Re: Video and sound not synchronized for 640x480 AVI

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Thanks again Neil... it will be next week before I have time to try your
suggestions out. I'll let you know how I fare. I really appreciate your help.

--Ward.

"Neil Smith [MVP Digital Media]" wrote:

Appreciate the timing info, I wasn't sure it was clear from your
original post that the camera wasn't doing 25fps after all.

What are the detailed specs for the video and the codecs in use, when
you load it into Gspot http://www.headbands.com/gspot/ to analyse the
file ? Does it definitely report 30fps there - and which decoder is
listed ? (It's not unheard of for codecs to have "bugs" too !)

WMP should probably display the FPS under the Statistics menu.

If you load the file into the VirtualDub program from
http://www.virtualdub.org/ : does everything look OK there ?

And then if you re-save it as a new file, any changes on playback ?

To quickly shortcut things, it might also be worth tinkering with the
audio acceleration as per http://zachd.com/pss/pss.html#chipmunks in
case that has effect on video playback.

I can't explain why there mihgt be differences in playback at 320 vs
640 without checking the individual file contents and filter graph.

Cheers - Neil


On Sun, 16 Nov 2008 10:55:01 -0800, wardles
<wardles@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

Thanks for the tips Neil... but the problem is not with the audio. I have
taken movies of a stopwatch that clicks at each second. Then I play the AVI
back while running the stopwatch simultaneously. The recorded audio clicks
play back exactly right. The video, however, takes exactly 30 seconds to play
back a 25-second clip. The clip was recorded at 30 frames per second, or 750
frames in total. Therefore WMP is playing it back at 25 frames per second.
The audio is correct, the video plays back at the wrong frame rate. Any ideas
on that one?

Note that the playback frame rate is correct in both Quicktime and on the
Canon camera that recorded it, AND WMP plays back the correct frame rate with
a 320 x 240 resolution video. It's just that WMP plays back incorrect video
frame rate with 640 x 480 resolution.

"Neil Smith [MVP Digital Media]" wrote:

On Tue, 11 Nov 2008 21:42:04 -0800, wardles
<wardles@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

I'm running Windows Media Player 11 on XP Service Pack 3. I have a Canon
Powershot 870Si digital camera that takes movies in AVI format. When I take
movies at 640x480 resolution, they play back on the camera fine, but on
Windows Media Player, the sound rate plays back correctly but the video plays
back at 25 fps rather than the 30 it was shot at. After a 25 second movie,
the sound has run out and stopped on time, but the video is in slight slo-mo
and doesn't finish until 30 seconds have elapsed. The AVIs play back
correctly on QuickTime (well, nearly... the frame rate is correct but the
video is about 1/4 second delayed from the sound). When movies are recorded
at 320 x 240, they play back precisely right on WMP. (still the 1/4-second
delay on QuickTime). Can't find anything on the web... any ideas?


ZachD's site has several useful suggestions about the Sync issue :
http://zachd.com/pss/pss.html#0x80040256

It's not completely unheard of in many programs and edits, e.g.
http://ediusforum.grassvalley.com/forum/archive/index.php/t-1566.html
http://www.danslagle.com/mac/iMovie/audio/1001.shtml

One possible suggestion is if the audio is sampled at 48khz then in
fact the video isn't in slow-mo, the audio is in fast-mo, when played
back at 44.1khz ;-)

HTH
Cheers - Neil
------------------------------------------------
Digital Media MVP : 2004-2008
http://mvp.support.microsoft.com/mvpfaqs

------------------------------------------------
Digital Media MVP : 2004-2008
http://mvp.support.microsoft.com/mvpfaqs

.

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