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Can anyone reliably ABX OPUS at 160kbps?

It's taken me around a year to settle on a bitrate that (to my ears) is truly transparent across all material. For a time, 144kbps did the trick well enough, but some tracks would present with slightly softened / less present high frequency detail (we're talking above 18,000Hz) - in particular, rides and hi-hats with sharp attacks and lots of energy above this range would sound slightly muted when awash other high frequency noise (like cymbal crashes with long tails). The difference at 144kbps was minimal, but definitely there, and so I was reliably able to tell the OPUS file apart from the original FLAC in these select cases 100% of the time. It seems that there is still synthetic rendering in this range that does a good, but not perfect job at capturing the true tone of these sounds when there is competition with other high frequency noise. For the record, my hearing tops out at 19,300Hz.

Upping the bitrate to 160kbps (VBR) takes care of these lingering cases and allows the high frequency sounds I mentioned to retain their crispness / presence even when awash with competing noise. This was the final audible difference left and now my entire library (not just the majority as was the case previously) sounds indistinguishable from the original lossless source. To my ears, it seems that this is the bitrate which achieves "true" transparency for those more sensitive to high frequency detail.

I'm curious if there are others out there who are sensitive to HF that have to push beyond 160kbps, and if so, are there any samples you can share that you've found that you can reliably ABX at this bitrate?

Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #1
It's possible to ABX Opus at 256+ kbps on killer samples but still I feel very comfortable listening it in range of 96-160 kbps.
Small impairments are far from being critical in that range.  

People use Opus at following bitrates https://hydrogenaud.io/index.php/topic,115386.0.html


Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #3
My opinion here is that if you're not starved for storage space, just encode everything at 192kbps and forget about it. Even if the bitrate is higher than needed, who cares?

Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #4
My opinion here is that if you're not starved for storage space, just encode everything at 192kbps and forget about it. Even if the bitrate is higher than needed, who cares?

QFT!

If not sufficiƫnt or in doubt, you should use FLAC and only use lossy for portable devices.

I personally have all music lossless and keep it that way. Buy 2x 2TB drives and you have a huge amount of music to be stored plus a backup. Would suggest to do that relatively small investment and you always have unaltered CD quality music you can transcode at any time if you need to fill a portable device.

Every time a new format or encoder version comes out I know from myself I would have regret I didn't have the lossless version anymore. I made a hell of a lot mp3's in 128kbit in 199x that are just inbearable to listen to, but I didn't know better then. So... lossless only for me.

Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #5
Damn. I was satisfied with 80 kbit until few days ago when I thought that hihats on particular album sound a bit muffled, upped the bitrate to 96 and did a quick ABX test, and there you go, I have a new standard for opus files... :)
Opus at 160 kbit seems like overkill for me.

Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #6
I do have an archive of my music library in FLAC format, with the occasional album in 320kbps MP3. I just enjoy playing with the cutting edge of lossy encoding, and OPUS is one of my favourites (Vorbis has its strengths too).

160kbps seemed overkill to me initially, but after ABXing a few of the tracks in question it felt like a sensible change. It probably is overkill for over half of my library, but certain genres required that extra boost to get them sounding that little bit better. State Azure is an artist whose music seems to be hungry for those extra bits, for example. Lots of intricate HF detail with sharp attacks.

Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #7
My opinion here is that if you're not starved for storage space, just encode everything at 192kbps and forget about it. Even if the bitrate is higher than needed, who cares?

While I don't think one could really fault you for saying that when you got storage space to burn, I think it's more of the thought of wasting storage space. basically it's mainly a efficiency thing why I avoid the higher bit rate settings.

when it comes to Opus I see 96kbps, or 128kbps tops, as the 'use it and forget about it' setting and it's still efficient at those rates as beyond 128kbps (hell, even 96kbps for that matter) I would imagine the gains on sound quality are minimal for a solid boost to file size. basically given the sound tests around here it seems like 96kbps is pretty much the sweet spot of sound quality/efficiency with Opus (like lowering file size as much as possible with minimal loss (as in not all that noticeable) to the sound quality) as they seem to be around the mid 4's or higher out of 5. so we are talking not far from perfection already.

