Digital Video Processing

The processing power of modern personal computers allows you to make wonders in your own home. You can for example encode a complete movie with MPEG1 or MPEG2 in full PAL resolution of 720 x 576 in less than a day.

On this page I aim to help you getting a head start on processing video and encoding your own digital video disks to be played on regular standalone DVD players. Most of the tools used are shareware and available for download from the internet. Those that are not shareware, have at least a demo version available.

Please note that in some countries making backups of some digital video material may be illegal.

Digital Video Glossary

Here is a list of some of the basic terms:

AVI	Audio Video Interlace	A very common movie format in PCs. A variety of encoders can be used to produce AVI. You need a lot of decoders installed in your computers to play all the AVIs that are out there.
CD-R	Compact Disk, Read many, Write once	A CD disk which is sold empty and can be written to once.
CD-RW	Compact Disk, Read many, Write many	A CD disk which is sold empty and can be written several times.
DivX	-	A very effective movie format. Video is encoded with MPEG4 and audio usually with MPEG1 Layer III.
CBR	Constant Bit Rate	The amount of bits per second is constant. For example a VCD video stream is constant 1150 kbits per second. This means it is easy to calculate how long piece of video you can put on a single 650 megabyte (equals to 5200 megabits) CD-R.
VBR	Variable Bit Rate	The amount of bits per second depends on how many are needed. Easily saves space on your media and can improve quality. Encoding is heavier task than with CBR.
MP3	MPEG1 Layer III	An effective way of encoding audio. Supports many bit rates.
VCD	Video Compact Disk	A regular CD disk with audio and video content. Video is encoded with MPEG1 and has a constant bit rate of 1150 kbps. Video on PAL VCD has a resolution of 352 x 288 and frame rate of 25 fps. Video on NTSC VCD has a resolution of 352 x 240, and the frame rate can be 29.97 fps or 23.976 fps. Audio encoding is MPEG1 Layer II. Audio bit rate on both PAL and NTSC VCD is 224 kbps. Practically all standalone DVD players play VCDs.
SVCD	Super Video Compact Disk	A regular CD disk with audio and video content. Video is encoded on MPEG2 and has a variable bit rate with a maximum of 2600 kbps. Video on PAL SVCD has a resolution of 480 x 576 and frame rate of 25 fps. Video on NTSC SVCD has a resolution of 480 x 480, and the frame rate can be 29.97 fps or 23.976 fps. Audio encoding is either MPEG1 Layer II or MPEG2. Audio on both PAL and NTSC SVCD has a selectable bit rate from 32 to 384 kbps. There can be two separate audio tracks. An SVCD disk can also contain a maximum of four selectable subtitles. Some standalone DVD players play SVCDs.
DVD	Digital Versatile Disk	A large capacity disk which looks like a CD. DVDs are mostly used for storing and viewing movies. Bit rate on DVD movies has a maximum of 9.8 Mbps. Video is encoded with MPEG2. PAL picture has a resolution of 720 x 576 at 25 fps. NTSC picture has a resolution of 720 x 480 at 29.97 fps or 23.976 fps. Audio can be Dolby AC3, DTS or PCM multichannel. DVDs may have two layers on one side, which are regognizable from the golden colour. DVDs can also use both of their sides for storing data. Depending on the total number of layers used, the capacity of one disk is 4.7 GB, 9 GB, 13.7 GB or 18 GB.

Converting AVI to VCD

You will need the following programs for this conversion:

• Avisynth
• VirtualDub
• TmpGENC
• VCDEasy

It may happen that you stumble into a nice AVI flick in the depths of internet and you want throw the movie into your DVD player. AVIs can have just about any shape and encoding, but VCD must be exactly like described in the Glossary table. But don't worry. Assuming you can play it in Windows Media Player, then most likely you are able to re-encode the movie into a VCD format also. If WMP doesn't play the movie, you are probably missing a decoder plugin a.k.a. a codec. In that case you should somehow figure out what codec you're missing, download it and install it.

Let's assume your AVI has correct frame size, but the frame rate is wrong. You can do frame rate conversion of AVI with Avisynth, an excellent program written by Ben Rudiak-Gould. Use a .avs script like this:

    ChangeFPS(AVIFileSource("d:\barbiq.avi"), 23.976)

Note: It seems that at least some versions of Avisynth still use the original number of frames in the AVI stream. This means that if you increased the frame rate with Avisynth, your player or frame server will stop before the end your movie. I fixed this by concatenating two streams together in Avisynth, and then finding a correct place to stop serving frames in VirtualDub:

    ChangeFPS(AVIFileSource("d:\barbiq.avi") + AVIFileSource("d:\barbiq.avi"), 23.976)

Several different transformations to the video and audio streams are possible in Avisynth. Have a look at the Avisynth site for full documentation.

Next open your .avs script like any ordinary AVI file in VirtualDub, which is another great program. Configure no changes to the video and audio and start a frame server. Frame serving means that a dummy file is introduced as a link between the server and the application that uses the data. The benefit is that nothing is actually written onto your hard drive, which means that valuable disk space is saved.

Start TmpGENC. You can configure the VCD parameters to video and audio encoders yourself, but I suggest you download and use ready-made TmpGENC template for VCD. Otherwise you may for example end up with a streaming MPEG1 file, which can be quite annoying to watch with your DVD player. After TmpGENC is configured, start the encoding process. The encoding can easily take hours.

When your .mpg file is finished, start VCDEasy. It is a very good GUI to VCDImager and Cdrdao. You can easily create chapters with VCDEasy, which will help moving back and forth on your VCD disk. After configuration is finished, you can burn your disk using Cdrdao which is also included in the VCDEasy package. It is also possible to use any burner capable of handling BIN/CUE files. One example of such a program is Blind Write. When the disk is burned, just put it into your DVD player and enjoy.

Tool Versions

Below is a list of known-to-be reliable versions of good digital video processing tools:

• Avisynth 1.0 beta 5
• Blind Write 1.1.0.7
• Dvd2Svcd 1.0.5 build 3
• VCDEasy 1.0.7
• VCDGear GUI 2.0
• VCDImager 0.6.2
• TMPGEnc 2.00.29.113
• VirtualDub 1.4.8

Further Information

Below is a list of essential sites when it comes to digital video processing:

• VCD Help
• Digital Digest
• Doom9