Opened 2 months ago

Last modified 2 months ago

#6641 open enhancement

Severe artifacts when decoding WMV / WMV3 (Windows Media Video 9) / VC-1 videos

Reported by: batou Owned by:
Priority: wish Component: avcodec
Version: git-master Keywords: vc1
Cc: Blocked By:
Blocking: Reproduced by developer: yes
Analyzed by developer: no

Description

Summary of the bug:
I've noticed that new versions of mpv video player cannot play WMV videos reliably anymore. There are always visual artifacts every minute or so (keyframes maybe?).

Today I had some time and decided to investigate. Artifacting only occurs with VC-1 WMV videos (not older codecs). I've asked for help from mpv team but they sent me here since it's not an mpv issue.

Here's an example of artifacts: Left is ffmpeg-based player (mpv) and right is a player that doesn't use ffmpeg:

https://i.imgur.com/jtHTe34.jpg

Usually, it's not as severe as this example but this bug makes WMV videos completely unwatchable in mpv.

Sample video: http://samples.mplayerhq.hu/V-codecs/WMV9/halo2_wmp9_WMV3+audio0x162.wmv

$ mpv --version
mpv 0.26.0-237-g5771f7abf4 (C) 2000-2017 mpv/MPlayer/mplayer2 projects
 built on Linux x86_64
ffmpeg library versions:
   libavutil       55.74.100
   libavcodec      57.105.100
   libavformat     57.81.100
   libswscale      4.7.103
   libavfilter     6.102.100
   libswresample   2.8.100
ffmpeg version: N-87204-gd8bc198d09

Attachments (1)

Screenshot from 2017-09-06 15-01-49.jpg (55.4 KB) - added by batou 2 months ago.
image of artifacts

Download all attachments as: .zip

Change History (7)

Changed 2 months ago by batou

image of artifacts

comment:1 Changed 2 months ago by cehoyos

  • Component changed from ffmpeg to avcodec
  • Keywords vc1 added; wmv vc-1 removed
  • Priority changed from normal to wish
  • Reproduced by developer set
  • Status changed from new to open
  • Type changed from defect to enhancement
  • Version changed from unspecified to git-master

comment:2 Changed 2 months ago by heleppkes

The issue seems to occur irregardless if software or hardware decoding is used, so that should limit where the bug occurs. Probably header parsing or reference management.

comment:3 Changed 2 months ago by cehoyos

I would have expected that hardware decoders do not support this kind of samples - do they?

comment:4 Changed 2 months ago by heleppkes

Its ordinary WMV3 Main Profile, they should. (contrary to the OPs ticket description, its not VC-1, that would be Advanced Profile)

comment:5 Changed 2 months ago by cehoyos

I thought the sample contains old, partly unknown WMV3 from a time when there were no profiles, no?

comment:6 Changed 2 months ago by batou

@cehoyos: I have no idea how old that WMV file is but I've been unable to play _any_ WMV3/VC-1 video with mpv recently. mpv produces visual errors on all of the files I tried even though other players play them fine. It only happens with VC-1/wmv3 files (other forms on .wmv don't produce visual artifacts with mpv). It's really annoying to have to use some other player.

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