**Description** The video is from the collaboration of Kamigami&Mabors&VCB-Studio. They did some slight AA and debanding. Both the remastered 5.1 and original 2.0 audio are from AK-Submarines, but I encoded them to Opus. I set 512kbps for the 5.1 and 192kbps for the 2.0. This cut the audio files to around 1/8 of the original 24bit audio, saving 3.66GB. The main subs are /ak/ Submarines v2. Also included are PGS Japanese subs from the BD. The chapters are from Kamigami&Mabors&VCB-Studio. This is a smaller audio version of my [FLAC release](https://nyaa.iss.one/view/1335657). **Info** Video: 1920x1080p x265 10-bit Audio 1: Opus 5.1 512kbps Remaster Audio 2: Opus 2.0 192kbps Original Sub 1: /ak/ Submarines (improved, great signs) Sub 2: Japanese PGS Chapters: yes **Tech Note** When encoding from 24bit audio to lossy codecs you shouldn’t dither since the lossy codec’s decoder already applies dither. I enabled the (non-default) improved Opus souround encoding in ffmpeg with -mapping_family 1. To begin, libopus 1.1+ allocates bitrate in a more desirable way instead of spreading it evenly. For 512kbps, libopus starts by allocating 170kbps for L+R, 170kbps for Lb+Rb (Ls+Rs must get remapped), 85kbps for C, and 77kbps for LFE. It then uses surround masking which takes advantage of cross-channel masking between free-field speakers. This of course is done in the context of retaining stereo downmixing. It also analyzes each channel’s relative audible contribution within the sound field per critical band, and adjusts bitrate accordingly. After all the optimizations the average bitrate turns out to be around 400kbps. I chose 512kbps and 192kbps because they’re a great balance between file size and quality. Those values are smaller than what’s being used for AAC yet Opus has superior quality. The tradeoff for anything smaller isn’t worth saving a handful of megabytes. TL;DR Proper Opus and FLAC sound the same.