I feel 96kbps is easily high enough quality to where it's unlikely most people would notice anything negative about it without nit picking with optimal listening environment etc as it's a setting where your not really going to notice anything bad when your just enjoying your music (hell, maybe even lower than 96kbps depending on listening environment etc).

but I think IgorC pretty much summed up most peoples opinions around here in that 96-160kbps (basically 96/128/160(these three have the most votes)) is best as going higher than 160kbps is largely a waste of storage space (basically overkill) and going under 96kbps you start to roll the dice on sound quality loss. that seems to be very similar to AAC to.

@hlloyge

Quote
Damn. I was satisfied with 80 kbit until few days ago

Yeah, I recently changed to 96kbps from 80kbps as I figure why gamble on sound quality for only a 16kbps difference in space savings especially since we know that 96kbps scores really well on listening tests around here this seems like a safe default choice for many people.

p.s. for my less important music... I been using 64kbps as that seems like a good choice if you want to roll the dice a bit, but not too much. hell, Opus is more usable at lower bit rates, say 64kbps or lower unlike AAC-LC and especially MP3 as it's like the lower the bit rate goes the more Opus shines over AAC-LC/MP3. so from what I can tell around here it seems Opus only has a real advantage over AAC-LC at about 96kbps and lower as once you get into the 128kbps and higher range it don't seem to matter much which encoder you use between Opus/AAC-LC and even MP3 comes into the conservation probably not much beyond the 128kbps range.

@Lumitopia

Quote
For the record, my hearing tops out at 19,300Hz.

I don't know how accurate this stuff is but based on this YouTube video... https://www.youtube.com/watch?v=ncWCrqKcusY ; on my PC's Klipsch Pro-Media speakers (which should be above average PC speakers), once it hits about 15000 Hz (maybe a hair over that) I can't no longer hear anything and I don't start hearing anything initially til about 25-30 Hz or so.

ill be 39 years old in October. so I assume me not being able to detect the full spectrum is normal for my age? ; or could it be my speakers etc?

but looking around online I found... "Almost everyone can hear 8,000 Hz. People under 50 years of age on average can hear 12,000 Hz. And 15,000 Hz can be heard by people under 40 (and people with better headphones than mine, at least I hope that's what it is). And so on." (source = http://www.iflscience.com/health-and-medicine/test-how-old-are-your-ears/ ) ; so apparently I am normal for my age range. who knows, with quality headphones etc I might be able to go a little higher but I can't see it being much as it's pretty safe for me to say I won't touch your 19300 Hz hearing level.
For music (especially on-the-go)...
-I suggest Opus @ 96kbps (or... 64kbps minimum, 128kbps maximum). *preferred choice*
-I suggest AAC(Apple) @ 96kbps (q45 TVBR) or 128kbps (q64 TVBR). *secondary choice*
-I use Foobar2000 (/w Encoders Pack etc) to convert FLAC to Opus/AAC(Apple).

Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #8
It's obviously my own personal experience and I know what I'm going to say has been said before umpteen times but, being really (really!) strapped for storage space seems to be the domain of mobile phones and what-not, more than any other device.

So, in fairness, that's exactly the kind of use, I at least, feel the least 'empowered' to be listening for this or that artifact; we all know why: noisy surroundings, our minds being usually occupied by some other more pressing demand (busy traffic, being late, etc.).

In short, Opu's being the outstandingly efficient low-bitrate format it is, fits the bill well with a public whose mobile storage space is at a premium, not someone sitting on an armchair.
Listen to the music, not the media.

Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #9
I don't know how accurate this stuff is but based on this YouTube video... https://www.youtube.com/watch?v=ncWCrqKcusY ; on my PC's Klipsch Pro-Media speakers (which should be above average PC speakers), once it hits about 15000 Hz (maybe a hair over that) I can't no longer hear anything and I don't start hearing anything initially til about 25-30 Hz or so.

YouTube uses a low pass filter at 17500 Hz.

Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #10
VBR or constrained VBR (CVBR)? which is better?

Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #11
One moment.
Opus has CVBR mode which is an equivalent to Apple AAC ABR.

At the same moment Apple AAC CVBR is constrained VBR but still with a big variations.

From best quality to worse.
Opus  : VBR > CVBR > hard-CBR
Apple AAC:  true VBR/ TVBR and CVBR > ABR > CBR

(TVBR and CVBR have similar quality).

Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #12
One moment.
Opus has CVBR mode which is an equivalent to Apple AAC ABR.

At the same moment Apple AAC CVBR is constrained VBR but still with a big variations.

From best quality to worse.
Opus  : VBR > CVBR > hard-CBR
Apple AAC:  true VBR/ TVBR and CVBR > ABR > CBR

(TVBR and CVBR have similar quality).

Gracias! Thanks, my english is not very good but I appreciate that you have answered my question. Then I will use the VBR mode.

Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #13
@seventhstar

With Foobar2000 it defaults to basically the best mode for Apple AAC and Opus which is VBR for Opus and TVBR for Apple AAC. TVBR or CVBR are all one really needs to use for Apple AAC and VBR for Opus is typical.

I prefer TVBR over CVBR in general because sound quality wise they are pretty much the same (some basically claim CVBR is about the same, maybe a hair better than TVBR (sound quality wise) but usually at a noticeable increase to bit rates) but TVBR generally gives you smaller files (not always, but typically does) which makes it a bit more efficient and being sound quality is pretty much the same, I would rather choose the one that generally uses less storage space since it's more efficient.

like on some of my music, TVBR(Apple AAC) at 96kbps can shoot down into the 6x kbps range (sometimes lower) and I have seen it hit roughly as high as the 12x kbps range (but usually in the ball park of 96kbps give or take 10kbps or so) where as doing the same thing with CVBR it tends to be more stable around the 96kbps range as CVBR seems to limit the bit rate from going too low etc.

but basically... use the default mode and choose a bit rate that suits you (likely 96kbps or 128kbps or 160 kbps) and just use it as that's going to be more of a determiner of quality than the whole TVBR/CVBR stuff. but in my opinion using anything higher than 128kbps is pretty much a waste of storage space as efficiency starts to drop off quite a bit because of little gains in sound quality for a solid increase to file size (I am basing this info around sound test and other info I noticed around here). but I usually go for 96kbps since at that rate your getting a great balance of sound quality/file size and I would imagine people will be using these lossy files on-the-go which makes it that much less likely you need anything TOO high on the sound quality side of things (plus, not to mention... most people probably don't have any fancy headphones etc). hence, I tend to see Apple AAC and Opus to stick with 128kbps or less for the vast majority of people. I would start with 96kbps and then go from there but if you don't want to mess with it and want to play it pretty safe, one can't go wrong with 128kbps.

just some thoughts ;)

p.s. but IgorC pretty much summed it up in much fewer words.
For music (especially on-the-go)...
-I suggest Opus @ 96kbps (or... 64kbps minimum, 128kbps maximum). *preferred choice*
-I suggest AAC(Apple) @ 96kbps (q45 TVBR) or 128kbps (q64 TVBR). *secondary choice*
-I use Foobar2000 (/w Encoders Pack etc) to convert FLAC to Opus/AAC(Apple).

Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #14
Opus has CVBR mode which is an equivalent to Apple AAC ABR.
Actually, as surprising as it may sound, Opus' CVBR is actually equivalent to what AAC encoders call CBR! That's because MPEG codec CBR modes use a bit reservoir where each frame is allowed to vary in bitrate so long as the cumulative deviation never exceeds the equivalent bits for one frame. Turns out that the Opus "constraint" in CVBR does exactly that. It's just that the bit packing is done more cleanly, without a bit reservoir. What Opus calls CBR (or sometimes hard CBR) is real CBR, with each frame being exactly the same size. That is something most MPEG codecs cannot do reliably without wasting bits.

Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #15
What Opus calls CBR (or sometimes hard CBR) is real CBR, with each frame being exactly the same size.

