Quantcast Recording Video: Virtualvcr and a/Vsync - digitalFAQ.com Forums [Archives]
  #1  
04-05-2006, 04:49 AM
the viking the viking is offline
Free Member
 
Join Date: Sep 2004
Location: Norway
Posts: 174
Thanks: 0
Thanked 0 Times in 0 Posts
Hello,

Until now I have been capturing with VVCR with these
AV sync settings:




But after searching/reading forums/guides,I came over a
tool called AVI Offset Calculator.You find it here http://darkfalz.kiczek.com/software/

The AVI Offset Calculator calculates the av offset so we can
fix that in VDub or other editing software.

So I opened one of my captured files in AVI Offset Calculator
and the results youll see on the next picture



As far as I can understand from that result,the video and audio
is -40ms out of sync.

So I picked up a tips from VDub forums,adjust stream offset
in VVCR until AVI Offset Calculator shows 0ms when opening
the captured file.

So I did some tests captures,and the next picture shows
the final settings



When opening the file in AVI Offset Calculator,the results
are this:




So as far as I can see,the captured video is now
perfectly in sync.?
I read that the -40ms offset was caused by the system,
bus speed,bus "bottleneck"etc.

Anyone have any comments to this?

thanks

-------------------------------------
Reply With Quote
Someday, 12:01 PM
admin's Avatar
Site Staff / Ad Manager
 
Join Date: Dec 2002
Posts: 42
Thanks: ∞
Thanked 42 Times in 42 Posts
  #2  
04-05-2006, 04:57 AM
Dialhot Dialhot is offline
Free Member
 
Join Date: May 2003
Posts: 10,463
Thanks: 0
Thanked 0 Times in 0 Posts
I don't see how this tool can determine how much the audio/video was unsynch but be carefull that is you set "40 ms" in vdub, this delayis just a muxing delay. That means that once you will demux the video and audio stream, then you will have again the synch problem.
Reply With Quote
  #3  
04-05-2006, 05:16 AM
the viking the viking is offline
Free Member
 
Join Date: Sep 2004
Location: Norway
Posts: 174
Thanks: 0
Thanked 0 Times in 0 Posts
oops,forgot to say that,I read somewhere that VVCR
writes the desync/offset in the AVI file header,that
way software avi players corrects the desync when playing the file.
I guess the AVI Offset Calculator reads the offset that way to.

But editing software and MPEG encoders doesnt read the avi file header,
so after converting to mpeg,Ill have the desync.

So adjusting stream offset in VVCR until the offset in avi file header
says 0 ms,should,at least theoretically,solve this problem.
Reply With Quote
  #4  
04-05-2006, 05:26 AM
Dialhot Dialhot is offline
Free Member
 
Join Date: May 2003
Posts: 10,463
Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by the viking
So adjusting stream offset in VVCR until the offset in avi file header says 0 ms,should,at least theoretically,solve this problem.
Right. I did confuse VVCR with Vdub.
Reply With Quote
  #5  
04-05-2006, 09:07 AM
Boulder Boulder is offline
Free Member
 
Join Date: Sep 2002
Location: Lahti, Finland
Posts: 1,652
Thanks: 0
Thanked 0 Times in 0 Posts
I've got something like 120-160ms of offset, I've not used the calculator but VDub always inserts 3-4 frames at the beginning of my captures.

So if you'd like to make sure you have a good a/v sync, use the latest VDub
Reply With Quote
  #6  
04-05-2006, 09:26 AM
the viking the viking is offline
Free Member
 
Join Date: Sep 2004
Location: Norway
Posts: 174
Thanks: 0
Thanked 0 Times in 0 Posts
Do you use the default timing settings in latest VDub?

I got 0 inserted frames at the beginning but some frames
inserted during capturing with VDub.(default settings.)

Read at VDub forums that Inserted frames in VDub
and Dropped frames in VVCR is the same,the last good
frame is inserted instead.

anyway I captured a 7 minute clip earlier today
with the offset 40 ms setting checked in VVCR,
ran it through CCEBasic,and uploaded it herehttp://www.yourfilelink.com/get.php?fid=69156
48MB

To me it seems to be in sync.if you have time,download,
I like to hear your opinions.
Reply With Quote
  #7  
04-05-2006, 09:40 AM
Boulder Boulder is offline
Free Member
 
Join Date: Sep 2002
Location: Lahti, Finland
Posts: 1,652
Thanks: 0
Thanked 0 Times in 0 Posts
Yes, except that "Correct video timing.." is disabled, it might be enabled by default, I'm not sure. I actually think that if it's enabled, you get zero inserted frames at the beginning but I only got problems during capture with it.

