[FFmpeg-cvslog] mp3dec: Fix VBR bit rate parsing

[Alexander Kojevnikov]

ffmpeg | branch: release/0.11 | Alexander Kojevnikov <alexander at kojevnikov.com> | Tue Feb 26 21:47:11 2013 -0800| [7cb24ecd4c41d3e31dd5d5f56e0f5bfa081ac5a7] | committer: Michael Niedermayer

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.

Signed-off-by: Alexander Kojevnikov <alexander at kojevnikov.com>
Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
(cherry picked from commit 29d8cd265a536063420afe78375b2176a9e1abc5)

Conflicts:

	tests/ref/lavf-fate/mp3

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=7cb24ecd4c41d3e31dd5d5f56e0f5bfa081ac5a7
---

 libavcodec/mpegaudio_parser.c |   10 +++++++---
 libavformat/mp3dec.c          |    6 ++++--
 tests/ref/lavf-fate/mp3       |    4 ++--
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/libavcodec/mpegaudio_parser.c b/libavcodec/mpegaudio_parser.c
index 6ceca83..83dbca0 100644
--- a/libavcodec/mpegaudio_parser.c
+++ b/libavcodec/mpegaudio_parser.c
@@ -29,6 +29,7 @@ typedef struct MpegAudioParseContext {
     int frame_size;
     uint32_t header;
     int header_count;
+    int no_bitrate;
 } MpegAudioParseContext;
 
 #define MPA_HEADER_SIZE 4
@@ -73,15 +74,18 @@ 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;
                 }
             }
diff --git a/libavformat/mp3dec.c b/libavformat/mp3dec.c
index 61405f7..87b3bb6 100644
--- a/libavformat/mp3dec.c
+++ b/libavformat/mp3dec.c
@@ -88,6 +88,7 @@ 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)
@@ -101,7 +102,8 @@ 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 & 0x1)
             frames = avio_rb32(s->pb);
@@ -132,7 +134,7 @@ 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;
diff --git a/tests/ref/lavf-fate/mp3 b/tests/ref/lavf-fate/mp3
index 48a5476..1af3652 100644
--- a/tests/ref/lavf-fate/mp3
+++ b/tests/ref/lavf-fate/mp3
@@ -1,3 +1,3 @@
-67cbcc79f018afb68f7d81625bfa234c *./tests/data/lavf-fate/lavf.mp3
-97230 ./tests/data/lavf-fate/lavf.mp3
+0f7b603ab305759ea4e853326f77da60 *./tests/data/lavf-fate/lavf.mp3
+96366 ./tests/data/lavf-fate/lavf.mp3
 ./tests/data/lavf-fate/lavf.mp3 CRC=0x6c9850fe