IPB

Welcome Guest ( Log In | Register )

 
Reply to this topicStart new topic
iTunes MP3 CODEC: Strange Setting? It use LAME or other?, Smart Encoding and 10 Hz Filter????
Antigen
post Apr 19 2012, 00:03
Post #1





Group: Members
Posts: 135
Joined: 21-July 09
Member No.: 71655



Hi to all,

I hope that some one have experience with the iTunes MP3 ENCODER.

I don't know if iTunes use LAME or other encoder for MP3 but I have see strange setting in the setup page-

My setting are:

- STEREO BIT RATE 320 KBPS
- SAMPLE RATE: AUTO
- CHANNELS: AUTO
- STEREO MODE: JOINT STEREO

- SMART ENCODING ADJUSTMENTS ON
- FILTER FREQUENCIES BELOW 10 Hz

But what is the SMART ENCODING ADJUSTMENT?

And is not a bad idea filter the frequencies below 10 Hz?

What do you suggest?

For LAME I know that is better JOINT STEREO but with iTUNES ENCODER?

Thanks

This post has been edited by Antigen: Apr 19 2012, 00:25
Go to the top of the page
+Quote Post
db1989
post Apr 19 2012, 00:10
Post #2





Group: Super Moderator
Posts: 5275
Joined: 23-June 06
Member No.: 32180



I looked these up recently in preparation for using iTunes to rip a bunch of CDs – Electric Light Orchestra’s The Classic Albums Collection cool.gif – to MP3, also at 320 kbps. Information is plentiful on Google, but I might as well give you some starting points here, with the caveat that I’m no expert.

QUOTE (Antigen @ Apr 19 2012, 00:03) *
But what is the SMART ENCODING ADJUSTMENT?
New and completely undescriptive (as befits the Apple of today): http://support.apple.com/kb/PH1547
Old but possibly still accurate, at least somewhat: http://support.apple.com/kb/TA25414?viewlocale=en_US

QUOTE
And is not a bad idea filter the frequencies below 10 Hz?
I’d say it is a bad idea. These are the kind of frequencies that, even if not heard, could definitely be felt via sufficiently bassy speakers (e.g. a subwoofer); and, especially considering how little space is required to encode them, there’s almost no point in removing them.

This post has been edited by db1989: Apr 19 2012, 00:10
Go to the top of the page
+Quote Post
Antigen
post Apr 19 2012, 00:25
Post #3





Group: Members
Posts: 135
Joined: 21-July 09
Member No.: 71655



Thank you.

I have see that if I use SMART ENCODING, if I use JOINT STEREO in the MENU, the smart encoding OVERRIDE the choice and go with STEREO...

But LAME at INSANE PRESET will filter the 10 Hz Frequencies?
Go to the top of the page
+Quote Post
db1989
post Apr 19 2012, 00:28
Post #4





Group: Super Moderator
Posts: 5275
Joined: 23-June 06
Member No.: 32180



QUOTE (Antigen @ Apr 19 2012, 00:25) *
I have see that if I use SMART ENCODING, if I use JOINT STEREO in the MENU, the smart encoding OVERRIDE the choice and go with STEREO...
Really? I might have to re-rip my files, if thatís the caseóeven if itís only out of principle! sick.gif

QUOTE
But LAME at INSANE PRESET will filter the 10 Hz Frequencies?
Not that I know of.
Go to the top of the page
+Quote Post
Antigen
post Apr 19 2012, 00:35
Post #5





Group: Members
Posts: 135
Joined: 21-July 09
Member No.: 71655



yes, I have tried with:

SMART ENCODING ON and OFF

With SMART ENCODING ON at 320 I see that it select automatically STEREO and not JOINT STEREO.

But is better STEREO or JOINT STEREO with iTunes? (With LAME at 320 for default is better JS)
Go to the top of the page
+Quote Post
db1989
post Apr 19 2012, 00:42
Post #6





Group: Super Moderator
Posts: 5275
Joined: 23-June 06
Member No.: 32180



Assuming proper (read: not incompetent) implementation, joint stereo will always be better than simple stereo. It’s a lossless mathematical process that can only free up bits for use elsewhere. iTunes may well be doing it wrong, here!

iTunes uses some version of Fraunhofer’s encoder, though I can’t recall how well it’s generally rated or how it has performed in listening tests. I saw some people casting doubt upon its quality in a few threads I found on Google, albeit none that had enough useful information/evidence to be worth my linking here; again, you will probably benefit most from searching yourself, particularly here on Hydrogenaudio.

