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Opus at over 40 or 60Kbps for voice sounds like overkill, nevermind 500kbps. What's the rationale for using such high bitrates?
by tincholio 6y ago
Opus at over 40 or 60Kbps for voice sounds like overkill, nevermind 500kbps. What's the rationale for using such high bitrates?
- pfalafel 6y agoI configured the max possible bitrate in the spec. I wanted to find out what is being used in the end. And how it sounds. Most people are calling without a microphone. Please use a headset.
- tincholio 6y agoYou should look up some subjective quality test results for Opus (voice). The MOS curve flattens at about 40kbps, IIRC.
- pfalafel 6y agoOpusFAQ: "Opus scales from about 6 to 512 kb/s" - https://wiki.xiph.org/OpusFAQ#In_what_ways_is_Opus_optimized_for_the_Internet https://wiki.xiph.org/OpusFAQ#In_what_ways_is_Opus_optimized...? Edit: quote from section 1.14 (direct link does not work bc of the question mark in their section ID)
- Zenst 6y agoProbably marketing and the HiFi industry has demonstrated that such people are a nice niche income stream. Some say a fool and their money, I say each to their own and their choice. But I'm sure there are always edge-case valid uses for such audio quality. Maybe talk to bats and dolphins in the future is now one step closer than before is another way of looking at this.
- astrange 6y agoOpus doesn't support any sample rates higher than 48khz, so no bat encoding. Some other audio codecs do, but it doesn't really make a lot of sense and I doubt they've been properly tuned for it.
- Zenst 6y agoOh indeed you are spot on - https://wiki.xiph.org/OpusFAQ#Does_Opus_support_higher_sampling_rates.2C_such_as_96_kHz_or_192_kHz.3F https://wiki.xiph.org/OpusFAQ#Does_Opus_support_higher_sampl...
- jancsika 6y agoBut that 500kbs sound just feels warmer to me (on my laptop).
- pfalafel 6y agoI think the 500 limit is a max bitrate setting, independent of any specific codec. If you deliver audio+video you will need to consider exactly how much of the bandwidth you use for audio. But when doing audio only, simply using the highest possible bitrate seems to be a reasonable choice. In most cases the network will set limited.
- astrange 6y agoSamplerate is an independent dimension of bitrate - although not really because lower bitrates can store fewer samples. It's equivalent to the resolution of an image.
- meepmorp 6y agoSample rate is limit on the frequencies in the original signal that you can represent in your digitization without aliasing.
- phkahler 6y agoSample rate != bit rate. 48khz samples at 16bits each is 768kbps mono. 1.5Mbps stereo. But that's before compression.
- deleted 6y ago[deleted]
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- keeganpoppen 6y ago"640k [bitrate] ought to be enough for everyone"...
- LeoPanthera 6y agoFor mono audio, even 32k Opus is nearly CD quality, and 64k is indistinguishable from uncompressed audio in non-audiophile contexts. 500k is simply ludicrous.
- javajosh 6y agoWould not be ridiculous for serious online musical collaboration where you might want to send many channels at once. Perhaps there is some benefit to multiplexing inside Opus, instead of having separate channels? (Probably a similar argument as the one in favor of monorepos).
- LeoPanthera 6y agoIn this context, latency is far more important than actual audio quality. Human ears are notoriously bad at judging the "quality" of sound, but extremely good at detecting latency between visuals and audio. This is why lip sync is such a problem in home cinema systems.
- namibj 6y agoWell, considering that I can hear a difference between lossless and ~80k Opus (stereo) with a decent headphone amp and 16 EUR Sony in-ear's, I can't share your sentiment. Granted, this is fairly pathological synth sound (the intro/first 30s of Night Club's "Magnetic"), but I would hardly call that listening equipment audiophile.
- LeoPanthera 6y ago80k stereo is (approximately) 40k mono. We seem to have the same sentiment.
- namibj 6y agoNo, I'm saying that this is very much distinguishable without exotic hardware, on music not deliberately created to expose compression artifacts. And at a bit rate higher than what you claimed to be transparent on non-audiophile setups. And calling <20$ headphones (that includes an in-line microphone) on a Thinkpad's built-in headphone amplifier "audiophile" seems inappropriate. I do hear a difference (on FLAC) between those cheap headphones and some ultra-low-distortion 2-way half-open headphones, with the latter being notably more clear. You said 64k stereo aren't distinguishable from FLAC with normal, consumer-grade listening equipment. I said I hear a difference between 80k stereo and FLAC using a laptop built-in headphone amp and the cheapest headphones that didn't look like a consumable.
- ksec 6y agoAt this sort of bitrate I am wondering if AAC-LD ( Low Delay ) could be used on Apple platform. And speaking of that I am wondering if patent has expired on that just like AAC-LC.