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  1. #1
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    Nov 2002
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    tytompg: TY to MPEG2 conversion in one step, alpha release

    Here's a beta release of tytompg. tytompg converts from TY/TY+/TMF to mpeg2 program streams in a single step. Ie it combines the TY demuxing operation with a loss-less re-multiplex operation. Inside it uses the mature hdemux code for demuxing, and a purpose-built muxer on the muxing side. For multiplexing, I'm preserving the timestamps from the original TY stream instead of trying to regenerate them, as was required with hdemux. This has some benefits and some drawbacks (mostly benefits I believe). Some benefits:
    • Preserving a/v sync regardless of errors in the audio or video streams. For example, the current tivo bug that plagues much of the FOX OTA broadcasts with audio dropouts does not phase tytompg.
    • tytompg's ability to pass-thru video with varying frame rates (these have historically been a deal-breaker for using the mplex muxer).
    • mpeg2 editors such as videoredo work with tytompg a lot better than hdemux+ffmpeg, as tytompg includes timestamps at all video I frame boundaries (so long as the original recording included them), whereas ffmpeg would often leave out some of these timestamps.
    Some issues:
    • Because tytompg does not try to re-generate the timestamps, this can cause problems for players and mpeg2 editors that assume that an mpeg2 program stream has no errors and/or is dvd compliant. For example, I've seen mplayer unable to properly recover from audio holes, but xine does so just fine. YMMV.
    • I'm not at this time generating DVD navigation records, so players that are unable to perform trick-play-like operations without them (ie simplistic players like MyHD's) will have trouble. This really should only be a real concern for DVD output, in which case you'll need to post-process the mpeg anyways (to fix other issues including the video GOPs not being DVD compliant).


    Typical usage:
    tytompg -y <show>.ty
    Output is to <show>.mpg by default. Some switches:
    -y Allow overwrite of output file without confirmation, even if it already exists
    -V Omit video stream from output file
    -A Omit audio stream from output file
    -s <number> Skip <number> chunks on input before processing. Note: if input file is a .tmf file, this option will not work correctly
    -n <number> Process <number> chunks from input


    Example:
    Code:
    % tytompg -y game7cut.ty
    tytompg: Copyright (c) 2004-2007 B.C. <bcc24x7@gmail.com>
    Multiplexer version 0.19, Demuxer version 0.26
    Source is game7cut.ty 
    AC3 audio at 48kHz, 384 kbps, 1536 bytes/sync frame
    Recovered AC3 sync, offset 134, chunk 0
    Video frame size is 1280x720  - high definition. Frame rate 59.940060
    Video bit rate is 19000000 bits/sec., 19000 Kbit/sec.
    Recovered AC3 sync, offset 134, chunk 0
    Warning: temporal_reference order problem.  Value: 3 group_start: 810 last: 836
    audio: Warning: Decoder buffer empty, scr ahead by 81 (0.81) 0.0
            ... and encoder buffer full
    audio: Warning: Dropping frame -- too old by 198662065 (662206.265) 7.32206
    Done!
    Stream audio: 1673 frames (62 seconds aprox.)
    Stream video: 3737 frames, 7474 fields (62 seconds aprox.)
    %
    Windows 32, linux-x86, linux-x86-64, mac-x86 binaries attached.

    Enjoy,

    B.C. <bcc24x7@gmail.com>
    Last edited by bcc; 12-27-2007 at 02:00 PM.

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