[FFmpeg-trac] #7124(swscale:reopened): Unexpected results from YUV-RGB color space conversion optimization on POWER8/LE

FFmpeg trac at avcodec.org
Thu Apr 5 14:33:07 EEST 2018


#7124: Unexpected results from YUV-RGB color space conversion optimization on
POWER8/LE
-------------------------------------+------------------------------------
             Reporter:  seiko        |                    Owner:
                 Type:  defect       |                   Status:  reopened
             Priority:  normal       |                Component:  swscale
              Version:  git-master   |               Resolution:
             Keywords:  ppc altivec  |               Blocked By:
             Blocking:               |  Reproduced by developer:  1
Analyzed by developer:  0            |
-------------------------------------+------------------------------------
Changes (by cehoyos):

 * keywords:  ppc => ppc altivec
 * status:  closed => reopened
 * version:  unspecified => git-master
 * resolution:  worksforme =>
 * reproduced:  0 => 1


Comment:

 Replying to [comment:3 seiko]:

 > It's not about the performance but the sanity of conversion.
 Sorry, I realized that by now. Allow me to repeat that the original report
 was just invalid, post all necessary information including the command
 line you tested together with the complete, uncut console output here in
 the ticket, do not use external resources except for large source files.

 {{{
 $ ffmpeg -lavfi testsrc2,format=yuv420p -pix_fmt rgb24 -vcodec png -t 10
 out.nut
 ffmpeg version N-90615-g53688b6 Copyright (c) 2000-2018 the FFmpeg
 developers
   built with gcc 6.3.1 (GCC) 20170515 (Advance-Toolchain-at10.0) IBM AT 10
 branch, based on subversion id 248065.
   configuration: --enable-gpl --cpu=power8 --cc=/opt/at10.0/bin/gcc
   libavutil      56. 13.100 / 56. 13.100
   libavcodec     58. 17.100 / 58. 17.100
   libavformat    58. 10.100 / 58. 10.100
   libavdevice    58.  2.100 / 58.  2.100
   libavfilter     7. 14.100 /  7. 14.100
   libswscale      5.  0.102 /  5.  0.102
   libswresample   3.  0.101 /  3.  0.101
   libpostproc    55.  0.100 / 55.  0.100
 Stream mapping:
   format -> Stream #0:0 (png)
 Press [q] to stop, [?] for help
 [swscaler @ 0x10019995be0] ALTIVEC: Color Space RGB24
 Output #0, nut, to 'out.nut':
   Metadata:
     encoder         : Lavf58.10.100
     Stream #0:0: Video: png (MPNG / 0x474E504D), rgb24, 320x240 [SAR 1:1
 DAR 4:3], q=2-31, 200 kb/s, 25 fps, 51200 tbn, 25 tbc (default)
     Metadata:
       encoder         : Lavc58.17.100 png
 frame=  250 fps=0.0 q=-0.0 Lsize=    2289kB time=00:00:09.96
 bitrate=1882.4kbits/s speed=56.6x
 video:2286kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: 0.130058%
 }}}
 The output file is clearly recognizable but looks broken.
 I tested a few of the libavcodec altivec optimizations and they work fine
 on le (and are tested by fate), this is indeed a specific issue in
 libswscale.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/7124#comment:4>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker


More information about the FFmpeg-trac mailing list