This post has been edited by db1989: Apr 19 2012, 00:43
Go to the top of the page
+Quote Post
Antigen
post Apr 19 2012, 00:46
Post #7





Group: Members
Posts: 135
Joined: 21-July 09
Member No.: 71655



The ABX test on iTunes MP3 codec that I have found on the net are too old, we need to make a new comparative.

I think that the better setting are:


- STEREO BIT RATE 320 KBPS
- SAMPLE RATE: 44 Khz (for CD)
- CHANNELS: STEREO
- STEREO MODE: NORMAL (Aka STEREO)

- SMART ENCODING ADJUSTMENTS----> OFF
- FILTER FREQUENCIES BELOW 10 Hz----> OFF


On Apple documentation they suggest to use STEREO on bitrate below 160 kbps.

I can't assure that STEREO is better on iTunes implementation but the documentation suggest this.

How to test it?

This post has been edited by Antigen: Apr 19 2012, 00:47
Go to the top of the page
+Quote Post
db1989
post Apr 19 2012, 00:50
Post #8





Group: Super Moderator
Posts: 5275
Joined: 23-June 06
Member No.: 32180



I hoped Iíd emphasised enough that you should not use Ďnormalí, a.k.a. simple, stereo. To which Apple default above 160 kbps, not below.

Just before your latest post, I found an old post but one that may still have some good information.

QUOTE (Cygnus X1 @ Sep 12 2004, 00:43) *
If you insist on using iTunes for MP3 encoding (not recommended, but even I do it in a pinch when I need something fast 'n crappy for the car, etc), I've found out several things of interest:

1) Turn off "smart encoding options." It forces full stereo on anything higher than 160kbps, which as we know is very stupid. Turning it off allows joint stereo at any bitrate, which may result in an audible improvement at 192kbps and higher.

2) Don't use iTunes VBR mode; it sucks.

3) Don't use anything less than 192kbps CBR.

4) As a general rule of thumb, iTunes MP3 encoder is so bad that you can safely figure on an encoding at x bitrate to sound similar to a LAME encoding at a step lower. In other words, iTunes 160kbps CBR is probably similar to LAME 128kbps, IMO. That's why I wouldn't suggest going lower than 192kbps, ever.

If you follow these steps, you'll get a 192kbps+ CBR encoding that is more than good enough for a car, etc. Not LAME quality, but then again, I would never use iTunes MP3 encoder for serious encoding, even at 320kbps. The point is, iTunes is fast on a Mac when one needs a quick disc for the road, whereas LAME is slow; it's the difference between 3x and 13x! Again, only do this if you are in a pinch , and proceed at your own risk laugh.gif

I canít guarantee that itís all accurate, but it confirms my suspicion that Appleís forcing of simple stereo is both existent and probably an ill-advised decision.
Go to the top of the page
+Quote Post
Antigen
post Apr 19 2012, 00:54
Post #9





Group: Members
Posts: 135
Joined: 21-July 09
Member No.: 71655



My assumption is based only on this

Stereo Mode:

In Normal mode, your MP3 files contain one track for the right stereo channel and one track for the left. In many cases, the two channels contain related information. In Joint Stereo mode, one channel carries the information thatís identical on both channels, and the other channel carries the unique information. At bit rates of 160 kbps and below, this can improve the sound quality of your converted audio.


Apple suggest that on bitrate below of 160 is better Joint Stereo.


I know that for LAME is suggested to use Joint stereo every time :-)

I hope that from 2004 to 2012 the MP3 encoder of iTunes is improved... but there is not the possibility to see what version it use?
Go to the top of the page
+Quote Post
db1989
post Apr 19 2012, 01:04
Post #10





Group: Super Moderator
Posts: 5275
Joined: 23-June 06
Member No.: 32180



Yes, joint stereo can improve quality at low bitrates. But considering it at a deeper level (which, again, seems to go against Apple’s ethos) reveals some sizeable gaps in Apple’s reasoning.

