Fix MediaSource code so it can handle HE-AAC content that uses implicit signalling.

Fix MediaSource code so it can handle HE-AAC content that uses implicit signalling.


BUG=135674
TEST=Manual testing with the content in the bug.

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=147747

[acolwell GONE FROM CHROMIUM, 2012-07-20 21:35:57]

This patch allows the MediaSource to deal with HE-AAC content that uses implicit
signalling. Implicit signalling only allows one to detect that SBR is present by
decoding the first frame. Since delaying audio device initialization until after
the first frame is decoded would be non-trivial change, I've created this
workaround that allows the presence of SBR to be signalled though the mimetype
codecs parameter. A codec value of 'mp4a.40.5' is the standardized way to
indicate that the content contains SBR content. We use that information to
trigger doubling the sample rate if the SBR information is not in the MP4
headers. 

I also added a check in the audio decoder to verify that the sample rate of the
decoded data matches what used to initialize the audio device. If they don't
match an error is signalled. This fixes the existing behavior where we were
allowing content to play when there was a mismatch between the decoder output
and the audio device sample rate.

[vrk (LEFT CHROMIUM), 2012-07-20 23:08:48]

LGTM modulo a few minor nits

Is it worth adding a bug (pri-3) to do detect SBR after decoding the first
frame, or is that something we'll probably never do?

http://codereview.chromium.org/10795050/diff/7001/media/mp4/aac.h
File media/mp4/aac.h (right):

http://codereview.chromium.org/10795050/diff/7001/media/mp4/aac.h#newcode37
media/mp4/aac.h:37: //  signalled in the mimetype. (ie mp4a.40.5 in the codecs
parameter).
nit: extra space "//  "

http://codereview.chromium.org/10795050/diff/7001/media/mp4/aac.h#newcode39
media/mp4/aac.h:39: //  AudioDecoderConfig.
nit: extra space "//  "

http://codereview.chromium.org/10795050/diff/11001/media/filters/chunk_demuxe...
File media/filters/chunk_demuxer.cc (right):

http://codereview.chromium.org/10795050/diff/11001/media/filters/chunk_demuxe...
media/filters/chunk_demuxer.cc:75: if (codecs[i] == "mp4a.40.5") {
nit: put string in a constant?

http://codereview.chromium.org/10795050/diff/11001/media/mp4/aac.cc
File media/mp4/aac.cc (right):

http://codereview.chromium.org/10795050/diff/11001/media/mp4/aac.cc#newcode77
media/mp4/aac.cc:77: // Read extension configuration
nit: period at end

http://codereview.chromium.org/10795050/diff/11001/media/mp4/aac.cc#newcode146
media/mp4/aac.cc:146: // The following code is written according to ISO 14496
Part 3 Table 1.11.
nit: Also include Table 1.22. (Table 1.11 refers to the capping to 48000, Table
1.22 refers to the "2 *")

[acolwell GONE FROM CHROMIUM, 2012-07-20 23:20:05]

http://codereview.chromium.org/10795050/diff/7001/media/mp4/aac.h
File media/mp4/aac.h (right):

http://codereview.chromium.org/10795050/diff/7001/media/mp4/aac.h#newcode37
media/mp4/aac.h:37: //  signalled in the mimetype. (ie mp4a.40.5 in the codecs
parameter).
On 2012/07/20 23:08:48, Victoria Kirst wrote:
> nit: extra space "//  "

Done.

http://codereview.chromium.org/10795050/diff/7001/media/mp4/aac.h#newcode39
media/mp4/aac.h:39: //  AudioDecoderConfig.
On 2012/07/20 23:08:48, Victoria Kirst wrote:
> nit: extra space "//  "

Done.

http://codereview.chromium.org/10795050/diff/11001/media/filters/chunk_demuxe...
File media/filters/chunk_demuxer.cc (right):

http://codereview.chromium.org/10795050/diff/11001/media/filters/chunk_demuxe...
media/filters/chunk_demuxer.cc:75: if (codecs[i] == "mp4a.40.5") {
On 2012/07/20 23:08:48, Victoria Kirst wrote:
> nit: put string in a constant?

Done.

http://codereview.chromium.org/10795050/diff/11001/media/mp4/aac.cc
File media/mp4/aac.cc (right):

http://codereview.chromium.org/10795050/diff/11001/media/mp4/aac.cc#newcode77
media/mp4/aac.cc:77: // Read extension configuration
On 2012/07/20 23:08:48, Victoria Kirst wrote:
> nit: period at end

Done.

http://codereview.chromium.org/10795050/diff/11001/media/mp4/aac.cc#newcode146
media/mp4/aac.cc:146: // The following code is written according to ISO 14496
Part 3 Table 1.11.
On 2012/07/20 23:08:48, Victoria Kirst wrote:
> nit: Also include Table 1.22. (Table 1.11 refers to the capping to 48000,
Table
> 1.22 refers to the "2 *")

Done.

[commit-bot: I haz the power, 2012-07-20 23:20:53]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/acolwell@chromium.org/10795050/13001

[commit-bot: I haz the power, 2012-07-21 00:22:45]

Try job failure for 10795050-13001 (retry) on mac_rel for step "browser_tests".
It's a second try, previously, step "browser_tests" failed.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=mac_rel&nu...