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Sur d’autres sites (7646)

  • How can I correctly provide a mock webcam video to Chrome ?

    15 décembre 2022, par doppelgreener

    I'm trying to run end-to-end testing in Chrome for a product that requires a webcam feed halfway through to operate. From what I understand this means providing a fake webcam video to Chrome using the --use-file-for-fake-video-capture="/path/to/video.y4m" command line argument. It will then use that as a webcam video.

    



    However, no matter what y4m file I provide, I get the following error from Chrome running under these conditions :

    



    DOMException: Could not start video source
{
  code: 0,
  message: "Could not start video source",
  name: "NotReadableError"
}


    



    Notably I can provide an audio file just fine using --use-file-for-fake-audio-capture and Chrome will work with it well. The video has been my sticking point.

    



    This error comes out of the following straightforward mediaDevices request :

    



    navigator.mediaDevices.getUserMedia({ video: true, audio: true })
  .then(data => {
    // do stuff
  })
  .catch(err => {
    // oh no!
  });


    



    (This always hits the “oh no !” branch when a video file is provided.)

    



    What I've tried so far

    



    I've been running Chrome with the following command line arguments (newlines added for readability), and I'm using a Mac hence the open command :

    





    open -a "Google Chrome" --args
  --disable-gpu
  --use-fake-device-for-media-stream
  --use-file-for-fake-video-capture="~/Documents/mock/webcam.y4m"
  --use-file-for-fake-audio-capture="~/Documents/mock/microphone.wav"


    



    webcam.y4m and microphone.wav were generated from a video file I recorded.

    



    I first recorded a twenty-second mp4 video using my browser's MediaRecorder, downloaded the result, and converted it using the following command line commands :

    



    ffmpeg -y -i original.mp4 -f wav -vn microphone.wav
ffmpeg -y -i original.mp4 webcam.y4m


    



    When this didn't work, I tried the same using a twenty-second movie file I recorded in Quicktime :

    



    ffmpeg -y -i original.mov -f wav -vn microphone.wav
ffmpeg -y -i original.mov webcam.y4m


    



    When that also failed, I went straight to the Chromium file that explains fake video capture, went to the example y4m file list it provided, and downloaded the grandma file and provided that as a command line argument to Chrome instead :

    



    open -a "Google Chrome" --args
  --disable-gpu
  --use-fake-device-for-media-stream
  --use-file-for-fake-video-capture="~/Documents/mock/grandma_qcif.y4m"
  --use-file-for-fake-audio-capture="~/Documents/mock/microphone.wav"


    



    Chrome provides me with the exact same error in all of these situations.

    



    The only time Chrome doesn't error out with that mediaDevices request is when I omit the video completely :

    



    open -a "Google Chrome" --args
  --disable-gpu
  --use-fake-device-for-media-stream
  --use-file-for-fake-audio-capture="~/Documents/mock/microphone.wav"


    



    Accounting for C420mpeg2

    



    TestRTC suggests Chrome will “crash” if I give it a C420mpeg2 file, and recommends that simply replacing the metadata fixes the issue. Indeed the video file I generate from ffmpeg gives me the following header :

    



    YUV4MPEG2 W1280 H720 F30:1 Ip A1:1 C420mpeg2 XYSCSS=420MPEG2


    



    Chrome doesn't actually crash when run with this file, I just get the error above. If I edit the video file to the following header though per TestRTC's recommendations I get the same situation :

    



    YUV4MPEG2 W1280 H720 F30:1 Ip A1:1 C420 XYSCSS=420MPEG2


    



    The video file still gives me the above error in these conditions.

    



    What can/should I do ?

    



    How should I be providing a video file to Chrome for this command line argument ?

    



    How should I be recording or creating the video file ?

    



    How should I convert it to y4m ?

    


  • How can I correctly provide a fake webcam input to Chrome ?

    30 août 2018, par doppelgreener

    I’m trying to run end-to-end testing in Chrome for a product that requires a webcam feed halfway through to operate. From what I understand this means providing a fake webcam video to Chrome using the --use-file-for-fake-video-capture="/path/to/video.y4m" command line argument. It will then use that as a webcam video.

    However, no matter what y4m file I provide, I get the following error from Chrome running under these conditions :

    DOMException: Could not start video source
    
{
    
  code: 0,
    
  message: "Could not start video source",
    
  name: "NotReadableError"
    
}

    Notably I can provide an audio file just fine using --use-file-for-fake-audio-capture and Chrome will work with it well. The video has been my sticking point.

