[FFmpeg-devel] [PATCH] avformat/mp3dec: improve junk skipping heuristic
nfxjfg at googlemail.com
Tue Oct 20 12:20:41 CEST 2015
On Tue, 20 Oct 2015 02:12:00 +0200
Michael Niedermayer <michael at niedermayer.cc> wrote:
> On Mon, Oct 19, 2015 at 11:12:03PM +0200, wm4 wrote:
> > Commit 2b3e9bbfb529e6bde238aeb511b55ebe461664c8 caused problems for a
> > certain API user:
> > https://code.google.com/p/chromium/issues/detail?id=537725
> > https://code.google.com/p/chromium/issues/detail?id=542032
> > The problem seems rather arbitrary, because if there's junk, anything
> > can happen. In this case, the imperfect junk skipping just caused it to
> > read different junk, from what I can see.
> > We can improve the accuracy of junk detection by a lot by checking if 2
> > consecutive frames use the same configuration. While in theory it might
> > be completely fine for the 1st frame to have a different format than the
> > 2nd frame, it's exceedingly unlikely, and I can't think of a legitimate
> > use-case.
> > This is approximately the same mpg123 does for junk skipping. The
> > set of compared header bits is the same as the libavcodec mp3 parser
> > uses for similar purposes.
> > ---
> > Now compares less header bits, as requested.
> > ---
> > libavformat/mp3dec.c | 28 +++++++++++++++++++++-------
> > 1 file changed, 21 insertions(+), 7 deletions(-)
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