Skip to main content ↑ ↓

Notice

Please note that most of the software linked on this forum is likely to be safe to use. If you are unsure, feel free to ask in the relevant topics, or send a private message to an administrator or moderator. To help curb the problems of false positives, or in the event that you do find actual malware, you can contribute through the article linked here.
Topic: QuickTime AAC encoding (Read 6886 times) previous topic - next topic
0 Members and 1 Guest are viewing this topic.

QuickTime AAC encoding

In QuickTime Pro, there seem to be more options for AAC encoding.

These include Quality (Options: Good, Better, Best) and
Precedence (Options: None, Bit Rate, Sample Rate)

Defaults are in bold.

So what I did was first take a long track with many changes (Dream Theater's Octavarium) and encode it to iTunes VBR (bitrate 160).

Size of file (m4a): 29,626,370 bytes

Then I encoded these files using QuickTime in all the different options at VBR bitrate 160 using the mov/mp4 passthrough method:

Best (none/bit rate/sample rate)
Size of file (mov): all 29,439,394
Size of file (mp4): all 29,442,359 bytes

Better (none/bit rate/sample rate)
Size of file (mov): all 29,438,373 bytes
Size of file (mp4): all 29,441,306 bytes

Good  (none/bit rate/sample rate)
Size of file (mov): all 30,760,125 bytes
Size of file (mp4): all 30,763,138 bytes

WAV comparison
Original WAV: 248,065 KB
Decompressed iTunes WAV: 248,073 KB
Decompressed QuickTime Wave: 248,065

iTunes even made the file longer.

What's the difference between mp4, m4a, iTunes, and QuickTime then?  Could this actually be a quality increase?  If mp4 = m4a, then I am using Best/Sample Rate from now on with QuickTime.

QuickTime AAC encoding

Reply #1 –
iTunes actually uses Quicktime to do what it does, but it goes a bit further and adds tags and formatting and other such niceities to the resulting file as well.

M4A and MP4 files are basically the same, just with different extensions. You can rename those MP4's to M4A's and drag them into iTunes and they'll work. They won't be tagged, of course, but they'll work okay.

QuickTime AAC encoding

Reply #2 –
Quote
iTunes actually uses Quicktime to do what it does, but it goes a bit further and adds tags and formatting and other such niceities to the resulting file as well.

M4A and MP4 files are basically the same, just with different extensions. You can rename those MP4's to M4A's and drag them into iTunes and they'll work. They won't be tagged, of course, but they'll work okay.
[a href="index.php?act=findpost&pid=353140"][{POST_SNAPBACK}][/a]


However, iTunes bloats their m4a files, and for some reason, the file sizes are different.

Just added tags, and now QuickTime m4a's are actually bigger than iTunes'.
QuickTime - Best: 29,784,624 bytes
iTunes: 29,624,627 bytes

QuickTime AAC encoding

Reply #3 –
I thought it was demonstrated at some point on here that messing with the settings in Quicktime was only worthwhile if you were encoding from 48.000 kHz material.  If you're just ripping from CDs at 44.100 kHz, then iTunes should be fine.

QuickTime AAC encoding

Reply #4 –
Hmm, I'm 90% sure it was quoted by a QuickTime developer that "Best" should be used for 24/96 or higher sources, and that it wouldn't be any better for 44/16 material, only slower. With that said this was back in the 6.0 days and the AAC encoder has changed so much since then, who knows whether it's still the case. Someone should do a test at 64kbps or something easy.

QuickTime AAC encoding

Reply #5 –
Quote
In QuickTime Pro, there seem to be more options for AAC encoding.
--
Precedence (Options: None, Bit Rate, Sample Rate)


Anyone know what this does and which setting iTunes uses?

QuickTime AAC encoding

Reply #6 –
There appears to be no difference as of now, but when it develops more, I think Sample Rate would give more of a true VBR, bit rate more like ABR, and none like something in between.  What the developer said could also be something to make iTunes seem better than QuickTime so people would use iTunes instead and not focus on the non-user friendly method you have to use to get QuickTime VBR.  I really don't think there would be much statistical difference unless you take many samples, but it would perform a small amount better.  When Nero or Applecomes out with a better version of their new codec or something else happens, I think both iTunes and QuickTime should be included in the listening test.

EDIT: I think QuickTime is gapless, while iTunes isn't.  Just something to think about.

QuickTime AAC encoding

Reply #7 –
Quote
(...) I think Sample Rate would give more of a true VBR
(...) but it would perform a small amount better
(...) I think QuickTime is gapless, while iTunes isn't
[a href="index.php?act=findpost&pid=353756"][{POST_SNAPBACK}][/a]

Busemann is asking for trustable knowledge, not for a brainstorming
During the iTunes 4.x era, iTunes didn't used the BEST mode of QuickTimes, but the intermediate one. The difference shouldn't be audible with 44.1/16 bit source. Situation has maybe changed in the meantime...
QuickTime's AAC encoder is not gapless - and if it is, I don't know the way to make it work.
Wavpack Hybrid -c4hx6

QuickTime AAC encoding

Reply #8 –
Well I was just giving a suggestion as they are the exact same file size as of now and I think they were bit identical too.

Also for the rare chance that there may be an audible difference, I would be happy to use Best because time isn't an issue for me.  I'm sure theres some others that would be as well.  Until an official listening test is done, however, then nothing can be proven.
 

QuickTime AAC encoding

Reply #10 –
My mistake.  Although tiny, the gaps exist.

Code: [Select]
INFO (CORE) : startup time: 1000 ms
INFO (CORE) : opening file for playback :
INFO (CORE) : location: "cdda://00C39C46,01" (0)
INFO (CORE) : opening file for playback :
INFO (CORE) : location: "cdda://00C39C46,02" (0)
INFO (foo_dsp_nogaps) : 113 samples removed (from end)
INFO (CORE) : opening file for playback :
INFO (CORE) : location: "cdda://00C39C46,03" (0)
INFO (foo_dsp_nogaps) : 31600 samples removed (from end)
INFO (foo_dsp_nogaps) : 18382 samples removed (from beginning)
INFO (CORE) : opening file for playback :
INFO (CORE) : location: "cdda://00C39C46,04" (0)
INFO (foo_dsp_nogaps) : 149 samples removed (from end)
INFO (foo_dsp_nogaps) : 5185 samples removed (from beginning)
INFO (CORE) : opening file for playback :
INFO (CORE) : location: "cdda://00C39C46,05" (0)
INFO (foo_dsp_nogaps) : 83591 samples removed (from end)
INFO (foo_dsp_nogaps) : 7914 samples removed (from beginning)
INFO (CORE) : opening file for playback :
INFO (CORE) : location: "cdda://00C39C46,06" (0)
INFO (foo_dsp_nogaps) : 17000 samples removed (from end)
INFO (foo_dsp_nogaps) : 10322 samples removed (from beginning)
INFO (CORE) : opening file for playback :
INFO (CORE) : location: "cdda://00C39C46,07" (0)
INFO (foo_dsp_nogaps) : 357 samples removed (from end)
INFO (foo_dsp_nogaps) : 5283 samples removed (from beginning)
INFO (CORE) : opening file for playback :
INFO (CORE) : location: "cdda://00C39C46,08" (0)
INFO (foo_dsp_nogaps) : 88200 samples removed (from end)
INFO (foo_dsp_nogaps) : 88200 samples removed (from beginning)