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iPod compatible formats listening evaluation, unfinished... personal... classical music only
CPKTV
post Mar 8 2008, 21:49
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Hi...
I want to know about the: MP3 Test: 128KBIT-CBR-Standard Stereo with latest FhG & LAME encoders.
Is this possible?
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moi
post Mar 9 2008, 02:07
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Using an Ipod now, so it would interest me a lot to hear any updated version of this test, to reflect the newest Itunes-QT, the newest Nero Digital, etc.

For instance, is the older Nero Digital still better than the current new version? (If so, has anyone contacted Nero to tell them about the defects in the newer versions? It shouldn't get worse.)

It would also be interesting to hear how the current Itunes stacks up against the current version of Nero Digital. Itunes is certainly more convenient to use. (Do you use some kind of GUI with Nero Digital? Or straight command-line usage?)

I think you wrote the Itunes encoding was VBR. Isn't the default encoding in Itunes CBR? How do you change it to VBR? Also, I read in another thread that Itunes VBR is constrained VBR? Is that still the case in the newest version? Could that be the cause of not winning against Nero?

Thank you for your insight.
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muaddib
post Mar 10 2008, 11:03
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QUOTE (moi @ Mar 9 2008, 02:07) *
For instance, is the older Nero Digital still better than the current new version? (If so, has anyone contacted Nero to tell them about the defects in the newer versions? It shouldn't get worse.)

Of course we are aware of the problem and trying to fix it.
See this thread: http://www.hydrogenaudio.org/forums/index....=14&t=61724
So far there were not many reports with provided samples. Only 2.
We ask everybody who can find a sample please to provide it in that thread.

QUOTE (moi @ Mar 9 2008, 02:07) *
It would also be interesting to hear how the current Itunes stacks up against the current version of Nero Digital. Itunes is certainly more convenient to use. (Do you use some kind of GUI with Nero Digital? Or straight command-line usage?)

For example Exact Audio Copy can be used with Nero AAC Encoder. Nero AAC Encoder can of course be used in Nero Burning Rom - there is an option in Extras "Save Tracks" where, among other formats, Nero Digital Audio is available. (There is a limitation that only VBR AAC can be used in Nero 8 and it will be fixed in Nero 9 allowing also CBR and ABR)
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Nick E
post Mar 10 2008, 12:35
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QUOTE (dbAmp @ Nov 8 2007, 18:15) *
Guruboolez, have you tried the new AAC encoder in iTunes 7.5 / QuickTime 7.3 yet? I've encoded about 20 CDs from various genres to do comparisons... and I'm finding that at the 128 VBR setting, I'm getting lower bitrate and lower quality files than I did with the same settings in iTunes 7.4 / QuickTime 7.2. I'm not entirely sure what the changes are... but this new encoder seems to be a step backward... especially when you consider that upping the settings to 160 VBR creates a significantly higher bitrate and larger sized file.


I just re-encoded some tracks to see what I got. With the current Apple encoder I get higher bitrates on the sample I tried -- recordings of Clifford Curzon playing piano. With an older version of Apple's AAC I had got: 165, 164, 163, 162, 161, 160, 160. With the latest I get: 175, 173, 170, 170, 168, 168.

I didn't make a note of when I made the original encoding. In both cases the encodings were made using Max, which uses Apple's Core Audio. The interface in Max allows one to access options that are in Core Audio but not revealed in iTunes GUI. (Presumably, Apple, like the GNOME people, consider a simpler UI with fewer options is better.) Anyway, in both cases the encoding chosen was 160 kbps + VBR + a "Maximum quality" switch. (Core audio, apparently, has -- had? -- five different switches for VBR, although you can only either enable or not enable VBR in iTunes.)

In general, I'd say Core Audio's AAC was giving me bitrates less than I seem to be getting with the latest version with the settings I use. With Nero's AAC encoder (latest version) at q 0.5 I often get bitrates of 145 or 150 with quiet stuff -- particularly guitar music -- it can drop down to 130 or less. Steve Hackett's latest album "Tribute", where he plays various Bach pieces and so forth gets encoded by Nero at around 110 kbps.

QUOTE
I stay with lossless and wait for an update because in some very silent parts (also classical here) the encoder chooses very low bitrates even at q6, resulting in kind of digital hiss artifacts.


Ouch! That's a very interesting observation. I noticed something like that the other day and wondered if it were on the original CD but didn't get around to checking. This was on an encoding I'd made with Ogg Vorbis for my Linux box. I hadn't recalled hearing hissing when listening to the CD (or the AAC version on my Mac/iPod), but, as I say, when I noticed the hiss I more-or-less assumed it must be on the CD. perhaps not, then. I'll have to look into that.

QUOTE
The most reliable VBR LC-AAC encoder in this situation seems to be iTunes which isn't (unfortunately) the most efficient one.


