[FFmpeg-devel] [PATCH 01/15] libavformat: Increase probe buffer to 16MB

[Mattias Wadman]

On Wed, Nov 13, 2024 at 3:26 PM Tomas Härdin <git at haerdin.se> wrote:

> ons 2024-11-13 klockan 14:40 +0100 skrev Michael Niedermayer:
> > Hi
> >
> > On Tue, Oct 29, 2024 at 03:44:30PM +0100, Tomas Härdin wrote:
> > > Needs a sample. An option or setting for probe size might be a good
> > > idea
> > >
> > > Spotify comments
> > > ----------------
> > > In mp3 files, id3v2 tag with huge cover art causes the probe code
> > > to
> > > not identify valid mp3 files as mp3. Increase default buffer so
> > > that
> > > probe can see mp3 frames.
> >
> > Does this work if its limited to cases where huge ID3 is detected ?
> > or we could seek forward over the ID3 detect format and then go
> > back and do the normal open code
>
> Can't we have it just rely on there being an ID3 header? Are there
> counterexamples?
>

Not sure if it is a good counter example but I've seen wav files with id3v2
tag prepended. The ffmpeg wav demuxer has comment about it also
https://github.com/FFmpeg/FFmpeg/blob/master/libavformat/wavdec.c#L67


>
> The probe logic (av_probe_input_format3()) has special logic for ID3
> headers, skipping past them to allow the normal MP3 probing to inspect
> the essence data following the header. This only works if it's given
> enough probe data
>
> Seeking can be expensive, especially when the data is served over HTTP
>
> /Tomas
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".
>