codec/mmal)
-* Installation:
-  * Raspbian: `export PKG_CONFIG_PATH=/opt/vc/lib/pkgconfig`
+* Installation: no installation needed, mmal should come built in Raspberry Pi devices
 
 #### openh264
 A codec library which supports H.264 encoding and decoding. It is suitable for use in real time applications.

examples/archive/README.md

@@ -18,6 +18,8 @@ git clone https://github.com/pion/mediadevices.git
 
 Run `cd mediadevices/examples/archive && go build && ./archive recorded.h264`
 
+To stop recording, press `Ctrl+c` or send a SIGINT signal.
+
 ### Playback recorded video
 
 Install GStreamer and run:

examples/rtp/README.md

@@ -2,17 +2,16 @@
 
 ### Install required codecs
 
-In this example, we'll be using x264 and opus as our video and audio codecs. Therefore, we need to make sure that these codecs are installed within our system. 
+In this example, we'll be using x264 as our video codec. Therefore, we need to make sure that these codecs are installed within our system. 
 
 Installation steps:
 
 * [x264](https://github.com/pion/mediadevices#x264)
-* [opus](https://github.com/pion/mediadevices#opus)
 
-### Download rtpexample
+### Download rtp example
 
 ```
-go get github.com/pion/mediadevices/examples/rtp
+git clone https://github.com/pion/mediadevices.git
 ```
 
 ### Listen RTP
@@ -30,7 +29,7 @@ vlc ./h264.sdp
 
 ### Run rtp
 
-Run `rtp localhost:5000`
+Run `cd mediadevices/examples/archive && go build && ./rtp localhost:5000`
 
 A video should start playing in your GStreamer or VLC window.
 It's not WebRTC, but pure RTP.

go.mod

@@ -3,11 +3,15 @@ module github.com/pion/mediadevices
 go 1.13
 
 require (
+	github.com/BurntSushi/xgb v0.0.0-20201008132610-5f9e7b3c49cd // indirect
 	github.com/blackjack/webcam v0.0.0-20200313125108-10ed912a8539
-	github.com/gen2brain/malgo v0.10.19
+	github.com/gen2brain/malgo v0.10.27
+	github.com/gen2brain/shm v0.0.0-20200228170931-49f9650110c5 // indirect
+	github.com/kbinani/screenshot v0.0.0-20191211154542-3a185f1ce18f
 	github.com/lherman-cs/opus v0.0.2
+	github.com/lxn/win v0.0.0-20201111105847-2a20daff6a55 // indirect
 	github.com/pion/logging v0.2.2
-	github.com/pion/rtp v1.6.0
+	github.com/pion/rtp v1.6.2
 	github.com/pion/webrtc/v2 v2.2.26
 	github.com/satori/go.uuid v1.2.0
 	golang.org/x/image v0.0.0-20200927104501-e162460cd6b5

