Producing MPEG-2 Files

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MPEG-2 is the video codec used in DVD discs, and until recently, it was my codec of choice for desktop playback. After comparing the quality of MPEG-2 to other technologies, however, I've abandoned MPEG-2 for most desktop use, and use Windows Media instead. I recommend that you do the same (test results are here: www.emedialive.com/Articles/ReadArticle.aspx?ArticleID=8422). This leaves producing for DVD playback as MPEG-2's primary use.

However, when outputting a video file from an editor for input into a DVD authoring program, you should consider outputting DV files rather than MPEG-2 for several reasons. First, producing an MPEG-2 file generally takes a lot longer than producing DV. If you decide to change your video file for some reason during authoring, you'll have to re-encode the file, and waste extra time encoding.

More important, once you produce an MPEG-2 file you're locked into that data rate. Suppose, for example, that you produce your MPEG-2 files at 8Mbps, anticipating only about 60 minutes of video on your DVD. Then you decide to add some additional content, which doesn't fit because you've already encoded your video files too high. Now you're forced to either re-encode the MPEG-2 files you produced, which means double compression and quality loss, or go back to your editor and render again at a lower bitrate.

Thankfully, all this is avoided when you delay all encoding until just before producing the DVD it saves time and provides maximum design flexibility. For this reason, when working with separate editing and authoring programs, I typically output in DV format, not MPEG-2. The only caveat is that DV files are generally at least three times larger than MPEG-2, so you'll need lots of extra disk space. We'll cover producing DV files in the next section.

When producing an MPEG-2 file for DVD authoring, keep the following points in mind:

  • Before encoding, check the help file of your authoring program to determine the required specifications for MPEG-2 files input into the program. For example, on the upper left of Figure 7.14, you see the option for Stream Type, which can either be Program (combined audio/video) or elementary (separate files for audio and video). Some authoring programs accept both, some one or the other, so check the specs beforehand to make sure you get it right.

    Figure 7.14. Producing an MPEG-2 file using Sorenson Squeeze.


  • Use a DVD preset when available, and use default parameters whenever you can (in Figure 7.14, for example, leave the I-Frame Rate alone). The DVD specification for video is very precise, and if you adjust a parameter the wrong way, the authoring program won't accept the file.

  • Always output at 720x480 resolution, in interlaced (rather than progressive) mode. Don't apply a deinterlacing filter.

  • Always use VBR with a maximum data rate of no more than 8Mbps.

  • Unless file size is an issue, don't use any audio compression, and output in PCM (Pulse Code Modulation) mode, the uncompressed format used for CD-Audio. If space is an issue, use the Dolby AC-3 audio codec rather than the MPEG-2 codec if both are available. I'll discuss the space available on DVD and bit-budgeting in Chapter 8.

When producing MPEG-2 files solely for computer playback, remember to output at 640x480 in progressive mode and to deinterlace the video when the option is available.

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    DV 101. A Hands-On Guide for Business, Government & Educators
    DV 101: A Hands-On Guide for Business, Government and Educators
    ISBN: 0321348974
    EAN: 2147483647
    Year: 2005
    Pages: 110
    Authors: Jan Ozer

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