[FFmpeg-devel] [PATCH v3 1/1] avfilter/buffersink: Add video frame allocation callback

[Andreas Rheinhardt]

John Cox:
> On Sat, 22 Jul 2023 21:14:24 +0200, you wrote:
> 
>> John Cox:
>>> Add a callback to enable user allocation of video frames on the final
>>> stage of a filter chain.
>>>
>>> Signed-off-by: John Cox <jc at kynesim.co.uk>
>>> ---
>>>  libavfilter/buffersink.c | 21 +++++++++++++++++++++
>>>  libavfilter/buffersink.h | 27 +++++++++++++++++++++++++++
>>>  libavfilter/version.h    |  2 +-
>>>  3 files changed, 49 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/libavfilter/buffersink.c b/libavfilter/buffersink.c
>>> index 306c283f77..e99d444530 100644
>>> --- a/libavfilter/buffersink.c
>>> +++ b/libavfilter/buffersink.c
>>> @@ -62,6 +62,11 @@ typedef struct BufferSinkContext {
>>>      int sample_rates_size;
>>>  
>>>      AVFrame *peeked_frame;
>>> +
>>> +    union {
>>> +        AVBuffersinkAllocVideoFrameFunc video;
>>> +    } alloc_cb;
>>> +    void * alloc_v;
>>>  } BufferSinkContext;
>>>  
>>>  #define NB_ITEMS(list) (list ## _size / sizeof(*list))
>>> @@ -154,6 +159,21 @@ int attribute_align_arg av_buffersink_get_samples(AVFilterContext *ctx,
>>>      return get_frame_internal(ctx, frame, 0, nb_samples);
>>>  }
>>>  
>>> +static AVFrame *alloc_video_buffer(AVFilterLink *link, int w, int h)
>>> +{
>>> +    AVFilterContext *const ctx = link->dst;
>>> +    BufferSinkContext *const buf = ctx->priv;
>>> +    return buf->alloc_cb.video ? buf->alloc_cb.video(ctx, buf->alloc_v, w, h) :
>>> +                                 ff_default_get_video_buffer(link, w, h);
>>> +}
>>> +
>>> +void av_buffersink_set_alloc_video_frame(AVFilterContext *ctx, AVBuffersinkAllocVideoFrameFunc cb, void *v)
>>> +{
>>> +    BufferSinkContext *const buf = ctx->priv;
>>> +    buf->alloc_cb.video = cb;
>>> +    buf->alloc_v = v;
>>> +}
>>> +
>>>  static av_cold int common_init(AVFilterContext *ctx)
>>>  {
>>>      BufferSinkContext *buf = ctx->priv;
>>> @@ -381,6 +401,7 @@ static const AVFilterPad avfilter_vsink_buffer_inputs[] = {
>>>      {
>>>          .name = "default",
>>>          .type = AVMEDIA_TYPE_VIDEO,
>>> +        .get_buffer = {.video = alloc_video_buffer},
>>>      },
>>>  };
>>>  
>>> diff --git a/libavfilter/buffersink.h b/libavfilter/buffersink.h
>>> index 64e08de53e..2419d1bd80 100644
>>> --- a/libavfilter/buffersink.h
>>> +++ b/libavfilter/buffersink.h
>>> @@ -166,6 +166,33 @@ int av_buffersink_get_frame(AVFilterContext *ctx, AVFrame *frame);
>>>   */
>>>  int av_buffersink_get_samples(AVFilterContext *ctx, AVFrame *frame, int nb_samples);
>>>  
>>> +/**
>>> + * Callback from av_buffersink_set_alloc_video_frame to allocate 
>>> + * a frame 
>>> + *  
>>> + * @param ctx pointer to a context of the abuffersink AVFilter.
>>> + * @param v opaque pointer passed to 
>>> + *          av_buffersink_set_alloc_video_frame
>>> + * @param w width of frame to allocate 
>>> + * @param height of frame to allocate 
>>> + *  
>>> + * @return 
>>> + *         - The newly allocated frame
>>> + *         - NULL if error
>>> + */
>>> +typedef AVFrame *(*AVBuffersinkAllocVideoFrameFunc)(AVFilterContext * ctx, void * v, int w, int h);
>>> +
>>> +/**
>>> + * Set a video frame allocation method for buffersink
>>> + *
>>> + * @param ctx pointer to a context of the abuffersink AVFilter.
>>> + * @param cb Callback to the allocation function. If set to NULL 
>>> + *           then the default avfilter allocation function will
>>> + *           be used.
>>> + * @param v  Opaque to pass to the allocation function
>>> + */
>>> +void av_buffersink_set_alloc_video_frame(AVFilterContext *ctx, AVBuffersinkAllocVideoFrameFunc cb, void * v);
>>> +
>>>  /**
>>>   * @}
>>>   */
>>> diff --git a/libavfilter/version.h b/libavfilter/version.h
>>> index c001693e3c..54950497be 100644
>>> --- a/libavfilter/version.h
>>> +++ b/libavfilter/version.h
>>> @@ -31,7 +31,7 @@
>>>  
>>>  #include "version_major.h"
>>>  
>>> -#define LIBAVFILTER_VERSION_MINOR   8
>>> +#define LIBAVFILTER_VERSION_MINOR   9
>>>  #define LIBAVFILTER_VERSION_MICRO 102
>>
>> Not commenting on the actual patch, but when bumping minor, you need to
>> reset micro.
> 
> To zero? or one? (I'm guessing 0)
> 

100

- Andreas