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Re: [mediacapture-record] ignoreMutedMedia on a combination of muted and unmuted tracks?

From: Miguel Casas-Sanchez via GitHub <sysbot+gh@w3.org>
Date: Thu, 15 Dec 2016 01:26:52 +0000
To: public-media-capture-logs@w3.org
Message-ID: <issue_comment.created-267209854-1481765211-sysbot+gh@w3.org>
> So you're saying that "ignoremutedmedia" means "freeze the picture 
rather than displaying black".

That's my interpretation/statement about the most likely behaviour to 
be found in media players :smile:.

> audio formats generally don't have timestamps

In a container, encoded audio is stored in packets, e.g. In Chrome 
([Opus in 
Webm](https://cs.chromium.org/chromium/src/content/renderer/media/audio_track_recorder.cc?q=opus+60+audio+trackrecorder&sq=package:chromium&l=44&dr=C))
 we split the incoming audio in 60ms sample sets, and each of those 
are encoded into a packet that has its own timestamp. The difference 
between consecutive audio packets' timestamps coming from the same 
audio Track should also be  60ms.

In the case of a muted audio source muted for a period of time, the 
sequence of encoded packets' timestamps will either jump (as much as 
the muted period length), or not (and the data will represent encoded 
silence), depending on `ignoreMutedMedia`. Why is this difference 
relevant to audio, I guess is a question for the media players.

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Received on Thursday, 15 December 2016 01:26:58 UTC

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