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Lyra audio codec enables high-quality voice calls at 3 kbps bitrate

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Re: Lyra audio codec enables high-quality voice calls at 3 kbps bitrate

#111

Post by ChuckMcM »

bscphil wrote: post #88
rectang wrote: post #82

Earlier quoted context omitted.

Excellent catch. To be precise you need a measure of perceptual loudness rather than raw waveform excursion, but I would expect the results to be in line with what you've found. > It's well known in the audio biz that if you ask people to compare two experiences, and one of them is a bit louder than the other, people will say that the louder one was better, or came through more clearly, or whatever it is you're tryin…

Here's an EBU R 128 measure using r128gain: File 'reference.flac': loudness = -25.7 LUFS, sample peak = -9.2 dBFS File 'lyra.flac': loudness = -19.9 LUFS, sample peak = -4.1 dBFS File 'opus.flac': loudness = -25.9 LUFS, sample peak = -9.7 dBFS So that also matches pretty closely what my ears heard.

So nearly 6dB louder. That is quite a bit.

Re: Lyra audio codec enables high-quality voice calls at 3 kbps bitrate

#112

Post by bscphil »

perfmode wrote: post #108
bscphil wrote: post #88

Earlier quoted context omitted.

Here's an EBU R 128 measure using r128gain: File 'reference.flac': loudness = -25.7 LUFS, sample peak = -9.2 dBFS File 'lyra.flac': loudness = -19.9 LUFS, sample peak = -4.1 dBFS File 'opus.flac': loudness = -25.9 LUFS, sample peak = -9.7 dBFS So that also matches pretty closely what my ears heard.

how do the samples compare when loudness is made constant/normalized?

I do still prefer Lyra overall, though not as much as some others (see sibling comment). To me, Lyra is cleaner and easier to understand, but the artifacts it introduces are more annoying and fatiguing than those introduced by Opus. Some people in this thread have reported trouble understanding Lyra, which I attribute to the strange artifacts it introduces.

Re: Lyra audio codec enables high-quality voice calls at 3 kbps bitrate

#113

Post by bscphil »

ChuckMcM wrote: post #111
bscphil wrote: post #88

Earlier quoted context omitted.

Here's an EBU R 128 measure using r128gain: File 'reference.flac': loudness = -25.7 LUFS, sample peak = -9.2 dBFS File 'lyra.flac': loudness = -19.9 LUFS, sample peak = -4.1 dBFS File 'opus.flac': loudness = -25.9 LUFS, sample peak = -9.7 dBFS So that also matches pretty closely what my ears heard.

So nearly 6dB louder. That is quite a bit.

Yes. Assuming this was done by the Lyra encoder directly, and not the person who wrote the blog post pushing the slider, you have to wonder how it would respond to an input with a peak around -3 dB. Would it clip? Is it performing some kind of normalization? Who knows!

It's also interesting that the Lyra clip is ever so slightly longer than the other two. The Opus clip has exactly the same number of samples as the reference. Maybe they didn't use a decoder for Lyra at all, just played the file on one system and recorded it using a line-in on another?

Re: Lyra audio codec enables high-quality voice calls at 3 kbps bitrate

#114

Post by giantrobot »

chrisseaton wrote: post #49
kevin_thibedeau wrote: post #46

Earlier quoted context omitted.

Just disable VoIP or disconnect from WiFi.

Isn't the actual phone network packet-switched and running over fibre optics now anyway? I don't think you can get a literally analog phone call anymore can you?

You haven't had "analog" phone calls for decades. Your analog line was converted to a digital signal at the central office or concentrator (ugly green boxes).

From the CO to a tandem through the core network your call was digitally switched to the endpoint where it was converted back to analog for the callee's phone.

Re: Lyra audio codec enables high-quality voice calls at 3 kbps bitrate

#115

Post by adrianmonk »

bscphil wrote: post #79

I've just taken a minute to confirm what my ears told me in Audacity. Please have a look at this screenshot: https://cloudflare-ipfs.com/ipfs/Qma41RMzieQ6ZGdGem9rLxnxEL1... The Lyra version is clearly much louder. This is a serious problem and it borders on being reasonable to call it "cheating". It's well known in the audio biz that if you ask people to compare two experiences, and one of them is a bit louder than t…

Definitely a real effect, but it seems like Google accounted for that in their listening tests.

The Google blog post links to the Lyra paper[1], and Section 5.2 of the paper says:

> To evaluate the absolute quality of the different systems on different SNRs a Mean Opinion Score (MOS) listening test was performed. Except for data collection, we followed the ITU-T P.800 (ACR) recommendation.

