Skip to main content

Topic: Apple TVBR vs CVBR (Read 4932 times) previous topic - next topic

0 Members and 1 Guest are viewing this topic.
  • Saucerful
  • [*]
Apple TVBR vs CVBR
I've been reading over these forums and I know similar topics have been covered before, but I couldn't find a clear and concise answer for a long-standing question I've had. I realize Fraunhofer FhG is another excellent choice for an AAC encoder, but for the purposes of this discussion, I will be referring solely to the Apple/qaac encoder.

So, let's open the can of worms:

I know TVBR uses the max bit-reservoir (between ~10 and 6144 bits) but I'm curious what advantage there is of using one over the other. Apple CVBR got an "about the same, but slightly better than" Apple TVBR in the most recent listening test at ~96 kbps, so what's the trade-off there? Should I interpret this as something like: TVBR is more efficient with space, CVBR may be "better" statistically, but there's little real-world difference between the two? I've read a bunch of threads on this already but I've never found a straightforward answer as to what the pros/cons are for each.

Re: Apple TVBR vs CVBR
Reply #1
Here's the thing: TVBR isn't tuned properly,  and it actually sounds worse than CVBR. I guess, though, that Apple bets that most of people using Apple AAC listen to it on pissant little headphones won't notice the quality downgrade. But if you do the ABX tests, you'll easily be able to hear the difference. Compared to FHG AAC? It's faster, but quality-wise, gets edged out a little by Apple AAC (which isn't saying much.)

FDK AAC, though, shows promise. Tests I've done show that it achieves transparency at 180 kbps. And that's compared to a similar Apple AAC file encoded at 320 kbps. And it's designed to use less battery power than other AAC versions. In any case, I'd do you own ABX tests so that you can decide for yourself what works best for you.

BTW: Apple using TVBR allows them to claim that you "get the same quality" at iTunes when you purchase AAC music files from them that you used to get with the previous version. That's total crap. The files are a little smaller, and don't sound as great as before.

  • Saucerful
  • [*]
Re: Apple TVBR vs CVBR
Reply #2
I've been researching this for a couple weeks now. I did a fair amount of ABX testing with various codecs at various settings. Here is one of the tracks I was able to ABX at ~96 kbps and ~128 kbps.

96 kbps Apple AAC TVBR:
Spoiler (click to show/hide)

128 kbps Apple AAC TVBR:
Spoiler (click to show/hide)

96 kbps Apple AAC CVBR:
Spoiler (click to show/hide)

128 kbps Apple AAC CVBR:
Spoiler (click to show/hide)

I failed both TVBR and CVBR at 160 kbps, but the lower bitrates were hardly what I could call terribly annoying. There were some tracks where I failed even at 96 kbps. I haven't noticed any discernible difference between TVBR and CVBR in my ABX testing yet, so I'm wondering what would be the reason to use one over the other.

Do you have any examples of tracks where you were able to ABX the TVBR at a given bitrate but not the CVBR at the same bitrate?

  • IgorC
  • [*][*][*][*][*]
Re: Apple TVBR vs CVBR
Reply #3
It has actually very simple explanation.

Settings for ~96 kbps: http://listening-tests.hydrogenaud.io/igorc/aac-96-a/index.htm
TVBR - --tvbr 46  - real bitrate  ~94-95 kbps - have score 4,391 in public test
CVBR  --cvbr 96 - real bitrate ~100-101 kbps - score is 4,342.

It's bitrate variation. Both CVBR and TVBR are pretty the same.
Use any of them.

FDK AAC, though, shows promise. Tests I've done show that it achieves transparency at 180 kbps. And that's compared to a similar Apple AAC file encoded at 320 kbps.
Far from reality. 
There is no AAC encoder better than Apple at 96 kbps and higher.  As simple as that.



  • lvqcl
  • [*][*][*][*][*]
  • Developer
Re: Apple TVBR vs CVBR
Reply #4
the score values for cvbr and tvbr are swapped in your text

Re: Apple TVBR vs CVBR
Reply #5
It has actually very simple explanation.

Settings for ~96 kbps: http://listening-tests.hydrogenaud.io/igorc/aac-96-a/index.htm
TVBR - --tvbr 46  - real bitrate  ~94-95 kbps - have score 4,391 in public test
CVBR  --cvbr 96 - real bitrate ~100-101 kbps - score is 4,342.

It's bitrate variation. Both CVBR and TVBR are pretty the same.
Use any of them.

FDK AAC, though, shows promise. Tests I've done show that it achieves transparency at 180 kbps. And that's compared to a similar Apple AAC file encoded at 320 kbps.
Far from reality. 
There is no AAC encoder better than Apple at 96 kbps and higher.  As simple as that.




