One question raised frequently is how to put MPEG files from various sources onto a VCD. Frequently, the answer is: you cannot - at least, not practically. That usually results in cries of protest: someone must have a simple way to 'fix' the file. The CD recording publishers are recognizing the VCD format straitjacket, so programs such as the VCD creator in Easy CD Creator are more tolerant than their predecessors and are even capable of compressing to VCD from AVI.
VCD is a strictly defined format - just as CD-DA audio is. If your original audio file is sampled at 44 Ksps instead of 44.1 Ksps, the only way you can make it into an audio disc is to resample it to 44.1. Similarly, NTSC video for VCD must be 29.97 fps. Other rates will play as MPG without a problem, but will not make a VCD. Rates that are frequently encountered on the Internet are 30 and 15 fps; 29.97 is a rare choice.
In some cases, a program such as FlasKMPEG will fix the problem; otherwise, if the original MPG does not conform, it must be opened in a suitable editor and recompressed in exactly the right format. First, there are not many editors which will do that; the best editors begin with AVI, not with MPEG. However, ULead Media Studio 5.2 will do it. Unfortunately, compression is a lossy process. In general, you begin with a file nearly conforming to the standard and end with one which has double the losses. While it is fully conforming, it looks bad. That's not because the compression process is done badly but because double compression is bad.
Returning to the audio analogy, if you download an MP3 sampled at 32 Ksps and want to convert it to CD-DA, you must first decompress it. You may do that by opening it in a WAV editor which accepts that input, such as GoldWave, or by opening it in a separate program, such as WinAmp, and saving it as a WAV. Once decompressed, the file must be resampled, typically in a WAV editor. The resampled WAV is then compressed again to MP3. Decompression is lossless. Resampling introduces problems depending on how well it is done; quick resampling can produce audible artifacts while precise conversion takes a long time. Finally, the resampled file is compressed to MP3. Whether the three steps are done in three, two or only one program, there are three stages of loss: the original compression, resampling and the second compression.
If I were forced to make a nonconforming MPEG conform, I would use two programs - in part because I prefer Xing's compression to ULead's. I would open the file in Media Studio and save it as an AVI, assuming it was not larger than 2 GB in that format. Then I would compress it with Xing. (Note: : Compression is very demanding of the computer. A 400 MHz Pentium II runs overnight on a 10-minute clip. That's another reason for using Xing - it's not as slow as Media Studio. The third reason is that Xing offers VCD settings which are absolutely compliant, where you have to set your own parameters correctly in Media Studio.
The conclusion I suggest from all of this is that the payoff for forcing conformance is too great to be worth the costs: software, learning curve to use it, time to process and quality loss. If your initial MPEG is not in whitebook format, you probably do not want to convert it to a VCD.
E-mail me at cdrecording@mrichter.com
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