[FFmpeg-devel] [PATCH] avfilter: do not write to unwritable frame

[wm4]

On Sat, 28 Jan 2017 15:59:11 +0700
Muhammad Faiz <mfcc64 at gmail.com> wrote:

> On 1/28/17, Nicolas George <george at nsup.org> wrote:
> > L'octidi 8 pluviôse, an CCXXV, Muhammad Faiz a écrit :  
> >> affect filters that set partial_buf_size
> >> test-case
> >> ffplay -i lavfi 'aevalsrc=sin(1000*t*t), aformat=sample_fmts=fltp, asplit
> >> [a][b];
> >> [a] firequalizer=fixed=on, showcqt=s=1280x360 [a1];
> >> [b] firequalizer=fixed=on, showcqt=s=1280x360 [b1];
> >> [a1][b1] vstack'
> >>
> >> Signed-off-by: Muhammad Faiz <mfcc64 at gmail.com>
> >> ---
> >>  libavfilter/avfilter.c | 17 +++++++++++++++++
> >>  1 file changed, 17 insertions(+)  
> >
> > Maybe this can be of use:
> >
> > https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/28c62df672865890cbb13e5f0e94bde29c8fbacd  
> 
> Unfortunately, this modify pointer to AVFrame, i think it is incompatible
> with framequeue framework.
> 
> Note that av_frame_make_writable() takes AVFrame*,
> while ff_inlink_make_frame_writable() takes AVFrame**.

There doesn't seem to be any reason that it takes AVFrame**. AVFrame
refs can be moved, so even if a frame is newly allocated it can be put
into the AVFrame passed to the function without replacing the pointer.

Also the code for copying the data in the function could have be
reduced to 1 line by using av_frame_copy().

Maybe someone should have reviewed the commit that added this.

Anyway, maybe you can fix it and use it. That would be the ideal
outcome.