QAAC: discussion, questions, feature requests, etc., [originally a thread for a feature request] Options

[twinspex]

I have been producing my own modified version of REACT for use in ripping my CDs and have nearly finished the task. I wanted to be able to produce iTunes compatible and tagged .m4a files for individual tracks from the react image.cfg script having ripped to a one-big-file album image with cuefile. I managed to do this with the NeroAAc Encoder, acdir and atomic parsley. I then came across QTAACENC and QAAC which looked very promising as they allow use of the Quicktime dlls.

I totally failed to get either encoder working with ACDIR passing the split wave files into the encoder via STDIN in the analogous manner to that I successfully managed with the Nero encoder. No great loss though because I found QAAC alone can process a OBF wave image and associated cuefile into separate .m4a tracks - and it even tags the .m4a filees with the information taken from the cuefile. Fantastic!

I am left with a problem though. When processing from a cuefile QAAC outputs the track files in a format
tracknumber[space]tracktitle.m4a
and this cannot be changed. I like my files to be formatted thus:
tracknumber-tracktitle.m4a.
I think I am a competent enough batch file programmer to handle the necessary file rename (just! ), but the problem arises with various artists compilations. I really would like to use the naming format:
tracknumber-trackartist-tracktitle.m4a in such an instance.

I have looked online for a commandline based rename utility that would read the artist field from the embedded tag and alow me to use that field to rename the files QAAC produces. Unfortunately I haven't found one. (I know I could use something like mp3tag to do the job from a GUI later, but I would like to be able to do it as part of the REACT-based rip operation. I have looked at using the cuefile to extract track based wave files, which come out correctly named, and then to encode the track based wave files without using the cuefile. This results in no embedded tags and quite complicated scripting.)

I have no idea how difficult it would be to implement the output of m4a files to a specified filename format with QAAC cuefile processing, but if it is possible, please could the author please consider this as an enhancement request? I had a look at the source code but it is way beyond my skills to make myself an amended version! Thank you very much in advance.

(By the way I plan to use the NeroAAcTag utility to add cover art and albumArtist and compilation meta-user tags to the QAAC encoded .m4a files to finish the ripping task. I will be using OBF flac with embedded cover art and cuefile for archiving, and m4a for day to day usage).

Incidentally, if one uses QAAC cuesheet processing to produce .m4a files and then inspects the embedded tags with the neroAActage.exe -meta-list command on *.m4a I have noticed that the tools field may have a bug. On a three track CD single, using --ignorelength and --tvbr=125, the note of the tvbr setting is repeated one more time in the field for every successive track in the cuesheet. I don't hink this is a problem with the neroAActag.exe utility because the same repeated data is visible with the Audio Shell v1.3.5 utility! This problem is not a showstopper so far as I can see, but I haven't tried to do a sizable encoding task, and I wondered if it might cause a field overflow in such a situation.

example from Audio Shell v1..3.5 for the m4a file produced as track "03 Tracktitle" from the cuesheet:
Encoder: qaac 0.20, Quicktime 7.6.8 TVBR Quality 125, TVBR Quality 125, TVBR Quality 125,

I am using windows XP SP3 (up to date fixes), QAAC 0.20 and Quicktime 7.6.8 The quality setting was merely an experiment.

To bring a verbose post to an end. Thank you for producing this utility. I will find a workaround if you can't help.

[xekon]

Why such different results? do the two applications really work that differently, when using more or less the same arguments?
I assumed since they both use quicktime that it would be similar results, just different methods of getting the job done.

Some of the tagging is different for the container, and a lot of that I dont even understand, but there is an obvious difference in the average bitrate for the audio stream between the two.

Both qtaacenc and qaac use a range of 0-127 for tvbr, so I am a little confused...

example:

CODE

E:\AviSynth\Wavi bd.avs - | qtaacenc --tvbr 90 --highest --samplerate keep --ignorelength - qtaacenc.m4a
E:\AviSynth\Wavi bd.avs - | qaac --tvbr 90 --quality 2 --rate keep --ignorelength - -o qaac.m4a

cmd window:


qaac encoded m4a mediainfo:

CODE

General
Complete name                    : E:\AviSynth\qaac.m4a
Format                           : MPEG-4
Format profile                   : Apple audio with iTunes info
Codec ID                         : M4A
File size                        : 1.17 MiB
Duration                         : 33s 259ms
Overall bit rate mode            : Variable
Overall bit rate                 : 295 Kbps
Encoded date                     : UTC 2011-10-23 03:57:01
Tagged date                      : UTC 2011-10-23 03:57:05
Writing application              : qaac 0.91, QuickTime 7.7.0, MPEG-4 AAC Encoder 1.7.1, Variable Bit Rate q91, Best

Audio
ID                               : 1
Format                           : AAC
Format/Info                      : Advanced Audio Codec
Format profile                   : LC
Codec ID                         : 40
Duration                         : 33s 259ms
Bit rate mode                    : Variable
Bit rate                         : 288 Kbps
Maximum bit rate                 : 355 Kbps
Channel(s)                       : 6 channels
Channel positions                : Front: L C R, Side: L R, LFE
Sampling rate                    : 48.0 KHz
Compression mode                 : Lossy
Stream size                      : 1.16 MiB (99%)
Encoded date                     : UTC 2011-10-23 03:57:01
Tagged date                      : UTC 2011-10-23 03:57:05

qtaacenc encoded m4a mediainfo:

