[FFmpeg-devel] [PATCH] lavfi: psnr filter

[Paul B Mahol]

On 7/7/13, Derek Buitenhuis <derek.buitenhuis at gmail.com> wrote:
> On 7/6/2013 7:54 AM, Paul B Mahol wrote:
>> diff --git a/libavfilter/vf_psnr.c b/libavfilter/vf_psnr.c
>> new file mode 100644
>> index 0000000..9b87a61
>> --- /dev/null
>> +++ b/libavfilter/vf_psnr.c
>> @@ -0,0 +1,310 @@
>> +/*
>> + * Copyright (c) 2011 Roger Pau Monn** <roger.pau at entel.upc.edu>
>
> This doesn't display right for me... maybe I'm mussing some unicode symbol?
> Seems to show up fine in Google Chrome, though.
>
>> +    {"stats_file", "set file where to store per-frame difference
>> information", OFFSET(stats_file_str), AV_OPT_TYPE_STRING, {.str=NULL},  0,
>> 0, FLAGS },
>> +    {"f",          "set file where to store per-frame difference
>> information", OFFSET(stats_file_str), AV_OPT_TYPE_STRING, {.str=NULL},  0,
>> 0, FLAGS },
>
> "Where to store per-frame difference information."
>
>> +    if (s->stats_file) {
>> +        fprintf(s->stats_file, "n:%d mse_avg:%0.2f ", s->nb_frames, mse);
>> +        for (j = 0; j < s->desc->nb_components; j++) {
>> +            c = s->is_rgb ? s->rgba_map[j] : j;
>> +            fprintf(s->stats_file, "mse_%c:%0.2f ", s->comps[j],
>> comp_mse[c]);
>> +        }
>> +        for (j = 0; j < s->desc->nb_components; j++) {
>> +            c = s->is_rgb ? s->rgba_map[j] : j;
>> +            fprintf(s->stats_file, "s%c:%0.2f ",
>> +                    s->comps[j], get_psnr(comp_mse[c], 1, s->max[c]));
>> +        }
>> +        fprintf(s->stats_file, "\n");
>> +    }
>
> This is really useless for anything but the ffmpeg CLI util. libavfilter now
> has facilities to to properly pass back information via the library API
> metadata.
>
> For example:
>
> http://git.videolan.org/?p=ffmpeg.git;a=blob;f=libavfilter/af_silencedetect.c;h=eb4718b268099d203562de57263ab56d929bc44e;hb=HEAD#l97
>
> It shouldn't be much work to change it to and/or add this, and it actually
> makes
> libavfilter useful.

Will add.

>
>> +    if (s->stats_file_str) {
>> +        s->stats_file = fopen(s->stats_file_str, "w");
>> +        if (!s->stats_file) {
>> +            av_log(ctx, AV_LOG_ERROR,
>> +                   "Could not open stats file %s: %s\n",
>> +                   s->stats_file_str, strerror(errno));
>> +            return AVERROR(EINVAL);
>> +        }
>> +    }
>
> Ditto.

?

>
>> +    s->desc = av_pix_fmt_desc_get(inlink->format);
>> +    if (ctx->inputs[0]->w != ctx->inputs[1]->w ||
>> +        ctx->inputs[0]->h != ctx->inputs[1]->h) {
>> +        av_log(ctx, AV_LOG_ERROR,
>> +               "Width and/or heigth of input videos are different, could
>> not calculate PSNR\n");
>> +        return AVERROR(EINVAL);
>> +    }
>> +    if (ctx->inputs[0]->format != ctx->inputs[1]->format) {
>> +        av_log(ctx, AV_LOG_ERROR,
>> +               "Input filters have different pixel formats, could not
>> calculate PSNR\n");
>> +        return AVERROR(EINVAL);
>> +    }
>
> Can we not compare nb_frames to make sure they're the same length? What
> sort of behavior does this filter exhibit if two clips of varying length
> are given?
>

It will stop when shortest stream ends.

>> +    s->is_rgb = ff_fill_rgba_map(s->rgba_map, inlink->format) >= 0;
>> +    s->comps[0] = s->is_rgb ? 'r' : 'y' ;
>> +    s->comps[1] = s->is_rgb ? 'g' : 'u' ;
>> +    s->comps[2] = s->is_rgb ? 'b' : 'v' ;
>> +    s->comps[3] = 'a';
>
> No XYZ? :P

patch welcome

>
> - Derek
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