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Old 11th February 2002, 15:53   #1  |  Link
cofferscuffs's Avatar
Join Date: Oct 2001
Location: munkee land whoosh!
Posts: 627
[VirtualDub] *** FAQ *** <11/10/2003>

Here is a quick VirtualDub FAQ because I'm getting fed up of people who can't be assed to search the forums... maybe this will help .

Where is the official VirtualDub website?
The official VirtualDub site is www.virtualdub.org, NOT www.virtualdub.net. See http://forum.doom9.org/showthread.ph...739#post165739 for more info about www.virtualdub.net

How do I get MPEG2 support in VirtualDub?
MPEG2 is not supported nativly in VirtualDub and it never will be according to the author, Avery Lee because of liscensing issues; however, MPEG1 is supported. MPEG2 can be framserved instead to VirtualDub, using an avs script; see http://forum.doom9.org/showthread.php?s=&threadid=27228 for more info. But if you don't want to learn a simple scripting language, do a search for AVSGen and download it, and that will create a script for you .
Other possibilites are to use VirtualDubMod or fccHandlers MPEG2 mod.

When I open a mpeg file I get a 'pack synchronization error', what does that mean?
The mpeg file most likely actually is a mpeg2 file which can't be opened by VirtualDub. See previous question for possible solutions.

I opened a avi file with ac3/dts sound and can't play it in virtualdub or convert the sound, why not?
VirtualDub is entirely vfw (Video for Windows) based, so it needs vfw compatible codecs for video and acm (Audio Compression Manager) compatible codecs for sound. To my knowledge there is neither a ac3 nor a dts acm codec (all are direct show and not usable by vdub).
The mpeg2 mod by fccHandler can handle (no pun intended ) ac3 sound, but only if the source is a mpeg2 file.

I tried to opened a avi file but I get a "Couldn't locate decompressor for format 'XXXX' (unknown)" error, although it plays fine with my movie player. What's the matter?
This is another facet of the acm/vfw/dshow trouble. You seem to only have a DirectShow filter installed for the respective codec, but VirtualDub needs a vfw (video) or acm (audio) codec. This happens e.g. with xvid when you have only ffdshow installed.
We can't tell you for every content where to get a acm/vfw codec (might even be there isn't such a thing, see previous question). What you can try to do is find out the FourCC value (File->File Information) and google for it.

I tried to opened a avi file I get a message "VirtualDub has detected an improper VBR audio encoding in the source AVI file and will rewrite the audio header with standard CBR values during processing for better compatibility.". What does that mean?
I means your AVI contains VBR (variable bitrate) audio, usually mp3. Neither VDub nor AVI supports this, writing it into AVI is a hack that can lead to troubles (namely inconsistant desync and uncompressable video frames). If you want to know more about this hack, read the IRC log in the VDubMod FAQ (#14).

Ok, I understood VBR audio is bad, so what do I do when I want to edit AVIs containing VBR audio?
Clean solutions:
  • Transmux the whole file to a container format supporting vbr audio and edit that (eg Matroska, OGM).
  • Save AVI with uncompressed audio, do your editting, recompress audio
  • Demux audio, recompress to cbr mp3, remux, do your editting
Hack solution:
  • Use NanDub or VDubMod (NanDub compatibility mode). I heard its a bad idea to try to recompress audio on the fly using this option.

Are there settings that I can use every time that will make my output look amazing?
There is no 'perfect' settings for filters, each movie is completly different and thus the settings will be different each time. Get filters & links to more filters here: http://sauron.mordor.net/dgraft/.

I want to capture ASF/RM streams... how can I do that?
There is no filter/plugin for capturing ASF/RM streams. You need ASFRecorder or StreamBoxVCR for that. And no, there is no support for this in VirtualDub

My ASF files don't work in VirtualDub no more!
ASF (NOT the WMV8 format) support is only in VirtualDub 1.3c or earlier. WMV8 support was never done. This also applies to encoding to MPEG4V1,V2 or V3 <- those codecs are locked unless you've downloaded unlocked ones (which are not availible from MS).

What audio formats can be used?
VirtualDub can only mux CBR MP3's when they have a wave-header, use Wavemp3 (availible on software page) to do this. It cannot mux VBR streams whatsoever. For VBR MP3/Vorbis/AC3 muxing, use Nandub (also availible on software page) or VirtualDubMod (no Vorbis muxing to avi, but that doesn't work anyways). If you want to extract audio, use the same programs that you would use to mux it

I know the file information dialog is wrong in VirtualDub, is that a problem?
The file info in VirtualDub is not always true. To be sure of the video codec used, look at the FourCC code.

Why can I not encode as fast as other people?
Encoding speed in VirtualDub depends on your CPU, RAM, HD, video source, filters applied etc.... go figure :P

My avs scripts do not load!
If you get an error like this "Cannot determine file type of ..." when opening an AVS file, then AviSynth is not installed correctly.

Why doesn't the frameserver work?
In VirtualDub 1.4.10, the frameserver is broken, fixable by putting msvcr70.dll in your system directory; here's what Avery Lee says:

Yes, the frameserver in 1.4.10 is linked with Visual C++ .NET, and yes, it doesn't include the MSVCR70.DLL file required to use it. No, I didn't intend to that. Yes, I am an idiot. No, I don't plan to include that file. Yes, you should use the 1.4.9 frameserver libraries instead. Yes, they will work with 1.4.10.
If you're using the framserver for the first time, make sure you have run AuxSetup.exe in the VirtualDub directory and clicked install AVI Handler

Why when capturing AVI is my capture resoltuion limited?
This only applies to AVI capture for old cards (ie. my aged ATI AIW 128 16mb ). VirtualDub uses a VFW WDM wrapper to capture, limiting the resolution on some cards to 352x288 or below... This is best explained by Avery Lee;

For the last time, yes, VirtualDub is compatible with Windows XP. It is, however, not compatible with DirectShow (Windows Driver Model) capture devices except when the Microsoft VFWWDM wrapper is installed, which does not let you capture integrated audio and is not available under XP. A solution is in the works but I can't tell you when it will be finished.
So there is hope, but if new cards don't work (all that utilise the Bt848 / Bt849 / Bt878 & Bt879 Chipsets), install the drivers from http://btwincap.sourceforge.net/ and then check out Koepi's BtWinCap driver mode switcher here.

Last edited by Belgabor; 23rd December 2003 at 01:07.
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