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

[Muhammad Faiz]

On 1/27/17, wm4 <nfxjfg at googlemail.com> wrote:
> 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()

OK, I have known this.

>
> Might not be fully equivalent though due to ff_get_audio_buffer()

If it is permitted to not use ff_get_audio_buffer(), I will use
av_frame_make_writable().

Thank's.