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Topic: AAC at 128kbps test - FINISHED (Read 64076 times) previous topic - next topic
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AAC at 128kbps test - FINISHED

Reply #76 –
 
    Sorry, Is there any one try to compare ODG of these AAC Codec ?

    I want to do this. but I dont know how to let QT output as wav file ?

    By the way, where can I download the samples ?

    I just see samples**.zip.torrent  but I dont have bitTorrent..


      Thanks a lot

AAC at 128kbps test - FINISHED

Reply #77 –
It would be nice to see MPC @128kbps added to the test, so that we can validate those comments saying that "subband can rule at 128kbps too!". 2 main problems I see:

1. Have we already hit our rule-of-thumb limit of maximum 6 test examples?
2. How do you control the MPC bitrate? In previous listening tests @128kbps, the performance of MPC depended on the resulting bitrate. MPC clearly won the first dogies test , but that can be attributed to bitrate bloat to 143kbps. For rawhiles and fossiles, MPC was at 136 and 138 and there were no significant results. For wayitis, MPC was tied at the top with Ogg Vorbis, but needed 140kbps to do that.

AAC at 128kbps test - FINISHED

Reply #78 –
The result of the test has been posted here as well...

http://www.cdfreaks.com/news/7355

I like some of the comments below....

AAC at 128kbps test - FINISHED

Reply #79 –
Quote
Sorry, Is there any one try to compare ODG of these AAC Codec ?

I want to do this. but I dont know how to let QT output as wav file ?

By the way, where can I download the samples ?

I just see samples**.zip.torrent  but I dont have bitTorrent..

You can use FAAD to decode the QT files, I believe. I haven't used QT, but I think that's how Roberto decompressed the test samples. I think FAAD can be downloaded at RareWares.

The test files are no longer available for download, since the test is over. You can still get the names of the samples, and then search for available copies. HA and ff123 still host some, if not all, of the samples used in the test.

As for ODG... isn't that the EAQUAL measurement standard? An EAQUAL comparison would be academic, not practical, since previous discussions have shown that its quality rankings are not very precise, nor are they appropriate for codec comparison.

AAC at 128kbps test - FINISHED

Reply #80 –
Quote
The result of the test has been posted here as well...

http://www.cdfreaks.com/news/7355

I like some of the comments below....

"I hope they are talking about Astrid/Quartex AAC, others AAC sux..."

Ladies and gentlemen: Hydrogen Audio, the ivory tower of psychoacoustic compression.

AAC at 128kbps test - FINISHED

Reply #81 –
Quote
2) What encoder does AOL use for the AAC tracks streamed via Radio@AOL?

Radio@AOL is using the now famous Dolby AAC encoder. More information can be found in the following link:

http://www.dolbylabs.com/DolbyAAC/

Given Dolby's comment:

Quote
Dolby® AAC is an enhanced version of MPEG-2 and MPEG-4 AAC that adds proprietary Dolby intellectual property and supports data rates from 14 kb/s (mono) to 128 kb/s (stereo) and up.

How does Dolby AAC differ from AAC?
Dolby AAC consists of a standard MPEG-AAC core plus proprietary enhancements that enable a wider frequency range and better audio quality at lower bit rates.


it seems that they don't simply use the FhG codec modified for speed but they must have done some work in order to improve the quality. This makes sense after the listening test results.

AAC at 128kbps test - FINISHED

Reply #82 –
Quote
The result of the test has been posted here as well...

http://www.cdfreaks.com/news/7355

I like some of the comments below....

This article is not entirely correct because the Sorenson encoder was voted second in quality and not the one in Nero.

AAC at 128kbps test - FINISHED

Reply #83 –
Nice board

I would just like to point out to anybody interested, is that iTunes 4 does use the same encoder as QuickTime 6.3, it's just that in the 4.0 release it was accidently hardcoded to the fastest setting. 4.01 has corrected this and it is now hard coded to highest quaiity (as seen by the extreme decrease in encoding speed on my powerbook (13.9x down to 7.2x)).

I am 99.99999% sure on this, but maybe someone with better ears than me could verify it.

AAC at 128kbps test - FINISHED

Reply #84 –
Quote
You can use FAAD to decode the QT files, I believe. I haven't used QT, but I think that's how Roberto decompressed the test samples. I think FAAD can be downloaded at RareWares.

I used FAAD.

QT has some issues and can't decode AAC files wrapped with mp4creator (Psytel and FAAC, in the test)

Quote
"I hope they are talking about Astrid/Quartex AAC, others AAC sux..."

