Lossless audio codec comparison revision 6 - multichannel part

Introduction

This document compares the performance of lossless audio codecs on multichannel material, which are PCM audio files with more than 2 channels present. Various so-called channel orderings exists, but by far the most common is 5.1, which consists of a front left, front right, center, low-frequency effects (LFE), surround left and surround right channel.

Most of the test corpus for this comparison consists of 5.1 surround sources, but included are also one 4.0 (uad) source and two 7.1 surround sources. The test corpus has changed since the previous multichannel comparison, revision 5, part 1: two sources have been added. One is of a lossy source, being the audio of 1 hour of gaming, to add a source very rich in special effects. The other is Robert Rich - Soundquest 2021.

Method

The method of testing is explained in here. As not all codecs are able to handle multichannel, some codecs are omitted: shorten, OptimFROG and LA. As some codecs do support this 5.1 surround channel ordering but no other orderings, the results are presented twice: first all used sources with only the codecs that support these, and second only the 5.1 surround sources with all tested codecs. In the first, ALAC, TAK, WMA and TTA are omitted.

Results (PDF)

• Average of all surround sources
• Average of 5.1 surround sources
• Results per source, PDF, CSV

Discussion

Compared with the previous multichannel comparison, revision 5, part 1, the performance of most codecs hasn't changed. MonkeysAudio became significantly faster at decoding and FLAC got faster at encoding and better compressing. All other observations are still valid.

Usability

While any of the listed codecs is very much suitable for storing multichannel audio on its own, it is often stored along with a moving picture. Therefore, the possibility of embedding the audio alongside the video is of concern. The Matroska container supports FLAC, ALAC, TTA and WavPack. For MP4, ALAC and FLAC are officially supported.