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Transparent bitrate for 5.1 channel audio?

A bit related to this: https://hydrogenaud.io/index.php/topic,113724.0.html but people went off  on defining terms and never really answered the question.

So I just want to know if anyone has done blind tests for 5.1 channel movie audio ( or similar to movie audio) with opus bitrates?  and what were the results?  Alternatively, anybody have any anecdotal evidence?

Re: Transparent bitrate for 5.1 channel audio?

Reply #1
According to the Opus recommended settings from the Xiph wiki , between 128 and 256 is the sweet spot for 6 channel(5.1 surround) audio, and I trust these recommendations as my own ABX tests proved them true except from VoIP, as discord(opus 1.2) at 24 usually results in some quality complaints and 32 results in none(default is 64, can go up to 96), even though all my friends listens to 14Kb/s whatsapp audio messages without a problem... this varies depending on encoder settings, but the default are the best for audio storage.

I use 128/160 for stereo and 192/256 for surround(4 and 6 channels), but if you have free time I encourage you to do ABX tests with your hardware and ears, as results may vary from person to person. I would start at 192, but you can go as low as you want.

For example: when I encode to mobile, I use 80 because I can't tell the difference with my cheap earbuds in a loud commute environment(and I also want a lot of music on my cheap low space phone), but I can still hear a slight difference between 128 and 160 using proper monitor headphones at home. ¯\_(ツ)_/¯

Pro tip: I recommend using the opus encoder through Foobar2000(right click the tracks you want to convert, convert > ...), it has access to all of the commands and facilitates converting from all the foobar supported formats as it will be decoded before being sent to to the encoder, it can also transfers all tags and attached pictures, calculate and apply opus gain, apply processing(for example, downmix from surround to stereo), and can handle complex but easy to use renaming and folder structures, and saving all these settings as custom encoding presets.

 
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