Target Quality

Target Quality --target-quality

Target a VMAF score for encoding.

For each chunk, Target Quality searches for the quantizer/crf needed to achieve a certain VMAF score. Target Quality mode is much slower than normal encoding, but can improve the consistency of quality in some cases.

The VMAF score range is 0-100 where 0 is the worst quality and 100 is the best.

Possible Values

Any float value between 0 and 100.

Examples

• > av1an -i input.mkv -o output.mkv --target-quality 80 - Target a VMAF score of 80
• > av1an -i input.mkv -o output.mkv --target-quality 90.5 - Target a VMAF score of 90.5

Probes --probes

Maximum number of probes allowed for Target Quality.

Possible Values

Can be any positive integer.

Default

If not specified, 4 is used.

Probing Rate --probing-rate

Framerate for probes.

Possible Values

Can be any integer from 1 to 4.

Default

If not specified, 1 is used.

Probing Speed --probing-speed

Speed for probes.

If used with --probe-slow, it overrides the respective speed parameter (eg. --cpu-used, --preset, etc.)

Possible Values

Can be any of the following:

• veryslow
• slow
• medium
• fast
• veryfast

Default

If not specified, veryfast is used unless --probe-slow is specified.

Probing Statistic --probing-stat

Statistical method for calculating target quality from sorted probe results.

Possible Values

Can be any of the following:

• mean - Arithmetic mean (average)
• median - Middle value
• harmonic - Harmonic mean (emphasizes lower scores)
• root-mean-square - Root mean square (quadratic mean)
• percentile=<FLOAT> - Percentile of a specified <FLOAT> value, where <FLOAT> is a value between 0.0 and 100.0
• standard-deviation=<FLOAT> - Standard deviation distance from mean (σ) clamped by the minimum and maximum probe scores of a specified <FLOAT> value, where <FLOAT> can be a positive or negative value
• mode - Most common integer-rounded value
• minimum - Lowest value
• maximum - Highest value

Default

If not specified, percentile-1 is used.

Examples

• > av1an -i input.mkv -o output.mkv --target-quality 80 --probing-statistic mean - Target a VMAF score of 80 using the mean statistic
• > av1an -i input.mkv -o output.mkv --target-quality 95 --probing-statistic percentile-25 - Target a VMAF score of 95 using the 25th percentile statistic
• > av1an -i input.mkv -o output.mkv --target-quality 90 --probing-statistic standard-deviation--0.8 - Target a VMAF score of 90 using the value that is 0.8 standard deviations below the mean
• > av1an -i input.mkv -o output.mkv --target-quality 75 --probing-statistic standard-deviation-2 - Target a VMAF score of 75 using the value that is 2 standard deviations above the mean.

Probe Slow --probe-slow

Use encoding settings for probes specified by --video-params rather than faster, less accurate settings.

Note that this always performs encoding in one-pass mode, regardless of --passes.

Minimum Quantizer --min-q

Lower bound for Target Quality Quantizer-search early exit.

If the minimum quantizer is tested and the probe's VMAF score is lower than the Target Quality (--target-quality), the Quantizer-search exits early and the minimum quantizer is used for the chunk.

Possible Values

Depends on the encoder.

Default

If not specified, the default value is used (chosen per encoder).

Maximum Quantizer --max-q

Upper bound for Target Quality Quantizer-search early exit.

If the maximum quantizer is tested and the probe's VMAF score is higher than the Target Quality (--target-quality), the Quantizer-search exits early and the maximum quantizer is used for the chunk.

Possible Values

Depends on the encoder.

Default

If not specified, the default value is used (chosen per encoder).