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mp3dec: Fix VBR bit rate parsing

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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.

Signed-off-by: Alexander Kojevnikov <alexander@kojevnikov.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Alexander Kojevnikov 2013-02-26 21:47:11 -08:00 committed by Michael Niedermayer
parent d2b0b839b9
commit 29d8cd265a
3 changed files with 13 additions and 7 deletions
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10
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
@ -74,15 +75,18 @@ static int mpegaudio_parse(AVCodecParserContext *s1,
if((state&SAME_HEADER_MASK) != (s->header&SAME_HEADER_MASK) && s->header)
s->header_count= -3;
s->header= state;
s->header_count++;
s->frame_size = ret-4;
if (s->header_count > 1) {
if (s->header_count > 0) {
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;
}
}
s->header_count++;
break;
}
}

6
libavformat/mp3dec.c
View File

@ -120,6 +120,7 @@ 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)
@ -135,7 +136,8 @@ 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);
@ -180,7 +182,7 @@ 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;

4
tests/ref/lavf-fate/mp3
View File

@ -1,3 +1,3 @@
40a4e41ae74ec8dacdf02402831a6a58 *./tests/data/lavf-fate/lavf.mp3
97230 ./tests/data/lavf-fate/lavf.mp3
7fcf80c2059b5c058a6cdd2e2f798b6c *./tests/data/lavf-fate/lavf.mp3
96366 ./tests/data/lavf-fate/lavf.mp3
./tests/data/lavf-fate/lavf.mp3 CRC=0x6c9850fe