Ladies and gentlemen: Hydrogen Audio, the ivory tower of psychoacoustic compression.


I know I should reply, talking about Pac and about stolen libraries. But I really don't feel like it. >_<

I mean, what the heck, since the days of the VQF forum people know Astrid was stolen from CelestialTech's AudioLib 1.0

AAC at 128kbps test - FINISHED

Reply #85 –
In order to clarify the challengers for the second (part of the) test, I did a quick blind test, and opposed WMA9 called 'PRO' to WMA9 standard. Results are here.

WMA9 PRO seems to be the best encoder, and should be prefered to the standard (and portable-compatible) one.

AAC at 128kbps test - FINISHED

Reply #86 –
Quote
I would just like to point out to anybody interested, is that iTunes 4 does use the same encoder as QuickTime 6.3, it's just that in the 4.0 release it was accidently hardcoded to the fastest setting. 4.01 has corrected this and it is now hard coded to highest quaiity (as seen by the extreme decrease in encoding speed on my powerbook (13.9x down to 7.2x)).

I am 99.99999% sure on this, but maybe someone with better ears than me could verify it.

I head about that at the 3ivX forum too. But they aren't sure either.

I'm waiting for some confirmation before I update the results page.

One way to confirm would be to encode a file with iTunes, then with QT in high mode, and compare them.

Regards;

Roberto.

AAC at 128kbps test - FINISHED

Reply #87 –
Quote
Quote
I would just like to point out to anybody interested, is that iTunes 4 does use the same encoder as QuickTime 6.3, it's just that in the 4.0 release it was accidently hardcoded to the fastest setting. 4.01 has corrected this and it is now hard coded to highest quaiity (as seen by the extreme decrease in encoding speed on my powerbook (13.9x down to 7.2x)).

I am 99.99999% sure on this, but maybe someone with better ears than me could verify it.

I head about that at the 3ivX forum too. But they aren't sure either.

I'm waiting for some confirmation before I update the results page.

One way to confirm would be to encode a file with iTunes, then with QT in high mode, and compare them.

Regards;

Roberto.

I will encode a file using QT6.3 (Highest) and iTunes 4.01 and compare the encoded files using a hex editor. I will report the results back to this thread.

AAC at 128kbps test - FINISHED

Reply #88 –
Tested (quickly) GT2 vs Post CVS release of ogg vorbis, here.
I changed my mind about GT2 virtue : final version is maybe more 'dirty' (hiss, noise added), there are less annoying artifacts (and size is a bit smaller), at least, on difficult samples.

AAC at 128kbps test - FINISHED

Reply #89 –
Quote
Quote
Quote
I would just like to point out to anybody interested, is that iTunes 4 does use the same encoder as QuickTime 6.3, it's just that in the 4.0 release it was accidently hardcoded to the fastest setting. 4.01 has corrected this and it is now hard coded to highest quaiity (as seen by the extreme decrease in encoding speed on my powerbook (13.9x down to 7.2x)).

I am 99.99999% sure on this, but maybe someone with better ears than me could verify it.

I head about that at the 3ivX forum too. But they aren't sure either.

I'm waiting for some confirmation before I update the results page.

One way to confirm would be to encode a file with iTunes, then with QT in high mode, and compare them.

Regards;

Roberto.

I will encode a file using QT6.3 (Highest) and iTunes 4.01 and compare the encoded files using a hex editor. I will report the results back to this thread.

That won't work because iTunes adds extra metadata. The files will be slightly different sizes. Someone will have to do a listening test I think.

AAC at 128kbps test - FINISHED

Reply #90 –
Quote
That won't work because iTunes adds extra metadata. The files will be slightly different sizes. Someone will have to do a listening test I think.

Hrm... maybe extracting the AAC tracks with MP4creator for Mac, and then comparing the AACs?

AAC at 128kbps test - FINISHED

Reply #92 –
Quote
Quote
That won't work because iTunes adds extra metadata. The files will be slightly different sizes. Someone will have to do a listening test I think.

Hrm... maybe extracting the AAC tracks with MP4creator for Mac, and then comparing the AACs?

Ok, I'll do that then and report back.

AAC at 128kbps test - FINISHED

Reply #93 –
Ok, I encoded an AIFF file with QuickTime 6.3 and then with iTunes 4.01 at 160Kbps. I then used mp4creator to extract the audio track and... the iTunes encoded file does not match any QuickTime 6.3 encoded file at any quality setting 

I also checked the tracks in a hex editor and they are clearly different. The sizes are also different i.e.

