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>

diff --git a/libavcodec/mpegaudio_parser.c b/libavcodec/mpegaudio_parser.c
index c904873a182ba88605ce00e69b7ef35a398a14fc..58ea452773ae2cc3c8f269a48862bc787f1ac112 100644 (file)
--- a/libavcodec/mpegaudio_parser.c
+++ b/libavcodec/mpegaudio_parser.c
@@ -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;
                 }

diff --git a/libavformat/mp3dec.c b/libavformat/mp3dec.c
index 7d0c2fb6ed403fff82ec01a8f912d89d83ea759a..48deefd126c5fd1a550aa19ff1a7ac2bfbd914a2 100644 (file)
--- a/libavformat/mp3dec.c
+++ b/libavformat/mp3dec.c
@@ -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;