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★ PROGRAMMER'S GUIDE ★ Supplementary explanation of CD builder script grammar
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CD builder script grammar supplementary explanation

4. Notes on building MPEG streams

When building an MPEG stream, please note the following:

●Sector rate specification
When building an MPEG stream with CD Builder, dummy data (empty sectors) will be included for the difference between the sector rate and bit rate. As a result, the following problems occur:

  1. The file size becomes large.
  2. The effect of reading ahead to the CD buffer is lost.

To remove empty sectors, specify a sector rate as low as possible while satisfying the following relationship: That is, the sector rate that is closest to and exceeds the sum of all bitrates.

Sector rate ≧ total of all bit rates

To calculate the sector rate, refer to the previous chapter, "About the relationship between sector rate and bit rate."
If you specify 0 or 65535 for the sector rate, the sector rate that minimizes the number of dummy sectors will be automatically calculated and set.

●Channel interleaving of MPEG files and multi-DOS files
Channel interleaving of MPEG files and multi-DOS files is done by multiplexing an MPEG video stream and an MPEG audio stream to build an ISO11172 stream, and then using this ISO11172 stream as a source file and performing channel interleaving with the multi-DOS file again. This can be achieved using a two-pass method.

[Execution steps]

  1. Create script 1 that multiplexes the MPEG video stream and MPEG audio stream and outputs the ISO11172 stream as a DOS file.

  2. Run CD Builder using script 1.

  3. Create script 2 to channel interleave the created ISO11172 stream and multi-DOS file.

  4. Run CD Builder using script 2.

●MPEG video stream definition
When defining an MPEG video stream using the FileSource command, write the file source type as MPEG_VIDEO.
This description identifies that the file source is an MPEG video stream, and adds 16 words of "0" data immediately after the sequence_end_code recorded at the end of the MPEG video stream.
This description is necessary for normal playback of MPEG video streams on Sega Saturn.

Also, when defining an MPEG video stream using the MpegStream command, the same process is performed by identifying the parameter VIDEO.

●ISO11172 stream subheader When building an ISO11172 stream by multiplexing an MPEG video stream and an MPEG audio stream, a value specific to the ISO11172 stream is set in the subheader.

(a) Coding information
- 7FH is set for the audio stream and 0FH is set for the video stream.

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★ PROGRAMMER'S GUIDE ★ Supplementary explanation of CD builder script grammar
Copyright SEGA ENTERPRISES, LTD. 1997