[FFmpeg-trac] #5822(avfilter:new): filter "scale_npp" fails to select correct algorithm (Nvidia CUDA/NPP scaler)

[FFmpeg]

#5822: filter "scale_npp" fails to select correct algorithm (Nvidia CUDA/NPP
scaler)
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             Reporter:  sdack       |                    Owner:
                 Type:  defect      |                   Status:  new
             Priority:  normal      |                Component:  avfilter
              Version:  git-master  |               Resolution:
             Keywords:  npp         |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
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Comment (by sdack):

 After getting some info from the Nvidia forums and further reading is this
 the situation as it presents itself to me:

 1. Nvidia's CUDA NPP functions are copies of Intel's IPP functions (NPP
 stands for Nvidia Performance Primitives and IPP stands for Intel
 Performance Primitives). Nvidia uses this fact to point to Intel's
 documentation when developers have questions about it.

 2. Intel have marked the corresponding function (and variations) as
 deprecated as of IPP v7. The current release is IPP v9.

 3. Intel have provided replacement functions with IPP v7, which users
 should be using instead. These allow to specify filter matrices, which I
 interpret as a sign of quality improvement and a confession on the poor
 quality of the ResizeSqrPixel function. ( see a light at the horizon...)

 4. Sadly (... and light is gone), Nvidia does not provide any of the
 replacement functions even when Intel have announced this change several
 versions ago. The replacements cannot be found in either CUDA 7.5
 (current) or CUDA 8.0rc1 (future). CUDA 8.0rc1 stills contain copy of the
 old functions, which Intel have now removed for the IPP libraries.

 In short, this function is a sinking ship. Sadly, is it the central part
 of the scale_npp module, too.

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Ticket URL: <https://trac.ffmpeg.org/ticket/5822#comment:7>
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