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mp3dec: Fix VBR bit rate parsing 

When parsing the Xing/Info tag, don't set the bit rate if it's an Info tag.

When parsing the stream, don't override the bit rate if it's already set,
otherwise calculate the mean bit rate from parsed frames. This way, the bit
rate will be set correctly both for CBR and VBR streams.

CC:libav-stable@libav.org

Signed-off-by: Anton Khirnov <anton@khirnov.net>
This commit is contained in:
Alexander Kojevnikov 2013-03-06 21:38:55 -08:00 committed by Anton Khirnov
parent 4be368b504
commit eae0879d96
2 changed files with 9 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
libavcodec/mpegaudio_parser.c
View File

@ -30,6 +30,7 @@ typedef struct MpegAudioParseContext {
int frame_size;
uint32_t header;
int header_count;
int no_bitrate;
} MpegAudioParseContext;
#define MPA_HEADER_SIZE 4
@ -80,7 +81,10 @@ static int mpegaudio_parse(AVCodecParserContext *s1,
avctx->sample_rate= sr;
avctx->channels = channels;
s1->duration = frame_size;
avctx->bit_rate = bit_rate;
if (s->no_bitrate || !avctx->bit_rate) {
s->no_bitrate = 1;
avctx->bit_rate += (bit_rate - avctx->bit_rate) / s->header_count;
}
}
break;
}

6
libavformat/mp3dec.c
View File

@ -128,6 +128,7 @@ static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
MPADecodeHeader c;
int vbrtag_size = 0;
int is_cbr;
v = avio_rb32(s->pb);
if(ff_mpa_check_header(v) < 0)
@ -143,7 +144,8 @@ static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
/* Check for Xing / Info tag */
avio_skip(s->pb, xing_offtbl[c.lsf == 1][c.nb_channels == 1]);
v = avio_rb32(s->pb);
if(v == MKBETAG('X', 'i', 'n', 'g') || v == MKBETAG('I', 'n', 'f', 'o')) {
is_cbr = v == MKBETAG('I', 'n', 'f', 'o');
if (v == MKBETAG('X', 'i', 'n', 'g') || is_cbr) {
v = avio_rb32(s->pb);
if(v & XING_FLAG_FRAMES)
frames = avio_rb32(s->pb);
@ -176,7 +178,7 @@ static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
if(frames)
st->duration = av_rescale_q(frames, (AVRational){spf, c.sample_rate},
st->time_base);
if(size && frames)
if (size && frames && !is_cbr)
st->codec->bit_rate = av_rescale(size, 8 * c.sample_rate, frames * (int64_t)spf);
return 0;