Opus - finally bringing you the glorious stupidity of real CBR!
*ducking*

Actually, this made me google for why there is a CBR mode (except for testing purposes). I found this by @polemon - is that it?
Memento: this is Hydrogenaudio. Do not assume good faith.

Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #16
In more broader terms: Whenever seeking in the file quickly and accurately is important, CBR is the way to go.

So in a scenario where you're seeking in files, and you also do live-mixing, CBR is much easier to work with (from a hardware designer's or firmware programmer's perspective). Equipment like that often simply ditches anything but CBR entirely and just requires all files to be CBR, period. To keep things synchronized and responsive in a time-critical scenario,  hardware manufacturers take the easier route.

Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #17
Hola! This says opusenc:

"Encoding options:
--bitrate N.nnn
    Set target bitrate in kbit/s (6-256 per channel).
    In VBR mode this specifies the average rate for a large and diverse collection of audio. In CVBR and Hard-CBR mode it specifies the specific output bitrate.
    The default for input with a sample rate of 44.1 kHz or higher is 64 kbit/s per mono stream and 96 kbit/s per coupled pair.
--vbr
    Use variable bitrate encoding (default)
    In VBR mode the bitrate may go up and down freely depending on the content to achieve more consistent quality.
--cvbr
    Use constrained variable bitrate encoding.
    Outputs to a specific bitrate. This mode is analogous to CBR in AAC/MP3 encoders and managed mode in Vorbis coders. This delivers less consistent quality than VBR mode but consistent bitrate.

--hard-cbr
    Use hard constant bitrate encoding.
    With hard-cbr every frame will be exactly the same size, similar to how speech codecs work. This delivers lower overall quality but is useful where bitrate changes might leak data in encrypted channels or on synchronous transports. "

I use 160 kbps VBR for heavy metal music and the sound is quite transparent. Excuse my bad English :P

Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #18
Actually, yes, that's another aspect I forgot about: low-delay, low-bandwidth speech codecs.

Not necessarily the ones used in VoIP, but the ones used in digital voice radio, like DMR, D-Star, Yaesu Fusion, etc.
Transmission errors are expected, and they routinely happen. Digital voice over SSB experiences "banding", which is basically like a moving attenuation, moving across the baseband and time.

You can see them here: https://www.rowetel.com/images/codec2/robust2/mod_test_2000_moderate_10dB_waterfall.png
(Picture taken from https://www.rowetel.com/?p=2905)

You can see the spectrogram of the channel, and dark squiggly lines permeating it. Having a fixed frame size helps discarding and expecting the next frame, when they're broken beyond recognition. Voice quality degradation is at times quite substantial, although that also depends on the codec itself. While DMR sounds pretty good, even if the signal is weak and when there's interference, D-Star sounds horrible, except if reception is excellent.

Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #19
Opus - finally bringing you the glorious stupidity of real CBR!
*ducking*

Actually, this made me google for why there is a CBR mode (except for testing purposes). I found this by @polemon - is that it?
CBR is useful because not every transport mechanisms can take VBR/CVBR, especially for real-time. Keep in mind that people use Opus for a whole lot of applications that have nothing to do with files. For example, if you want to play live music across a network, you need minimal latency, which means you probably want to use the highest bitrate that'll go through without causing delay, but not a single byte more. Then there's people using Opus in real-time over a fixed-bandwidth wireless link (e.g. DECT, possibly Bluetooth too). You'd be surprised to see all the places Opus ends up in.

Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #20
Then there's people using Opus in real-time over a fixed-bandwidth wireless link (e.g. DECT, possibly Bluetooth too). You'd be surprised to see all the places Opus ends up in.
DECT, really? I've only seen DECT (DECT-GAP) using G.726. Is there some commercial product that uses Opus for DECT?
DECT uses 32kb/s, so it sounds quite sensible to use Opus for that.


Re: Can anyone reliably ABX OPUS at 160kbps?

Reply #22
What program do you recommend to convert to opus? Because foobar2k and TAudioConverter (both with opus 1.3RC) give me different results in the Spek.

 
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