Jan 30 2010

Fixing an AVI index with mencoder

This is more a “note to self”, but I’m sure others find it useful as well.

Quite often I run across AVI files with a broken index. That index is used in media players to seek rapidly in the movie file. Without an index or with a corrupt index, seeking either does not work at all or takes a long time.

mencoder, which is available on almost any platform, allows you to massage AVI files besides tons of other operations on a never-ending list of video formats.

Here’s the command to repair a broken AVI index (I used the mplayer/mencoder version that comes with the FreeBSD ports collection):

$ mencoder -idx in.avi -ovc copy -oac copy -o out.avi
MEncoder 1.0rc2-4.2.1 (C) 2000-2007 MPlayer Team
CPU: Intel(R) Pentium(R) 4 CPU 3.60GHz (Family: 15, Model: 4, Stepping: 10)
CPUflags: Type: 15 MMX: 1 MMX2: 1 3DNow: 0 3DNow2: 0 SSE: 1 SSE2: 1
Compiled with runtime CPU detection.
success: format: 0  data: 0x0 - 0x2aea0000
AVI file format detected.
[aviheader] Video stream found, -vid 0
[aviheader] Audio stream found, -aid 1
AVI: Generated index table for 332070 chunks!
VIDEO:  [XVID]  640x272  12bpp  23.976 fps  994.0 kbps (121.3 kbyte/s)
[V] filefmt:3  fourcc:0x44495658  size:640x272  fps:23.98  ftime:=0.0417
videocodec: framecopy (640x272 12bpp fourcc=44495658)
audiocodec: framecopy (format=55 chans=2 rate=48000 bits=0 B/s=17579 sample-0)
Writing header...
ODML: Aspect information not (yet?) available or unspecified, not writing vprp header.
Writing header...
ODML: Aspect information not (yet?) available or unspecified, not writing vprp header.
Writing index...81f (99%) 7391.58fps Trem:   0min 690mb  A-V:0.047 [993:140]]
Writing header...
ODML: Aspect information not (yet?) available or unspecified, not writing vprp header.
Video stream:  993.962 kbit/s  (124245 B/s)  size: 628485708 bytes  5058.428 secs
Audio stream:  140.323 kbit/s  (17540 B/s)  size: 88735536 bytes  5058.936 secs
$

You guessed it right: “in.avi” is the broken file and “out.avi” is the repaired avi-file. The whole operation took a few seconds on this 700MB file.

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