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  1. Member
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    Hi,

    I use the correct formula to calculate the bitrate for encoding, but sometimes the resulting DVD exceeds the standard size

    For example, if the calculated bitrate is about 3.000kbps I use this settings :

    Q-FACTOR : 40
    MIN BITR : 2000
    AVG BITR : 3000
    MAX BITR : 4500

    Is this correct ? or must I use the MAX BITR with the calculated BITRATE ?

    thanks
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  2. Hi-

    The Q-Factor doesn't correspond to a particular bitrate. Different movies compress differently, and where one movie might need only an average bitrate of 3000 to produce an average Q of 40, a different movie might need 5000 or more.

    In fact, CCE doesn't even offer an average bitrate when in OPV mode, just min, max, and Q. Maybe you're using a different encoder.
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  3. Member
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    Originally Posted by manono
    Hi-

    The Q-Factor doesn't correspond to a particular bitrate. Different movies compress differently, and where one movie might need only an average bitrate of 3000 to produce an average Q of 40, a different movie might need 5000 or more.

    In fact, CCE doesn't even offer an average bitrate when in OPV mode, just min, max, and Q. Maybe you're using a different encoder.
    No, I'm using CCE

    But what I usually do is this :

    The formula I use for manually calculate the bitrate is this :

    Calculated Bitrate = (Size - (Audio x Length )) / Length

    Then I use this Bitrates Values Arrangement for CCE, either for OPV or 2 PASS..3 PASS..

    Q-FACTOR = 40
    MIN BITRATE = Calculated Bitrate - 1000
    AVG BITRATE = Calculated Bitrate
    MAX BITRATE = Calculated Bitrate + 1500

    I know that OPV doesn't use AVG bitrate, but I use this as a generic template, but what happens is that some of the encoded video exceeds a DVD stantard size

    Is this generic arrangement for CCE correct ?
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  4. Originally Posted by Delta2
    I know that OPV doesn't use AVG bitrate, but I use this as a generic template, but what happens is that some of the encoded video exceeds a DVD stantard size

    Is this generic arrangement for CCE correct ?
    AVG bitrate would determine the file size. If it is not used (OPV case) the file size might be anything - over or under or what ever.
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  5. Hi-

    Is this generic arrangement for CCE correct ?

    If you ask me, you're doing everything wrong:
    1. You seem to think there's a connection between Q and ave bitrate, when there's none.
    2. You're setting your min as ave-1000
    3. You're setting max as ave+1500 (very bad).

    The purpose of an OPV encoding is to achieve even quality throughout the entire video. Put another way, it's to achieve full VBR encoding. With your settings, you achieve neither.
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  6. Member
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    Thanks manono for your reply and advice, I sent you a PM

    ======
    If you ask me, you're doing everything wrong:
    1. You seem to think there's a connection between Q and ave bitrate, when there's none.
    ======

    But I know that

    It is a generic template, I think that 2 PASS or more will ignore Q-FACTOR, and OPV will ignore AVG Bitrate

    ====
    2. You're setting your min as ave-1000
    3. You're setting max as ave+1500 (very bad).
    ====

    That's because I want to avoid hiccups during playback, If I have a calculated bitrate of 3000 there must not exists big differences between MAX and MIN....I think...but I don't know how to arrange this with OPV encoding

    Because I know that big differences cause hiccups during playback, and I know that

    audio + video + subtitles must be less than 9800kbps for playback, in order to be compatible with most of DVD players

    I really don't know how to arrange this
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  7. Hi-

    I'll ignore the PM and answer here.

    When you use OPV, you lose complete control over file size. That's why you sometimes go oversized with a fixed Q. If you want to combine OPV Mode with a given filesize, then I might recommend AutoQ3:

    http://forum.doom9.org/showthread.php?t=110612

    However, it will change your Q value.

    That's because I want to avoid hiccups during playback

    Now say your average bitrate is 3000, so your max bitrate is 4500. Are you saying that with bitrates over 4500 you begin to see hiccups in playback? If so, I would argue that there are other issues involved, such as media or burning issues. Either that or your DVD player is a piece of junk and only good for the nearest trash can. No, all DVD players are required to handle the full DVD spec range of bitrates. For video alone, it's 9800 kbps. For video+audio+subs+overhead it's 10080 kbps. Me, I make the max bitrate as close to max as possible, but you should be safe (unless you have WAV audio) by making the max bitrate of the video 9000. By making your max bitrate only 4500 (for example), complex scenes will often look very bad, with mosquito noise, lack of detail, color smearing, and macroblocking.

    I usually make my minimum bitrate 250 or 500, unless my average is high, in which case my min might be higher. I know people that use a min of 0. The idea is to achieve full VBR encoding.
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  8. There is no way to predict file size when using constant quality encoding. If the video is bright and has lots of detail, motion, and action it may come out pegged at the MAX bitrate. If the video is all black it will come out at the MIN bitrate. Anything else will come out somewhere in between.
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  9. Member
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    Originally Posted by manono

    When you use OPV, you lose complete control over file size. That's why you sometimes go oversized with a fixed Q. If you want to combine OPV Mode with a given filesize, then I might recommend AutoQ3:

    http://forum.doom9.org/showthread.php?t=110612
    didn't know all you said, I was wrong

    but that tool, AutoQ3...does it have any CLI support ? i.e, some batch processing or command line support ?

    didn't found nothing about that
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  10. Hi-

    does it have any CLI support ?

    I don't know. Why don't you register at Doom9 and ask the guy in that thread? Before then you might give it a try and see if in other ways it does what you want, like give you even quality with fast 1-pass encoding for the file size you want.
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