go.sum

@@ -1,3 +1,5 @@
+github.com/BurntSushi/xgb v0.0.0-20201008132610-5f9e7b3c49cd h1:u7K2oMFMd8APDV3fM1j2rO3U/XJf1g1qC3DDTKou8iM=
+github.com/BurntSushi/xgb v0.0.0-20201008132610-5f9e7b3c49cd/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
 github.com/blackjack/webcam v0.0.0-20200313125108-10ed912a8539 h1:1aIqYfg9s9RETAJHGfVKZW4ok0b22p4QTwk8MsdRtPs=
 github.com/blackjack/webcam v0.0.0-20200313125108-10ed912a8539/go.mod h1:G0X+rEqYPWSq0dG8OMf8M446MtKytzpPjgS3HbdOJZ4=
 github.com/cheekybits/genny v1.0.0 h1:uGGa4nei+j20rOSeDeP5Of12XVm7TGUd4dJA9RDitfE=
@@ -7,8 +9,10 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/fsnotify/fsnotify v1.4.7 h1:IXs+QLmnXW2CcXuY+8Mzv/fWEsPGWxqefPtCP5CnV9I=
 github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
-github.com/gen2brain/malgo v0.10.19 h1:IUVF6WdVV7Txt47Kx2ajz0rWQ0MU0zO+tbcKmhva7l8=
-github.com/gen2brain/malgo v0.10.19/go.mod h1:zHSUNZAXfCeNsZou0RtQ6Zk7gDYLIcKOrUWtAdksnEs=
+github.com/gen2brain/malgo v0.10.27 h1:KlNitZIO8V4W2VnjtTM8AGMy/XBb2pN+fnIB5bEps8E=
+github.com/gen2brain/malgo v0.10.27/go.mod h1:zHSUNZAXfCeNsZou0RtQ6Zk7gDYLIcKOrUWtAdksnEs=
+github.com/gen2brain/shm v0.0.0-20200228170931-49f9650110c5 h1:Y5Q2mEwfzjMt5+3u70Gtw93ZOu2UuPeeeTBDntF7FoY=
+github.com/gen2brain/shm v0.0.0-20200228170931-49f9650110c5/go.mod h1:uF6rMu/1nvu+5DpiRLwusA6xB8zlkNoGzKn8lmYONUo=
 github.com/golang/mock v1.2.0 h1:28o5sBqPkBsMGnC6b4MvE2TzSr5/AT4c/1fLqVGIwlk=
 github.com/golang/mock v1.2.0/go.mod h1:oTYuIxOrZwtPieC+H1uAHpcLFnEyAGVDL/k47Jfbm0A=
 github.com/golang/protobuf v1.2.0 h1:P3YflyNX/ehuJFLhxviNdFxQPkGK5cDcApsge1SqnvM=
@@ -17,6 +21,8 @@ github.com/google/uuid v1.1.1 h1:Gkbcsh/GbpXz7lPftLA3P6TYMwjCLYm83jiFQZF/3gY=
 github.com/google/uuid v1.1.1/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/hpcloud/tail v1.0.0 h1:nfCOvKYfkgYP8hkirhJocXT2+zOD8yUNjXaWfTlyFKI=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
+github.com/kbinani/screenshot v0.0.0-20191211154542-3a185f1ce18f h1:5hWo+DzJQSOBl6X+TDac0SPWffRonuRJ2///OYtYRT8=
+github.com/kbinani/screenshot v0.0.0-20191211154542-3a185f1ce18f/go.mod h1:f8GY5V3lRzakvEyr49P7hHRYoHtPr8zvj/7JodCoRzw=
 github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
@@ -26,6 +32,8 @@ github.com/lherman-cs/opus v0.0.2 h1:fE9Du3NKXDBztqvoTd6P2y9eJ9vgIHahGK8yQostnhA
 github.com/lherman-cs/opus v0.0.2/go.mod h1:v9KQvlDYMuvlwniumBVMlrB0VHQvyTgxNvaXjPmTmps=
 github.com/lucas-clemente/quic-go v0.7.1-0.20190401152353-907071221cf9 h1:tbuodUh2vuhOVZAdW3NEUvosFHUMJwUNl7jk/VSEiwc=
 github.com/lucas-clemente/quic-go v0.7.1-0.20190401152353-907071221cf9/go.mod h1:PpMmPfPKO9nKJ/psF49ESTAGQSdfXxlg1otPbEB2nOw=
+github.com/lxn/win v0.0.0-20201111105847-2a20daff6a55 h1:4BxFx5XCtXc+nFtXDGDW+Uu5sPtsAbvPh6RObj3fG9o=
+github.com/lxn/win v0.0.0-20201111105847-2a20daff6a55/go.mod h1:KxxjdtRkfNoYDCUP5ryK7XJJNTnpC8atvtmTheChOtk=
 github.com/marten-seemann/qtls v0.2.3 h1:0yWJ43C62LsZt08vuQJDK1uC1czUc3FJeCLPoNAI4vA=
 github.com/marten-seemann/qtls v0.2.3/go.mod h1:xzjG7avBwGGbdZ8dTGxlBnLArsVKLvwmjgmPuiQEcYk=
 github.com/onsi/ginkgo v1.6.0/go.mod h1:lLunBs/Ym6LB5Z9jYTR76FiuTmxDTDusOGeTQH+WWjE=
@@ -53,6 +61,8 @@ github.com/pion/rtcp v1.2.3 h1:2wrhKnqgSz91Q5nzYTO07mQXztYPtxL8a0XOss4rJqA=
 github.com/pion/rtcp v1.2.3/go.mod h1:zGhIv0RPRF0Z1Wiij22pUt5W/c9fevqSzT4jje/oK7I=
 github.com/pion/rtp v1.6.0 h1:4Ssnl/T5W2LzxHj9ssYpGVEQh3YYhQFNVmSWO88MMwk=
 github.com/pion/rtp v1.6.0/go.mod h1:QgfogHsMBVE/RFNno467U/KBqfUywEH+HK+0rtnwsdI=
+github.com/pion/rtp v1.6.2 h1:iGBerLX6JiDjB9NXuaPzHyxHFG9JsIEdgwTC0lp5n/U=
+github.com/pion/rtp v1.6.2/go.mod h1:bDb5n+BFZxXx0Ea7E5qe+klMuqiBrP+w8XSjiWtCUko=
 github.com/pion/sctp v1.7.10 h1:o3p3/hZB5Cx12RMGyWmItevJtZ6o2cpuxaw6GOS4x+8=
 github.com/pion/sctp v1.7.10/go.mod h1:EhpTUQu1/lcK3xI+eriS6/96fWetHGCvBi9MSsnaBN0=
 github.com/pion/sdp/v2 v2.4.0 h1:luUtaETR5x2KNNpvEMv/r4Y+/kzImzbz4Lm1z8eQNQI=
@@ -109,6 +119,7 @@ golang.org/x/sys v0.0.0-20190228124157-a34e9553db1e/go.mod h1:STP8DvDyc/dI5b8T5h
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200724161237-0e2f3a69832c/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20201018230417-eeed37f84f13/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20201029080932-201ba4db2418 h1:HlFl4V6pEMziuLXyRkm5BIYq1y1GAbb02pRlWvI54OM=
 golang.org/x/sys v0.0.0-20201029080932-201ba4db2418/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=

