FFmpeg curiously uses 'sowt' as the fourcc when writing 8-bit signed
QuickTime data, so cater for this as well. Description follows:
Since mkvmerge doesn't set the bit depth for A_QUICKTIME audio (as far
as I know), the track->audio.bitdepth variable will be zero, and its
value needs to be retrieved from the sound sample description. Also,
confine the 0x to 'raw '/'twos' fourcc mapping to old version 0
sound sample descriptions, since they are the only valid sample
descriptions for this type of mapping.
Also, 'twos' and 'sowt' audio can be signed 8-bit.
--
Mats Peterson
http://matsp888.no-ip.org/~mats/
>From 0fce7d158725fe9c3fe673cebba3c42e328a8aad Mon Sep 17 00:00:00 2001
From: Mats Peterson
Date: Fri, 15 Jan 2016 13:01:40 +0100
Subject: [PATCH v3] lavf/matroskadec: Set A_QUICKTIME bit depth
Since mkvmerge doesn't set the bit depth for A_QUICKTIME audio (as far
as I know), the track->audio.bitdepth variable will be zero, and its
value needs to be retrieved from the sound sample description. Also,
confine the 0x to 'raw '/'twos' fourcc mapping to old version 0
sound sample descriptions, since they are the only valid sample
descriptions for this type of mapping.
Also, 'twos' and 'sowt' audio can be signed 8-bit.
---
libavformat/matroskadec.c | 25 ++---
1 file changed, 18 insertions(+), 7 deletions(-)
diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index cc5ec19..95faf4a 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -1891,17 +1891,28 @@ static int matroska_parse_tracks(AVFormatContext *s)
/* Normally 36, but allow noncompliant private data */
&& (track->codec_priv.size >= 32)
&& (track->codec_priv.data)) {
+uint16_t stsd_version;
int ret = get_qt_codec(track, &fourcc, &codec_id);
if (ret < 0)
return ret;
-if (fourcc == 0) {
-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);
+stsd_version = AV_RB16(track->codec_priv.data + 16);
+if (stsd_version == 0) {
+/* Currently not set by mkvmerge, so get the bit depth
+ * from the sample description. */
+track->audio.bitdepth = AV_RB16(track->codec_priv.data + 26);
+if (fourcc == 0) {
+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);
+}
}
+/* 'twos' and 'sowt' audio can be 8-bit */
+if ((fourcc == MKTAG('t','w','o','s') || fourcc == MKTAG('s','o','w','t')) &&
+track->audio.bitdepth == 8)
+codec_id = AV_CODEC_ID_PCM_S8;
}
} else if (!strcmp(track->codec_id, "V_QUICKTIME") &&
(track->codec_priv.size >= 21) &&
--
1.7.10.4
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