[FFmpeg-trac] #6260(ffmpeg:new): NVENC H.264 encoding causes aliasing / stair-stepping colors, worse on interlaced than progressive

FFmpeg trac at avcodec.org
Fri Mar 24 17:37:49 EET 2017


#6260: NVENC H.264 encoding causes aliasing / stair-stepping colors, worse on
interlaced than progressive
-------------------------------------+-------------------------------------
             Reporter:  alexpigment  |                     Type:  defect
               Status:  new          |                 Priority:  important
            Component:  ffmpeg       |                  Version:
             Keywords:  NVENC,       |  unspecified
  aliasing, interlaced,              |               Blocked By:
  progressive, chroma                |  Reproduced by developer:  0
             Blocking:               |
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:

 When encoding to H.264 with the NVENC encoder, I'm seeing a pronounced
 aliasing or stair-stepping effect that happens on the colors (chroma-
 only?) during motion. This occurs on progressive encodes, but is worse on
 interlaced encodes. I have verified this behavior on both an Nvidia 1060
 and an Nvidia 750 while using the newest static Win64 build from Zeranoe
 as well as a build from January.

 To rule out a problem with the GPU, driver, or NVENC itself, I used
 Staxrip x264 1.4.0.0 to encode with NVENC H.264 on 2 samples and saw no
 issues. Therefore, this issue appears to be specific to the FFMPEG
 implementation of NVENC. FFMPEG x264 does not suffer from this issue
 either.

 How to reproduce:

 % ffmpeg -i interlacedsample.mp4 -c:v h264_nvenc -b:v 20000000 -flags
 +ilme+ildct interlacedoutput.mp4

 View the file in a player that supports deinterlacing (I'm using WMP 12
 for consistency). Notice that the colors of the rings have massive stair-
 stepping around the curves, particularly in the lower right where the red
 and green intersect.

 As mentioned above, this also occurs on progressive, albeit to a lesser
 but still very problematic degree.

 % ffmpeg -i progressivesample.mp4 -c:v h264_nvenc -b:v 20000000
 progressiveoutput.mp4

 The same problem occurs here, most notably at hte top of the blue right
 and at the intersection of the green and red rings at the bottom left.

 ffmpeg version N-84348-gdb7a05d
 built on 2017-03-21

--
Ticket URL: <https://trac.ffmpeg.org/ticket/6260>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker


More information about the FFmpeg-trac mailing list