    This error comes out of the following straightforward mediaDevices request :

    navigator.mediaDevices.getUserMedia({ video: true, audio: true })
    
  .then(data => {
    
    // do stuff
    
  })
    
  .catch(err => {
    
    // oh no!
    
  });

    (This always hits the “oh no !” branch when a video file is provided.)

    What I’ve tried so far

    I’ve been running Chrome with the following command line arguments (newlines added for readability), and I’m using a Mac hence the open command :

    open -a "Google Chrome" --args
    
  --disable-gpu
    
  --use-fake-device-for-media-stream
    
  --use-file-for-fake-video-capture="~/Documents/mock/webcam.y4m"
    
  --use-file-for-fake-audio-capture="~/Documents/mock/microphone.wav"

    webcam.y4m and microphone.wav were generated from a video file I recorded.

    I first recorded a twenty-second mp4 video using my browser’s MediaRecorder, downloaded the result, and converted it using the following command line commands :

    ffmpeg -y -i original.mp4 -f wav -vn microphone.wav
    
ffmpeg -y -i original.mp4 webcam.y4m

    When this didn’t work, I tried the same using a twenty-second movie file I recorded in Quicktime :

    ffmpeg -y -i original.mov -f wav -vn microphone.wav
    
ffmpeg -y -i original.mov webcam.y4m

    When that also failed, I went straight to the Chromium file that explains fake video capture, went to the example y4m file list it provided, and downloaded the grandma file and provided that as a command line argument to Chrome instead :

    open -a "Google Chrome" --args
    
  --disable-gpu
    
  --use-fake-device-for-media-stream
    
  --use-file-for-fake-video-capture="~/Documents/mock/grandma_qcif.y4m"
    
  --use-file-for-fake-audio-capture="~/Documents/mock/microphone.wav"

    Chrome provides me with the exact same error in all of these situations.

    The only time Chrome doesn’t error out with that mediaDevices request is when I omit the video completely :

    open -a "Google Chrome" --args
    
  --disable-gpu
    
  --use-fake-device-for-media-stream
    
  --use-file-for-fake-audio-capture="~/Documents/mock/microphone.wav"

    Accounting for C420mpeg2

    TestRTC suggests Chrome will “crash” if I give it a C420mpeg2 file, and recommends that simply replacing the metadata fixes the issue. Indeed the video file I generate from ffmpeg gives me the following header :

    YUV4MPEG2 W1280 H720 F30:1 Ip A1:1 C420mpeg2 XYSCSS=420MPEG2

    Chrome doesn’t actually crash when run with this file, I just get the error above. If I edit the video file to the following header though per TestRTC’s recommendations I get the same situation :

    YUV4MPEG2 W1280 H720 F30:1 Ip A1:1 C420 XYSCSS=420MPEG2

    The video file still gives me the above error in these conditions.

    What can/should I do ?

    How should I be providing a video file to Chrome for this command line argument ?

    How should I be recording or creating the video file ?

    How should I convert it to y4m ?

  • How to compress webcam videos recorded by html5 MediaRecorder api ?

    19 mai 2017, par JasonY

    I successfully recorded my webcam using MediaRecorder api and the resulting filesizes seemed far too big for their quality.

    For example, for an 8 second video that was 480x640 I got a 1mB file size. That does not seem right.

    My code to record()

    navigator.mediaDevices.getUserMedia({video: true, audio: true})
    
    .then(function(stream){
    
        var options = {
    
            mimeType : "video/webm;codecs=vp9"
    
            //I don't set bitrate here even if I do the quality is too bad
    
        }
    
        var media_recorder = new MediaRecorder(media_stream, options);
    
        var recorded_data = [];
    
        media_recorder.ondataavailable = function(e){
    
             recorded_data.push(e.data);
    
        }
    
        media_recorder.onstop = function(e){
    
            recorded_data.push(e.data);
    
            var recorded_blob = new Blob(recorded_data, { 'type' : 'video/webm; codecs=vp9' });
    
            var recorded_video_url = window.URL.createObjectURL(recorded_blob);
    
            //here I write some code to download the blob from this url through a href
    
        }
    
    })

    The file obtained by this method is unreasonably large which makes me wonder if it was even compressed when encoded by VP9 ? A 7 second video is about 870kB !

