[FFmpeg-devel] MP3 streaming/seeking broken in new Chrome release using newer ffmpeg

Andrew Armstrong phplasma at gmail.com
Thu Sep 10 12:35:21 CEST 2015


A recent Chrome update today has caused seeking in audio files streamed on
the web (eg, via SoundCloud and others) to no longer work. Instead, the
file is slowly buffered until the required position in the data stream is

I added some notes about this problem at the Chrome bug report list at

I'm not sure how to directly test this in the ffmpeg toolset, perhaps it
has been corrected in a recent commit? Please see below for my analysis.

ffmpeg has been updated in the new Chrome release. Various mp3 seeking
commits were included that made large changes, breaking this feature. Other
commits have since been added that have not been merged in, I do not know
if these fix the issue - potentially.

I noticed a new seek "mode" was added to ffmpeg for mp3's that causes
seeking to either by disabled or use the "slow but accurate" mode of
reading data until the byte position is available, instead of causing a
seek like before.

This commit, which was not part of the merge, is also of interest

I noticed that ffmpeg was updated, and ffmpeg had a lot of changes
regarding mp3 seeking, and more changes after the commit that Chrome merged.

1. Chrome stable release diff:

2.These are the ffmpeg DEPS submodule versions
44x ffmpeg deps: ffmpeg cc2ec2825b0cc25cf27c5843847e7028c1cdb075
45x ffmpeg deps: ffmpeg 833732528c1873f37b490b289eeaded2ae86349c

3. Diff of ffmpeg from the previous stable release to this one:

4. Commits affecting mp3 seeking in this diff:
avformat/mp3: large id3 tags break concatenated file detection

avformat/mp3dec: fix gapless audio when seeking in CBR mode

avformat/mp3dec: Allow forcing the use of the xing TOC for CBR files

avformat/mp3dec: offset seek index to end of id3v2 tag

avformat/mp3: skip junk at the beginning of mp3 files

avformat/mp3dec: allow enabling generic seek mode

5. I notice that further commits, that were not merged, have been made to
ffmpeg seeking at


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