[FFmpeg-devel] [PATCH v16 01/16] global: Prepare AVFrame for subtitle handling

[Anton Khirnov]

Quoting Soft Works (2021-11-25 18:53:24)
> @@ -759,9 +802,39 @@ void av_frame_move_ref(AVFrame *dst, AVFrame *src);
>   *              recommended to pass 0 here unless you know what you are doing.
>   *
>   * @return 0 on success, a negative AVERROR on error.
> + *
> + * @deprecated Use @ref av_frame_get_buffer2 instead and set @ref AVFrame.type
> + * before calling.
>   */
> +attribute_deprecated
>  int av_frame_get_buffer(AVFrame *frame, int align);
>  
> +/**
> + * Allocate new buffer(s) for audio, video or subtitle data.
> + *
> + * The following fields must be set on frame before calling this function:
> + * - format (pixel format for video, sample format for audio)
> + * - width and height for video
> + * - nb_samples and channel_layout for audio
> + * - type (AVMediaType)
> + *
> + * This function will fill AVFrame.data and AVFrame.buf arrays and, if
> + * necessary, allocate and fill AVFrame.extended_data and AVFrame.extended_buf.
> + * For planar formats, one buffer will be allocated for each plane.
> + *
> + * @warning: if frame already has been allocated, calling this function will
> + *           leak memory. In addition, undefined behavior can occur in certain
> + *           cases.
> + *
> + * @param frame frame in which to store the new buffers.
> + * @param align Required buffer size alignment. If equal to 0, alignment will be
> + *              chosen automatically for the current CPU. It is highly
> + *              recommended to pass 0 here unless you know what you are doing.
> + *
> + * @return 0 on success, a negative AVERROR on error.
> + */
> +int av_frame_get_buffer2(AVFrame *frame, int align);

Not sure whether this was asked already - why do we need this new
function? Seems to me you can accomplish the same thing by just adding
the type field to AVFrame. Then
- if type is AVMEDIA_TYPE_SUBTITLE -> allocate a subtitle
- if type is AVMEDIA_TYPE_{VIDEO,AUDIO} -> allocate video/audio
- otherwise detect video/audio as we do now

-- 
Anton Khirnov