Presets and Tuning Options

Presets

Aurora4 has ten predefined presets that optimize the trade-off between encoding speed (encoded frames per second) and compression efficiency (quality per bit in the bitstream). The default preset is medium. It does a reasonably good job of finding the best possible quality without spending excessive CPU cycles looking for the absolute most efficient way to achieve that quality.

When you use faster presets, the encoder takes shortcuts to improve performance at the expense of quality and compression efficiency. When you use slower presets, Aurora4 tests more encoding options, using more computations to achieve the best quality at your selected bit rate (or in the case of –crf rate control, the lowest bit rate at the selected quality).

The presets adjust encoder parameters as shown in the following table. Any parameters below that are specified in your commandline will be changed from the value specified by the preset.

  1. ultrafast
  2. superfast
  3. veryfast
  4. faster
  5. fast
  6. medium
  7. slow
  8. slower
  9. veryslow
  10. superslow

Tune Options

There are a few tune options available in Aurora4

Tune Effect
default Default configuration, no special optimization.
psnr Obtain higher PSNR scores and may have some impact on perceptual visual quality.
ssim Obtain higher SSIM scores and may have some impact on perceptual visual quality.
vmaf Obtain higher VMAF scores and may have some impact on perceptual visual quality.
screen Improve encode quality for screen content.
movie Improve encode quality for movie content.
game Improve encode quality for game content.
zerolatency No rc-lookahead, no B-frames.
universe Under development.
film Improve encode quality for film content.
grain Improve encode quality for grain content.
animation Improve encode quality for animation content.
stillimage Improve encode quality for static images.
arm Under development.
fastdecode This tunes a few encoding tools to achieve fast decoding.
mpass Improve encode quality for 2-pass encoding. Each pass should add this tune parameter.

Support Matrix

Input format Support Status
8-bit 400 √
10-bit 400 √
8-bit 420 √
10-bit 420 √
8-bit 422 √
10-bit 422 √
8-bit 444 √
10-bit 444 √
interlaced √
progressive √