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Topic: Converting FLAC to Opus. 160 or 192kbps for universal transparency? (Read 19825 times) previous topic - next topic
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Converting FLAC to Opus. 160 or 192kbps for universal transparency?

So I think I've read most of the information available regarding people's opinions (here and elsewhere on the internet) going back as far as probably 2011 to today. From what I've read Opus has improved over time, in the sense that 128kbps and higher were relatively easy to spot as not transparent when only earlier versions of Opus were available, but for some number of years even lower bitrates have been considered transparent to many people for most music. So far I'm thinking maybe 160kbps is enough to ensure universal transparency across all music (perhaps some "killer samples" excluded), but before I start converting my FLACs, I wanted to make sure there's no advantage to converting to 192kbps in Opus (or perhaps even higher).

This is one of the main links I've used to help decide on this range (160 to 192kbps) for converting my files: https://wiki.hydrogenaud.io/index.php?title=Opus#Music_encoding_quality

I've mainly written this post because I want to get an up-to-date set of opinions from people. I've read more than once certain people's opinion that you should just use 192kbps to ensure optimal quality under all conditions. I'm not really worried about what is likely a minor space saving difference between 160 or 192kbps, so if it might be worth it from an audio quality perspective to use 192kbps, even if it's only worth it in rare cases, I might go with that just to be on the safe side.

Let me know what you think, thanks.

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #1
Funny that I also convert my large library and I arrived at the decision that I convert music I regard poorly mastered / poor quality at 160 kbs (I am talking of original CD-s but many had poor engineers. Approx 50% of my collection. Just today I listened to 2 Manic Street Preachers albums and they sound very poor). I want to have a piece of mind, but I cringe hence 160 kbp. I would want 128 kbp, but I thought some must be so bad that I have to throw some bits to help the encoder. Totally unfounded but there you go.

Good CD-s that sound crisp and clear and undistoried (mostly end up Jazz and classical, and good vocals) I decided to convert at 192kbs. Just want the extra safety.

I do not see the point going above that based on the feedbacks and listening tests on the forum.

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #2
So far I'm thinking maybe 160kbps is enough to ensure universal transparency across all music (perhaps some "killer samples" excluded),
In my opinion it is 100% correct.

Quote
I'm not really worried about what is likely a minor space saving difference between 160 or 192kbps, so if it might be worth it from an audio quality perspective to use 192kbps, even if it's only worth it in rare cases, I might go with that just to be on the safe side.
Be careful, here is exactly where begins the slippery slope. There is an inflationary pressure at the exact moment you want to replace lossless by lossy and ask to avoid all possible risk of hearing slight artifacts on exceptional case, or minor differences under extreme listening conditions. 160 kbps is fine but 192 mathematically reduces the risk. But what about using 220 kbps to reduce further the risk: it's only 15% bigger? Finally, doesn't 256 kbps provide a better safety margin? Oh wait, I found a topic and someone was able to ABX one sample at 256 kbps: shit, I now really think it's better to maintain at least 320 kbps. But now I'm not even sure to use perceptual lossy encoder anymore. So my question is: WavPack lossy or LossyFLAC? And in this case, I see many people recommanding to go up to 380 kbps if not more.
At the end, you stay with your FLAC library untouched.

You want to make a smart use of modern lossy encoders like OPUS? 160 kbps is really fine. It's not absolutely perfect but nothing is (it's the exact meaning of lossy). You'll save a lot of space and I doubt you'll regret it.

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #3
I use 256 kbps and resampling with SoX DSP.

 

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #4
Unless your collection is truly gargantuan it shouldn't take that long to batch convert your entire library as needed. At worst maybe leaving it running overnight on a modern CPU?

In this circumstance I just choose the highest bitrate that will fit the whole collection on whatever disk the opus is going on, with a little extra room to add more later.

If you are not storage space constrained than there is no reason not to just use your flacs. If you are storage space constrained then that constraint makes the bitrate decision for you.

