Changes between Version 32 and Version 33 of Encode/H.264


Ignore:
Timestamp:
Nov 17, 2012, 7:08:50 AM (7 years ago)
Author:
llogan
Comment:

add more tune and profile information

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  • Encode/H.264

    v32 v33  
    1010
    1111== Constant Rate Factor (CRF) ==#crf
    12 This method allows you to choose a certain output quality for the whole file when output file size is of less importance. This provides maximum compression effectiveness with a single pass and each frame gets the bitrate it needs to keep the requested quality level. The downsides is that you can't tell it to get a specific filesize or not go over a specific size or bitrate.
     12This method allows the encoder to attempt to achieve a certain output quality for the whole file when output file size is of less importance. This provides maximum compression effectiveness with a single pass and each frame gets the bitrate it needs to keep the requested quality level. The downsides is that you can't tell it to get a specific filesize or not go over a specific size or bitrate.
    1313
    1414=== 1. Choose a CRF value ===
    15 The 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.
     15The 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 or nearly 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.
    1616
    1717  '''Note:''' The CRF quantizer scale mentioned on this page only 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`. 8-bit is more common amongst distributors.
    1818
    1919=== 2. Choose a preset ===
    20 A preset is a collection of options that will provide a certain encoding speed:compression ratio. A slower preset will provide better compression (compression is quality per filesize). General usage is to use the slowest preset that you have patience for. Current presets in descending order of speed are: `ultrafast`, `superfast`, `veryfast`, `faster`, `fast`, `medium`, `slow`, `slower`, `veryslow`, `placebo`. Ignore `placebo` as it is a joke and a waste of time (see [#faq FAQ]).
     20A preset is a collection of options that will provide a certain encoding speed to compression ratio. A slower preset will provide better compression (compression is quality per filesize). General usage is to use the slowest preset that you have patience for. Current presets in descending order of speed are: `ultrafast`, `superfast`, `veryfast`, `faster`, `fast`, `medium`, `slow`, `slower`, `veryslow`, `placebo`. Ignore `placebo` as it is a joke and a waste of time (see [#faq FAQ]).
    2121
    22 You can also choose a tune and/or profile.
     22You can optionally use `-tune` to change settings based upon the specifics of your input. Current tunings include: `film`, `animation`, `grain`, `stillimage`, `psnr`, `ssim`, `fastdecode`, `zerolatency`. For example, if your input is animation then use the `animation` tuning, or if you want to preserve grain then use the `grain` tuning. If you are unsure of what to use or your input does not match any of tunings then omit the `-tune` option. You can see a list of current `-tune` values and what settings they apply with `x264 --fullhelp`.
     23
     24Another optional setting is `-profile:v` which will limit the output to a specific H.264 profile. This can generally be omitted unless the target device only supports a certain profile. Current profiles include: `baseline`, `main`, `high`, `high10`, `high422`, `high444`. Note that usage of `-profile:v` is incompatible with lossless encoding.
    2325
    2426=== 3. Use your settings ===
    25 Use 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.
     27Use these same settings for the rest of your videos if you are encoding more. This will ensure that they will all have similar quality.
    2628
    2729=== CRF Example ===