Mr. City's Knowledge Base

DVD Ripping - bbtools is an excellent suite for extracting audio & video streams from VOB files. It works under MS-DOS, and if you're not used to it, the commands to run it are somewhat esoteric. However, they tend to be the same commands over and over, so once you get used to it, it's very easy. You can even write MS-DOS batch files (*.bat) to run the bbdmux tool repeatedly in order to demux several files.

The MPEG2 video stream is usually found in stream 0xE0, so you can have bbdmux output the stream to a .m2v file and any good media player will be able to play it right off the bat. These files can also be imported directly into DVD Studio Pro & DVD-Lab Pro without any trouble.

The audio streams can come in several different flavors, two of which are mentioned here:

• AC3 Audio Stream - This kind of stream is stored in stream number 0xBD, substream 0x80. iTunes on a Mac is compatible with this file type; PC users usually need to manually install codecs in order to play AC3 files. I also don't know of any software that can edit AC3 tracks; luckily, there is a really nice & easy converter (px3?) that can convert AC3 to AIFF so you can edit it in Adobe Audition or your sound editor of choice. These files can be imported directly into DVD Studio Pro & DVD-Lab Pro without any trouble.


• RAW PCM Audio Stream - This kind of stream is stored in stream number 0xBD, substream 0xA0. You need a little bit of background knowledge & some good software in order to work with these kinds of streams; here I will impart you with the knowledge, and it's up to you to find the software. :-P
  
  Any electrical engineer can tell you PCM stands for Pulse Code Modulation; this is the standard way audio is recorded digitally, where at every sample of time the amplitude is represented by a number. In this case, that "sampling rate" is 32,000 times per second (32kHz) and that number for the amplitude is 32 bits long, meaning there is very good resolution of amplitudes. PCM is the standard used for typical uncompressed WAV and AIFF files, but unfortunately these RAW streams do not have any headers, so you need a program like Adobe Audition that can interpret the data so you can save it as a file you can actually import into DVD Studio Pro.
  
  So, to actually cut to the chase, here is what you do with RAW PCM audio streams to get them in your DVD project:
  1. Run bbdmux on stream 0xbd, substream 0xa0 on your VOB file. Save it as a .raw file.
  2. Open the resulting .raw file in Adobe Audition. In order to open it, you will have to choose the .raw file type from the dropdown list.
  3. On the first dialog box, select to interpret audio as 32000Hz, stereo, 32-bit float.
  4. In the next dialog box, select 24 bit packed (either Intel or Motorola) PCM--it does not seem to matter, so if you like Intel better, then pick it. :-P Data offset can be 0, and you don't need to worry about creating a DAT file.
  5. Save the file as an AC3 if you can; otherwise use AIFF. AC3 is preferable because it is smaller than AIFF, and is compatible with DVD Lab Pro. DVD Studio Pro understands both AIFF & AC3.
  After you open the file, you may notice that the right channel is a bunch of garbage. If this is the case, you can delete the contents of the right channel, and copy and paste the contents of the left channel into it. If you take some extra time to add a filter to the audio that only produces phase shifts (and does nothing to perceptually affect the audio), then you can add some interesting decorrelation effects to your audio. Decorrelation aids in producing the effect of sound localization in loudspeakers, and externalization in headphone speakers (i.e. the sound won't sound like it's coming straight from the center of your head). If you're interested in this topic, please read my former professor Gary Kendall's paper, The Decorrelation of Audio Signals and Its Impact on Spatial Imagery (Computer Music Journal, 19:4, pp. 71-87, Winter 1995). You can also ask me for some convolution kernels that are effective in producing a large phase shift between two identical audio signals.

UPDATE 10/23/2011 (Mole Day): It seems like bbtools doesn't work on Windows 7 SP1 64-bit Edition (though I'm pretty sure it still works on regular Windows 7). As such, I've abandoned bbtools and have gone on to some other GUI-based demuxing applications, which also haven't been maintained since President Lincoln took the oath of office. :-P However, the instructions for converting a raw PCM audio file to AC3 should still apply. Enjoy, and thanks to bbtools for many great years of service!