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Thread: Which CMD LINE program will create MPEG2 files from raw TyStreams (or M2V/M2A files)?

  1. #16
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    Originally posted by digitalAir
    Ahhh, no...

    DirecTV IS mpeg2... It's just a slightly misbehaved mpeg2...

    Mainly because of the variable frame rate, but mpeg2 none-the-less...

    Most of the multiplexers seem to get confused with the variable frame rates...
    Ahhh, yes and no...

    Can't find anything in the specs about frame rate. Maybe I've missed it. There's a huge slew of information about HOW the compression works. There are also different optional layers to the specs. jdiner made a comment about hardware vs. software clocks for playback and how that affects things. I was sure VFR was not part of the MPEG-2 specs which would make DirecTV MPEG-2-like, not compliant. Yes, the video and audio portions are compressed with compliant algorithms but the stream format is unique.

    Bet THIS would help jdiner but the licensing is probably killer:

    http://www.oaktech.com/products/tera...garDirecTV.pdf

    Or one of these in a PCI card:

    http://www.oaktech.com/products/tera...docs/TL851.pdf
    http://www.broadcom.com/products/4500.html

    IF DirecTV was fully DVB, we could get this stuff using a motorized mount:

    http://www.bealenet.com/~jimsat/free_chanel_listing.htm
    Collecting 9/11, Afghan/Iraq, Mail Call, Trains, Cooking, Woodworking, Fighting Illini - Let's chat
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  2. #17
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    Well,

    it's one thing to say that it's not "mpeg2"; it's another thing altogether to say it's not "mpeg2 standards compliant."

    and technically speaking, since there is absolutely no mention (as I understand it) of VFR in the standards docs, then implementing VFR would no be against the standards... as long as no other spec's are violated in the process.

    However, in this case the way that VFR was implemented, it does break the standards... IOW, the standards say that the header should say how many frames/sec, and that's how many there should be, but dtv uses that field of the header to represent how many "equivalent" frames/sec.... This is against the standards (as I understand it)...

    but I'm just being argumentative, so someone just slap me with a trout or something...
    -- digitalAir

    1 DSR6000R (35 hour) currently running Xtreme 3.1 and tivonet

  3. #18
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    Geez, louise,

    When I typed the first comment I thought the transport stream was part of the MPEG-2 specs. It may have been wrong. That I freely admit. Still haven't found an actual, authoritative copy of the full MPEG-2 standard so I can't say either way.

    If it's not 100% compliant with the standard, it's not the standard. That's how standards work.

    Microsoft uses many file formats that are extensions of a standard. Thus, they are not compliant with the standard and they don't meet the standard.

    Same thing here. If VFR isn't permitted by the MPEG-2 standard (if you've got a link to a full copy, please share it) and CBR is, the use of VFR means the file isn't MPEG-2.

    If the standard discusses the transport stream and DirecTV's format is not 100% compliant, it isn't an MPEG-2 file. It's a file with MPEG-2 elements. Those are two very different things.

    As another example, there are many plastic discs which contain digitized audio with some form of physical copy protection. Those discs violate the audio Compact Disc standard and are NOT compact discs. They have many elements that are the same but they don't meet the complete standard and therefore are not audio compact discs.

    Standalone DVD players don't seem to have problems with the files because their clocks are hardware based. That doesn't mean the streams are MPEG-2.

    Having said that, it may very well be that what is commonly considered MPEG-2 includes the delivery format and those formats may be de facto or associated standards. Certainly, people who create MPEG-2 editing programs design them to work with the commonly used formats which would mean PAL and NTSC. Neither of those is VFR, nor is the vast majority of AV equipment.

    It may very well be that the MPEG-2 standard doesn't specify the formats of the delivery stream.

    This thread seems to have taken a turn away from the original post partly because of my comments and partly because of the collective ambiguity of what "MPEG-2" really means vs. common usage of the term.

    If you've got a link for the full MPEG-2 specs, please share it.
    Collecting 9/11, Afghan/Iraq, Mail Call, Trains, Cooking, Woodworking, Fighting Illini - Let's chat
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  4. #19
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    Doesn't DTVs format predate the official MPEG2 specifications regardless?

    As I remember, they went ahead and launched their service while it was still a draft.

  5. #20
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    The dangers of being an early adopter....

    Skorous

  6. #21
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    Originally posted by Kythorn
    Doesn't DTVs format predate the official MPEG2 specifications regardless?

    As I remember, they went ahead and launched their service while it was still a draft.
    Yup

    The packet size is smaller than the rest of the world thinks it should be and there's some extra info stuffed in as well. Dunno if they did that to save $ initially or if they had to get operational to keep their license/bandwidth or what the reasons could have been.
    Last edited by FredThompson; 11-22-2002 at 03:20 PM.
    Collecting 9/11, Afghan/Iraq, Mail Call, Trains, Cooking, Woodworking, Fighting Illini - Let's chat
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  7. #22
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    Originally posted by skorous
    The dangers of being an early adopter....
    or advantage...

    anyhow... we're debating semantics here, not technical merits...

    so...


    UNCLE hehe
    -- digitalAir

    1 DSR6000R (35 hour) currently running Xtreme 3.1 and tivonet

  8. #23
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    I'm going to ask the moderators to establish a theology forum.

  9. #24
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    Originally posted by rd001
    I'm going to ask the moderators to establish a theology forum.
    Ummm... I hope I'm not being obtuse here but "theology"? I don't get it.

    Skorous

  10. #25
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    Oct 2002
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    Thanks very much rc3105 ! Not that I wasn't enjoying the lively discussion on whether DTV MPEG2 is really MPEG2 or not ... but it is nice to be back on topic and get a direct answer to my original question.

    Thanks again

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