I use 120kbps as it lets me fit my whole library on the 64GB sd card in my phone. If I'm listening using my phone it's almost certainly in a noisy environment anyway... and going over APTX bluetooth... even 120kbps is overkill.

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #5
Given what the OP said, 192kbps is likely what you want to use given this listening test from Oct 2020 from IgorC as every single sample he tested was a perfect 5.00... https://hydrogenaud.io/index.php?topic=120007.0

because for someone who's concerned with getting peak sound quality with Opus, but without pegging the bitrate ridiculously high and defeating the purpose of using a lossy format in the first place, 192kbps seems to be what you probably want.

so between 160kbps vs 192kbps on Opus... I think you sort of answered your own question as if your concerned with perfection then 192kbps is the safer option even though 160kbps is probably minimally worse and is a bit more efficient.

with that said... I am of the mindset if someone is going to use any higher than 96kbps or 128kbps you might as well just jump to 192kbps range and forget about it as it seems like once people are in this 192kbps range or so, it does not really matter which lossy format you choose as they are all close enough to each other overall. hell, even MP3 (i.e. LAME V2 (190kbps average)), as shown in IgorC's test from Oct 2020, gives high quality sound overall lacking 'maybe' a couple of samples or so.

p.s. but in the real world... 96kbps or 128kbps (especially with Opus) is probably more than enough for most people, if not the vast majority of people when just sitting back and listening to their music straight up. or if someone is THAT concerned with perfection, you might as well switch to a lossless format (i.e. FLAC etc) since the whole point of lossy audio is to get the smallest file size while maintaining a high enough level of sound quality and in this regard it's hard to go wrong with Opus @ 96kbps or 128kbps. hell, even 64kbps is a viable option for many people since it's in the ball park of MP3 @ LAME V5 (130kbps average) which is good enough for many people.
For music I suggest (using Foobar2000)... MP3 (LAME) @ V5 (130kbps). NOTE: using on AGPTEK-U3 as of Mar 18th 2021. I use 'fatsort' (on Linux) so MP3's are listed in proper order on AGPTEK-U3.

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #6
So far I'm thinking maybe 160kbps is enough to ensure universal transparency across all music (perhaps some "killer samples" excluded),
In my opinion it is 100% correct.


Is this also relevant when using bluetooth device such as headphones/speakers or is better to use higher bitrate source which is better at transcoding when using bluetooth device?
As I understand, no matter which format/codec is used, transcoding to bluetooth codec always occur.
lame --abr 288 -f --lowpass 17 (+ mp3gain@92 dB)

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #7
Given what the OP said, 192kbps is likely what you want to use given this listening test from Oct 2020 from IgorC as every single sample he tested was a perfect 5.00... https://hydrogenaud.io/index.php?topic=120007.0

because for someone who's concerned with getting peak sound quality with Opus, but without pegging the bitrate ridiculously high and defeating the purpose of using a lossy format in the first place, 192kbps seems to be what you probably want.

so between 160kbps vs 192kbps on Opus... I think you sort of answered your own question as if your concerned with perfection then 192kbps is the safer option even though 160kbps is probably minimally worse and is a bit more efficient.

with that said... I am of the mindset if someone is going to use any higher than 96kbps or 128kbps you might as well just jump to 192kbps range and forget about it as it seems like once people are in this 192kbps range or so, it does not really matter which lossy format you choose as they are all close enough to each other overall. hell, even MP3 (i.e. LAME V2 (190kbps average)), as shown in IgorC's test from Oct 2020, gives high quality sound overall lacking 'maybe' a couple of samples or so.

p.s. but in the real world... 96kbps or 128kbps (especially with Opus) is probably more than enough for most people, if not the vast majority of people when just sitting back and listening to their music straight up. or if someone is THAT concerned with perfection, you might as well switch to a lossless format (i.e. FLAC etc) since the whole point of lossy audio is to get the smallest file size while maintaining a high enough level of sound quality and in this regard it's hard to go wrong with Opus @ 96kbps or 128kbps. hell, even 64kbps is a viable option for many people since it's in the ball park of MP3 @ LAME V5 (130kbps average) which is good enough for many people.