Wasn't talking about 96 kbps, but FDK AAC 180 VBR vs Apple AAC 320kbps. Again, people should do their own ABX tests to find out what works for them. At that setting, FDK AAC sounded pretty damned transparent to my ears.

  • lvqcl
  • [*][*][*][*][*]
  • Developer
Re: Apple TVBR vs CVBR
Reply #6
So show us where Apple AAC isn't transparent at 180 kbps.
This 180 kbps vs 320 kbps comparison is meaningless.

  • IgorC
  • [*][*][*][*][*]
Re: Apple TVBR vs CVBR
Reply #7
Wasn't talking about 96 kbps, but FDK AAC 180 VBR vs Apple AAC 320kbps. Again, people should do their own ABX tests to find out what works for them. At that setting, FDK AAC sounded pretty damned transparent to my ears.
And I wasn't talking  just about 96 kbps either.
if You make a claim You should back them with something.

  • Saucerful
  • [*]
Re: Apple TVBR vs CVBR
Reply #8
It has actually very simple explanation.

Settings for ~96 kbps: http://listening-tests.hydrogenaud.io/igorc/aac-96-a/index.htm
TVBR - --tvbr 46  - real bitrate  ~94-95 kbps - have score 4,391 in public test
CVBR  --cvbr 96 - real bitrate ~100-101 kbps - score is 4,342.

It's bitrate variation. Both CVBR and TVBR are pretty the same.
Use any of them.

FDK AAC, though, shows promise. Tests I've done show that it achieves transparency at 180 kbps. And that's compared to a similar Apple AAC file encoded at 320 kbps.
Far from reality. 
There is no AAC encoder better than Apple at 96 kbps and higher.  As simple as that.

Thank you, IgorC. Looks like I'm going to use TVBR since the file size is typically smaller. As for the bitrate, I have more ABX testing to do before I decide but I'm leaning more toward either ~96 kbps or ~128 kbps. I'm not looking for 100% transparency on all tracks; I'm just looking for something that's transparent for most tracks and not annoying for the ones that aren't.

Re: Apple TVBR vs CVBR
Reply #9
I agree with igorc I've had issues with FHG at mode 5. where some ambient/tamer noise music/doom metal sound iffy because there bitrates are 90 to 140kbps. My Sunn 0))) sample thread says the same.

But i just use it as a back up for albums that fail with apple AAC, like Damaged + Destroyed by Emil Beaulieau.

  • Saucerful
  • [*]
Re: Apple TVBR vs CVBR
Reply #10
I did some more ABX testing (and updated my ABX component). These results aren't directly related to the TVBR vs CVBR discussion, but I found them quite shocking.

Apple AAC TVBR ~96 kbps (V45):
Spoiler (click to show/hide)

Apple AAC TVBR ~128 kbps (V63):
Spoiler (click to show/hide)

LAME MP3 VBR ~190 kbps (V2):
Spoiler (click to show/hide)

Here I was tinkering with the AAC bitrate, not realizing that the format I'm trying to replace (LAME MP3) is not even as good at 190 kbps as 128 AAC in this particular example! 96 is too low; for the tracks I am able to ABX at that bitrate, it's too noticeable. I'm a little late to the party, but I'm pretty impressed with AAC so far.

  • Saucerful
  • [*]
Re: Apple TVBR vs CVBR
Reply #11
I have redone some tests from the previous post and I guess this track is just hard to encode. Maybe I got a little too excited earlier but either way, I don't find the AAC artifacts as annoying as the MP3.

Apple AAC TVBR ~128 kbps (V63) (.m4a SHA-1 doesn't match previous test because I re-encoded):
Spoiler (click to show/hide)

Apple AAC TVBR ~160 kbps (V82):
Spoiler (click to show/hide)

For the files I am able to ABX, it seems as though increasing the bitrate doesn't give me a huge boost in quality. I may end up settling on 128 since it's a good trade-off between space and quality (for me).

  • Kamedo2
  • [*][*][*][*]
Re: Apple TVBR vs CVBR
Reply #12
TVBR and CVBR have roughly the same quality as of 2012.
https://hydrogenaud.io/index.php/topic,97913.0.html

  • sven_Bent
  • [*][*][*][*][*]
Re: Apple TVBR vs CVBR
Reply #13
To my ears, Apple AAC sounds totally fucking horrible, even at 320 kbps. It's not tuned properly at all.

Yet no ABX test.

If you have an issue with proving statements with ABX testing you should probably have read the rules for the forum before joining.
This is no a placebo tolerant place.  Prove you statements or don't spread unproven nonsense.


8. All members that put forth a statement concerning subjective sound quality, must -- to the best of their ability -- provide objective support for their claims.  Acceptable means of support are double blind listening tests (ABX or ABC/HR) demonstrating that the member can discern a difference perceptually, together with a test sample to allow others to reproduce their findings.  Graphs, non-blind listening tests, waveform difference comparisons, and so on, are not acceptable means of providing support.

