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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| Unofficial VirtualDub Support Forums > Advanced Video Processing > Audio Sync |
| Posted by: PoBear Jun 26 2010, 07:34 PM |
| 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 |
| Posted by: gss Jun 30 2010, 12:03 PM |
| 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 |
| Posted by: DacPier Jul 7 2010, 06:48 PM |
| 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. |
| Posted by: fredgiblet Jul 7 2010, 07:25 PM |
| Is it only off at the end or is it off throughout? |
| Posted by: gss Jul 9 2010, 03:01 PM |
| Throughout. 1200ms is my estimation... |
| Posted by: and22 Aug 17 2010, 06:43 AM |
| 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 |
| Posted by: XEQtor Sep 7 2010, 06:54 AM |
| @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... |