Phrasing that soundbite properly: joint stereo increases the efficiency with which bits are allocated, and therefore it’s more likely to create an audible increase in quality at lower bitrates. Now, is there any possible reason why this same (mathematical) benefit is not equally applicable to all bitrates?

If reports about this encoder are accurate, you’ll want to squeeze as much chance of quality from it as you can—and joint stereo, assuming it’s done properly (which I imagine Fraunhofer can do), can only contribute positively towards this goal.

This post has been edited by db1989: Apr 19 2012, 01:09
Go to the top of the page
+Quote Post
Antigen
post Apr 19 2012, 01:09
Post #11





Group: Members
Posts: 135
Joined: 21-July 09
Member No.: 71655



I think that Joint Stereo, that is a lossless compression, can improve only the quality... I think that Apple has not clear what is JOINT STEREO... the same problem is present in DBPOWER guide, they suggest JOINT STEREO only for <160.

The only question is... the MP3@320 created by iTunes is good as LAME320?

I have dismissed XLD only because I want a "all one" program, with library and all into my PC...

This post has been edited by Antigen: Apr 19 2012, 01:10
Go to the top of the page
+Quote Post
db1989
post Apr 19 2012, 01:15
Post #12





Group: Super Moderator
Posts: 5275
Joined: 23-June 06
Member No.: 32180



QUOTE (Antigen @ Apr 19 2012, 01:09) *
I think that Joint Stereo, that is a lossless compression, can improve only the quality.
Hooray! Iím getting somewhere.

QUOTE
The only question is... the MP3@320 created by iTunes is good as LAME320?
Theoretically? Probably not. In practice? Even with their differing levels of technical optimisation, the two encoders might not produce audibly different streams from any single source file, for the majority of material. A bitrate of 320 kbps has a good chance of being transparent, whatever the encoder. You can always test this for yourself with some tracks from your own collection.

Someone with knowledge of historical comparisons between these two encoders, save me!
Go to the top of the page
+Quote Post
Antigen
post Apr 19 2012, 01:17
Post #13





Group: Members
Posts: 135
Joined: 21-July 09
Member No.: 71655



QUOTE (db1989 @ Apr 19 2012, 02:15) *
QUOTE (Antigen @ Apr 19 2012, 01:09) *
I think that Joint Stereo, that is a lossless compression, can improve only the quality.
Hooray! Iím getting somewhere.

QUOTE
The only question is... the MP3@320 created by iTunes is good as LAME320?
Theoretically? Probably not. In practice? Even with their differing levels of technical optimisation, the two encoders might not produce audibly different streams from any single source file, for the majority of material. A bitrate of 320 kbps has a good chance of being transparent, whatever the encoder. You can always test this for yourself with some tracks from your own collection.

Someone with knowledge of historical comparisons between these two encoders, save me!




I have find and interesting comment on a forum:



Joint Stereo does not create smaller files. Difference is only in quality of sound! Teach theory! It only significantly increases the efficiency by more than a clever arrangement of data. In fact, it reduces data redundancy, which allows you to use freed space for nonredundant data. Joint Stereo should be used even at 320 kbps. It makes winning even with this bitrate! If you do not understand why, I recall that the original bitrate CDDA - 1411kbps!

And the difference in the sound very much! She felt even at 320kbps. In simple Stereo sound is empty. In order to verify this is enough to compare the same track in Joint Stereo and Simple Stereo on normal (or high quality) equipment.
Go to the top of the page
+Quote Post
Antigen
post Apr 19 2012, 01:38
Post #14





Group: Members
Posts: 135
Joined: 21-July 09
Member No.: 71655



Here and interesting link

http://myweb.tiscali.co.uk/mostync/
Go to the top of the page
+Quote Post
greynol
post Apr 19 2012, 01:59
Post #15





Group: Super Moderator
Posts: 10009
Joined: 1-April 04
From: San Francisco
Member No.: 13167



QUOTE (Antigen @ Apr 18 2012, 17:17) *
And the difference in the sound very much! She felt even at 320kbps. In simple Stereo sound is empty. In order to verify this is enough to compare the same track in Joint Stereo and Simple Stereo on normal (or high quality) equipment.

