Re: MPEG2 encode from video. Q--problem with sound sliding out of sync
- From: "B. Peg" <bent_peg@xxxxxxxxxxxxxxxx>
- Date: Fri, 22 Jul 2005 15:53:31 GMT
> "Charlie+" wrote:
> Problem:
> The VHS tape plays sound perfectly in sync as does the .mpg file from
> HD. If I look at the final DVD at 2/3 through - the sound has
> slipped by about 1/2 second which is seriously out. It seems to be
> sliding out of sync rather than a sudden jump and seems to start a
> little bit in the Author stage and by the Shrunk stage is far worse -
> Anyone clued up know what the problem might be? TIA
> If it were a sudden jump it could be possibly corrected with TMPEnc
> Pro - but sliding out of sync it would need the whole sound track
> shortening and then resync to the video! Much better to stop the
> problem in the first place if possible? net searches dont seem to
> have any answers. Novice in this so KIS please!
AH, the slipping out of sync problem -- again.
Charles:
This is what I have saved and written down on an AVI rip I did where the
audio synch was off at the end. This seems to be a problem that pops up now
and then. Maybe it'll help, maybe not.
Anyway, here it is (at least I saved this!):
One theory is if the sound card is not really at 44,100 Hz and is actually
at 44,109 then the audio could be off several seconds at the end of the
movie - sort of a compression or expansion of the audio file. This one
might explain why a ripped movie is different when played on various players
or computers.
I did one where the audio and video synch was off a few seconds on a
DivX AVI movie rip that I did to put it in my portable Archos player. The
thing was off a little at the beginning and a whole bunch at the end.
A couple of pieces of software can help: VirtualDub and SoundForge
(VirtualDub is free, other is trial I believe but I bought SF as I like it).
There may be another freeware sound editor out there that can do the same
resample.
Here is the outline as I wrote it down:
Open the AVI file in VirtualDub and make note of the frame counter time
(bottom of screen) for a sound near the beginning and one near the end. I
used someone banging a hammer for one near the beginning and a door slam at
the end for the second test point.
In VirtualDub, you can rip a WAV file out of the AVI file. Using
SoundForge, load the large WAV file and scan to the two "approximate" times
noted above and listen for the sounds you are using to mark the file (i.e.
the hammer and shout noise in mine). Make an exact note of the "real
occurring time" of the two noises at the bottom of the screen in SoundForge.
Add or subtract the two times in SoundForge from the frame video times in
VirtualDub. The object is to get the two times to agree with each other as
close as you can.
For the first sample (door slam), you can shift the WAV file time ahead or
back using either an "Insert Silence" at the beginning of the WAV file or
"Delete" it to match the above video frame time for the door slam. Still,
the end synch
may be off.
Now come the little trick. You can use "Resample" in SoundForge and shift
the audio (either compress or expand the length of the track) for the end
sample
(shout noise).
Open "Resample" (leave anti-alias off), check the box regarding "Sample
Only" so you do not save it (yet), and change the Sample Rate from 44,100 Hz
to say 44,110 and
see where the new audio times are in comparison to the frame times earlier
done.
You can increment or decrement the 44,100 number and watch the audio times
change in SoundForge. The idea is to change it and get it to closely match
the video frames. You cannot get it exact but pretty darn close.
Once done, set the Resample back to 44,100, uncheck the Sample only box, and
save the WAV file. You can then set both the video and audio pulldowns in
VirtualDub to Streaming and load the AVI file. Under the Audio select your
new WAV,
Press F7 (or Save AVI), and let it rip. It's pretty fast here (4-5
minutes).
However, now you have a DivX AVI with a WAV file and it's pretty large. Run
it back through VirtualDub. Turn on Full Processing Mode in both Video and
Audio pulldowns. Set the video Compression codecs for DivX; the audio
Compression for LAME Mp3 (set to around 44,100 Hz, 128 Constant Bit Rate
(CBR - not variable or average), Stereo. You can also alter the Video
filter with a bit of Brightness and Contrast (mine always seems so dark in
Windows Media Player). This run will take longer (30 mins) and the file
will be much smaller.
That's as much as I remember.....whew!
Good luck.
Also, Microsoft posted a fix on their site regarding this sync/timing
problem. Didn't bookmark like I should have.
B~
.
- Prev by Date: Re: Best Utility to Create and Mount ISO Files?
- Next by Date: What would cause DVD to roll when playing
- Previous by thread: Re: MPEG2 encode from video. Q--problem with sound sliding out of sync
- Next by thread: Cannot read Video DVDs, but can read Data DVDs
- Index(es):
Relevant Pages
|
