Opened 5 months ago
#10726 new defect
SMPTE 7.1DS channel layout not usable in mappings bc of missing channel IDs
| Reported by: | Martin | Owned by: | |
|---|---|---|---|
| Priority: | minor | Component: | ffmpeg |
| Version: | unspecified | Keywords: | channel_layout |
| Cc: | Martin | Blocked By: | |
| Blocking: | Reproduced by developer: | no | |
| Analyzed by developer: | no |
Description
Summary of the bug:
1) The channel layout description (https://ffmpeg.org/ffmpeg-utils.html#Channel-Layout) lists two channel IDs ‘SDL’ = surround direct left and ‘SDR’ = surround direct right, but the two IDs are not used in any of the standard channel layout compositions. SDL/SDR map to Lsd/Lsr in E-AC-3 (see ETSI TS 102 366 v1.4.1, https://www.etsi.org/deliver/etsi_ts/102300_102399/102366/01.04.01_60/ts_102366v010401p.pdf), Quicktime, AAC, and Mediainfo.
2) Channel IDs are missing for "Surround Left/Right" which map to Lss/Rss in SMPTE, DTS-HD, AAC, and Mediainfo. Because of that there's currently no way to specify a '7.1DS' channel layout composition using channel IDs (see SMPTE ST 428-12:2013, https://ieeexplore.ieee.org/document/7291368/).
This is not just a documentation flaw as one can check by using the command line below.
How to reproduce:
% ffmpeg -hide_banner -layouts | grep -e 'SD[LR]' ffmpeg version git-2023-11-02-ec8b8cd5c built on 2023-11-02
Patches should be submitted to the ffmpeg-devel mailing list and not this bug tracker.