internal/codec/measurement_test.go

@@ -2,12 +2,18 @@ package codec
 
 import (
 	"io"
+	"runtime"
 	"sync"
 	"testing"
 	"time"
 )
 
 func TestMeasureBitRateStatic(t *testing.T) {
+	// https://github.com/pion/mediadevices/issues/198
+	if runtime.GOOS == "darwin" {
+		t.Skip("Skipping because Darwin CI is not reliable for timing related tests.")
+	}
+
 	r, w := io.Pipe()
 	const (
 		dataSize       = 1000
@@ -54,6 +60,11 @@ func TestMeasureBitRateStatic(t *testing.T) {
 }
 
 func TestMeasureBitRateDynamic(t *testing.T) {
+	// https://github.com/pion/mediadevices/issues/198
+	if runtime.GOOS == "darwin" {
+		t.Skip("Skipping because Darwin CI is not reliable for timing related tests.")
+	}
+
 	r, w := io.Pipe()
 	const (
 		dataSize       = 1000

ioreader.go

@@ -1,14 +1,61 @@
 package mediadevices
 
+type EncodedBuffer struct {
+	Data    []byte
+	Samples uint32
+}
+
+type EncodedReadCloser interface {
+	Read() (EncodedBuffer, func(), error)
+	Close() error
+}
+
 type encodedReadCloserImpl struct {
-	readFn  func([]byte) (int, error)
+	readFn  func() (EncodedBuffer, func(), error)
 	closeFn func() error
 }
 
-func (r *encodedReadCloserImpl) Read(b []byte) (int, error) {
-	return r.readFn(b)
+func (r *encodedReadCloserImpl) Read() (EncodedBuffer, func(), error) {
+	return r.readFn()
 }
 
 func (r *encodedReadCloserImpl) Close() error {
 	return r.closeFn()
 }
+
+type encodedIOReadCloserImpl struct {
+	readFn  func([]byte) (int, error)
+	closeFn func() error
+}
+
+func newEncodedIOReadCloserImpl(reader EncodedReadCloser) *encodedIOReadCloserImpl {
+	var encoded EncodedBuffer
+	release := func() {}
+	return &encodedIOReadCloserImpl{
+		readFn: func(b []byte) (int, error) {
+			var err error
+
+			if len(encoded.Data) == 0 {
+				release()
+				encoded, release, err = reader.Read()
+				if err != nil {
+					reader.Close()
+					return 0, err
+				}
+			}
+
+			n := copy(b, encoded.Data)
+			encoded.Data = encoded.Data[n:]
+			return n, nil
+		},
+		closeFn: reader.Close,
+	}
+}
+
+func (r *encodedIOReadCloserImpl) Read(b []byte) (int, error) {
+	return r.readFn(b)
+}
+
+func (r *encodedIOReadCloserImpl) Close() error {
+	return r.closeFn()
+}

mediastream_test.go

@@ -38,7 +38,11 @@ func (track *mockMediaStreamTrack) NewRTPReader(codecName string, mtu int) (RTPR
 	return nil, nil
 }
 
-func (track *mockMediaStreamTrack) NewEncodedReader(codecName string) (io.ReadCloser, error) {
+func (track *mockMediaStreamTrack) NewEncodedReader(codecName string) (EncodedReadCloser, error) {
+	return nil, nil
+}
+
+func (track *mockMediaStreamTrack) NewEncodedIOReader(codecName string) (io.ReadCloser, error) {
 	return nil, nil
 }
 

meta.go

@@ -14,7 +14,7 @@ func detectCurrentVideoProp(broadcaster *video.Broadcaster) (prop.Media, error)
 	// buffered frame or a new frame from the source. This also implies that no frame will be lost
 	// in any case.
 	metaReader := broadcaster.NewReader(false)
-	metaReader = video.DetectChanges(0, func(p prop.Media) { currentProp = p })(metaReader)
+	metaReader = video.DetectChanges(0, 0, func(p prop.Media) { currentProp = p })(metaReader)
 	_, _, err := metaReader.Read()
 
 	return currentProp, err

pkg/codec/mmal/mmal.go

@@ -3,7 +3,8 @@
 // Reference: https://github.com/raspberrypi/userland/tree/master/interface/mmal
 package mmal
 
-// #cgo pkg-config: mmal
+// #cgo CFLAGS: -I/opt/vc/include
+// #cgo LDFLAGS: -L/opt/vc/lib -lmmal -lmmal_core -lmmal_util -lmmal_vc_client -lbcm_host -lvcsm -lvcos
 // #include "bridge.h"
 import "C"
 import (

pkg/codec/x264/bridge.h

@@ -16,7 +16,7 @@ typedef struct Slice {
 
 typedef struct Encoder {
   x264_t *h;
-  x264_picture_t pic_in, pic_out;
+  x264_picture_t pic_in;
   x264_param_t param;
 } Encoder;
 
