[FFmpeg-devel] [PATCH 1/6] avutil/mastering_display_metadata: add av_mastering_display_metadata_alloc2()

[wm4]

On Sun, 11 Dec 2016 00:33:03 -0300
James Almer <jamrial at gmail.com> wrote:

> Also deprecate av_mastering_display_metadata_alloc().
> 
> This new alloc function optionally returns the size of the AVMasteringDisplayMetadata
> struct.
> 
> Signed-off-by: James Almer <jamrial at gmail.com>
> ---
>  libavutil/mastering_display_metadata.c | 12 ++++++++++++
>  libavutil/mastering_display_metadata.h | 17 +++++++++++++++++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/libavutil/mastering_display_metadata.c b/libavutil/mastering_display_metadata.c
> index e1683e5..872f14b 100644
> --- a/libavutil/mastering_display_metadata.c
> +++ b/libavutil/mastering_display_metadata.c
> @@ -29,6 +29,18 @@ AVMasteringDisplayMetadata *av_mastering_display_metadata_alloc(void)
>      return av_mallocz(sizeof(AVMasteringDisplayMetadata));
>  }
>  
> +AVMasteringDisplayMetadata *av_mastering_display_metadata_alloc2(size_t *size)
> +{
> +    AVMasteringDisplayMetadata *mastering = av_mallocz(sizeof(AVMasteringDisplayMetadata));
> +    if (!mastering)
> +        return NULL;
> +
> +    if (size)
> +        *size = sizeof(*mastering);
> +
> +    return mastering;
> +}
> +
>  AVMasteringDisplayMetadata *av_mastering_display_metadata_create_side_data(AVFrame *frame)
>  {
>      AVFrameSideData *side_data = av_frame_new_side_data(frame,
> diff --git a/libavutil/mastering_display_metadata.h b/libavutil/mastering_display_metadata.h
> index 936533f..32357b3 100644
> --- a/libavutil/mastering_display_metadata.h
> +++ b/libavutil/mastering_display_metadata.h
> @@ -21,6 +21,10 @@
>  #ifndef AVUTIL_MASTERING_DISPLAY_METADATA_H
>  #define AVUTIL_MASTERING_DISPLAY_METADATA_H
>  
> +#include <stddef.h>
> +#include <stdint.h>
> +
> +#include "attributes.h"
>  #include "frame.h"
>  #include "rational.h"
>  
> @@ -74,10 +78,23 @@ typedef struct AVMasteringDisplayMetadata {
>   *
>   * @return An AVMasteringDisplayMetadata filled with default values or NULL
>   *         on failure.
> + *
> + * @deprecated Use av_mastering_display_metadata_alloc2().
>   */
> +attribute_deprecated
>  AVMasteringDisplayMetadata *av_mastering_display_metadata_alloc(void);
>  
>  /**
> + * Allocate an AVMasteringDisplayMetadata structure and set its fields to
> + * default values. The resulting struct can be freed using av_freep().
> + *
> + * @param size pointer for AVMasteringDisplayMetadata structure size to store (optional)
> + * @return An AVMasteringDisplayMetadata filled with default values or NULL
> + *         on failure.
> + */
> +AVMasteringDisplayMetadata *av_mastering_display_metadata_alloc2(size_t *size);
> +
> +/**
>   * Allocate a complete AVMasteringDisplayMetadata and add it to the frame.
>   *
>   * @param frame The frame which side data is added to.

I guess it's ok to deprecate the old function, since it couldn't be
used correctly.

Here are some brainstormed alternative ideas to adding those ...2()
functions:
- add functions to add side data by type to AVFrames etc.
- provide a generic function that allocates side data by passing the
  side data ID to it (would need separate ones for packet and stream
  side data)
- unify the side data enums into one (i.e. merge packet and frame side
  data), and provide a central function to allocate or retrieve size by
  side data ID
- provide functions that return the struct size, and let the user
  use av_mallocz() (instead of both allocating and returning the size)