av1-encoding-scripts/parameters_hdr.md

HDR Encoding Configuration Parameters

This document details the configuration parameters used in the hdr_svt_opus_encoder.py script.

Audio Normalization & Encoding

Audio tracks are normalized using ffmpeg's loudnorm filter and then encoded to Opus.

Loudness Normalization Parameters

The script uses a two-pass loudness normalization with the following target values:

• Integrated Loudness (I): -23 LUFS
• Loudness Range (LRA): 7 LU
• True Peak (tp): -1.5 dBTP

Opus Encoding Bitrates

Audio is encoded with the following bitrates based on the original channel count:

• Mono (1 channel): 64k
• Stereo (2 channels): 128k
• 5.1 Surround (6 channels): 256k
• 7.1 Surround (8 channels): 384k
• Other/Uncommon Layouts: 192k (fallback default)

SVT-AV1 Encoder Parameters

Encoder Version: SVT-AV1-Essential from https://github.com/nekotrix/SVT-AV1-Essential/

Default parameters initialized for the svt-av1 encoder for HDR content:

--speed slower
--quality medium
--film-grain 12
--color-primaries 9
--transfer-characteristics 16
--matrix-coefficients 9
--scd 0
--keyint 0
--lp 2
--auto-tiling 1
--tune 1
--progress 2

(Note: Parameters such as --speed, --quality, and --film-grain can be overridden with command-line arguments when executing the script).
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av1an Initiation Command

Arguments used to start av1an with the SVT-AV1 encoder:

av1an -i <vpy_script> -o <encoded_mkv> -n \
  -e svt-av1 \
  --resume \
  --sc-pix-format yuv420p \
  -c mkvmerge \
  --set-thread-affinity 2 \
  --pix-format yuv420p10le \
  --force \
  --no-defaults \
  -w <calculated_workers> \
  -v "<svt_av1_encoder_parameters_above>"