@@ -52,15 +52,21 @@ Encoder *enc_new(x264_param_t param, char *preset, int *rc) {
     goto fail;
   }
 
-  if (x264_picture_alloc(&e->pic_in, param.i_csp, param.i_width, param.i_height) < 0) {
+  x264_picture_t pic_in;
+  if (x264_picture_alloc(&pic_in, param.i_csp, param.i_width, param.i_height) < 0) {
     *rc = ERR_ALLOC_PICTURE;
     goto fail;
   }
 
+  // FIXME: we use x264_picture_alloc to set the metadata only, we don't need the allocated memory
+  //        to store the frame. Since we free the frame memory here, we don't need to call
+  //        x264_picture_clean later.
+  e->pic_in = pic_in;
+  x264_picture_clean(&pic_in);
+
   e->h = x264_encoder_open(&e->param);
   if (!e->h) {
     *rc = ERR_OPEN_ENGINE;
-    x264_picture_clean(&e->pic_in);
     goto fail;
   }
 
@@ -75,24 +81,24 @@ Slice enc_encode(Encoder *e, uint8_t *y, uint8_t *cb, uint8_t *cr, int *rc) {
   x264_nal_t *nal;
   int i_nal;
 
+  x264_picture_t pic_out;
   e->pic_in.img.plane[0] = y;
   e->pic_in.img.plane[1] = cb;
   e->pic_in.img.plane[2] = cr;
 
-  int frame_size = x264_encoder_encode(e->h, &nal, &i_nal, &e->pic_in, &e->pic_out);
+  int frame_size = x264_encoder_encode(e->h, &nal, &i_nal, &e->pic_in, &pic_out);
   Slice s = {.data_len = frame_size};
   if (frame_size <= 0) {
     *rc = ERR_ENCODE;
     return s;
   }
 
-  e->pic_in.i_pts++;
+  // e->pic_in.i_pts++;
   s.data = nal->p_payload;
   return s;
 }
 
 void enc_close(Encoder *e, int *rc) {
   x264_encoder_close(e->h);
-  x264_picture_clean(&e->pic_in);
   free(e);
 }

pkg/driver/camera/camera_linux.go

@@ -21,6 +21,7 @@ import (
 
 const (
 	maxEmptyFrameCount = 5
+	prioritizedDevice  = "video0"
 )
 
 var (
@@ -94,9 +95,14 @@ func init() {
 
 			discovered[reallink] = struct{}{}
 			cam := newCamera(device)
+			priority := driver.PriorityNormal
+			if label == prioritizedDevice {
+				priority = driver.PriorityHigh
+			}
 			driver.GetManager().Register(cam, driver.Info{
 				Label:      label,
 				DeviceType: driver.Camera,
+				Priority:   priority,
 			})
 		}
 	}

pkg/driver/microphone/microphone.go

@@ -37,12 +37,6 @@ type microphone struct {
 
 func init() {
 	var err error
-	/*
-		backends := []malgo.Backend{
-			malgo.BackendPulseaudio,
-			malgo.BackendAlsa,
-		}
-	*/
 	ctx, err = malgo.InitContext(nil, malgo.ContextConfig{}, func(message string) {
 		logger.Debugf("%v\n", message)
 	})
@@ -56,11 +50,18 @@ func init() {
 	}
 
 	for _, device := range devices {
-		// TODO: Detect default device and prioritize it
-		driver.GetManager().Register(newMicrophone(device), driver.Info{
-			Label:      device.ID.String(),
-			DeviceType: driver.Microphone,
-		})
+		info, err := ctx.DeviceInfo(malgo.Capture, device.ID, malgo.Shared)
+		if err == nil {
+			priority := driver.PriorityNormal
+			if info.IsDefault > 0 {
+				priority = driver.PriorityHigh
+			}
+			driver.GetManager().Register(newMicrophone(info), driver.Info{
+				Label:      device.ID.String(),
+				DeviceType: driver.Microphone,
+				Priority:   priority,
+			})
+		}
 	}
 
 	// Decide which endian
@@ -133,7 +134,7 @@ func (m *microphone) AudioRecord(inputProp prop.Media) (audio.Reader, error) {
 		return nil, err
 	}
 
