Change #286506

Comments

avfilter/vf_scale_cuda: add YUV to RGB color space conversion
When the input colorspace is unspecified, BT.601 (SMPTE 170M) is used
as the default, matching swscale behavior. Both limited and full range
inputs are handled, with full range high bit depth input normalized by
the code maximum. BT.2020 constant luminance is rejected, as it is not
a plain matrix transform. Results are rounded to the nearest value.

The conversion kernels use direct texture reads for luma and simple
coordinate mapping for chroma upsampling, avoiding unnecessary
Subsample_Nearest overhead since color conversion operates at the same
resolution. Simultaneous resize and color conversion is rejected
with an error directing users to chain separate scale_cuda instances.
Hardware cropping is honored, by checking the visible frame size
against the output size per frame.

As the software format of CUDA frames is unknown during negotiation,
the input and output color properties are negotiated independently.
RGB output is always negotiated as full range RGB, so that following
filters see the properties of the converted frames, while other output
follows the input. Plain scaling rejects a matrix or range on the
output that differs from the input, as it cannot convert the samples.

Co-authored-by: Timo Rothenpieler <timo@rothenpieler.org>
Co-authored-by: Reinhard Nißl <rnissl@gmx.de>
Assisted-By: Claude Opus 5.5

Changed files

• libavfilter/vf_scale_cuda.c
• libavfilter/vf_scale_cuda.cu
• libavfilter/vf_scale_cuda.h