[FFmpeg-trac] #7507(avfilter:new): hwupload: missing device platform

FFmpeg trac at avcodec.org
Mon Oct 22 14:37:55 EEST 2018

#7507: hwupload: missing device platform
             Reporter:  msiders      |                     Type:
               Status:  new          |  enhancement
            Component:  avfilter     |                 Priority:  normal
             Keywords:  hwupload,    |                  Version:
  hwaccel                            |  unspecified
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
 Summary of the bug:
 How to reproduce:
 % ffmpeg -hwaccel cuvid -hwaccel qsv -i input ... -filter_complex
 "hwupload" ... output


 The use of multiple "-hwaccel" parameters is valid, as they only
 initialize the gpu libraries.

 However, at time it's impossible to use two different GPUs because the
 lack of a "hwupload" filter parameter for selecting the target platform.

 Consider this example:
 - One PC with one nVidia card and an Intel i7 CPU.
 - This plaform has support for CUDA and QSV, and you can compile FFmpeg
 for supporting both.
 - Imagine then you execute the decoding part using CUDA, and the enconding
 with QSV.
 - In this case the graph of filters can be constructed: backtrace for the
 encoder, and fordward for the decoder.
 - And in the middle, you need to use one "hwdownload" plus "hwupload" to
 complete the graph filter.

 But, the problem is that the "hwupload" can't distinguish which hardware
 context to select.

 This problem doesn't exist with the "hwdownload" filter, as the target is
 all the time the software memory; and the source is based on the previous

 So, please can you expand the "hwupload" to support the target platform?
 Thank you.

Ticket URL: <https://trac.ffmpeg.org/ticket/7507>
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