This of course is not reliable and is certainly not admissible to be posted on this forum directly without corroborating objective evidence in the way of double-blind test results. I don't think we need to get into equipment quality except to say that those types of casual and overly-general statements typically seem only to be given by those who completely lack any understanding about psychoacoustics.

This post has been edited by greynol: Apr 19 2012, 02:18


--------------------
Your eyes cannot hear.
Go to the top of the page
+Quote Post
RobertoDomenico
post Apr 19 2012, 03:56
Post #16





Group: Members
Posts: 87
Joined: 16-November 11
Member No.: 95208



I don't know if this is any help but it's a listening test done with iTunes with abx logs http://www.vel.co.nz/vel.co.nz/Blog/Entrie...troduction.html

This post has been edited by RobertoDomenico: Apr 19 2012, 03:56
Go to the top of the page
+Quote Post
Nessuno
post Apr 19 2012, 05:47
Post #17





Group: Members
Posts: 423
Joined: 16-December 10
From: Palermo
Member No.: 86562



QUOTE (Antigen @ Apr 19 2012, 02:09) *
The only question is... the MP3@320 created by iTunes is good as LAME320?

I have dismissed XLD only because I want a "all one" program, with library and all into my PC...


I don't see the point: if you are so concerned about quality issues @320kbs (which anyway is generally overkill for listening and still not suitable for archival), XLD has the option to import directly into iTunes library, so you can rip (whit Accuraterip or other secure options, definitely better than iTunes ripping), convert using Lame and import in your library all in a single shot.


--------------------
... I live by long distance.
Go to the top of the page
+Quote Post
RobertoDomenico
post Apr 19 2012, 07:46
Post #18





Group: Members
Posts: 87
Joined: 16-November 11
Member No.: 95208



Totally agree with what Nessuno said. XLD is by far the best option on the MAc.
Go to the top of the page
+Quote Post
Antigen
post Apr 19 2012, 09:17
Post #19





Group: Members
Posts: 135
Joined: 21-July 09
Member No.: 71655



Thanks very much, I think that I will use XLD in association with iTunes for Play my collection
Go to the top of the page
+Quote Post
pdq
post Apr 19 2012, 12:57
Post #20





Group: Members
Posts: 3412
Joined: 1-September 05
From: SE Pennsylvania
Member No.: 24233



QUOTE (Antigen @ Apr 18 2012, 20:17) *
Joint Stereo does not create smaller files. Difference is only in quality of sound!

This is true for cbr encoding, because NOTHING will create smaller cbr files except specifying a lower cbr bitrate. For vbr encoding, on the other hand, where the encoder can choose the bitrate, it could result in smaller, or better quality, or both, depending on the implementation.
Go to the top of the page
+Quote Post
[JAZ]
post Apr 19 2012, 19:50
Post #21





Group: Members
Posts: 1783
Joined: 24-June 02
From: Catalunya(Spain)
Member No.: 2383



10Hz Filtering: This is not a setting about improving efficiency or removing things that cannot be heard.

Generally, these types of filter are used to kill any DC offset that could exist in the signal. This should not exist in CD's but should not be strange at all with Vinyl rips or other analog sources. (Note: killing 50/60Hz Hum is acomplished with a notch band filter, which is not this case).
Said that, compression (as in dynamics) might also generate sub 10Hz "noise".


stereo/joint stereo and iTunes: I've heard several things about iTunes encoder. First, that it was the one that existed in the original software that Apple bought. Then, that it was an in-house version, then also that it was a derived version from frauhofer's encoder.

Said that, the sentences about using joint stereo at 128kbps and below, and stereo at 160Kbps and above come from before year 2000. The idea is that the more one lowers the bitrate, the more that joint stereo is needed. Not using it at higher bitrates had only sense in using less power or less complex selection algorithms on encoding (Remember MP3 was invented around 1994, and that originally, doing automatic switching between joint stereo and simple stereo like LAME, was not too common).

This post has been edited by [JAZ]: Apr 19 2012, 19:52
Go to the top of the page
+Quote Post

Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



RSS Lo-Fi Version Time is now: 1st October 2014 - 01:36