Changes between Version 8 and Version 9 of x264EncodingGuide


Ignore:
Timestamp:
08/14/2012 02:56:39 AM (9 months ago)
Author:
llogan
Comment:

remove step 2.5 from CRF section; clarify 8-bit info

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  • x264EncodingGuide

    v8 v9  
    3838 
    3939=== 1. Choose a CRF value === 
    40 The range is 0-51 where 0 is lossless, 23 is default, and 51 is worst possible. A lower value is a higher quality and a subjectively sane range is 18-28. Consider 18 to be visually lossless: it should look the same as the input but it isn't technically lossless. Increasing the CRF value +6 is roughly half the bitrate while -6 is roughly twice the bitrate. General usage is to choose the highest quality that still provides an acceptable quality. If the output looks good then try a higher value and if it looks bad then choose a lower value. 
     40The range of the quantizer scale is 0-51; where 0 is lossless, 23 is default, and 51 is worst possible. A lower value is a higher quality and a subjectively sane range is 18-28. Consider 18 to be visually lossless: it should look the same as the input but it isn't technically lossless. Increasing the CRF value +6 is roughly half the bitrate while -6 is roughly twice the bitrate. General usage is to choose the highest quality that still provides an acceptable quality. If the output looks good then try a higher value and if it looks bad then choose a lower value. 
    4141 
    42   '''Note:''' The CRF values mentioned apply to 8-bit x264 (the typical). 
     42  '''Note:''' The CRF quantizer scale mentioned applies to 8-bit x264 (10-bit x264 quantizer scale is 0-63). You can see what you are using with `x264 --help` listed under `Output bit depth`. 
    4343 
    4444=== 2. Choose a preset === 
    … …  
    4747You can also choose a tune and/or profile. 
    4848 
    49 === 2.5 Output file size === 
    50  
    51 As you can see, there are actually several things that contribute to file size.  If you have a high CRF value, then that will tend to increase file size.  If you encode with "veryslow" then that will tend to decrease file size.  They both play a role in the output size. 
    52  
    5349=== 3. Continue encoding === 
    54  
    5550Use these same settings for the rest of your videos if you are encoding more. This will ensure that they will all have the same quality. 
    5651