[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>
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