[FFmpeg-devel] [PATCH 1/2] avfilter: change ff_inlink_make_frame_writable() to take AVFrame* argument

[Marton Balint]

On Sat, 28 Jan 2017, Nicolas George wrote:

> Le nonidi 9 pluviôse, an CCXXV, Muhammad Faiz a écrit :
>> so the behavior will be similar to
>> av_frame_make_writable().
>
> The point was to move away from that. Who copies a struct when you can
> move a pointer?
>

By the way, why av_frame_make_writable copies the struct?

As far as I see it can be implemented just like this:

int av_frame_make_writable(AVFrame *frame)
{
     int ret;
     int i;

     if (!frame->buf[0])
         return AVERROR(EINVAL);

     for (i = 0; i < FF_ARRAY_ELEMS(frame->buf); i++) {
         if (frame->buf[i]) {
             ret = av_buffer_make_writable(&frame->buf[i]);
             if (ret < 0)
                 return ret;
             frame->data[i] = frame->buf[i]->data;
         }
     }
     for (i = 0; i < frame->nb_extended_buf; i++) {
         ret = av_buffer_make_writable(&frame->extended_buf[i]);
         if (ret < 0)
             return ret;
         frame->extended_data[i] = frame->extended_buf[i]->data;
     }

     return 0;
}

It even passes fate. What do I miss?

Don't get me wrong, I know that this approach cannot be implemented 
directly into the filtering case, because of the custom get buffer 
callback and the frame pool, but for the generic frame function, is there 
any downside doing this?

Thanks,
Marton