From ca1fa4144fbde99a88589c4b02648980b7d4c2d8 Mon Sep 17 00:00:00 2001
From: Alex Converse <alex.converse@gmail.com>
Date: Thu, 4 Mar 2010 02:30:51 +0000
Subject: [PATCH] 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
---
libavcodec/aac_ac3_parser.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/libavcodec/aac_ac3_parser.c b/libavcodec/aac_ac3_parser.c
index 85993c09b76..83ad9c56f92 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;
}
--
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