CODE

General
Complete name                    : E:\AviSynth\qtaacenc.m4a
Format                           : MPEG-4
Format profile                   : Base Media / Version 2
Codec ID                         : mp42
File size                        : 1.62 MiB
Duration                         : 33s 259ms
Overall bit rate mode            : Variable
Overall bit rate                 : 409 Kbps
Encoded date                     : UTC 2011-10-23 04:56:58
Tagged date                      : UTC 2011-10-23 04:56:58
Writing application              : qtaacenc 20110816, QuickTime 7.7.0, True VBR Quality 90
Encoding Params                  : (Binary)

Audio
ID                               : 1
Format                           : AAC
Format/Info                      : Advanced Audio Codec
Format profile                   : LC
Codec ID                         : 40
Duration                         : 33s 259ms
Bit rate mode                    : Variable
Bit rate                         : 407 Kbps
Maximum bit rate                 : 428 Kbps
Channel(s)                       : 6 channels
Channel positions                : Front: L C R, Side: L R, LFE
Sampling rate                    : 48.0 KHz
Compression mode                 : Lossy
Stream size                      : 1.61 MiB (99%)
Language                         : English
Encoded date                     : UTC 2011-10-23 04:56:58
Tagged date                      : UTC 2011-10-23 04:56:58

This post has been edited by xekon: Oct 23 2011, 05:20

[nu774]

Hi,
As far as I know, 5.1ch encoding with qtaacenc is not properly working, due to QuickTime side mixer problem. qaac has built in workaround for it.
Listen to the result, and confirm the channel layout.

However, I also confirmed that qtaacenc doesn't produce the same bitstream as qaac, even on 2ch stereo.
I tried on qtaacenc version 20110816 by tmkk;

Try --cvbr 256 on qaac, and compare them with "iTunes Plus" encoding by iTunes.
Also, try the same with qtaacenc.

On qaac, at least --cvbr 256 produces the exactly same bitstream with iTunes Plus.
You can use foobar2000 "bit compare" menu or something for it.
Also, if you have working Python interpreter (version 2.x), you can use my silly script (mdatcmp.py) to simply compare mdat in mp4 files.
https://github.com/nu774/mdatcmp

However, I couldn't get the same result with qtaacenc.
Maybe I'm missing something...

[nu774]

I'm sorry, forget about 2ch difference in the previous post.
It seems there was a problem in my enviromnent / testing.

[nu774]

It seems that new iTunes 10.5.0 (which doesn't require QT) produces different result for iTunesPlus
compared to iTunes 10.4.1...

When I tested before, qaac -v256 used to produce the same result with iTunes 10.4.1, but not with 10.5.0;
I tried to downgrade iTunes to re-confirm it, but unfortunately my iTunes library is already upgraded to 10.5.0, so iTunes refused to start up.

Anyway, this is what I have encoded with the both version;
https://sites.google.com/site/qaacpage/cabi...rects=0&d=1
Could someone confirm this?

[nu774]

Hi, forget about this post.
It seems that iTunes 10.5 installs new CoreAudioToolBox.dll. It's version is 7.9.7.3, and the same as QT 7.7.0; However, it's a bit bigger in size, and seems AAC encoder is updated.
I confirmed qaac -v256 produces identical bitstream as iTunesPlus of iTunes 10.5.

It seems that new iTunes 10.5.0 (which doesn't require QT) produces different result for iTunesPlus
compared to iTunes 10.4.1...

When I tested before, qaac -v256 used to produce the same result with iTunes 10.4.1, but not with 10.5.0;
I tried to downgrade iTunes to re-confirm it, but unfortunately my iTunes library is already upgraded to 10.5.0, so iTunes refused to start up.

Anyway, this is what I have encoded with the both version;
https://sites.google.com/site/qaacpage/cabi...rects=0&d=1
Could someone confirm this?

[overfloater]

I confirmed qaac -v256 produces identical bitstream as iTunesPlus of iTunes 10.5.

Interesting. I'm not getting identical files with qaac -v256 and iTunes Plus via iTunes 10.5.0.142. CoreAudioToolbox.dll is version 7.9.7.8.

Disclaimer: I'm no expert. (I only just registered to post this!) Source material was a standard CD quality WAV ripped by EAC, than manually pushed through iTunes and qaac separately. I assumed I'd see identical output files from each, hence I stumbled across this thread. But perhaps I'm making a newbie mistake, overlooking something obvious, or simply don't know what I'm talking about.


Edit: Ignore me. I keyed in on the "bitstream" part and realized that the files can be non-identical while the bitstream is the same. (Though I'm not 100% sure I understand where the file differences actually are.) Downloaded and used the foobar Bit Compare component to confirm the qaac/iTunes bitsreams are, in fact, identical. My bad! Told you I was a newbie...

This post has been edited by overfloater: Nov 5 2011, 23:06