[FFmpeg-devel] [PATCH 1/4] avfilter/scale_vt: implement frame crop

[Koushik Dutta]

Is anyone reviewing videotoolbox or qsv filters? The scale_cuda
version of this patch was merged.

On Sat, Oct 19, 2024 at 10:58 PM Koushik Dutta <koushd at gmail.com> wrote:
>
> The crop filter has no effect on scale_vt:
>
> -vf crop=100:100,scale_vt=300x300
>
> Hardware frames (AV_PIX_FMT_FLAG_HWACCEL) are expected to use the crop_* properties,
> as seen in the implementation vf_crop.c.
>
> The current workaround is to hwdownload the full frame
> and perform the crop on CPU.
>
> Signed-off-by: Koushik Dutta <koushd at gmail.com>
> ---
>  libavfilter/vf_scale_vt.c | 50 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
>
> diff --git a/libavfilter/vf_scale_vt.c b/libavfilter/vf_scale_vt.c
> index 05f4e7b797..3da46a6cd5 100644
> --- a/libavfilter/vf_scale_vt.c
> +++ b/libavfilter/vf_scale_vt.c
> @@ -109,6 +109,8 @@ static av_cold int scale_vt_init(AVFilterContext *avctx)
>          VTSessionSetProperty(s->transfer, kVTPixelTransferPropertyKey_DestinationYCbCrMatrix, value);
>      }
>
> +    VTSessionSetProperty(s->transfer, kVTPixelTransferPropertyKey_ScalingMode, kVTScalingMode_CropSourceToCleanAperture);
> +
>      return 0;
>  }
>
> @@ -132,6 +134,18 @@ static int scale_vt_filter_frame(AVFilterLink *link, AVFrame *in)
>      CVPixelBufferRef src;
>      CVPixelBufferRef dst;
>
> +    int left;
> +    int top;
> +    int width;
> +    int height;
> +    CFNumberRef crop_width_num;
> +    CFNumberRef crop_height_num;
> +    CFNumberRef crop_offset_left_num;
> +    CFNumberRef crop_offset_top_num;
> +    const void *clean_aperture_keys[4];
> +    const void *source_clean_aperture_values[4];
> +    CFDictionaryRef source_clean_aperture;
> +
>      AVFrame *out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
>      if (!out) {
>          ret = AVERROR(ENOMEM);
> @@ -153,8 +167,43 @@ static int scale_vt_filter_frame(AVFilterLink *link, AVFrame *in)
>      if (s->colour_matrix != AVCOL_SPC_UNSPECIFIED)
>          out->colorspace = s->colour_matrix;
>
> +    width = (in->width - in->crop_right) - in->crop_left;
> +    height = (in->height - in->crop_bottom) - in->crop_top;
> +    // The crop offsets are relative to the center of the frame.
> +    // the crop width and crop height are relative to the center of the crop rect, not top left as normal.
> +    left = in->crop_left - in->width / 2 + width / 2;
> +    top = in->crop_top - in->height / 2 + height / 2;
> +    crop_width_num = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &width);
> +    crop_height_num = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &height);
> +    crop_offset_left_num = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &left);
> +    crop_offset_top_num = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &top);
> +
> +    clean_aperture_keys[0] = kCVImageBufferCleanApertureWidthKey;
> +    clean_aperture_keys[1] = kCVImageBufferCleanApertureHeightKey;
> +    clean_aperture_keys[2] = kCVImageBufferCleanApertureHorizontalOffsetKey;
> +    clean_aperture_keys[3] = kCVImageBufferCleanApertureVerticalOffsetKey;
> +
> +    source_clean_aperture_values[0] = crop_width_num;
> +    source_clean_aperture_values[1] = crop_height_num;
> +    source_clean_aperture_values[2] = crop_offset_left_num;
> +    source_clean_aperture_values[3] = crop_offset_top_num;
> +
> +    source_clean_aperture = CFDictionaryCreate(kCFAllocatorDefault,
> +                                                    clean_aperture_keys,
> +                                                    source_clean_aperture_values,
> +                                                    4,
> +                                                    &kCFTypeDictionaryKeyCallBacks,
> +                                                    &kCFTypeDictionaryValueCallBacks);
> +
> +    CFRelease(crop_width_num);
> +    CFRelease(crop_height_num);
> +    CFRelease(crop_offset_left_num);
> +    CFRelease(crop_offset_top_num);
> +
>      src = (CVPixelBufferRef)in->data[3];
>      dst = (CVPixelBufferRef)out->data[3];
> +    CVBufferSetAttachment(src, kCVImageBufferCleanApertureKey,
> +                           source_clean_aperture, kCVAttachmentMode_ShouldPropagate);
>      ret = VTPixelTransferSessionTransferImage(s->transfer, src, dst);
>      if (ret != noErr) {
>          av_log(ctx, AV_LOG_ERROR, "transfer image failed, %d\n", ret);
> @@ -162,6 +211,7 @@ static int scale_vt_filter_frame(AVFilterLink *link, AVFrame *in)
>          goto fail;
>      }
>
> +    CFRelease(source_clean_aperture);
>      av_frame_free(&in);
>
>      return ff_filter_frame(outlink, out);
> --
> 2.39.5 (Apple Git-154)
>