In many older QuickTime files, the audio format, or "fourcc", is
0x00000000 (AV_CODEC_ID_NONE). The QuickTime File Format Specification
states the following regarding this situation:
"This format descriptor should not be used, but may be found in some
files. Samples are assumed to be stored in either 'raw ' or 'twos'
format, depending on the sample size field in the sound description."
MPlayer handles this logic by itself, but FFmpeg/FFplay currently does
not.
Also, Michael Niedermayer, at least in this case, MPlayer seems to look
at the codec tag rather than the codec ID in order to determine the
codec. Therefore, your patch from 2014 for SMI -> SVQ3 needs to set the
'fourcc' variable to 'SVQ3' as well, which is later copied to
st->codec->codec_tag in matroskadec.c.
Mats
--
Mats Peterson
http://matsp888.no-ip.org/~mats/
>From 23eaed6643438aad492df6ef820f5297688078e1 Mon Sep 17 00:00:00 2001
From: Mats Peterson <matsp...@yahoo.com>
Date: Tue, 5 Jan 2016 13:38:51 +0100
Subject: [PATCH v3] lavf/matroskadec: A_QUICKTIME/AV_CODEC_ID_NONE + SMI->SVQ3
In many older QuickTime files, the audio format, or "fourcc", is
0x00000000 (AV_CODEC_ID_NONE). The QuickTime File Format Specification
states the following regarding this situation:
"This format descriptor should not be used, but may be found in some
files. Samples are assumed to be stored in either 'raw ' or 'twos'
format, depending on the sample size field in the sound description."
MPlayer handles this logic by itself, but FFmpeg/FFplay currently does
not.
Also, Michael Niedermayer, at least in this case, MPlayer seems to look
at the codec tag rather than the codec ID in order to determine the
codec. Therefore, your patch from 2014 for SMI -> SVQ3 needs to set the
'fourcc' variable to 'SVQ3' as well, which is later copied to
st->codec->codec_tag in matroskadec.c.
Mats
---
libavformat/matroskadec.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index 9de7cfb..9b4dd98 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -1869,6 +1869,15 @@ static int matroska_parse_tracks(AVFormatContext *s)
fourcc = AV_RL32(track->codec_priv.data);
codec_id = ff_codec_get_id(ff_codec_movaudio_tags, fourcc);
}
+ if (codec_id == AV_CODEC_ID_NONE) {
+ if (track->audio.bitdepth == 8) {
+ fourcc = MKTAG('r','a','w',' ');
+ codec_id = ff_codec_get_id(ff_codec_movaudio_tags, fourcc);
+ } else if (track->audio.bitdepth == 16) {
+ fourcc = MKTAG('t','w','o','s');
+ codec_id = ff_codec_get_id(ff_codec_movaudio_tags, fourcc);
+ }
+ }
} else if (!strcmp(track->codec_id, "V_QUICKTIME") &&
(track->codec_priv.size >= 21) &&
(track->codec_priv.data)) {
@@ -1878,8 +1887,10 @@ static int matroska_parse_tracks(AVFormatContext *s)
fourcc = AV_RL32(track->codec_priv.data);
codec_id = ff_codec_get_id(ff_codec_movvideo_tags, fourcc);
}
- if (codec_id == AV_CODEC_ID_NONE && AV_RL32(track->codec_priv.data+4) == AV_RL32("SMI "))
- codec_id = AV_CODEC_ID_SVQ3;
+ if (codec_id == AV_CODEC_ID_NONE && AV_RL32(track->codec_priv.data+4) == AV_RL32("SMI ")) {
+ fourcc = MKTAG('S','V','Q','3');
+ codec_id = ff_codec_get_id(ff_codec_movaudio_tags, fourcc);
+ }
if (codec_id == AV_CODEC_ID_NONE) {
char buf[32];
av_get_codec_tag_string(buf, sizeof(buf), fourcc);
--
1.7.10.4
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