Changes between Version 2 and Version 3 of Encode/AV1


Ignore:
Timestamp:
Jun 3, 2018, 3:24:27 PM (3 months ago)
Author:
Gyan
Comment:

a few rewrites and clean-up

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  • Encode/AV1

    v2 v3  
    33[[PageOutline(2, Contents)]] 
    44 
    5 `libaom-av1` is the AOMedia video encoder for AV1, an open, royalty-free media file format. `libaom-av1` can save about 30% bitrate compared to VP9 and H.265 / HEVC while retaining the same visual quality. 
     5`libaom-av1` is the AOMedia video encoder for AV1, an open source & royalty-free video codec. `libaom-av1` can save about 30% bitrate compared to VP9 and H.265 / HEVC while retaining the same visual quality. 
    66 
    7 To install FFmpeg with support for `llibaom-av1`, look at the [https://ffmpeg.org/trac/ffmpeg/wiki/CompilationGuide Compilation Guides] and compile FFmpeg with the {{{--enable-libaom}}} option. 
     7To install FFmpeg with support for `libaom-av1`, look at the [https://ffmpeg.org/trac/ffmpeg/wiki/CompilationGuide Compilation Guides] and compile FFmpeg with the {{{--enable-libaom}}} option. 
    88 
    9 The default audio encoder for AV1 is `libopus`. 
    109 
    11 libaom offers different rate control modes, which determine the quality and file size: 
     10libaom offers the following rate-control modes, which determine the quality and file size obtained: 
    1211 
    1312- 1-pass average bitrate 
     
    2726 
    2827{{{ 
    29 ffmpeg -i input.mp4 -c:v libaom-av1 -b:v 2M -c:a opus -strict -2 av1_test.mkv 
     28ffmpeg -i input.mp4 -c:v libaom-av1 -b:v 2M -strict -2 av1_test.mkv 
    3029}}} 
    3130 
    32 Only use this option if you do not care about acheiving the best possible quality. 
     31Use this option if file size and encoding time are more important. 
    3332 
    3433=== Constant Quality ===#constantq 
    3534 
    36 In addition to the "default" VBR mode, there's a constant quality (CQ) mode (like CRF in the x264 encoder) that will ensure that every frame gets the number of bits it deserves to achieve a certain (perceptual) quality level, rather than forcing the stream to have an average bit rate. This results in better overall quality. If you do not care about the file size, this should be your method of choice. 
     35In addition to the "default" VBR mode, there's a constant quality (CQ) mode (like CRF in x264 and x265) which will ensure that every frame gets the number of bits it deserves to achieve a certain (perceptual) quality level, rather than encoding each frame to meet a bit rate target. This results in better overall quality. If there isn't a fixed target file size, this should be your method of choice. 
    3736 
    3837{{{ 
    39 ffmpeg -i input.mp4 -c:v libaom-av1 -crf 30 -c:a opus -strict -2 av1_test.mkv 
     38ffmpeg -i input.mp4 -c:v libaom-av1 -crf 30 -strict -2 av1_test.mkv 
    4039}}} 
    4140 
    42 The CRF value can be from 0–63. Lower values mean better quality.  
     41The CRF value can be from 0–63. Lower values mean better quality and greater file size.  
    4342 
    4443=== Controlling Speed / Quality === 
    4544 
    46 `-cpu-used` sets how efficient the compression will be. The default is 1. Lower values mean slower encoding with better quality, and vice-versa. 
     45`-cpu-used` sets how efficient the compression will be. Default is 1. Lower values mean slower encoding with better quality, and vice-versa.