-	return audio.ReaderFunc(func() (wave.Audio, func(), error) {
+	var reader audio.Reader = audio.ReaderFunc(func() (wave.Audio, func(), error) {
 		chunk, ok := <-m.chunkChan
 		if !ok {
 			device.Stop()
@@ -145,7 +146,12 @@ func (m *microphone) AudioRecord(inputProp prop.Media) (audio.Reader, error) {
 		// FIXME: the decoder should also fill this information
 		decodedChunk.(*wave.Float32Interleaved).Size.SamplingRate = inputProp.SampleRate
 		return decodedChunk, func() {}, err
-	}), nil
+	})
+
+	// FIXME: The current audio detection and audio encoder can only work with a static latency. Since the latency from the driver
+	//        can fluctuate, we need to stabilize it. Maybe there's a better way for doing this?
+	reader = audio.NewBuffer(int(inputProp.Latency.Seconds() * float64(inputProp.SampleRate)))(reader)
+	return reader, nil
 }
 
 func (m *microphone) Properties() []prop.Media {
@@ -159,46 +165,36 @@ func (m *microphone) Properties() []prop.Media {
 	}
 
 	for ch := m.MinChannels; ch <= m.MaxChannels; ch++ {
-		for sampleRate := m.MinSampleRate; sampleRate <= m.MaxSampleRate; sampleRate += sampleRateStep {
-			for i := 0; i < int(m.FormatCount); i++ {
-				format := m.Formats[i]
+		// FIXME: Currently support 48kHz only. We need to implement a resampler first.
+		// for sampleRate := m.MinSampleRate; sampleRate <= m.MaxSampleRate; sampleRate += sampleRateStep {
+		sampleRate := 48000
+		for i := 0; i < int(m.FormatCount); i++ {
+			format := m.Formats[i]
 
-				supportedProp := prop.Media{
-					Audio: prop.Audio{
-						ChannelCount: int(ch),
-						SampleRate:   int(sampleRate),
-						IsBigEndian:  isBigEndian,
-						// miniaudio only supports interleaved at the moment
-						IsInterleaved: true,
-					},
-				}
-
-				switch malgo.FormatType(format) {
-				case malgo.FormatF32:
-					supportedProp.SampleSize = 4
-					supportedProp.IsFloat = true
-				case malgo.FormatS16:
-					supportedProp.SampleSize = 2
-					supportedProp.IsFloat = false
-				}
-
-				supportedProps = append(supportedProps, supportedProp)
+			supportedProp := prop.Media{
+				Audio: prop.Audio{
+					ChannelCount: int(ch),
+					SampleRate:   int(sampleRate),
+					IsBigEndian:  isBigEndian,
+					// miniaudio only supports interleaved at the moment
+					IsInterleaved: true,
+					// FIXME: should change this to a less discrete value
+					Latency: time.Millisecond * 20,
+				},
 			}
-		}
-	}
 
-	// FIXME: remove this hardcoded value. Malgo doesn't support "ma_context_get_device_info" API yet. The above iterations
-	//        will always return nothing as of now
-	supportedProps = append(supportedProps, prop.Media{
-		Audio: prop.Audio{
-			Latency:       time.Millisecond * 20,
-			ChannelCount:  1,
-			SampleRate:    48000,
-			SampleSize:    4,
-			IsFloat:       true,
-			IsBigEndian:   isBigEndian,
-			IsInterleaved: true,
-		},
-	})
+			switch malgo.FormatType(format) {
+			case malgo.FormatF32:
+				supportedProp.SampleSize = 4
+				supportedProp.IsFloat = true
+			case malgo.FormatS16:
+				supportedProp.SampleSize = 2
+				supportedProp.IsFloat = false
+			}
+
+			supportedProps = append(supportedProps, supportedProp)
+		}
+		// }
+	}
 	return supportedProps
 }

pkg/driver/screen/screen.go

@@ -1 +1,81 @@
+// +build !linux
+
 package screen
+
+import (
+	"fmt"
+	"image"
+	"io"
+
+	"github.com/kbinani/screenshot"
+	"github.com/pion/mediadevices/pkg/driver"
+	"github.com/pion/mediadevices/pkg/frame"
+	"github.com/pion/mediadevices/pkg/io/video"
+	"github.com/pion/mediadevices/pkg/prop"
+)
+
+type screen struct {
+	displayIndex int
+	doneCh       chan struct{}
+}
+
+func init() {
+	activeDisplays := screenshot.NumActiveDisplays()
+	for i := 0; i < activeDisplays; i++ {
+		priority := driver.PriorityNormal
+		if i == 0 {
+			priority = driver.PriorityHigh
+		}
+
+		s := newScreen(i)
+		driver.GetManager().Register(s, driver.Info{
+			Label:      fmt.Sprint(i),
+			DeviceType: driver.Screen,
+			Priority:   priority,
+		})
+	}
+}
+
+func newScreen(displayIndex int) *screen {
+	s := screen{
+		displayIndex: displayIndex,
+	}
+	return &s
+}
+
+func (s *screen) Open() error {
+	s.doneCh = make(chan struct{})
+	return nil
+}
+
+func (s *screen) Close() error {
+	close(s.doneCh)
+	return nil
+}
+
+func (s *screen) VideoRecord(selectedProp prop.Media) (video.Reader, error) {
+	r := video.ReaderFunc(func() (img image.Image, release func(), err error) {
+		select {
+		case <-s.doneCh:
+			return nil, nil, io.EOF
+		default:
+		}
+
+		img, err = screenshot.CaptureDisplay(s.displayIndex)
+		release = func() {}
+		return
+	})
+	return r, nil
+}
+
+func (s *screen) Properties() []prop.Media {
+	resolution := screenshot.GetDisplayBounds(s.displayIndex)
+	supportedProp := prop.Media{
+		Video: prop.Video{
+			Width:       resolution.Dx(),
+			Height:      resolution.Dy(),
+			FrameFormat: frame.FormatRGBA,
+		},
+	}
+	return []prop.Media{supportedProp}
+}

pkg/io/video/detect.go

@@ -2,6 +2,7 @@ package video
 
 import (
 	"image"
+	"math"
 	"time"
 
