How to recode an AVI with Virtualdub

To remove QPEL, GMC, etc., or to convert between codecs

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Text originally published by Jefferson Ryan on jan. 04, 2005 and is still subject to some revision. Translated from Portuguese by Gianni Dioro.

This text is part of my review of the Philips DVP642K/78 (Portuguese)

• 16/01 – I tested this same method with an xvid copy of “The Incredibles” which was unplayable on the DVP642. It didn’t have GMC or anything else that I could identify with GSPOT, but using this procedure, recoding with XviD, solved the problem!
• 15/01 – Initially this tutorial had the intention of only removing QPEL and GMC, but afterwards I realised that if you wanted to convert from XviD to DivX, and vice versa, all you need to do is follow the same steps!
• 08/01 – Thanks to Carlos Holanda for a tip that explained where the option was that I had wanted. Now my tutorial also supports XviD!

In this tutorial, we need the original Virtualdub. Don’t use VirtualDubMod, Nandub or another similar version, because the menus don’t follow the same structure and don’t have the same results as the original program. We will also need to have the DivX 5 or Xvid codec installed.

For this tutorial I used DivX PRO Trial, but you can also try to use DivX Free. If I get the chance, I will ammend the tutorial for both versions. The Xvid version that I used was 1.02.

Also keep in mind that:

This tutorial is not intended to give the best quality possible. This is only a introduction to Virtualdub and a quick and dirty solution. It´s enough for me, but not for the quality fanatics out there. For the best results, you will need to play with Virtualdub and codec settings.

Recoding a video always provokes a loss in quality and never a gain. The exception to the rule is when the original file is especially bad and you use special filters and techniques to remove or repair defects from the original or you just needs to solve a compatibility problem with standalone players. What I am trying to say is that by simply passing from one codec to another is not going to improve the image because codec X is better than codec Y. There is always going to be a small loss which may or not be noticeable to your eyes.

First, we need a little help from GSPOT. Open the AVI file in GSPOT and note down the original bitrate:

Start Virtualdub and use it to open the problematic AVI.

In the Audio menu. Make sure that “Source Audio” and “Direct stream copy” are selected.

Source Audio tells VirtualDub to use the AVI’s original audio as its source. You can substitute the original audio for a different .wav audio file by selecting WAV Audio, or you can even remove the audio file by clicking on No Audio Direct stream copy tells VirtualDub to directly copy the original audio without reprocessing it.

In the Video menu, select “Fast Recompress” and then click on “Compression…”

Note: “Fast Recompress” was chosen only because is the fastest option.

Now you will have to choose between using DivX (which immediately follows below)
or using XviD (further below)

Using DivX 5 PRO

In this window select the DivX 5 codec and then click on “Configure”

Now, you will need to make use of the bitrate that you noted down earlier. Also certify that the selected profile is “Home Theater”. If you are not using DivX Pro, then this option won’t exist. Just ignore this and continue.

Click on OK to leave this screen and then click OK again to leave the Codecs screen. Now skip the XviD section below and go to Back to Virtualdub

Using XviD

Select the XviD codec. If you hve more than one, make sure you choose the one that has the FOURCC code ” ‘xvid’ ” (see image below). Now click on Configure.

The numbers on the image to the left are detailed below: 1) Select the “AS @ L5” profile. Only pick the others (principally “unrestricted”) if you know exactly what you are doing; 2) I prefer “single pass” because it’s faster. You can experiment with the other options if you want. They don’t have any compatibilty issues with the DVP642; 3) Click on this button until the writing “Target bitrate (kbps)” appears on the same button; 4) Type in the bitrate that we noted down earlier when using GSPOT. 5)Click on this button (“MORE…” to the right of Profile”@ Level)…

1) These 2 options must be unchecked! 2) I am still not certain that choosing the default “2” is best. Perhaps it might be necessary to select “1”, but I still need to research this further. Click on the Aspect Ratio tab.

Make sure it is like this (Square) because if you choose otherwise, your video will be totally useless for the DVP642.

Hit OK to leave this screen, OK to leave from Configuration, and OK once more to leave the Codecs screen.

Please not that the process for XviD seems more complicated than that for DivX only because I made you go into various menus inorder to make sure that the configurations were correct (in fact, I simplified the DivX section too much) but once you make sure it’s okay and don’t change the settings, every time you recode a film, all you need to do is insert the bitrate and nothing more!

Back to VirtualDub

Now let’s start the process:

Yes, in Virtualdub the process starts when you save a file (Save as AVI…) There is no START button 🙂

Give a name to the future video file and click on OK (ed. note: you can’t use the same name and location as the source video because Virtualdub needs to use that original file in the process of recoding).

The process will begin:

Take a look at “Total Time (estimated)” to see roughly how much time you have to go out and get a cup of coffee 🙂

When the process is finished, open the resulting video file with GSPOT. You will see that GMC and QPEL have been removed. If everything went okay, your copy should be almost the same size as the original.

Also See:

How to reprocess a film to sincronize the audio with the vídeo