[FFmpeg-devel] [PATCH] libavfilter: created a new filter that obtains the average peak signal-to-noise ratio (PSNR) of two input video files in YUV format.

[Stefano Sabatini]

On date Tuesday 2011-06-21 16:01:36 +0200, Stefano Sabatini encoded:
> On date Tuesday 2011-06-21 14:44:50 +0200, Roger Pau Monné encoded:
> > Hello,
> > 
> > Sorry for the delay, I'm really busy these weeks, I will like to
> > implement the option to store the results in a qpsnr style, but right
> > now I don't have time, let's see if I can do it in a week or two. I've
> > applied the suggested changes, thanks Stefano.
[...]
> > +static void start_frame(AVFilterLink *inlink, AVFilterBufferRef *inpicref)
> > +{
> > +    AVFilterBufferRef *outpicref = avfilter_ref_buffer(inpicref, ~0);
> > +    AVFilterContext *ctx = inlink->dst;
> > +    PSNRContext *psnr = ctx->priv;
> > +
> > +    inlink->dst->outputs[0]->out_buf = outpicref;

> > +    outpicref->pts = av_rescale_q(inpicref->pts,
> > +                                  ctx->inputs [0]->time_base,
> > +                                  ctx->outputs[0]->time_base);

Is this required?

> > +
> > +    if (psnr->picref) {
> > +        avfilter_unref_buffer(psnr->picref);
> > +        psnr->picref = NULL;
> > +    }

> > +    avfilter_request_frame(ctx->inputs[1]);
> > +
> > +    avfilter_start_frame(inlink->dst->outputs[0], outpicref);

Note: here we should fail in case avfilter_request_frame returns an
error. Not necessary for this patch since this would possibly require
to change the start_frame signature, but at least we may add a fixme.

> > +}
> > +
> > +static void start_frame_ref(AVFilterLink *inlink, AVFilterBufferRef *inpicref)
> > +{
> > +    AVFilterContext *ctx = inlink->dst;
> > +    PSNRContext *psnr = ctx->priv;
> > +
> > +    psnr->picref = inpicref;

> > +    psnr->picref->pts = av_rescale_q(inpicref->pts,
> > +                                     ctx->inputs [1]->time_base,
> > +                                     ctx->outputs[0]->time_base);

Is this required? AFAIK the reference PTS is just ignored.

[...]
> (or we could change avfilter_unref_buffer to accepts a ** and set the
> pointer reference to NULL).
> 
> Looks fine otherwise. I'll fix the nits myself if you don't have time
> or you don't care, as for the syntax thing I'd like to think a bit
> about it and get advices.

I addressed some of the nits and did some more changes to the filter,
please keep working on this copy.
-- 
FFmpeg = Freak Funny Mastodontic Plastic Exxagerate Geisha
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