The only troll is you that does not adhere to the basic rules of the forum.
Sven Bent - Denmark

Re: Apple TVBR vs CVBR
Reply #14
To my ears, Apple AAC sounds totally fucking horrible, even at 320 kbps. It's not tuned properly at all.

Yet no ABX test.

If you have an issue with proving statements with ABX testing you should probably have read the rules for the forum before joining.
This is no a placebo tolerant place.  Prove you statements or don't spread unproven nonsense.


8. All members that put forth a statement concerning subjective sound quality, must -- to the best of their ability -- provide objectivMe? Troll? HAH! This from somebody who represents a forum who lets a so-called moderator, who's really a troll (i..e greynol) go after people all the time, then do nothing when he abuses his power to get away with it. The guy & his friends tricked me once into doing an ABX test & posting the results afterwards. Guess what? All they could do was make excuses, questioning the methodology of the test itself while "coincidentally" avoiding the results, which proved I was right, All they cared about what their agenda, attacking anyboe support for their claims.  Acceptable means of support are double blind listening tests (ABX or ABC/HR) demonstrating that the member can discern a difference perceptually, together with a test sample to allow others to reproduce their findings.  Graphs, non-blind listening tests, waveform difference comparisons, and so on, are not acceptable means of providing support.

The only troll is you that does not adhere to the basic rules of the forum.

Troll? Me? That's funny. Especially coming from somebody who represents a forum that looks the other way when a particular "moderator" (i.e. troll) regularly goes after people here, then uses his power to get away with it. That dude & his friends actually tricked me into that "posting ABX results" thing awhile back. Didn't matter that the results proved him wrong. He & his friends just attacked me, questioning the very methodology of the test to try and shut me up. That's why I not going to bother wasting my time with that crap.

But I guess it's just "coincidence" that Apple came up with that "Mastered for iTunes" crap? That was their way of telling the world "Yeah, we know TVBR sucks. That's why we convinced the music industry to help us make it not sound as much like crap." I can take any song, convert it into both TVBR & CVBR (at the highest settings), and CVBR will win every single time. But, again, nobody has to believe me. Do your own ABX tests. Despite what some think, this stuff ain't rocket science.

And lets get real here. "Rules" are whatever the hell certain people here pull out of their asses to try and shut people up when their world view is threatened. This thread is a reminder of that. Lame move harassing me by PM'ing me troll messages. And one of the from a so-called "moderator" What are you? A bunch of goddamned 5 yr. olds? And some people wonder why some leave this forum and never come back? You people are pathetic!

  • Case
  • [*][*][*][*][*]
  • Developer (Donating)
Re: Apple TVBR vs CVBR
Reply #15
Apple uses constant bitrate because it gives predictable file size.

All listening test results I have seen suggests their quality is practically identical at the same bitrate.
Your comment about the quality difference is against test results and user experiences. People have used Apple's AAC in TVBR mode for years with software such as QAAC and there have been no quality complaints.

If you have a sample file that turns bad with TVBR many people would be eager to see it. I know I would.

  • greynol
  • [*][*][*][*][*]
  • Global Moderator
Re: Apple TVBR vs CVBR
Reply #16
Troll? Me?
How many accounts have you had here and why did you create them?

Especially coming from somebody who represents a forum
sven_Bent doesn't represent this forum any more than you do, though I would happily prefer for people aware of the rules to represent it and for people like yourself who flagrantly violate them to go away.

That dude & his friends actually tricked me into that "posting ABX results" thing awhile back. Didn't matter that the results proved him wrong. He & his friends just attacked me, questioning the very methodology of the test to try and shut me up.
Link please.

That's why I not going to bother wasting my time with that crap.
...and people here shouldn't bother wasting their time reading about your unsubstantiated unicorn sightings.

But I guess it's just "coincidence" that Apple came up with that "Mastered for iTunes" crap?
What does that have to do with TVBR vs. CVBR?

That was their way of telling the world "Yeah, we know TVBR sucks.
It doesn't take a rocket scientist to see that you have absolutely no idea what you're talking about.

"Rules" are whatever the hell certain people here pull out of their asses to try and shut people up when their world view is threatened.
*Their* world view is threatened?!? I love the irony!

some leave this forum and never come back
That certainly wouldn't be you, now, would it?  :D

You people are pathetic!
Says the sock puppet throwing yet another temper tantrum.

For those who are curious, I can honestly say that I have no record of ever sending "ghostman6842" a PM, nor have I taken any administrative action against him (issued warnings, restricted posting privileges, binned or deleted posts, etc.).
  • Last Edit: 28 March, 2017, 12:27:02 PM by greynol
Is 24-bit/192kHz good enough for your lo-fi vinyl, or do you need 32/384?

