Decompress ALAC file

[Foxman50]

Hi all

I have stored all my ripped CD's in uncompressed FLAC format, by which i mean the file is 100% the original size. Anyway i now find the need to import these files into itunes, and i need to convert these into ALAC. No big deal really as i use dbpoweramp to rip which allows you to convert the flac to alac, however this outputs a file with an m4a extension, which i think is ok. However what concerns me is the fact that the m4a file is 40% compressed. dbpoweramp allows you to adjust the amount of compression when converting flac files, but not as far as i can see when converting alac files. Does anyone know how i can convert the alac files without any compression taking place. Apologies for making that long winded. Im sure its ok for the files to be compressed but id rather they were not.

[El Heggunte]

Hi there,

it seems you don't perceive there is a difference between "uncompressed" and "losslessly-compressed".

AFAIK there is no such thing as "uncompressed FLAC"

Also, the whole point of FLAC, ALAC, TTA, WavPack, MLP, etc., is exactly reduce the storage space requirements...

[Foxman50]

Hi there,

it seems you don't perceive there is a difference between "uncompressed" and "losslessly-compressed".

AFAIK there is no such thing as "uncompressed FLAC"

Also, the whole point of FLAC, ALAC, TTA, WavPack, MLP, etc., is exactly reduce the storage space requirements...

I realise that flac and alac are both lossless formats, and hence losslessly compressed. This isn't my question though. when i download a flac album from say HDtracks the tracks are compressed. If you use dbpoweramp then you can see this by hovering over the track. it varies but is often around 45% compressed. Again within dbpoweramp you can then decompress this file so that is is 0% compressed. Thus when streaming there is less stress on the player to decompress as its streaming. This is thought by some the reason why wav sounds better than flac. Anyway thats an argument for another day. So my question is, is it possible to save the alac to be 0% compressed

[Selur]

I think he is mixing up compression with lossless.
Since iTunes probably does not support flac in general he could:
a. use a lossless conversion from flac to (uncompressed) wav (and feed that file to iTunes)
or
b. use a lossy conversion from flac to (highly compressed) aac (and feed that file to iTunes)
or
c. try fluke for mac

Cu Selur

[Foxman50]

a. use a lossless conversion from flac to (uncompressed) wav (and feed that file to iTunes)

Unfortunately wav does not handle tags well at all, and would take too long to set everything right i think.

b. use a lossy conversion from flac to (highly compressed) aac (and feed that file to iTunes)

Want the best possible sound quality so dont want to use a lossy format

c. try fluke for mac

I dont use a mac at present but what does fluke do??

[Selur]

I dont use a mac at present but what does fluke do??

since I don't use iTunes at all, I have no clue, but probably either:
- extends iTunes (unlikely)
- converts to Apple Lossless format (possible but probably still unlikely)
- modifies the iTunes database (probably the likeliest)

Unfortunately wav does not handle tags well at all, and would take too long to set everything right i think.

wav can be put in a mov container, which can be tagged like mp4 and should be supported by iTunes

Cu Selur

[Foxman50]

wav can be put in a mov container, which can be tagged like mp4 and should be supported by iTunes

That sounds promising, do you have any information on how this would be done as to be honest thats going over my head

[Selur]

conversion and adding metadata should be possible with ffmpeg (multiplexing wave to mov and changing tags should also be possible with Quicktime Pro iirc.)

btw. just googled and saw http://www.any-audio-converter.com/flac-to-apple-lossless-converter.php which seems to be a tool which converts to apple lossless and from the looks of it, it uses mp4 (with m4a extension) as container which should allow to use normal mp4 tagging tools.

qaac also can also be used to apple lossless and it too support tagging.
(personally I would use qaac, since I used it quite a few times to create aac content)

[El Heggunte]

I realise that flac and alac are both lossless formats, and hence losslessly compressed. This isn't my question though. when i download a flac album from say HDtracks the tracks are compressed. If you use dbpoweramp then you can see this by hovering over the track. it varies but is often around 45% compressed. Again within dbpoweramp you can then decompress this file so that is is 0% compressed. Thus when streaming there is less stress on the player to decompress as its streaming. This is thought by some the reason why wav sounds better than flac. Anyway thats an argument for another day. So my question is, is it possible to save the alac to be 0% compressed

No, because ALAC doesn't offer various levels of compression efficiency.

[Foxman50]

Many thanks Selur for your input. I will have a look into your suggestions. Cheers

[Foxman50]

No, because ALAC doesn't offer various levels of compression efficiency.

Ah i see, oh well. Thanks for your help El Heggunte

[poisondeathray]

No, because ALAC doesn't offer various levels of compression efficiency.

The Apple implementation does through quicktime; the filesizes are different between "faster" and "best"

[Foxman50]

The Apple implementation does through quicktime; the filesizes are different between "faster" and "best"

Sorry how do you mean. is this when your are ripping to alac?

