[FFmpeg-trac] #5936(avcodec:new): Purple haze in mpeg4 decoding
FFmpeg
trac at avcodec.org
Thu Nov 10 03:03:39 EET 2016
#5936: Purple haze in mpeg4 decoding
---------------------------------+----------------------------------
Reporter: te36 | Type: defect
Status: new | Priority: normal
Component: avcodec | Version: 2.3.6
Keywords: | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
---------------------------------+----------------------------------
Summary:
I have ca. 3 TB/10 years of free-TV recordings created with (older
versions) of Mencoder (aka: ffmpeg). These play back fine with older
versions of XBMC/VLC (decoded by ffmpeg/libavcodec / mpeg4), but since
XBMC 13.1 and VLC 2.2, ffmpeg produces purple haze that is creeping in
from the side of the screen when the video is panning.
How to reproduce:
ffplay purple-haze-bug.avi
(on upload.ffmpeg.org or ticket)
Duration: 00:00:16.63, start: 0.000000, bitrate: 1454 kb/s
Stream #0:0: Video: mpeg4 (Simple Profile) (FMP4 / 0x34504D46),
yuv420p, 720x576 [SAR 64:45 DAR 16:9], 1383 kb/s, 25 fps, 25 tbr, 25 tbn,
25 tbc
...
Latest working versions:
<=ffmpeg 2.2.x (tested 2.2.16, 2.1, 2.0)
ffmpeg
tag 03bb99ae1a99fa315621308b885a8fc70702c9bc Jun 1, 2014 master
branch
ffplay version N-63655-g03bb99a Copyright (c) 2003-2014 the FFmpeg
developers
built on Nov 9 2016 14:43:54 with gcc 4.9.3 (Gentoo 4.9.3 p1.5,
pie-0.6.4)
configuration:
libavutil 52. 88.100 / 52. 88.100
libavcodec 55. 66.100 / 55. 66.100
libavformat 55. 42.100 / 55. 42.100
libavdevice 55. 13.101 / 55. 13.101
libavfilter 4. 5.100 / 4. 5.100
libswscale 2. 6.100 / 2. 6.100
libswresample 0. 19.100 / 0. 19.100
First purple haze version:
>=ffmpeg 2.3.0 (tested 2.3 and later).
ffmpeg
tag 9236f7b5a23b4907f7b2bf6346ecd88e6d76f1e0 Jun 14, 2014 master
branch
ffplay version N-63957-g9236f7b Copyright (c) 2003-2014 the FFmpeg
developers
built on Nov 9 2016 14:50:33 with gcc 4.9.3 (Gentoo 4.9.3 p1.5,
pie-0.6.4)
configuration:
libavutil 52. 89.100 / 52. 89.100
libavcodec 55. 66.101 / 55. 66.101
libavformat 55. 43.100 / 55. 43.100
libavdevice 55. 13.101 / 55. 13.101
libavfilter 4. 8.100 / 4. 8.100
libswscale 2. 6.100 / 2. 6.100
libswresample 0. 19.100 / 0. 19.100
I am only _guessing_ this is an avcodec issue because it looks very
much related to mpeg4 decoding of blocks panning in from "offscreen".
git diff 03bb99ae1a99fa315621308b885a8fc70702c9bc
9236f7b5a23b4907f7b2bf6346ecd88e6d76f1e0
produce 700k diff and i can not figure out what a likely cause is ;-(
I am sure there is some problem in mencoder, but i hope that ffmpeg will
continue to try to decode as good as possible even potentially buggy
videos as it did in the past. Especially videos encoded with (older
versions of) ffmpeg.
The example video is encoded with MEncoder 1.0rc1-4.1.2, but the problem
exists with at least up to Mencoder-1.1(which uses 0.10.2.git).
Sorry for reporting so late, did not have the time earlier and was hoping
somebody else would find this too.
--
Ticket URL: <https://trac.ffmpeg.org/ticket/5936>
FFmpeg <https://ffmpeg.org>
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