 	"github.com/pion/mediadevices/pkg/prop"
@@ -9,7 +10,7 @@ import (
 
 // DetectChanges will detect frame and video property changes. For video property detection,
 // since it's time related, interval will be used to determine the sample rate.
-func DetectChanges(interval time.Duration, onChange func(prop.Media)) TransformFunc {
+func DetectChanges(interval time.Duration, fpsDiffTolerance float64, onChange func(prop.Media)) TransformFunc {
 	return func(r Reader) Reader {
 		var currentProp prop.Media
 		var lastTaken time.Time
@@ -40,11 +41,12 @@ func DetectChanges(interval time.Duration, onChange func(prop.Media)) TransformF
 			elapsed := now.Sub(lastTaken)
 			if elapsed >= interval {
 				fps := float32(float64(frames) / elapsed.Seconds())
-				// TODO: maybe add some epsilon so that small changes will not mark as dirty
-				currentProp.FrameRate = fps
 				frames = 0
 				lastTaken = now
-				dirty = true
+				if math.Abs(float64(currentProp.FrameRate-fps)) > fpsDiffTolerance {
+					currentProp.FrameRate = fps
+					dirty = true
+				}
 			}
 
 			if dirty {

pkg/io/video/detect_test.go

@@ -28,7 +28,7 @@ func BenchmarkDetectChanges(b *testing.B) {
 		src := src
 		b.Run(fmt.Sprintf("WithDetectChanges%d", n), func(b *testing.B) {
 			for i := 0; i < n; i++ {
-				src = DetectChanges(time.Microsecond, func(p prop.Media) {})(src)
+				src = DetectChanges(time.Microsecond, 0, func(p prop.Media) {})(src)
 			}
 
 			for i := 0; i < b.N; i++ {
@@ -74,6 +74,27 @@ func TestDetectChanges(t *testing.T) {
 		}
 	}
 
+	SlowDownAfterThrottle := func(rate float32, factor float64, after time.Duration) TransformFunc {
+		return func(r Reader) Reader {
+			sleep := float64(time.Second) / float64(rate)
+			start := time.Now()
+			f := 1.0
+			return ReaderFunc(func() (image.Image, func(), error) {
+				for {
+					img, _, err := r.Read()
+					if err != nil {
+						return nil, func() {}, err
+					}
+					if time.Since(start) > after {
+						f = factor
+					}
+					time.Sleep(time.Duration(sleep * f))
+					return img, func() {}, nil
+				}
+			})
+		}
+	}
+
 	t.Run("OnChangeCalledBeforeFirstFrame", func(t *testing.T) {
 		var detectBeforeFirstFrame bool
 		var expected prop.Media
@@ -81,7 +102,7 @@ func TestDetectChanges(t *testing.T) {
 		expected.Width = 1920
 		expected.Height = 1080
 		src, _ := buildSource(expected)
-		src = DetectChanges(time.Second, func(p prop.Media) {
+		src = DetectChanges(time.Second, 0, func(p prop.Media) {
 			actual = p
 			detectBeforeFirstFrame = true
 		})(src)
@@ -104,7 +125,7 @@ func TestDetectChanges(t *testing.T) {
 		expected.Width = 1920
 		expected.Height = 1080
 		src, update := buildSource(expected)
-		src = DetectChanges(time.Second, func(p prop.Media) {
+		src = DetectChanges(time.Second, 0, func(p prop.Media) {
 			actual = p
 		})(src)
 