160kbps would be my upper limit for any post MP3 codec, Any higher like 192 ~ 320kbps may as well use Lossless codec. Outside of few hard samples on MP3, LAME V5 ~ V4 still hold up very well for many people.
Got locked out on a password i didn't remember. :/

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #8
160kbps would be my upper limit for any post MP3 codec, Any higher like 192 ~ 320kbps may as well use Lossless codec. Outside of few hard samples on MP3, LAME V5 ~ V4 still hold up very well for many people.

Yeah, I would largely agree, especially taking efficiency into account.

even for MP3 using the Hydrogenaudio Wiki page (i.e. https://wiki.hydrogenaud.io/index.php/LAME#Recommended_encoder_settings ) as a guide... given what it says there I tend to figure V4 (165kbps average) is probably not worth using considering there is only 10kbps difference going to V3 (175kbps average) which is the early stage of 'very high quality' mode where as V4 is still a bit shy of that status and is barely lower in bit rate.

that's why when it comes to MP3 I tend to be of the mindset to use either V5 (130kbps average) or switch to at least V3 (175kbps average). even V2 (190kbps) probably ain't a bad idea either since it's only minimally more bit rate than V3. but I have no idea whether V3 (175kbps average) to V2 (190kbps average) has much, if any, real world difference in sound quality(?). but some might just see it as a little safety buffer. but once you start getting into V1(225kbps) or V0(245kbps), MP3's efficiency starts to go out the window. NOTE: even for those who like to nit pick over fine tuning MP3's bit rates may consider one users suggestion of V1.7 which I think floats around 200kbps off the top of my head.

but yeah, I think V5 is pretty good for myself and is still quite efficient to. I tend to see V5 (130kbps average) as a good minimum bitrate guideline when it comes to MP3 and, like you said, holds up well for many people, especially given this public listening test from 2014 (i.e. https://listening-test.coresv.net/results.htm ) which pretty much sums up that MP3 V5 is a solid performer all-around even though I am sure there are some who claim one needs V0(245kbps average) or 320kbps for MP3 to be good which is largely not true given the data we got to say otherwise, especially for anyone who's anywhere near the average person.

so given this whole V5 (130kbps average) with MP3 doing pretty well for many, that's kind of why I think with Opus many (hell, I think it's safe to say most people) will be okay with 64kbps or no more than 96kbps, since as you already know, 96kbps is better than MP3 @ V5 (130kbps average) and will probably challenge the higher bit rate MP3 ranges. I think it was IgorC that said Opus @ 80kbps is roughly the same as MP3 @ V5 (130kbps average). hell, I don't think it's a stretch to claim that Opus @ 64kbps could challenge MP3 @ V5 (130kbps average) for many people (since many people tend not to be able to hear the finer details that people like IgorC etc can around here) and it's about half the bit rate.

