audio visualisation to synch video?

[Arcon]

i've got once more an avi where audio and video are out of synch and i'd like to find the correct skew. i know that it can be done by trial and error, but i wonder if there is some kind of application that can show the video frames and visualize the audio track as e.g. a wave editor does so that i can use a scene with a shot to exactly determine the skew between the muzzle flash and the peak in the audio visualisation.

that would come in handy to speed up this process and make it more exact :)

[KpeX]

http://forum.doom9.org/showthread.php?s=&threadid=59412&highlight=audiograph

Here's a thread over in the avisynth forum about an avisynth filter that does about what you're looking for. hth,

[Arcon]

thanks, thats what i was looking for.
SetWorkingDir("G:\MISC\gnot\")
LoadPlugin("audgraph.dll")
audio=avisource("e:\tmp\jd.avi")
video=avisource("e:\tmp\jd.avi")
video=converttoyuy2(video)
return AudioGraph(AudioDub(video, audio), 20)

as .avs gives me both sound and video. i wonder if it is possible to convert the video from yv12 to something audgraph can process without losing the keyframes. seeking takes very long this way. any avisynth expert who knows of a way? if not i'll probably try it in the avisynth forum and post the final script here later.

[KpeX]

Avisynth doesn't have keyframes no matter what the colorspace, avisynth simulates an uncompressed AVI, so you'll probably have to deal with the seeking speed. You could use Trim() to only examine a certain part of the video, perhaps.

[Arcon]

and one probably last question: how can i import files with ac3-audio? avisource says 'acm failed to suggest a compatible pcm format' in that case.

[KpeX]

There are only two options I know of:

Grab one of the lastest CVS builds from sh0dan's homepage, and use DirectShowSource(), assuming you have an AC3 direct show filter installed. DirectShowSource audio support is still in early stages, however, so good luck.

Second option is ACM, There are two experimental AC3 ACM codecs that I know of, one by fcchandler:
http://fcchandler.home.comcast.net/AC3ACM/index.html

and one by Valex:
http://forum.doom9.org/showthread.php?s=&threadid=61119

[Arcon]

thanks for the hints :)