[FFmpeg-devel] [PATCH V4 1/2] avutil: add ROI data struct and bump version

[Vittorio Giovara]

On Fri, Dec 28, 2018 at 3:17 AM Guo, Yejun <yejun.guo at intel.com> wrote:

> The encoders such as libx264 support different QPs offset for different
> MBs,
> it makes possible for ROI-based encoding. It makes sense to add support
> within ffmpeg to generate/accept ROI infos and pass into encoders.
>
> Typical usage: After AVFrame is decoded, a ffmpeg filter or user's code
> generates ROI info for that frame, and the encoder finally does the
> ROI-based encoding.
>
> The ROI info is maintained as side data of AVFrame.
>
> Signed-off-by: Guo, Yejun <yejun.guo at intel.com>
> ---
>  libavutil/frame.c   |  1 +
>  libavutil/frame.h   | 23 +++++++++++++++++++++++
>  libavutil/version.h |  2 +-
>  3 files changed, 25 insertions(+), 1 deletion(-)
>
> diff --git a/libavutil/frame.c b/libavutil/frame.c
> index 34a6210..bebc50e 100644
> --- a/libavutil/frame.c
> +++ b/libavutil/frame.c
> @@ -841,6 +841,7 @@ const char *av_frame_side_data_name(enum
> AVFrameSideDataType type)
>      case AV_FRAME_DATA_QP_TABLE_DATA:               return "QP table
> data";
>  #endif
>      case AV_FRAME_DATA_DYNAMIC_HDR_PLUS: return "HDR Dynamic Metadata
> SMPTE2094-40 (HDR10+)";
> +    case AV_FRAME_DATA_ROIS: return "Regions Of Interest";
>      }
>      return NULL;
>  }
> diff --git a/libavutil/frame.h b/libavutil/frame.h
> index 582ac47..3460b01 100644
> --- a/libavutil/frame.h
> +++ b/libavutil/frame.h
> @@ -173,6 +173,12 @@ enum AVFrameSideDataType {
>       * volume transform - application 4 of SMPTE 2094-40:2016 standard.
>       */
>      AV_FRAME_DATA_DYNAMIC_HDR_PLUS,
> +
> +    /**
> +     * Regions Of Interest, the data is an array of AVROI type, the array
> size
> +     * is implied by AVFrameSideData::size / sizeof(AVROI).
> +     */
> +    AV_FRAME_DATA_ROIS,
>

Any chance i could convince you of unfolding this acronym into
AV_FRAME_REGIONS_OF_INTEREST (and AVRegionOfInterest)?
When I first read it I thought you were talking about Return of Investments
or Request of Invention, which were mildly confusing.

The "AVFrameSideData::size" is a C++-ism, could you please use
"AVFrameSideData.size" like elsewhere in the header?

You should probably document that sizeof() of this struct is part of the
public ABI.


>  };
>
>  enum AVActiveFormatDescription {
> @@ -201,6 +207,23 @@ typedef struct AVFrameSideData {
>  } AVFrameSideData;
>
>  /**
> + * Structure to hold Region Of Interest.
> + *
> + * top/bottom/left/right are coordinates at frame pixel level.
>

what does  "pixel level" mean? May I suggest better wording?

    Number of pixels to discard from the the top/bottom/left/right border
of the frame to obtain the region of interest of the frame.

+ * They will be extended internally if the codec requires an alignment.
> + * If the regions overlap, the last value in the list will be used.
>

Isn't this encoder dependent too?


> + *
> + * qoffset is quant offset, it is encoder dependent.

+ */
> +typedef struct AVROI {
> +    size_t top;
> +    size_t bottom;
> +    size_t left;
> +    size_t right;
> +    int qoffset;
>

so int instead of float?

+} AVROI;
> +
> +/**
>   * This structure describes decoded (raw) audio or video data.
>   *
>   * AVFrame must be allocated using av_frame_alloc(). Note that this only
> diff --git a/libavutil/version.h b/libavutil/version.h
> index f997615..1fcdea9 100644
> --- a/libavutil/version.h
> +++ b/libavutil/version.h
> @@ -79,7 +79,7 @@
>   */
>
-- 
Vittorio