[FFmpeg-devel] FFmpeg A/V filtering questions

[Clément Bœsch]

On Mon, Feb 13, 2012 at 08:14:43PM +0100, Michael Niedermayer wrote:
> On Mon, Feb 13, 2012 at 04:15:12PM +0100, Clément Bœsch wrote:
> > Hi,
> > 
> > I have a few questions about this part of the code in ffmpeg.c (around L2140):
> > 
> >     avcodec_get_frame_defaults(ist->filtered_frame);
> >     filtered_frame = ist->filtered_frame;
> >     *filtered_frame= *decoded_frame; //for me_threshold
> >     if (ost->picref) {
> >         avfilter_fill_frame_from_video_buffer_ref(filtered_frame, ost->picref);
> >         filtered_frame->pts = av_rescale_q(ost->picref->pts, ist_pts_tb, AV_TIME_BASE_Q);
> >     }
> >     if (ost->picref->video && !ost->frame_aspect_ratio)
> >         ost->st->codec->sample_aspect_ratio = ost->picref->video->sample_aspect_ratio;
> >     do_video_out(output_files[ost->file_index].ctx, ost, ist, filtered_frame);
> > 
> > 1) how is *filtered_frame = *decoded_frame (only?) related to me_threshold?
> 
> copying the motion vectors & macroblock types
> 
> 
> > 
> > 2) what is the point of getting the frame defaults if they are overwritten just
> >    after that (first 3 lines)?
> 
> theres no point
> 
> 
> > 
> > 3) ost->picref can't be changed in the "if (ost->picref)" scope, so it looks
> >    like to me that "if (ost->picref->video)" will leads to a sigsegv if
> >    ost->picref was NULL in the first place. Since no such bug exists at
> >    the moment (AFAIK), couldn't we just drop the "if (ost->picref)" block?
> 
> yes
> 

Thank you for your answers, I just sent a related patchset.

[...]

-- 
Clément B.
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