I think that inserted frames means in VDub that a new frame is inserted to compensate the timing error which occurs even if you have resampling enabled. This inserted frame is created like you suspected. A dropped frame means that the frame is lost and it is compensated by copying the last good frame. So the difference is that inserted frame means you do not lose anything from the original stream but a copied frame is added, dropped frame means you lost those frames.

You probably won't notice a 40ms delay anyway, I think it's closer to 100ms before it gets noticable.
Reply With Quote
  #8  
04-05-2006, 09:41 AM
Dialhot Dialhot is offline
Free Member
 
Join Date: May 2003
Posts: 10,463
Thanks: 0
Thanked 0 Times in 0 Posts
Sounds good too me also.
Reply With Quote
  #9  
04-05-2006, 09:59 AM
the viking the viking is offline
Free Member
 
Join Date: Sep 2004
Location: Norway
Posts: 174
Thanks: 0
Thanked 0 Times in 0 Posts
Yes, correct video timing is enabled by default.
If I disable it I got a inserted frame every 5 second.
After what I read at the VDub forums,if it is enabled,both
audio and video is resampled. Reason :"Beacuse two is better than one".

But I guess different hardware need different settings.
Im running a AMD Athlon XP 2,1GHz with 1,25GB RAM,PCI Sound Card,
Terratec PCI TV Card.

Anyway it seems that the VDub author has done a great job
improving the capture part of VDub.
Reply With Quote
  #10  
04-05-2006, 10:32 AM
kwag kwag is offline
Free Member
 
Join Date: Apr 2002
Location: Puerto Rico, USA
Posts: 13,537
Thanks: 0
Thanked 0 Times in 0 Posts
@the viking,

Have you tried capturing with "VirtualDub-Sync": http://www-user.rhrk.uni-kl.de/~dittrich/sync/

-kwag
Reply With Quote
  #11  
04-05-2006, 11:12 AM
Boulder Boulder is offline
Free Member
 
Join Date: Sep 2002
Location: Lahti, Finland
Posts: 1,652
Thanks: 0
Thanked 0 Times in 0 Posts
It's obsolete now that the VDub 1.6-branch does the same thing. The good thing about VDub 1.6.x is that it'll work with WDM drivers as well whereas the 1.5-based programs need VfW.
Reply With Quote
  #12  
04-05-2006, 11:16 AM
kwag kwag is offline
Free Member
 
Join Date: Apr 2002
Location: Puerto Rico, USA
Posts: 13,537
Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by Boulder
It's obsolete now that the VDub 1.6-branch does the same thing.
I didn't know that
Are you sure they commited the same code mods
Quote:
The good thing about VDub 1.6.x is that it'll work with WDM drivers as well whereas the 1.5-based programs need VfW.
Thanks Boulder

-kwag
Reply With Quote
  #13  
04-05-2006, 11:22 AM
Boulder Boulder is offline
Free Member
 
Join Date: Sep 2002
Location: Lahti, Finland
Posts: 1,652
Thanks: 0
Thanked 0 Times in 0 Posts
VirtualDub-sync is based on some VDub 1.5-build. The same resampling code is found in VDubMod as well, which is based on VDub 1.5.10 I think.

There's no reason to use any 1.5-based programs, v1.6 has proven to be very stable and troublefree. And in case of problems, Avery Lee has often come up with a fix
Reply With Quote
Reply




Similar Threads
Thread Thread Starter Forum Replies Last Post
Captura de video com VirtualVCR estranho74 Conversão e Codificação de Vídeo (Português) 10 06-19-2004 03:23 PM
Recording Video: VirtualVCR scheduler vmesquita Video Capturing / Recording 1 03-10-2004 10:53 AM
Recording Video: Best budget-priced video capture card? digitalvideo Video Capturing / Recording 2 04-17-2003 09:31 AM
Recording Video: IVTC poor quality video? segfault Video Capturing / Recording 5 01-13-2003 02:52 PM
Recording Video in Huffyuv with Ulead video studio SE? mpierce Video Capturing / Recording 0 09-06-2002 12:34 PM

Thread Tools



 
All times are GMT -5. The time now is 12:18 AM  —  vBulletin © Jelsoft Enterprises Ltd