even with your post-MP3 encoder comment of 160kbps being upper limit... I doubt I can tell a difference between Opus @ 96kbps and maybe not even at 64kbps in most cases. so, at least speaking for myself, I almost surely won't even need to be close to 160kbps to have WELL more than enough quality sound (although I get your reasoning taking into account a bit more picky listeners in which case I can easily see you arguing 160kbps is the sweet spot for those types of people). when I think Opus I tend to have the mindset 'use 96kbps and forget about it' as a general guideline as that will likely please a lot of people short of a small amount of golden eared types. but if someone is a bit tight on space, 'use 64kbps and forget about it'. NOTE: I tend to consider 64kbps a good minimum for Opus as going lower than that, while still respectable sound quality given the bit rates, it's not worth the largely minimal storage space savings for the sound quality decline at that point and I also feel basically the same in another way when it comes to 96kbps in that going higher than that point one is not increasing sound quality enough to justify 1/4th or more bit rate increase (i.e. like say 96kbps to 128kbps or higher). but then I am sure, especially at this point in time when storage space is cheap, one could argue it does not even matter (i.e. jack up the bit rate (say 192kbps+) and forget about it). still, I think, as you basically think, that the whole point of lossy is to find that sweet spot of sound quality/storage space as it defeats the purpose of using lossy files with ridiculously high bit rates (i.e. lets call 'ridiculously high' over about 192kbps or so), especially with modern encoders like Opus which can really drop bit rates (i.e. 64kbps) without sound quality taking too much of a hit for the common person or thereabouts.
For music I suggest (using Foobar2000)... MP3 (LAME) @ V5 (130kbps). NOTE: using on AGPTEK-U3 as of Mar 18th 2021. I use 'fatsort' (on Linux) so MP3's are listed in proper order on AGPTEK-U3.

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #9
160kbps would be my upper limit for any post MP3 codec, Any higher like 192 ~ 320kbps may as well use Lossless codec. Outside of few hard samples on MP3, LAME V5 ~ V4 still hold up very well for many people.

There's a huge amount of space between 320k and the 840k+ rate of the original FLAC. For a random track in my library, 320k is 38% of the original. At the complete extreme of 512k Opus, that's still only 58% of the original size. Another extreme, lossyFLAC at insane quality, 69%; Standard quality: 48%. So even for the absolute most discerning and picky individuals, there are several insanely preserving, yet lossy, options to pick from for significant savings. For this track, at least 30% reduction.

Then for me, lossless is purely for paranoid archival purposes, to which I unashamedly subscribe, but I don't see any reproduction scenario (other than having a paranoid archive on the same machine you are doing your listening on, of course) where I feel I may as well use lossless. On the contrary, I may as well give it a pass through insane lossyFLAC, or resample. Resampling to your audible range will probably give you at least 10% reduction.

Some people may reach a point of having to make a time/space trade-off, but really it's at least 80-90% space reduction for the vast, vast majority of people, at least 50% reduction nigh-certainly, and encoding is not that slow, especially if you compare encoding time vs listening time, so really there's a lossy option out there for everybody, whether for mobile reproduction, or even outright archival.

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #10
There's a huge amount of space between 320k and the 840k+ rate of the original FLAC. For a random track in my library, 320k is 38% of the original. At the complete extreme of 512k Opus, that's still only 58% of the original size.

A factor of two (or three) is much less than the ratio hard drive to cell phone storage.

To those of us who cannot possibly fit our entire collection on our phones, I guess we want to transfer disposable lossies to phone in a reasonable time. 1/3 size -> 3x speed, that improves - but 9x speed, that improves more. 

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #11
I forgot about transfer speed, another reason to basically always transcode.

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #12
There's a huge amount of space between 320k and the 840k+ rate of the original FLAC.
Side note: Piano music compresses really well with FLAC often in the 300-400k range.

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #13
@thacirp

With lame 3.100  the gap between V4 and V3 is closer to 20 kbps. 
You can expect 155 / 175 on average.
For lame 3.98 they were closer.

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #14
Just as a fun fact: higher bitrate doesn't necessarily sound better. For example, this Opus killer sample sounds fine at 150kbps, but has artifacts at 256kbps. That's an atypical, not "real-world" sample, though, so make of it what you will.

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #15
Playing back a @96 kbps opus file on my rockboxed Fiio M3K is always OK, bigger bitrates can stutter(especially with eq or DSP). My 2 cents

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #16
Just as a fun fact: higher bitrate doesn't necessarily sound better. For example, this Opus killer sample sounds fine at 150kbps, but has artifacts at 256kbps. That's an atypical, not "real-world" sample, though, so make of it what you will.

