PDA

View Full Version : strange audio sync




macyman
18 Dec 2002, 12:24 AM
I always extract audio but this one
is really getting me frustrated.
The .avi starts out fine and then gradually
gets out of sync. Ok, no big deal....I extract
audio and shrink/stretch depending on length
of video, but this does not work (actually I usually
do this when encoding, but should work here as well).
Not only the file information shows, under VirtualDub/Frame Rate:
Source Rate Adjustment
no change (current: 23.976 fps)
change so video and audio durations match (10799.018 fps)
Of course, I get the usual error message when
opening the file:
....has detected an improper VBR...etc.
What am I doing wrong?

Enchanter
18 Dec 2002, 06:55 AM
Sounds like you have an audio file with low sampling rate (22KHz or below), which always gives synch. problems. I have no definite fix for this, but you could try upsampling the audio to at least 44.1KHz and mux it with the original AVI file. See how it goes.

macyman
18 Dec 2002, 07:59 AM
actually, the audio stream info is as follows:

sampling rate: 48000Hz
Channels: 2 (stereo)
Sample precision: 0-bit
Compression: Fraunhofer IIS MPEG Layer-3 Codec
Preload skew: 384 samples (0.01s)
# of frames: 248379

Does this help...because nothing has, yet!
Thanks:(

Enchanter
18 Dec 2002, 08:21 AM
Is the audio length the same with the video's? You will need to take into account any difference between the play length and input that in the Interleaving settings.

macyman
18 Dec 2002, 09:41 AM
what identifies the video length? Is it the #
of frames?
If so, it shows 142925, while audio is 248379.
Is this what you mean?
So how would I calculate digit to input
under Interleaving settings?
Thanks!