You can download those ITU test procedures[2], and skimming through that, it does mention making "the necessary gain adjustments, so as to bring each group of sentences to the standardized active speech level" and a 1000 Hz calibration test tone related to that. (See sections B.1.7 and B.1.8.)

So, if I skimmed correctly, and if the ITU's method of distilling speech loudness into a single number is an effective way to match the volume levels[3], then it seems like they did what they could to avoid cheating at the listening tests.

It is still interesting that Lyra makes things louder, though.

---

[1] https://arxiv.org/pdf/2102.09660.pdf

[2] https://www.itu.int/rec/T-REC-P.800-199608-I

[3] and even for speech that passes through different codecs before its loudness is determined

Re: Lyra audio codec enables high-quality voice calls at 3 kbps bitrate

#116

Post by kroltan »

bentcorner wrote: post #94
reaperducer wrote: post #45

Earlier quoted context omitted.

I had the pleasure of using a real landline just before the pandemic. Honest wire-to-wire connection between two ranches, so no silly VOIP steps between. It was fantastic. You don't appreciate how much latency is destroying our ability to communicate verbally until you go back to the old way. One example is arguing. It's no wonder people used to be able to argue with one another on a telephone. You could raise your v…

I'm glad you bring up latency - I've experienced several second latency in discord and it's really terrible when it happens (diagnosed via side-channel). The worst thing is that the app does nothing to try to salvage the conversation and the app doesn't tell you it's in a degraded state, so you'd never know this was a problem.

It has a quality indicator on the bottom right, and if you click it there's a nice chart that shows the latency.

https://i.imgur.com/vR7NSpG.png

Or are you talking about something else?

Re: Lyra audio codec enables high-quality voice calls at 3 kbps bitrate

#117

Post by eeZah7Ux »

colordrops wrote: post #75
rectang wrote: post #53

Earlier quoted context omitted.

Between miserable latency, not-so-great fidelity, and the fecklessness of phone companies in the face of the robocall epidemic, I have come to hate phone calls. I'm rooting for something to replace phone communications. Any chance that Matrix can do better on any of those fronts? Especially on fidelity and latency since they're germane to the high-level subject of this discussion.

One conspiracy theory is that tech companies have lobbied to prevent real action on robo-calls, in order to get people like you to hate calls and migrate to online services.

> conspiracy theory

Sounds like a run-the-mill everyday business decision.

Re: Lyra audio codec enables high-quality voice calls at 3 kbps bitrate

#118

Post by wrs »

giantrobot wrote: post #114
chrisseaton wrote: post #49

Earlier quoted context omitted.

Isn't the actual phone network packet-switched and running over fibre optics now anyway? I don't think you can get a literally analog phone call anymore can you?

You haven't had "analog" phone calls for decades. Your analog line was converted to a digital signal at the central office or concentrator (ugly green boxes). From the CO to a tandem through the core network your call was digitally switched to the endpoint where it was converted back to analog for the callee's phone.

However, those were circuit-switched, not packet-switched. (At least for a while.)

Re: Lyra audio codec enables high-quality voice calls at 3 kbps bitrate

#119

Post by lxgr »

tyingq wrote: post #103
lxgr wrote: post #63

Earlier quoted context omitted.

In-band fax will certainly not work over a lossy voice codec, unless your fax modem is able to mimic human speech patterns.

I thought I remembered getting 2400 baud fax (unreliably) working on G.729. Though I guess, yes, if this codec is trained on voices that probably doesn't bode well for fax.

Ah, I keep forgetting how low bandwidth fax modems are. That might actually work – 2400 baud is basically a person whistling or humming one out of two tones :)

Re: Lyra audio codec enables high-quality voice calls at 3 kbps bitrate

#120

Post by 908B64B197 »

reaperducer wrote: post #45
rectang wrote: post #39

What I want to know is whether Lyra takes any longer to encode than the alternatives. Because as far as I can tell, nobody cares in the slightest about latency. Phone calls are getting to be like writing postcards to each other. Speak in a whole paragraph. Wait several seconds for the latency to clear. Then the other party responds with a whole paragraph, waits several seconds for the latency to clear... Improvements…

I had the pleasure of using a real landline just before the pandemic. Honest wire-to-wire connection between two ranches, so no silly VOIP steps between. It was fantastic. You don't appreciate how much latency is destroying our ability to communicate verbally until you go back to the old way. One example is arguing. It's no wonder people used to be able to argue with one another on a telephone. You could raise your v…

I remember switching to VoIP and noticing the voice quality getting better compared to the old twisted pair. No noticeable latency.
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