[FFmpeg-trac] #10095(ffmpeg:new): contradictory documentation

FFmpeg trac at avcodec.org
Wed Dec 7 06:00:18 EET 2022

#10095: contradictory documentation
             Reporter:  Alin         |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:  ffmpeg       |                  Version:  4.4.3
             Keywords:               |               Blocked By:
  documentation abiguous misleading  |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
 Summary of the bug:
 on the page: https://trac.ffmpeg.org/wiki/Hardware/VAAPI
 " The -compression_level option controls the local speed/quality tradeoff
 in the encoder (that is, the amount of effort expended on trying to get
 the best results from local choices like motion estimation and mode
 decision), using a nebulous per-device scale. The argument is a small
 integer, from 1 up to some limit dependent on the device (not more than 7)
 - '''higher values are faster / lower stream quality'''."
 --> higher value is faster.

 "-compression_level integer

     For lossy, this is a quality/speed tradeoff. Higher values give better
 quality for a given size at the cost of increased encoding time. For
 lossless, this is a size/speed tradeoff. '''Higher values give smaller
 size at the cost of increased encoding time'''. More specifically, it
 controls the number of extra algorithms and compression tools used, and
 varies the combination of these tools. This maps to the method option in
 libwebp. The valid range is 0 to 6. Default is 4.
 --> higher value is increasing the encoding time (this is higher quality
 in my understanding).

 1. So what is the right statement:
 - Higher value is higher quality or lower quality?
 - Higher value is more processing or less processing?
 2. Valid range is 0 to 6 or 1 to 7?
 I am interested in connection to VAAPI with Intel iGPU (video encoding).
Ticket URL: <https://trac.ffmpeg.org/ticket/10095>
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