[FFmpeg-devel] [PATCH 05/15] libavformat/flacdec: Export samples md5 as metadata

[Tomas Härdin]

tis 2024-10-29 klockan 16:01 +0100 skrev Tomas Härdin:
> tis 2024-10-29 klockan 11:57 -0300 skrev James Almer:
> > On 10/29/2024 11:47 AM, Tomas Härdin wrote:
> > > Could maybe use some kind of compile-time assert that
> > > FLAC_STREAMINFO_SIZE == MD5_BYTE_SIZE + 18. I'm thinking putting in
> > > st-
> > > > codecpar->extradata + st->codecpar->extradata_size -
> > > > MD5_BYTE_SIZE for
> > > the offset
> > > 
> > > Spotify comments
> > > ----------------
> > > Make it possible to verify sample checksum for FLAC files
> > > 
> > > Possible other solutions:
> > >      • Make ffmpeg FLAC demuxer capable of optionally check sample
> > > checksum. One tricky thing is that we currently have heuristics to
> > > not
> > > trust the checksums based on other metadata (known broken
> > > transcoding
> > > software)
> > 
> > If this is available in extradata, why export it a second time as
> > metadata?
> 
> Good question. My guess is it's because extradata isn't available in
> ffprobe output

Ah except ffprobe -show_data does output extradata when used in
compbination with -show_streams. But we often parse stuff out of
extradata that could theoretically be done with a small shell script so
I see no harm in doing this here. We could even add a test that checks
that the md5sum of the decoded output matches the hash stored in the
file

/Tomas