Well that is unfortunate as it looks like the high bitrates haven't been
tuned well enough. Yes its atypical -its occured in mp3 but with something
like MPC or vorbis, I don't think it happens. With mpc standard (175k) something like
that constructed signal may be transparent or not a major deal .
If there was some issue; the next level or two; extreme or insane would almost certainly
bring it down to zero or close. With vorbis aotuv, I estimate a range of Q5 to Q7 is what would take
to do similar.

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #17
Funny that I also convert my large library and I arrived at the decision that I convert music I regard poorly mastered / poor quality at 160 kbs (I am talking of original CD-s but many had poor engineers. Approx 50% of my collection. Just today I listened to 2 Manic Street Preachers albums and they sound very poor). I want to have a piece of mind, but I cringe hence 160 kbp. I would want 128 kbp, but I thought some must be so bad that I have to throw some bits to help the encoder. Totally unfounded but there you go.

Good CD-s that sound crisp and clear and undistoried (mostly end up Jazz and classical, and good vocals) I decided to convert at 192kbs. Just want the extra safety.


You're right. The cleaner the sound, the less it need bits to encode. If the sound is crappy and full of noise, you'll need more bits.



Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #18
. I'm not really worried about what is likely a minor space saving difference between 160 or 192kbps
Let me know what you think, thanks.

If I love the music I go for 192Kb. If not - album with lesser interest - 96Kb is more than enough.





Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #19
Google encodes into 160kbps Opus and I have yet to find a song/track which has encoding artifacts or any audio issues.

This bitrate is 100% transparent for me.

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #20
Google encodes into 160kbps Opus
If you're talking YouTube then 160kbps is often assumed as an upper limit for Opus bitrate, not an average or constant one. Average is something like 128 kbps on YouTube.

It's close to transparency at that bitrate, but absolutely not 100% even for me.
Opus VBR 256 + SoX

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #21
Google encodes into 160kbps Opus
If you're talking YouTube then 160kbps is often assumed as an upper limit for Opus bitrate, not an average or constant one. Average is something like 128 kbps on YouTube.

It's close to transparency at that bitrate, but absolutely not 100% even for me.

I'd like to get a few YT Music tracks which you consider not to be 100% transparent. I've heard about that twice already without a single example which I find a little bit insincere if not outright deceitful.

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #22
I'd like to get a few YT Music tracks which you consider not to be 100% transparent. I've heard about that twice already without a single example which I find a little bit insincere if not outright deceitful.

According to @Eurobeat_fan , it's (some?) tracks from the album Load by Metallica.

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #23
I'd like to get a few YT Music tracks which you consider not to be 100% transparent.
If we talk about YouTube quality then it's basically almost any Eurobeat track, for example this one: https://www.youtube.com/watch?v=YagYWlbcU1o .

Honestly I haven't listened to a lot of songs in Opus VBR 128 kbps because after I started transcoding Eurobeat, I immediately felt the sound being wrong, ABXed my transcodes pretty much easily and just moved to 192 kbps.


With 192 kbps I have got two problematic areas in my music that I was able to ABX:

https://youtu.be/WE0ReQJ-Kfk (from Metallica - Load album, like mentioned above) - basically hi-hat is smeared, as simple as that.

https://youtu.be/wwztcDndzJE - starting from 3:18 there's a tremolo on the left side, it gets muffled in Opus VBR 192 kbps comparing to my FLAC encodings. Ironically bitrate is pretty low during this section, I get something like 170-180 kbps when quality-based target is 192 kbps. Seems logical because there're almost no transients in this overcompressed song (I don't like the sound), but the problem is the problem and I can ABX it. BTW this problem is not present in Musepack Q5 despite being lower bitrate, I can't ABX it comparing to FLAC.

If this gives you idea where I could be wrong, I used SoX resampler with default settings before the Opus encoder to convert all my music into 48 khz.
Opus VBR 256 + SoX

Re: Converting FLAC to Opus. 160 or 192kbps for universal transparency?

Reply #24
There is no universal transparency with any lossy codec, regardless of bitrate. All lossy codecs have killer samples.