That's another very interesting comment to come out of this thread. I guess the choice between reliability and efficiency isn't an obvious one at all -- specially, if space is not an issue.
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dbAmp
post Mar 11 2008, 07:17
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QUOTE (Nick E @ Mar 10 2008, 07:35) *
I just re-encoded some tracks to see what I got. With the current Apple encoder I get higher bitrates on the sample I tried -- recordings of Clifford Curzon playing piano. With an older version of Apple's AAC I had got: 165, 164, 163, 162, 161, 160, 160. With the latest I get: 175, 173, 170, 170, 168, 168.

I didn't make a note of when I made the original encoding. In both cases the encodings were made using Max, which uses Apple's Core Audio. The interface in Max allows one to access options that are in Core Audio but not revealed in iTunes GUI. (Presumably, Apple, like the GNOME people, consider a simpler UI with fewer options is better.) Anyway, in both cases the encoding chosen was 160 kbps + VBR + a "Maximum quality" switch. (Core audio, apparently, has -- had? -- five different switches for VBR, although you can only either enable or not enable VBR in iTunes.)

In general, I'd say Core Audio's AAC was giving me bitrates less than I seem to be getting with the latest version with the settings I use. With Nero's AAC encoder (latest version) at q 0.5 I often get bitrates of 145 or 150 with quiet stuff -- particularly guitar music -- it can drop down to 130 or less. Steve Hackett's latest album "Tribute", where he plays various Bach pieces and so forth gets encoded by Nero at around 110 kbps.


AFAIK Max can use different profiles than iTunes to encode, i.e. Max, through Core Audio, has access to the "true" VBR profile in QuickTime, while iTunes uses the "VBR_Constrained" profile. Therefore I would expect very different results using Max than iTunes, even using the same version of QuickTime.

Since a vast majority of iTunes users are on Windows, expect most listening tests of "iTunes" to use the "VBR_Constrained" profile. The "true" VBR used by Core Audio may sound better... but that won't do me much good unless I purchase a mac. tongue.gif

All that being said... it seems like guru has been mysteriously absent for some time... I hope all is well...

This post has been edited by dbAmp: Mar 11 2008, 07:19
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Nick E
post Mar 11 2008, 09:59
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QUOTE (dbAmp @ Mar 11 2008, 00:17) *
AFAIK Max can use different profiles than iTunes to encode, i.e. Max, through Core Audio, has access to the "true" VBR profile in QuickTime, while iTunes uses the "VBR_Constrained" profile. Therefore I would expect very different results using Max than iTunes, even using the same version of QuickTime.


Maybe. But I think these five options in Max may all be different adjustments you can make to the "VBR_Constrained" mode. I know there have always been more options available in Core Audio (and accessible from the CLI or from something like Max) than were revealed in iTunes, but the "true" VBR is quite new. And actually, I'm not even sure that the current version of Max can access the "true" VBR: there's not been a release version of Max for quite some time.

According to a thread here XLossless Decoder can access the true VBR mode:

http://www.hydrogenaudio.org/forums/index....w=&st=&

Here's the program:

http://tmkk.hp.infoseek.co.jp/xld/index_e.html

QUOTE
Since a vast majority of iTunes users are on Windows, expect most listening tests of "iTunes" to use the "VBR_Constrained" profile. The "true" VBR used by Core Audio may sound better... but that won't do me much good unless I purchase a mac.


That's a good point: it's not of so much interest if most users can't access it.

But I'm not sure it would sound better, anyway -- perhaps, to go back to those earlier terms, it also would be more "efficient" but not more "reliable". And if most people can't access it and can't use it how would Apple get any feedback on its performance?
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kikke
post Mar 15 2008, 20:16
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I want to check the bitrate of nero aac encoded files. How can I check this?
I curious about the bug of 3.1.0.2 version (http://www.listening-tests.info/mf-128-1/miscellaneous/nero.txt) exists in the February 2007 release? If the encoded files sounds better at the beginning, then it's possible. Anybody care about the full length files quality?

---

I was sceptical about the full lenght stability of bitrate so I make a test.

I created a 10 sec testloop and repeated in wave-editor (without any smoothing of course) 12 times, the loops marked with an impulse.
After encode-decode process, the second and last loop extracted, inverted and mix-pasted to first loop.
The difference of noise-spectrum of two result is insignificant.

I repeated this with cutting out from some jazz recording and find that a banding effect appears in the difference of first and second loop spectrum, not between in first and last loop differences. It's looks like harmonics, the difference is -1 dB at 2.7kHz, 5.5kHz, 8.2kHz, 11kHz, 13.8kHz ... Maybe the encoding bitrate is changing in the process?

This post has been edited by kikke: Mar 15 2008, 22:20
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frozenspeed
post Mar 15 2008, 21:56
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QUOTE (Enig123 @ Nov 3 2007, 07:39) *
It's more fun to get the upcoming new Apple's vbr aac encoder in this test in the near future. With all fixes of the regressions found maybe the next version of Nero digital would get much better, which is also worth waiting.


OT- have we heard anything about the release of this? I'd love to know smile.gif
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