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| PoBear |
| Posted: Jun 26 2010, 07:34 PM |
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Advanced Member
Group: Members
Posts: 51
Member No.: 23022
Joined: 10-February 08
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Hi everybody - I know this topic has been several times before, but please be patient with me.
I am trying to convert a 13Gb .wtv file to a divx encoded .avi, but I am having problems with audio sync on the end file.
I have converted the .wtv to an mpeg-2 file and as far as I can tell from playing it back in WMP12 and VDub the audio is still synced, however, after conversion it is out at the end of the file by maybe .5 seconds, just enough to be noticable and annowing. So the questions...
Q. VDub is showing the audio on the source file as
48KHz stereo 256kbps Layer II
607226 Frames
455420K Total Size
-161ms Skew (internal)
What does the last param (skew) mean?
Q. Can I get an accrurate value for how much the audio and video are adrift and how?
Q. How do I calculate the audio skew correction from this?
I know the ideal way is to unload the audio and process it seperately before re-combining but this error happens a lot and I don't really have time for all the extra processing!
Many thanks |
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| gss |
| Posted: Jun 30 2010, 12:03 PM |
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Newbie
Group: Members
Posts: 3
Member No.: 22203
Joined: 5-October 07
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I see the same problem.
I'm trying to convert mpeg-2 file to *.avi (using ffdshow h.264 and mp3 sound) and see about 1200ms lag.
I do not know a solution  |
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| DacPier |
| Posted: Jul 7 2010, 06:48 PM |
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Newbie
Group: Members
Posts: 4
Member No.: 20680
Joined: 16-January 07
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First : sorry for my english...
I put the following in this thread, to avoid another one on this desync stuff.
I don't know if it is strictly related to previous posts but here ya go.
I capture mpeg2 vidz on digital tv, directly with a dvb card.
From time to time, there is desync visible in vdub: some pictures are lost, but the corresponding audio is recorded absolutely blank.
The trick would be:
if audio is absolute nil-nothing-nada, hold on video processing, keep on reading audio until there's some sound. When you get it, restart video processing.
I guess that would remove 99% of the desync I can observe with mpeg2 source files...
Can it be done, as an option maybe ?
Cheers.
M.
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| fredgiblet |
| Posted: Jul 7 2010, 07:25 PM |
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Advanced Member
Group: Members
Posts: 356
Member No.: 22601
Joined: 13-December 07
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Is it only off at the end or is it off throughout? |
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| gss |
| Posted: Jul 9 2010, 03:01 PM |
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Newbie
Group: Members
Posts: 3
Member No.: 22203
Joined: 5-October 07
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Throughout.
1200ms is my estimation...
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| and22 |
| Posted: Aug 17 2010, 06:43 AM |
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Member
Group: Members
Posts: 14
Member No.: 22337
Joined: 29-October 07
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I have audio sync problem too.
I loaded a video file from the net (see below MediaInfo), re-encoded video in VD 1.9 using internal resize filter, saved audio (File - Save WAV), normalized audio in Adobe Audition 3.0 and tried to combine video (Xvid) and WAV audio (MP3 Lame codec in VD) again as a new AVI file. Unfortunately audio now is not synchronized with video. All attempts to make it synchronized failed. Please explaine how how to handle audio to get it fit well with video.
General
Complete name : I:\Video\03_Life.BDRip.avi
Format : AVI
Format/Info : Audio Video Interleave
File size : 1.52 GiB
Duration : 59mn 2s
Overall bit rate : 3 694 Kbps
Writing library : VirtualDub build 30586/release
Video
ID : 0
Format : MPEG-4 Visual
Format profile : AdvancedSimple@L5
Format settings, BVOP : Yes
Format settings, QPel : No
Format settings, GMC : No warppoints
Format settings, Matrix : Default (H.263)
Codec ID : XVID
Codec ID/Hint : XviD
Duration : 59mn 2s
Bit rate : 3 492 Kbps
Width : 1 280 pixels
Height : 720 pixels
Display aspect ratio : 16:9
Frame rate : 25.000 fps
Resolution : 24 bits
Colorimetry : 4:2:0
Scan type : Progressive
Bits/(Pixel*Frame) : 0.152
Stream size : 1.44 GiB (95%)
Writing library : XviD 1.1.2 (UTC 2006-11-01)
Audio
ID : 1
Format : MPEG Audio
Format version : Version 1
Format profile : Layer 3
Codec ID : 55
Codec ID/Hint : MP3
Duration : 59mn 2s
Bit rate mode : Constant
Bit rate : 192 Kbps
Channel(s) : 2 channels
Sampling rate : 48.0 KHz
Resolution : 16 bits
Stream size : 81.1 MiB (5%)
Alignment : Split accross interleaves
Interleave, duration : 40 ms (1.00 video frame)
Interleave, preload duration : 500 ms
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| XEQtor |
| Posted: Sep 7 2010, 06:54 AM |
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Newbie
Group: Members
Posts: 2
Member No.: 15885
Joined: 13-July 05
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@and22:
You did not say if you "save as WAV" in VDub under "Direct Stream Copy" or "Full Processing". There is a difference. The former is "mp3 wave", while the later is "PCM wave". I call the later "original WAV" and the former "bastardized" (since it only has RIFF headers to make it legit).
Since you're converting "lossy" to "lossy", you might as well do "full processing" and let VDub decode the MP3 to PCM first, before feeding this to Audition/CoolEdit. And in Audition/CoolEdit, you should resample this to 32-bit (otherwise dont bother using Audition/CoolEdit) before you normalize and then, dither it back down to 16-bit when saving the normalized WAV.
If you want, you can also check the "audio rip" for sync with the original at each step of the way by slapping the new audio back into VDub using "Audio->Audio from other file...". Just after ripping it out from VDub, and after Audition/CoolEdit has molested it. You should be able to know who is causing this to mess things up... But from experience, I'll let VDub deliver the PCM WAV rather than asking Audition/CoolEdit to uncompress the MP3 "wav" from VDub. I find this to be my main source of AV sync issues.
@gss:
You did not mention which version of ffdshow-tryouts you're playing with. Last time I knew, ffdshow encodes of vfw H.264 gives you 41 drop frames before the 1st key frame. This is good enough to guarantee you AV sync. For your 25fps encode, this is easily an extra 1640 ms. You should go to the ffdshow-tryouts forum for this. There's a simple workaround using VDub there. You wanna see this in VDub? Reload the newly created AVI, press the "next key frame" button. A dirty fix is to separate out your precious audio under DSC, load the AVI, lobe off the 1st 0-40 frames, slap back your precious audio stream, DSC for both, save a new AVI.
@PoBear:
"-161ms Skew (internal)" looks to me like "audio delay". I have no experience with .wtv containers, but you can just pull out that audio track (under DSC) and then slap it back into VDub using "Audio->Audio from other file..." and see if VDub corrects this during the DSC phase (prolly not). Then, you can ask VDub to add "-161ms" under "Audio->Interleaving->Audio skew correction" and see if this works for you, or you'll need more/less...
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