@@ -137,7 +158,7 @@ func TestDetectChanges(t *testing.T) {
 		expected.FrameRate = 30
 		src, _ := buildSource(expected)
 		src = Throttle(expected.FrameRate)(src)
-		src = DetectChanges(time.Second*5, func(p prop.Media) {
+		src = DetectChanges(time.Second*5, 0, func(p prop.Media) {
 			actual = p
 			count++
 		})(src)
@@ -155,4 +176,31 @@ func TestDetectChanges(t *testing.T) {
 			assertEq(t, actual, expected, frame, checkFrameRate)
 		}
 	})
+
+	t.Run("OnChangeNotCalledForToleratedFrameRateVariation", func(t *testing.T) {
+		// https://github.com/pion/mediadevices/issues/198
+		if runtime.GOOS == "darwin" {
+			t.Skip("Skipping because Darwin CI is not reliable for timing related tests.")
+		}
+
+		var expected prop.Media
+		var count int
+		expected.Width = 1920
+		expected.Height = 1080
+		expected.FrameRate = 30
+		src, _ := buildSource(expected)
+		src = SlowDownAfterThrottle(expected.FrameRate, 1.1, time.Second)(src)
+		src = DetectChanges(time.Second, 5, func(p prop.Media) {
+			count++
+		})(src)
+		for start := time.Now(); time.Since(start) < 3*time.Second; {
+			src.Read()
+		}
+		// onChange is called once before first frame: prop.FrameRate still 0.
+		// onChange is called again after receiving frames during the specified interval: prop.FrameRate is properly calculated
+		// So if the frame rate only changes within the specified tolerance, onChange should no longer be called.
+		if count > 2 {
+			t.Fatalf("onChange was called more than twice.")
+		}
+	})
 }

track.go

@@ -58,8 +58,10 @@ type Track interface {
 	// NewRTPReader creates a new reader from the source. The reader will encode the source, and packetize
 	// the encoded data in RTP format with given mtu size.
 	NewRTPReader(codecName string, mtu int) (RTPReadCloser, error)
+	// NewEncodedReader creates a EncodedReadCloser that reads the encoded data in codecName format
+	NewEncodedReader(codecName string) (EncodedReadCloser, error)
 	// NewEncodedReader creates a new Go standard io.ReadCloser that reads the encoded data in codecName format
-	NewEncodedReader(codecName string) (io.ReadCloser, error)
+	NewEncodedIOReader(codecName string) (io.ReadCloser, error)
 }
 
 type baseTrack struct {
@@ -185,31 +187,6 @@ func (track *baseTrack) unbind(pc *webrtc.PeerConnection) error {
 	return nil
 }
 
-func (track *baseTrack) newEncodedReader(reader codec.ReadCloser) (io.ReadCloser, error) {
-	var encoded []byte
-	release := func() {}
-	return &encodedReadCloserImpl{
-		readFn: func(b []byte) (int, error) {
-			var err error
-
-			if len(encoded) == 0 {
-				release()
-				encoded, release, err = reader.Read()
-				if err != nil {
-					reader.Close()
-					track.onError(err)
-					return 0, err
-				}
-			}
-
-			n := copy(b, encoded)
-			encoded = encoded[n:]
-			return n, nil
-		},
-		closeFn: reader.Close,
-	}, nil
-}
-
 func newTrackFromDriver(d driver.Driver, constraints MediaTrackConstraints, selector *CodecSelector) (Track, error) {
 	if err := d.Open(); err != nil {
 		return nil, err
@@ -291,20 +268,52 @@ func (track *VideoTrack) Unbind(pc *webrtc.PeerConnection) error {
 	return track.unbind(pc)
 }
 
-func (track *VideoTrack) NewRTPReader(codecName string, mtu int) (RTPReadCloser, error) {
+func (track *VideoTrack) newEncodedReader(codecNames ...string) (EncodedReadCloser, *codec.RTPCodec, error) {
 	reader := track.NewReader(false)
 	inputProp, err := detectCurrentVideoProp(track.Broadcaster)
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 
-	encodedReader, selectedCodec, err := track.selector.selectVideoCodecByNames(reader, inputProp, codecName)
+	encodedReader, selectedCodec, err := track.selector.selectVideoCodecByNames(reader, inputProp, codecNames...)
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 
 	sample := newVideoSampler(selectedCodec.ClockRate)
 
+	return &encodedReadCloserImpl{
+		readFn: func() (EncodedBuffer, func(), error) {
+			data, release, err := encodedReader.Read()
+			buffer := EncodedBuffer{
+				Data:    data,
+				Samples: sample(),
+			}
+			return buffer, release, err
+		},
+		closeFn: encodedReader.Close,
+	}, selectedCodec, nil
+}
+
+func (track *VideoTrack) NewEncodedReader(codecName string) (EncodedReadCloser, error) {
+	reader, _, err := track.newEncodedReader(codecName)
+	return reader, err
+}
+
+func (track *VideoTrack) NewEncodedIOReader(codecName string) (io.ReadCloser, error) {
+	encodedReader, _, err := track.newEncodedReader(codecName)
+	if err != nil {
+		return nil, err
+	}
+	return newEncodedIOReadCloserImpl(encodedReader), nil
+}
+
+func (track *VideoTrack) NewRTPReader(codecName string, mtu int) (RTPReadCloser, error) {
+	encodedReader, selectedCodec, err := track.newEncodedReader(codecName)
+	if err != nil {
+		return nil, err
+	}
+
 	// FIXME: not sure the best way to get unique ssrc. We probably should have a global keeper that can generate a random ID and does book keeping?
 	packetizer := rtp.NewPacketizer(mtu, selectedCodec.PayloadType, rand.Uint32(), selectedCodec.Payloader, rtp.NewRandomSequencer(), selectedCodec.ClockRate)
 
