[FFmpeg-devel] Should add AVProbeData change to API changes + release notes

[Andreas Cadhalpun]

Hi,

On 11.08.2014 22:22, Michael Niedermayer wrote:
> On Mon, Aug 11, 2014 at 08:05:38PM +0200, Reimar Döffinger wrote:
>> Hello,
>> (sorry for being too lazy to send a patch)
>> With the major version bump AVProbeData was extended by a new field.
>> This so far has broken 3 places within FFmpeg and one within MPlayer,
>> where AVProbeData was only initialized field-by-field.
>> This will cause "random" crashes.
>> I'm at this point fairly certain a lot of other software will have the
>> same issue.

That's for sure.

>> I suggest we make add a big note with the release that everyone should
>> check their software for uses of AVProbeData that might result in parts
>> of that struct not being initialized.
>
> agree

Please really document this!

It broke mpd [1] and the mpd developer wasn't happy that this is not 
documented [2].

But there is also another problem, as can be seen from the comment in 
the fix [3]:
/* this attribute was added in libav/ffmpeg version 11, but
    unfortunately it's "uint8_t" instead of "char", and it's
    not "const" - wtf? */

I'm also wondering, why AVProbeData.mime_type is a uint8_t* instead of a 
const char*.

This was introduced in commit 3a19405d574a467c68b48e4b824c76617fd59de0 
(merged from Libav) and in the same commit lpd.mime_type is used as 
argument for av_match_name, which takes const char* ...
And mime_type was added as const char* to AVInputFormat, so this is even 
inconsistent.

So should this be changed to const char*?

Looking at the commit closer, I just noticed another strange thing:
It introduces AVPROBE_SCORE_MIME, but then still only uses 
AVPROBE_SCORE_EXTENSION. I guess this was intended differently.

Best regards,
Andreas


1: https://bugs.debian.org/760669
2: https://bugs.debian.org/760669#30
3: 
http://git.musicpd.org/cgit/master/mpd.git/diff/?id=219c42522f938c5fff08d962a1a54c0872322f00