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

[Koushik Dutta]

Thanks! I believe I have made the necessary fixes and resubmitted the
patch. I also resubmitted another related patch that adds support for
negative scale values that preserve aspect ratio, similar to what the
scale, scale_cuda, and scale_vaapi filters support.

Koush

On Sun, Nov 24, 2024 at 8:58 AM Zhao Zhili <quinkblack at foxmail.com> wrote:
>
>
>
> > On Nov 21, 2024, at 00:40, Koushik Dutta <koushd at gmail.com> wrote:
> >
> > 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);
>
> After applied crop, the output frame still holding crop info which are copied from input frame
> via
>     ret = av_frame_copy_props(out, in);
>
> The output frame crop info should be reset.
>
>
> >>     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);
>
> Should be released early in case of error which leading to leak (the goto fail).
>
> >>     av_frame_free(&in);
> >>
> >>     return ff_filter_frame(outlink, out);
> >> --
> >> 2.39.5 (Apple Git-154)
> >>
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