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avformat/mp3: large id3 tags break concatenated file detection

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If the file size is much larger than what is indicated in the XING
header, the demuxer assumes it's a concatenated file, and throws away
the (presumably) incorrect duration information. Unfortunately, this
also triggers if the id3 tags are very large (embedded pictures and
such). Then the half-baked heuristic not only breaks the duration
display, but also gapless audio.

Fix it by subtracting the size of the headers (the check is off by some
bytes, but that doesn't matter at all). Note that there could be an
arbitrary amount of tags _after_ the mp3 data, but hopefully these are
not too large to trigger the heuristic in practice.

Also add a warning when this happens.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
wm4 2015-04-24 12:26:39 +02:00 committed by Michael Niedermayer
parent 00a452a9ad
commit 537ab68053
1 changed files with 3 additions and 0 deletions
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libavformat/mp3dec.c
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@ -147,6 +147,7 @@ static void mp3_parse_info_tag(AVFormatContext *s, AVStream *st,
MP3DecContext *mp3 = s->priv_data;
static const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
uint64_t fsize = avio_size(s->pb);
fsize = fsize >= avio_tell(s->pb) ? fsize - avio_tell(s->pb) : 0;
/* Check for Xing / Info tag */
avio_skip(s->pb, xing_offtbl[c->lsf == 1][c->nb_channels == 1]);
@ -166,6 +167,8 @@ static void mp3_parse_info_tag(AVFormatContext *s, AVStream *st,
delta = FFMAX(fsize, mp3->header_filesize) - min;
if (fsize > mp3->header_filesize && delta > min >> 4) {
mp3->frames = 0;
av_log(s, AV_LOG_WARNING,
"invalid concatenated file detected - using bitrate for duration\n");
} else if (delta > min >> 4) {
av_log(s, AV_LOG_WARNING,
"filesize and duration do not match (growing file?)\n");