Comments on: Why is it so friggin’ hard to make trivial changes to a video?

By: AVS Video Converter to the rescue « Something better to do

AVS Video Converter to the rescue « Something better to do — Thu, 30 Jul 2009 04:40:55 +0000

[...] Something better to do Musings of an indignant mind « Why is it so friggin’ hard to make trivial changes to a video? [...]

By: jik

jik — Wed, 29 Jul 2009 21:54:15 +0000

My mencoder / ffmpeg plan failed. One of them — not sure which — is causing the video and audio to get out of sync with each other. Damn.

By: jik

jik — Wed, 29 Jul 2009 20:57:21 +0000

VirtualDub doesn’t support ASF files. *sigh*

By: abbasegal

abbasegal — Wed, 29 Jul 2009 20:46:05 +0000

VirtualDub with “Direct Stream Copy” enabled theoretically should do this (at least according to http://www.doom9.org/index.html?/virtualdub_procedures.htm). The one time I tried it it still wanted to re-encode, but I think I may have forgotten to tell it direct stream copy for audio as well as video.

It does seem like this shouldn’t be so difficult to do!

By: jik

jik — Wed, 29 Jul 2009 20:32:22 +0000

I tried using mencoder as you indicated and encountered two different problems:

1. With the input file format I’ve got, -oac copy -ovc copy produces a file that can’t be viewed by the players that were able to view the original file.

2. With the input file format I’ve got, -ss doesn’t work properly. The time specified to -ss isn’t the time that mencoder actually starts at — it gets blown up somehow to a much larger delay, although I wasn’t able to figure out exactly the relationship between the value specified to -ss and the delay that mencoder actually uses.

What I’m trying now is using mencoder without -ss or -endpos to produce a really big AVI file that ffmpeg is capable of reading, and then using ffmpeg with -ss and -t to produce a QuickTime movie. Yes, this means the file format is changed, but least the resolution is preserved.

By: Greg

Greg — Wed, 29 Jul 2009 20:27:01 +0000

I agree, everything having to do with video encoding is unnecessarily complex. All the tools are written either by windows programmers who think we just want a big lickable button and don’t understand anything or by pimply kids who want to prove how smart they are by making sure their documentation doesn’t explain anything and their tools are as baroque and complex as possible.

As it happens I did just this earlier today and this is what I came up with:

mencoder -ss 5:45 -endpos 5:25 -oac copy -ovc copy -o /tmp/output.mpeg input.mpeg

That starts at 5:45 in and keeps going until 11:05, ie, the resulting video is 5:25. Actually it doesn’t work perfectly because mencoder can only seek into to a key frame. Even then the first second or so was a bit corrupted because it wasn’t the right kind of key frame? Not sure.