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Re: [mediacapture-main] Add replaceTrack method to MediaStream (#586)

From: guest271314 via GitHub <sysbot+gh@w3.org>
Date: Fri, 10 May 2019 07:52:49 +0000
To: public-webrtc-logs@w3.org
Message-ID: <issue_comment.created-491195092-1557474768-sysbot+gh@w3.org>
@youennf Re https://bugs.chromium.org/p/chromium/issues/detail?id=528523#c14 

> Status: WontFix (was: Assigned) 
> 
> I don't think we are going to implement this feature
> any time soon, partially due to container lack of
> support.

from own minimal experimentation the primary issue appears to be setting `timecode` elements in sequential order given a frame rate https://gist.github.com/guest271314/f942fb9febd9c197bd3824973794ba3e, https://gist.github.com/guest271314/17d62bf74a97d3f111aa25605a9cd1ca

```
<mkv2xml>
<EBML>
  <EBMLVersion>1</EBMLVersion>
  <EBMLReadVersion>1</EBMLReadVersion>
  <EBMLMaxIDLength>4</EBMLMaxIDLength>
  <EBMLMaxSizeLength>8</EBMLMaxSizeLength>
  <DocType>webm</DocType>
  <DocTypeVersion>2</DocTypeVersion>
  <DocTypeReadVersion>2</DocTypeReadVersion>
</EBML>
<Segment>
<Info>
  <TimecodeScale>1000000</TimecodeScale>
  <MuxingApp>webm-writer-js</MuxingApp>
  <WritingApp>webm-writer-js</WritingApp>
  <Duration>1966.66666667</Duration>
</Info>
<Tracks>
  <TrackEntry>
    <TrackNumber>1</TrackNumber>
    <TrackUID>1</TrackUID>
    <FlagLacing>0</FlagLacing>
    <Language>und</Language>
    <CodecID>V_VP8</CodecID>
    <CodecName>VP8</CodecName>
    <TrackType>1</TrackType>
    <Video>
      <PixelWidth>320</PixelWidth>
      <PixelHeight>240</PixelHeight>
    </Video>
  </TrackEntry>
</Tracks>
<Cluster>
  <Timecode>0</Timecode>
  <SimpleBlock>
    <track>1</track>
    <timecode>0.0</timecode>
    <keyframe/>
    <data>
    ..
```

(https://github.com/guest271314/mkvparse; https://github.com/guest271314/webm-writer-js (uncompressed the resulting webm file is considerably greater size than Chromium or Firefox resulting webm files, which are each differ between each other as well, both in general and depending on the codec used, `video/x-matroska;codecs=avc1` being the least amount of total bytes)) - without delving into setting cues.


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