Opened 3 years ago

Last modified 2 years ago

#4360 open enhancement

reencode mbs even at -mbd 0 when coeffs require cliping

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

Description

Summary of the bug:

A specific sample video experiences heavy artifacts when transcoded to MPEG-1 video using -mbd 0 (or leaving it as default), even at very high bit rates. -q:v 1 increases the severity.

How to reproduce:

Download this video:
http://trailers.divx.com/divx_prod/profiles/Micayala_DivX1080p_ASP.divx

Run this (used Zoranoe git-9d7e42e 64-bit static build)

% ffmpeg -i Micayala_DivX1080p_ASP.divx -b:v 30000k -bf 5 -report -y artifacts.m1v

Notice artifacts on the DivX logo animations and both the start and end of the video.

Changing -b:v to 5000k or 30000k did not have any effect. -q:v 1 increased the severity. The problem does not occur when using -mbd 1 or -mbd 2.

Attachments (4)

artifacts-frame-22-qv1.png (34.7 KB) - added by ejlasota 3 years ago.
Frame 22 of encoded video using -q:v 1
artifacts-frame-15-b.png (16.7 KB) - added by ejlasota 3 years ago.
Artifacts on frame 15 (a B-frame)
artifacts-frame-30-p.png (32.8 KB) - added by ejlasota 3 years ago.
Artifacts on frame 30 (a P-frame)
ffmpeg-20150308-151313.log (193.7 KB) - added by ejlasota 3 years ago.
Report log

Download all attachments as: .zip

Change History (6)

Changed 3 years ago by ejlasota

Frame 22 of encoded video using -q:v 1

Changed 3 years ago by ejlasota

Artifacts on frame 15 (a B-frame)

Changed 3 years ago by ejlasota

Artifacts on frame 30 (a P-frame)

Changed 3 years ago by ejlasota

Report log

comment:1 Changed 2 years ago by michael

  • Component changed from undetermined to avcodec
  • Status changed from new to open
  • Summary changed from -mbd 0 causes artifacts when encoding a specific video to MPEG-1 to reencode mbs even at -mbd 0 when coeffs require cliping
  • Type changed from defect to enhancement

comment:2 Changed 2 years ago by cehoyos

  • Priority changed from normal to wish
  • Reproduced by developer set
  • Version changed from unspecified to git-master
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