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  1. Anonymous543
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    when should I use
    Constant Bit Rate(CBR) ,
    Constrained encoding (VBV / maximum bit rate) ,
    Average Bit Rate(ABR) ,
    and
    Two-Pass encoding

    If am missing any other encoding method then please specify



    Like for short videos like 2-3 minutes which encoding method will be good?

    And for 10-20 minutes long video which encoding method will be good?

    And for more then 30 minutes video which encoding method will be good?





    One more question is ,can we do more then 2 pass encoding?
    Like 3 pass or 4 pass or more then that?



    If I download some webseries episode , movie or any other media from a site ,then which method they use to encode that media?
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  2. Member DB83's Avatar
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    Jul 2007
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    Firstly the choice of encoding method has no relationship to the length of the video. It is the actual content that might influence you.


    CBR is what it says on the tin. Applies a set bitrate regardless of content. So if your video was a mix of slow and fast-moving action this could be a waste of bitrate (for the slow scenes)


    ABR is more flexible since you normally also set a lower and higher bitrate. The encoder will then apply these as it deems fit.


    Both of these would apply if you wanted to encode to a specific file size.


    My take on VBR is that no minimum is set. Only the higher. (I am probably wrong on this)


    The advantage of two-pass encoding, which is itself not a stand-alone method but used in tandem with the above, is that the first pass scans the video to select the optimal bitrate for the actual encode. Would have no effect for CBR and I guess it is not even offered then. Some encoders will offer 3 or more passes. Back in the day one guy in a community I frequented insisted on three-pass and boasted of the smaller file sizes he achieved without, I guess, appreciating that, if I read correctly, the third pass is a re-encode of the second so there will be a loss of quality.


    What you have not stated is your intended codec. If you use AVC (h264) you also have an option of CFR (Constant Rate Factor). You have no control of file size whereas the lower the number provides for better quality.


    As for your final question that can not be answered since it inevitably depends on both codec and the encoder used.
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  3. Anonymous543
    Guest
    So overall which method provides best video quality?
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  4. 2 pass and CRF encode video the same way (assuming all other x264 settings are the same), so use 2 pass if you want to specify the bitrate, or CRF if you want to specify the quality.
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  5. Member
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    Mar 2011
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    I use crf mode. It's almost as fast as one pass bit rate mode (which is incapable of high quality) and gets the same quality as 2 pass bit rate mode.

    The only downsides I can see to crf mode is that you don't have much control over the output file size, and, while I haven't experienced this, I've read that some devices don't support crf mode. Could be wrong on the latter.
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  6. 2 pass if you dont mind the added time , alot seem to just want a rush encode these days ... time = quality
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  7. Anonymous543
    Guest
    Thanks all
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  8. Member
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    Oct 2021
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    Wheeling WV USA
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    if a smaller file size is desired in a lossy encoding then i suggest the VP9 encoding which is found in the WEBM format, all released by Google. i have hundreds of videos i converted from MP4 to save space. there was an amazing reduction of space used on the order of 1/8 in size.
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  9. I'm a Super Moderator johns0's Avatar
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    Jun 2002
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    canada
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    Never seen a device that didn't play crf encoded files,only variable frame rate encodings that some players couldn't play.
    I think,therefore i am a hamster.
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