@@ -318,29 +327,13 @@ func (track *VideoTrack) NewRTPReader(codecName string, mtu int) (RTPReadCloser,
 			}
 			defer release()
 
-			samples := sample()
-			pkts := packetizer.Packetize(encoded, samples)
+			pkts := packetizer.Packetize(encoded.Data, encoded.Samples)
 			return pkts, release, err
 		},
 		closeFn: encodedReader.Close,
 	}, nil
 }
 
-func (track *VideoTrack) NewEncodedReader(codecName string) (io.ReadCloser, error) {
-	reader := track.NewReader(false)
-	inputProp, err := detectCurrentVideoProp(track.Broadcaster)
-	if err != nil {
-		return nil, err
-	}
-
-	encodedReader, _, err := track.selector.selectVideoCodecByNames(reader, inputProp, codecName)
-	if err != nil {
-		return nil, err
-	}
-
-	return track.newEncodedReader(encodedReader)
-}
-
 // AudioTrack is a specific track type that contains audio source which allows multiple readers to access, and
 // manipulate.
 type AudioTrack struct {
@@ -379,9 +372,6 @@ func newAudioTrackFromDriver(d driver.Driver, recorder driver.AudioRecorder, con
 		return nil, err
 	}
 
-	// FIXME: The current audio detection and audio encoder can only work with a static latency. Since the latency from the driver
-	//        can fluctuate, we need to stabilize it. Maybe there's a better way for doing this?
-	reader = audio.NewBuffer(int(constraints.selectedMedia.Latency.Seconds() * float64(constraints.selectedMedia.SampleRate)))(reader)
 	return newAudioTrackFromReader(d, reader, selector), nil
 }
 
@@ -411,20 +401,52 @@ func (track *AudioTrack) Unbind(pc *webrtc.PeerConnection) error {
 	return track.unbind(pc)
 }
 
-func (track *AudioTrack) NewRTPReader(codecName string, mtu int) (RTPReadCloser, error) {
+func (track *AudioTrack) newEncodedReader(codecNames ...string) (EncodedReadCloser, *codec.RTPCodec, error) {
 	reader := track.NewReader(false)
 	inputProp, err := detectCurrentAudioProp(track.Broadcaster)
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 
-	encodedReader, selectedCodec, err := track.selector.selectAudioCodecByNames(reader, inputProp, codecName)
+	encodedReader, selectedCodec, err := track.selector.selectAudioCodecByNames(reader, inputProp, codecNames...)
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 
 	sample := newAudioSampler(selectedCodec.ClockRate, inputProp.Latency)
 
+	return &encodedReadCloserImpl{
+		readFn: func() (EncodedBuffer, func(), error) {
+			data, release, err := encodedReader.Read()
+			buffer := EncodedBuffer{
+				Data:    data,
+				Samples: sample(),
+			}
+			return buffer, release, err
+		},
+		closeFn: encodedReader.Close,
+	}, selectedCodec, nil
+}
+
+func (track *AudioTrack) NewEncodedReader(codecName string) (EncodedReadCloser, error) {
+	reader, _, err := track.newEncodedReader(codecName)
+	return reader, err
+}
+
+func (track *AudioTrack) NewEncodedIOReader(codecName string) (io.ReadCloser, error) {
+	encodedReader, _, err := track.newEncodedReader(codecName)
+	if err != nil {
+		return nil, err
+	}
+	return newEncodedIOReadCloserImpl(encodedReader), nil
+}
+
+func (track *AudioTrack) NewRTPReader(codecName string, mtu int) (RTPReadCloser, error) {
+	encodedReader, selectedCodec, err := track.newEncodedReader(codecName)
+	if err != nil {
+		return nil, err
+	}
+
 	// FIXME: not sure the best way to get unique ssrc. We probably should have a global keeper that can generate a random ID and does book keeping?
 	packetizer := rtp.NewPacketizer(mtu, selectedCodec.PayloadType, rand.Uint32(), selectedCodec.Payloader, rtp.NewRandomSequencer(), selectedCodec.ClockRate)
 
@@ -438,25 +460,9 @@ func (track *AudioTrack) NewRTPReader(codecName string, mtu int) (RTPReadCloser,
 			}
 			defer release()
 
-			samples := sample()
-			pkts := packetizer.Packetize(encoded, samples)
+			pkts := packetizer.Packetize(encoded.Data, encoded.Samples)
 			return pkts, release, err
 		},
 		closeFn: encodedReader.Close,
 	}, nil
 }
-
-func (track *AudioTrack) NewEncodedReader(codecName string) (io.ReadCloser, error) {
-	reader := track.NewReader(false)
-	inputProp, err := detectCurrentAudioProp(track.Broadcaster)
-	if err != nil {
-		return nil, err
-	}
-
-	encodedReader, _, err := track.selector.selectAudioCodecByNames(reader, inputProp, codecName)
-	if err != nil {
-		return nil, err
-	}
-
-	return track.newEncodedReader(encodedReader)
-}