Changes between Version 61 and Version 62 of Encode/H.264


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Timestamp:
Jul 7, 2017, 1:09:17 PM (4 months ago)
Author:
shintaroid
Comment:

I encoded a file by specifying the -maxrate to 24M, but the result is around 32M. It seems only two-pass strictly control the max rate

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  • Encode/H.264

    v61 v62  
    148148=== Constained encoding (VBV / maximum bit rate) === 
    149149 
    150 You can also also use `-crf` or `-b:v` with a maximum bit rate by specifying both  `-maxrate` and `-bufsize`: 
     150You can also use `-crf` or `-b:v` with a maximum bit rate by specifying both  `-maxrate` and `-bufsize`: 
    151151 
    152152{{{ 
     
    154154}}} 
    155155 
    156 This will effectively "target" `-crf 23`, but if the output were to exceed 1 MBit/s, the encoder would increase the CRF to prevent bitrate spikes. 
     156This will effectively "target" `-crf 23`, but if the output were to exceed 1 MBit/s, the encoder would increase the CRF to prevent bitrate spikes. However, be aware that `libx264` does not strictly control the maximum bit rate as you specified (the maximum bit rate may be well over 1M for the above file). To reach a perfect maximum bit rate, use two-pass. 
    157157 
    158158In another example, instead of using constant quality (CRF) as a target, the average bitrate is set. A two-pass approach is preferred here: