Hi there,
I would like to discuss two topics here, both closely related to channel mapping in standard 5.1 and 7.1 multi-channel configurations. If we look at the CEA-861(ancient revision D) channel mapping table below, all 8 channels are numbered and their presence in various configs is labeled with the channel id. Two configs are highlighted - 5.1 and 7.1:
1. Odd-numbered are left channels in digital transmission pairs, even-numbered are right channels. Channel #3 - left in the second stereo pair - is LFE, channel #4 is Centre. Could someone please point out where the expectation/standard of Center channel being transferred in the left channel of the second stereo pair came from? It must be something else than the CEA/CTA standard.
2. Many listeners would like to check the correct channel mapping and there is a number of test files for that available for download or speaker setup utilities with test tones built in many universal players and streamers. Here is an interesting observation. If we play 5.1 test file, for example from this page
https://www2.iis.fraunhofer.de/AAC/multichannel.htmland specifically this file
https://www2.iis.fraunhofer.de/AAC/ChID-BLITS-EBU-Narration441-16b.wavall the channels are mapped as expected. But if we play this 7.1 file
https://www2.iis.fraunhofer.de/AAC/7.1auditionOutLeader%20v2.wavthen the Surround pair seems to be swapped with Surround-Back pair, which I find quite strange. With the CTA-861 as a reference the difference between 5.1 and 7.1 should be just addition of the rear surround pair, certainly not rearrangement of the whole surround part. This has been confirmed with multiple players, via HDMI as well as player's analogue outputs, for which the connector channel labelling would become incorrect with the 7.1 test file.
Could someone with a 5.1/7.1 setup try the files above and report the results back here, please?
Many thanks.
Best Regards,
Pavel