  • sven_Bent
  • [*][*][*][*][*]
Re: Apple TVBR vs CVBR
Reply #17
Troll? Me? That's funny. Especially coming from somebody who represents a forum that looks the other way when a particular "moderator" (i.e. troll) regularly goes after people here, then uses his power to get away with it. That dude & his friends actually tricked me into that "posting ABX results" thing awhile back. Didn't matter that the results proved him wrong. He & his friends just attacked me, questioning the very methodology of the test to try and shut me up. That's why I not going to bother wasting my time with that crap.

But I guess it's just "coincidence" that Apple came up with that "Mastered for iTunes" crap? That was their way of telling the world "Yeah, we know TVBR sucks. That's why we convinced the music industry to help us make it not sound as much like crap." I can take any song, convert it into both TVBR & CVBR (at the highest settings), and CVBR will win every single time. But, again, nobody has to believe me. Do your own ABX tests. Despite what some think, this stuff ain't rocket science.

And lets get real here. "Rules" are whatever the hell certain people here pull out of their asses to try and shut people up when their world view is threatened. This thread is a reminder of that. Lame move harassing me by PM'ing me troll messages. And one of the from a so-called "moderator" What are you? A bunch of goddamned 5 yr. olds? And some people wonder why some leave this forum and never come back? You people are pathetic!

1: Yes. you are spewing out stuff without backing it up with some real evidence when asked for it. That is  troll'ish behavior

2: I am not representing the forum .I have nothing to do with it beside being and user for many years. But I do believe in its objective to filter out placebo and none-scientific nonsense .

3: it is normal when you put forth theories that it gets scrutinized. That you take that as an attack against you, just shows your lack of understanding the scientific way.

4: babbling about slogans and homebrewed theories does not validate as an evidence. you have been asked and showned a proper way for it. yet you still all back on this child like argumentation.

5: The rules are states and objectively count for all of us. if you think the burden of proof is to high to lift maybe it just you that is wrong. but they are made to empower theories and change by validating them in a scientific way. that oyu cnat life the wualtiy of argumentation to that level does not mean it shut people up. it just means you probably need to do so until you have enough evidence to support it.  Plenty of people have showed lack of quality or founds issues through these means without any issues.

6: people have been leaving rational thinking for decades. that is not only this forum sadly. we cant educate people that don't want to be educated but prefer to stay in their blissful ignorance. I can only show you the way. You have to step through it yourself

if you still believe in what you are saying. You could have proven this a lot faster than the time you have been using on fighting  people asking you for a proof, being it test-samples or ABX.
People have asked into it because they are curios of your claim. You are acting like a spoiled child because people just don't jump aboard your hyper train immediately .
  • Last Edit: 29 March, 2017, 04:41:14 PM by sven_Bent
Sven Bent - Denmark

  • Makaki
  • [*][*][*]
Re: Apple TVBR vs CVBR
Reply #18
The Listening Tests wiki page quotes the following for the most recent AAC Test:

http://wiki.hydrogenaud.io/index.php?title=Hydrogenaudio_Listening_Tests
"Quicktime CVBR ~> TVBR ~>Fraunhofer > CT > Nero"

meaning "About the same, but slightly better than". And in the Plot of the complete result, you can also witness that "slightly"

Those tests used:

 QuickTime True VBR (via qtaacenc)
--tvbr 46 --highest --samplerate keep
QuickTime Constrained VBR (via qtaacenc)
--cvbr 96 --highest --samplerate keep

Onto the bitrate comparison. Quote: "The codecs and settings were calibrated to provide ~96kbps on a large variety of music." In most samples TVBR had a lower bitrate. Leading to a mean of 93-94 versus 101 of CVBR.

Which raises the question. Are the small quality differences between the two just proportional to the bitrate difference?

It has been a while since the last test (2011) what has changed since then?

Would this be a reasonable test: TVBR is encoded first and then the CVBR bitrate is selected to match the TVBR (per song sample)

  • JunkieXL
  • [*][*][*][*]
Re: Apple TVBR vs CVBR
Reply #19
The difference in bitrate is not the cause.  The purpose of the variable bitrate is keep quality constant by applying more or less bits per sample depending on the complexity of the music...  more complex...more bits...less complex...less bits.

The TVBR files are not properly tuned, as has been mentioned before, which leads to noticeable artifacts in the resulting encoded file.  These artifacts get more noticeable the lower the bitrate gets.

I personally use the iTunes Plus preset (qaac), which uses TVBR at a bitrate around 256 kbps.  The resulting file is completely transparent to me when I've tried to ABX it.

I don't believe there is any other way to get TVBR files out of iTunes, but that may have changed since I last checked.  The other VBR settings were actually ABR files... IIRC.
JXL
  • Last Edit: 06 July, 2017, 07:25:36 PM by JunkieXL