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

[wm4]

On Fri, 27 Jan 2017 18:42:03 +0700
Muhammad Faiz <mfcc64 at gmail.com> wrote:

> 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(+)
> 
> diff --git a/libavfilter/avfilter.c b/libavfilter/avfilter.c
> index c12d491..7e7e83c 100644
> --- a/libavfilter/avfilter.c
> +++ b/libavfilter/avfilter.c
> @@ -1235,6 +1235,23 @@ static int take_samples(AVFilterLink *link, unsigned min, unsigned max,
>          frame = ff_framequeue_peek(&link->fifo, 0);
>          av_samples_copy(buf->extended_data, frame->extended_data, p, 0, n,
>                          link->channels, link->format);
> +
> +        if (!av_frame_is_writable(frame)) {
> +            AVFrame *new = ff_get_audio_buffer(link, frame->nb_samples);
> +            if (!new)
> +                return AVERROR(ENOMEM);
> +            ret = av_frame_copy_props(new, frame);
> +            if (ret < 0)
> +                return ret;
> +            av_samples_copy(new->extended_data, frame->extended_data,
> +                            0, 0, frame->nb_samples,
> +                            av_frame_get_channels(frame),
> +                            frame->format);
> +            av_frame_unref(frame);
> +            av_frame_move_ref(frame, new);
> +            av_frame_free(&new);
> +        }
> +
>          frame->nb_samples -= n;
>          av_samples_copy(frame->extended_data, frame->extended_data, 0, n,
>                          frame->nb_samples, link->channels, link->format);

There's a function that does this automatically:
av_frame_make_writable()

Might not be fully equivalent though due to ff_get_audio_buffer()