QT6.3 High  - 1994056 bytes
QT6.3 Better - 1994053 bytes
QT6.3 Good  - 1994087 bytes
iTunes 4.01  - 1995001 bytes

I then tried AAChoo (front-end for QT) and the encoded tracks were the same to those produced by QT for each quality setting, although the .mp4 files were slightly different in size because of the addition of extra tags.

I am confused... Is iTunes passing some special parameters to QT?

AAC at 128kbps test - FINISHED

Reply #94 –
i did a quick encode of one 6+ minute track in itunes 4.0.1 @ 160 and qt 6.3 @ 160 "best" -- itunes took 24 seconds, qt took 44 seconds. dunno if itnues is more altivec or mp savvy, tho. so . . . fwiw . . . might not be worth much.

AAC at 128kbps test - FINISHED

Reply #95 –
Quote
Ok, I encoded an AIFF file with QuickTime 6.3 and then with iTunes 4.01 at 160Kbps. I then used mp4creator to extract the audio track and... the iTunes encoded file does not match any QuickTime 6.3 encoded file at any quality setting 

What options did you select with QT?

iTunes only lets you set bitrate but QT has a load of other options. Surely the setting of those would have an effect? In particular there are options for optimizing the file for streaming.

Now I would, on first thought, switch them all off but one of the major features of iTunes 4 is LAN streaming (with internet streaming to specific clients due to return in a future update according to rumour) so it makes sense for iTunes to use these settings if it doesn't massively affect encoding time.

AAC at 128kbps test - FINISHED

Reply #96 –
Quote
In particular there are options for optimizing the file for streaming.

Optimize for streaming only affects the MP4 container. If you strip the AAC file from inside, there should be no difference.

AAC at 128kbps test - FINISHED

Reply #97 –
It might make it easier to compare if you decode to WAV.

ff123

AAC at 128kbps test - FINISHED

Reply #98 –
Quote
Quote
Ok, I encoded an AIFF file with QuickTime 6.3 and then with iTunes 4.01 at 160Kbps. I then used mp4creator to extract the audio track and... the iTunes encoded file does not match any QuickTime 6.3 encoded file at any quality setting 

What options did you select with QT?

iTunes only lets you set bitrate but QT has a load of other options. Surely the setting of those would have an effect? In particular there are options for optimizing the file for streaming.

Now I would, on first thought, switch them all off but one of the major features of iTunes 4 is LAN streaming (with internet streaming to specific clients due to return in a future update according to rumour) so it makes sense for iTunes to use these settings if it doesn't massively affect encoding time.

I encoded the file using QT and each quality setting without any other special parameters. The option to hint for streaming was disabled but that does not affect the encoding. I then extracted the tracks using mp4creator and I could not match any of them with the extracted track from the iTunes 4.01 encoded file. I managed to match them with encodings using AAChoo which is a front-end for QT (like iTunes for AAC). The iTunes 4.01 speed of encoding was faster than the QT one in high quality.

My guess is that iTunes calls the QT encoder with some special parameters to optimise the speed resulting in a file which cannot be generated by simply using the QT interface.

AAC at 128kbps test - FINISHED

Reply #99 –
Quote
Quote
Quote
Ok, I encoded an AIFF file with QuickTime 6.3 and then with iTunes 4.01 at 160Kbps. I then used mp4creator to extract the audio track and... the iTunes encoded file does not match any QuickTime 6.3 encoded file at any quality setting 

What options did you select with QT?

iTunes only lets you set bitrate but QT has a load of other options. Surely the setting of those would have an effect? In particular there are options for optimizing the file for streaming.

Now I would, on first thought, switch them all off but one of the major features of iTunes 4 is LAN streaming (with internet streaming to specific clients due to return in a future update according to rumour) so it makes sense for iTunes to use these settings if it doesn't massively affect encoding time.

I encoded the file using QT and each quality setting without any other special parameters. The option to hint for streaming was disabled but that does not affect the encoding. I then extracted the tracks using mp4creator and I could not match any of them with the extracted track from the iTunes 4.01 encoded file. I managed to match them with encodings using AAChoo which is a front-end for QT (like iTunes for AAC). The iTunes 4.01 speed of encoding was faster than the QT one in high quality.

My guess is that iTunes calls the QT encoder with some special parameters to optimise the speed resulting in a file which cannot be generated by simply using the QT interface.

Hmm, I wonder what the quality is like tho. Maybe in the next test have an iTunes encoded AAC file and a QuickTime encoded one. Who knows. I just wish iTunes had a quality option so I could be sure.