[SCM] libav/experimental: AAC parser: Don't write channels, sample rate, and frame size each frame.
siretart at users.alioth.debian.org
siretart at users.alioth.debian.org
Sun Jun 30 17:02:49 UTC 2013
The following commit has been merged in the experimental branch:
commit ca1fa4144fbde99a88589c4b02648980b7d4c2d8
Author: Alex Converse <alex.converse at gmail.com>
Date: Thu Mar 4 02:30:51 2010 +0000
AAC parser: Don't write channels, sample rate, and frame size each frame.
Thanks to backwards compatible HE-AAC signalling these values are unreliable.
Originally committed as revision 22194 to svn://svn.ffmpeg.org/ffmpeg/trunk
diff --git a/libavcodec/aac_ac3_parser.c b/libavcodec/aac_ac3_parser.c
index 85993c0..83ad9c5 100644
--- a/libavcodec/aac_ac3_parser.c
+++ b/libavcodec/aac_ac3_parser.c
@@ -71,10 +71,16 @@ get_next:
*poutbuf_size = buf_size;
/* update codec info */
- avctx->sample_rate = s->sample_rate;
if(s->codec_id)
avctx->codec_id = s->codec_id;
+ /* Due to backwards compatible HE-AAC the sample rate, channel count,
+ and total number of samples found in an AAC ADTS header are not
+ reliable. Bit rate is still accurate because the total frame duration in
+ seconds is still correct (as is the number of bits in the frame). */
+ if (avctx->codec_id != CODEC_ID_AAC) {
+ avctx->sample_rate = s->sample_rate;
+
/* allow downmixing to stereo (or mono for AC-3) */
if(avctx->request_channels > 0 &&
avctx->request_channels < s->channels &&
@@ -83,12 +89,14 @@ get_next:
(avctx->codec_id == CODEC_ID_AC3 ||
avctx->codec_id == CODEC_ID_EAC3)))) {
avctx->channels = avctx->request_channels;
- } else if (avctx->codec_id != CODEC_ID_AAC || s->channels) {
+ } else {
avctx->channels = s->channels;
avctx->channel_layout = s->channel_layout;
}
- avctx->bit_rate = s->bit_rate;
avctx->frame_size = s->samples;
+ }
+
+ avctx->bit_rate = s->bit_rate;
return i;
}
--
Libav/FFmpeg packaging
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