    Inspecting the file with a mediainfo tool gives me

    General
    
Count                                    : 323
    
Count of stream of this kind             : 1
    
Kind of stream                           : General
    
Kind of stream                           : General
    
Stream identifier                        : 0
    
Count of video streams                   : 1
    
Count of audio streams                   : 1
    
Video_Format_List                        : VP9
    
Video_Format_WithHint_List               : VP9
    
Codecs Video                             : V_VP9
    
Video_Language_List                      : English
    
Audio_Format_List                        : Opus
    
Audio_Format_WithHint_List               : Opus
    
Audio codecs                             : Opus
    
Audio_Language_List                      : English
    
Complete name                            : recorded_video.webm
    
File name                                : recorded_video
    
File extension                           : webm
    
Format                                   : WebM
    
Format                                   : WebM
    
Format/Url                               : http://www.webmproject.org/
    
Format/Extensions usually used           : webm
    
Commercial name                          : WebM
    
Format version                           : Version 2
    
Internet media type                      : video/webm
    
Codec                                    : WebM
    
Codec                                    : WebM
    
Codec/Url                                : http://www.webmproject.org/
    
Codec/Extensions usually used            : webm
    
File size                                : 867870
    
File size                                : 848 KiB
    
File size                                : 848 KiB
    
File size                                : 848 KiB
    
File size                                : 848 KiB
    
File size                                : 847.5 KiB
    
File last modification date              : UTC 2017-05-19 05:48:00
    
File last modification date (local)      : 2017-05-19 17:48:00
    
Writing application                      : Chrome
    
Writing application                      : Chrome
    
Writing library                          : Chrome
    
Writing library                          : Chrome
    
IsTruncated                              : Yes
    

    
Video
    
Count                                    : 332
    
Count of stream of this kind             : 1
    
Kind of stream                           : Video
    
Kind of stream                           : Video
    
Stream identifier                        : 0
    
StreamOrder                              : 1
    
ID                                       : 2
    
ID                                       : 2
    
Unique ID                                : 62101435245162993
    
Format                                   : VP9
    
Commercial name                          : VP9
    
Codec ID                                 : V_VP9
    
Codec ID/Url                             : http://www.webmproject.org/
    
Codec                                    : V_VP9
    
Codec                                    : V_VP9
    
Width                                    : 640
    
Width                                    : 640 pixels
    
Height                                   : 480
    
Height                                   : 480 pixels
    
Pixel aspect ratio                       : 1.000
    
Display aspect ratio                     : 1.333
    
Display aspect ratio                     : 4:3
    
Frame rate mode                          : VFR
    
Frame rate mode                          : Variable
    
Language                                 : en
    
Language                                 : English
    
Language                                 : English
    
Language                                 : en
    
Language                                 : eng
    
Language                                 : en
    
Default                                  : Yes
    
Default                                  : Yes
    
Forced                                   : No
    
Forced                                   : No
    

    
Audio
    
Count                                    : 272
    
Count of stream of this kind             : 1
    
Kind of stream                           : Audio
    
Kind of stream                           : Audio
    
Stream identifier                        : 0
    
StreamOrder                              : 0
    
ID                                       : 1
    
ID                                       : 1
    
Unique ID                                : 32224324715799545
    
Format                                   : Opus
    
Format/Url                               : http://opus-codec.org/
    
Commercial name                          : Opus
    
Internet media type                      : audio/opus
    
Codec ID                                 : A_OPUS
    
Codec ID/Url                             : http://opus-codec.org
    
Codec                                    : Opus
    
Codec                                    : Opus
    
Codec/Family                             : PCM
    
Channel(s)                               : 1
    
Channel(s)                               : 1 channel
    
Channel positions                        : Front: C
    
Channel positions                        : 1/0/0
    
Sampling rate                            : 48000
    
Sampling rate                            : 48.0 KHz
    
Compression mode                         : Lossy
    
Compression mode                         : Lossy
    
Delay                                    : 718
    
Delay                                    : 718ms
    
Delay                                    : 718ms
    
Delay                                    : 718ms
    
Delay                                    : 00:00:00.718
    
Delay, origin                            : Container
    
Delay, origin                            : Container
    
Language                                 : en
    
Language                                 : English
    
Language                                 : English
    
Language                                 : en
    
Language                                 : eng
    
Language                                 : en
    
Default                                  : Yes
    
Default                                  : Yes
    
Forced                                   : No
    
Forced                                   : No

    What did I do wrong ? Do I have to re-encode it after the chunks get appended ? Is there some attribute I’m missing ? VP9 is supposed to reduce file sizes drastically.

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