Fix channel mapping for 8-ch audio in ffmpeg_aac_bitstream_converter

Fix channel mapping for 8-ch audio in ffmpeg_aac_bitstream_converter

FFmpeg's AVCodecContext->channels contains "raw number of channels"
(e.g. "2" for 2 channels, "8" for 8 channels). The change ensures that:
- the value of "8" is correctly mapped to 0b111 ADTS channel
config (aka MPEG-4 Channel Configuration),
- the value of "7" becomes unsupported.

BUG=640610
Committed: https://crrev.com/a5cd9c49bcb56a12f04555cc218c4a940a579a4e
Cr-Commit-Position: refs/heads/master@{#414685}

[jwalczak, 2016-08-25 14:58:38]

Description was changed from

==========
Fix channel mapping for 8-ch audio in ffmpeg_aac_bitstream_converter

FFmpeg's AVCodecContext->channels contains "raw number of channels"
(e.g. "2" for 2 channels, "8" for 8 channels). The change ensures that:
- the value of "8" is correctly mapped to 0b111 ADTS channel
config (aka MPEG-4 Channel Configuration),
- the value of "7" becomes unsupported.

BUG=640610
==========

to

==========
Fix channel mapping for 8-ch audio in ffmpeg_aac_bitstream_converter

FFmpeg's AVCodecContext->channels contains "raw number of channels"
(e.g. "2" for 2 channels, "8" for 8 channels). The change ensures that:
- the value of "8" is correctly mapped to 0b111 ADTS channel
config (aka MPEG-4 Channel Configuration),
- the value of "7" becomes unsupported.

BUG=640610
==========

[jwalczak, 2016-08-25 14:58:38]

jwalczak@opera.com changed reviewers:
+ dalecurtis@chromium.org

[jwalczak, 2016-08-25 14:59:28]

PTAL

[DaleCurtis, 2016-08-25 17:49:34]

dalecurtis@chromium.org changed reviewers:
+ kjoswiak@chromium.org

[DaleCurtis, 2016-08-25 17:49:34]

lgtm, +original author kjoswiak in case he wants to weigh in.

[DaleCurtis, 2016-08-25 17:49:43]

Thanks for the fix!

[jwalczak, 2016-08-26 08:05:28]

The CQ bit was checked by jwalczak@opera.com

[commit-bot: I haz the power, 2016-08-26 08:05:51]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-26 11:16:37]

Description was changed from

==========
Fix channel mapping for 8-ch audio in ffmpeg_aac_bitstream_converter

FFmpeg's AVCodecContext->channels contains "raw number of channels"
(e.g. "2" for 2 channels, "8" for 8 channels). The change ensures that:
- the value of "8" is correctly mapped to 0b111 ADTS channel
config (aka MPEG-4 Channel Configuration),
- the value of "7" becomes unsupported.

BUG=640610
==========

to

==========
Fix channel mapping for 8-ch audio in ffmpeg_aac_bitstream_converter

FFmpeg's AVCodecContext->channels contains "raw number of channels"
(e.g. "2" for 2 channels, "8" for 8 channels). The change ensures that:
- the value of "8" is correctly mapped to 0b111 ADTS channel
config (aka MPEG-4 Channel Configuration),
- the value of "7" becomes unsupported.

BUG=640610
==========

[commit-bot: I haz the power, 2016-08-26 11:16:38]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-26 11:18:11]

Description was changed from

==========
Fix channel mapping for 8-ch audio in ffmpeg_aac_bitstream_converter

FFmpeg's AVCodecContext->channels contains "raw number of channels"
(e.g. "2" for 2 channels, "8" for 8 channels). The change ensures that:
- the value of "8" is correctly mapped to 0b111 ADTS channel
config (aka MPEG-4 Channel Configuration),
- the value of "7" becomes unsupported.

BUG=640610
==========

to

==========
Fix channel mapping for 8-ch audio in ffmpeg_aac_bitstream_converter

FFmpeg's AVCodecContext->channels contains "raw number of channels"
(e.g. "2" for 2 channels, "8" for 8 channels). The change ensures that:
- the value of "8" is correctly mapped to 0b111 ADTS channel
config (aka MPEG-4 Channel Configuration),
- the value of "7" becomes unsupported.

BUG=640610

Committed: https://crrev.com/a5cd9c49bcb56a12f04555cc218c4a940a579a4e
Cr-Commit-Position: refs/heads/master@{#414685}
==========

[commit-bot: I haz the power, 2016-08-26 11:18:12]

Patchset 1 (id:??) landed as
https://crrev.com/a5cd9c49bcb56a12f04555cc218c4a940a579a4e
Cr-Commit-Position: refs/heads/master@{#414685}