Opened 9 years ago

Last modified 9 years ago

#4360 open enhancement

reencode mbs even at -mbd 0 when coeffs require cliping

Reported by: Eric Lasota 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 Eric Lasota 9 years ago.
Frame 22 of encoded video using -q:v 1
artifacts-frame-15-b.png (16.7 KB ) - added by Eric Lasota 9 years ago.
Artifacts on frame 15 (a B-frame)
artifacts-frame-30-p.png (32.8 KB ) - added by Eric Lasota 9 years ago.
Artifacts on frame 30 (a P-frame)
ffmpeg-20150308-151313.log (193.7 KB ) - added by Eric Lasota 9 years ago.
Report log

Download all attachments as: .zip

Change History (6)

by Eric Lasota, 9 years ago

Attachment: artifacts-frame-22-qv1.png added

Frame 22 of encoded video using -q:v 1

by Eric Lasota, 9 years ago

Attachment: artifacts-frame-15-b.png added

Artifacts on frame 15 (a B-frame)

by Eric Lasota, 9 years ago

Attachment: artifacts-frame-30-p.png added

Artifacts on frame 30 (a P-frame)

by Eric Lasota, 9 years ago

Attachment: ffmpeg-20150308-151313.log added

Report log

comment:1 by Michael Niedermayer, 9 years ago

Component: undeterminedavcodec
Status: newopen
Summary: -mbd 0 causes artifacts when encoding a specific video to MPEG-1reencode mbs even at -mbd 0 when coeffs require cliping
Type: defectenhancement

comment:2 by Carl Eugen Hoyos, 9 years ago

Priority: normalwish
Reproduced by developer: set
Version: unspecifiedgit-master
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