As I noted in CR, "mp3" as a codec ID doesn't appear compliant with https://tools.ietf.org/html/rfc6381, which MSE bytestream spec for mp2ts says user-agents *should* use.

Note that https://tools.ietf.org/html/rfc6381 however doesn't seem to make specific reference to MPEG-2 codec IDs, so I'm unsure if the MSE bytestream spec is correct in it's reference to rfc6381, nor am I certain of the correct codec-id for mp2ts to indicate at least mp3. I've only just now skimmed rfc6381 so could be missing something pertinent, and I haven't looked yet at the DASH-IF format specifier for mp3 in mpeg2-ts. servolk@, do you have such info readily available?

(CR comment referenced in #1 is https://codereview.chromium.org/2773793002/diff/1/media/filters/stream_parser_factory.cc#newcode301)

Note also that DASH-IF mpd format references RFC6381 also for codec IDs (see ISO 23009-1:2014), strengthening the case that the current MSE bytestream spec's reference of RFC6381 is correct.

RFC6381 references http://www.mp4ra.org/object.html for ISO-BMFF. The problem I'm having is finding a definitive reference from RFC6381 for mpeg2-ts.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9ad504653bc097753e522941f47d7ce761476706

commit 9ad504653bc097753e522941f47d7ce761476706
Author: servolk <servolk@chromium.org>
Date: Tue Mar 28 18:19:58 2017

Allow mp3 audio codec for mpeg2ts containers in MSE

Some Chromecast apps use H.264 video + MP3 audio in mpeg2ts container.

BUG= 704638 

Review-Url: https://codereview.chromium.org/2773793002
Cr-Commit-Position: refs/heads/master@{#460170}

[modify] https://crrev.com/9ad504653bc097753e522941f47d7ce761476706/media/base/audio_codecs.cc
[modify] https://crrev.com/9ad504653bc097753e522941f47d7ce761476706/media/filters/chunk_demuxer.cc
[modify] https://crrev.com/9ad504653bc097753e522941f47d7ce761476706/media/filters/stream_parser_factory.cc
[modify] https://crrev.com/9ad504653bc097753e522941f47d7ce761476706/media/formats/mp2t/mp2t_stream_parser.cc
[modify] https://crrev.com/9ad504653bc097753e522941f47d7ce761476706/media/test/data/README
[add] https://crrev.com/9ad504653bc097753e522941f47d7ce761476706/media/test/data/bear-audio-mp4a.69.ts
[add] https://crrev.com/9ad504653bc097753e522941f47d7ce761476706/media/test/data/bear-audio-mp4a.6B.ts
[modify] https://crrev.com/9ad504653bc097753e522941f47d7ce761476706/media/test/pipeline_integration_test.cc