2012-01-13.

== AVI

Problem with some old AVI files -- audio making shrill noises,
skipping quickly, and lots of errors from mplayer console output.

Looked up some programs (on a website recommendation):

http://sourceforge.net/projects/divfixpp/
"DivFix++ is yours AVI video repair and preview software.
It can repair AVI and DivX files (for now.)"

http://meteorite.sourceforge.net/download.php
"C++ code that repairs Matroska files."

But (when puzzled by not finding sourcecode for divfix), found
the useful link http://forums.gentoo.org/viewtopic-t-478357-start-0.html
claiming that mplayer/mencoder as usual can do everything:

mencoder -forceidx -ovc copy -oac copy -o out.avi in.avi

This worked perfectly for the multiple problematic avi files that stimulated the search.
There's still the matter of how some mkv files recode badly into mkv (poor/abysmal a/v sync)
in mencoder, in spite of playing fine in mplayer, whereas almost any avi that works will 
recode ok.

A good list of programs available for correcting/converting video files:
http://www.videohelp.com/tools/sections/linux-video-tools

== MKV

The "meteorite" (above) is claimed to be still the only mkv-fixer.
There's a linux binary (didn't find source-code), but this program has the annoying feature 
of being (apparently) purely GUI-based: "'drop' a file here".  Not handy for batches.

As with the simple mencoder line above that fixed the avi sync, there is here 
http://blog.mymediasystem.net/avchd/how-to-fixrepair-broken-matroska-mkv-files-with-linux/2/
the claim that extracting the tracks from the container, then re-merging them, solves many 
problems (due to the corrections applied during extraction).
mkvinfo -s $IN.mkv | head -3   
	# study disposition of tracks, and frame-rate
mkvextract tracks $IN.mkv 1:$IN-vid 3:$IN-aud
	# (1: and 3: are examples only!)
mkvmerge --default-duration 0:23.976fps $IN-vid $IN-aud -o $IN-corrected.mkv 
	# some claims of importance of video coming first (hard to believe?)
	# --default-duration to be the fps given for the video by mkvinfo


== mplayer audio-dump problem
[2012-04-15]

Similar to: http://lists.mplayerhq.hu/pipermail/mplayer-users/2011-April/082369.html
AVI file input, gives mplayer sitting at end after dumping audio, keeping updating
the console line about timing, but staying on the same time, drawing full cpu.
Using the option ":fast:" within the -ao options (pcm:fast:waveheader:file=...) 
prevents this, but using "-vc null" makes no difference.  Choice: always use fast.