[Selur]

btw. qaac interfaces with apples application support, so if apple supports it, so should qaac

[poisondeathray]

The Apple implementation does through quicktime; the filesizes are different between "faster" and "best"

Sorry how do you mean. is this when your are ripping to alac?

I don't use alac, but I just tested in quicktime pro - different encoding settings in alac.

If the compression was the same between "faster" and "best" , the filesize and thus bitrate should be the same

faster, fast, normal, better, best

[El Heggunte]

The Apple implementation does through quicktime; the filesizes are different between "faster" and "best"

Thanks for well-informing the uninformed

And you dared to say that I am the Apple fanboy

[poisondeathray]

But I can't find any official documentation on the ALAC settings

I've used qaac for aac, but not for alac; but the help doesn't show any switches for alac encoding

[Foxman50]

The Apple implementation does through quicktime; the filesizes are different between "faster" and "best"

Sorry how do you mean. is this when your are ripping to alac?

I don't use alac, but I just tested in quicktime pro - different encoding settings in alac.

If the compression was the same between "faster" and "best" , the filesize and thus bitrate should be the same

faster, fast, normal, better, best

Many thanks i will try this.

[poisondeathray]

But I doubt it will make any difference in CPU/resource utilization for decoding. Even at "faster" it's still significantly compressed (compared to uncompressed). It's obviously going to differ for different types of content, but the difference wasn't very big for "faster" vs. "best"

[Selur]

@poisondeathray:

I've used qaac for aac, but not for alac; but the help doesn't show any switches for alac encoding

sure it does: "-A, --alac ALAC encoding mode"

nu774 also made a separate tools for alac en-/decoding: reflac (https://github.com/nu774/qaac/wiki/refalac-usage)

[poisondeathray]

@poisondeathray:

I've used qaac for aac, but not for alac; but the help doesn't show any switches for alac encoding

sure it does: "-A, --alac ALAC encoding mode"

nu774 also made a separate tools for alac en-/decoding: reflac (https://github.com/nu774/qaac/wiki/refalac-usage)

I meant it doesn't show switches for type of ALAC encoding (ie. "faster", "best" etc...)

[El Heggunte]

btw. qaac interfaces with apples application support, so if apple supports it, so should qaac

I agree --- but it seems the author of qaac has never implemented ALL the capabilities of the CoreAudioToolbox DLL

[Selur]

probably nobody ever asked for them

[Foxman50]

Found the answer. Dont use ALAC, use AIFF. Apparently AIFF is to ALAC what WAV is to FLAC. i.e. WAV and AIFF are both uncompressed lossless formats. The good thing about AIFF is that is has quality tagging, which WAV does not. Anyway if anyone can suggest a reason for not using AIFF for itunes i'd appreciate a responce. Many thanks

[El Heggunte]

Found the answer. Dont use ALAC, use AIFF. Apparently AIFF is to ALAC what WAV is to FLAC. i.e. WAV and AIFF are both uncompressed lossless formats. The good thing about AIFF is that is has quality tagging, which WAV does not. Anyway if anyone can suggest a reason for not using AIFF for itunes i'd appreciate a responce. Many thanks

We're glad you've found a solution or workaround.
Notwithstanding, from now on please keep in mind the following,

precise terminology IS important

AIFF, WAV, MOV and MP4 are digital media containers, whereas ALAC is a compression "method":

http://en.wikipedia.org/wiki/Digital_container_format

fyi, WAV can store lossily-compressed audio, as long as it uses constant bitrate and constant frame duration
(MP2, MP3, AC3, DTS, ATRAC3, Speex, etc.)

[Foxman50]

precise terminology IS important

AIFF, WAV, MOV and MP4 are digital media containers, whereas ALAC is a compression "method":

http://en.wikipedia.org/wiki/Digital_container_format

fyi, WAV can store lossily-compressed audio, as long as it uses constant bitrate (MP2, MP3, AC3, DTS, ATRAC3, Speex, etc.)

Well i never, most of that article has gone over my head, but is this why when you choose alac as an output file type it comes out with an m4a extension. Because the container is m4a but the internal file has used alac to be compressed.

If that assumption is correct, why do we refer to some files as WAV, FLAC, ALAC etc. Would it not be correct to say WAV, FLAC, M4A, etc

Again if this assumption is correct and your statement "WAV can store lossily-compressed audio, as long as it uses constant bitrate (MP2, MP3, AC3, DTS, ATRAC3, Speex, etc.)" how would you know if a WAV file is lossless or lossily compressed.

Many thanks, very informative

[Selur]

Normally if you speak of wav, you refer to PCM with wav headers and PCM is lossless.
Some folks attach wav headers around other formats, but that is not the typical thing. (they normally do it to fool some other tool into processing the audio)

[Foxman50]

Well to be honest i find it very confusing. If i buy a ferrari, if only i could afford one, id expect it to have a ferrari engine not a ford engine. And before any one jumps on it fords are good too .

Does itunes show you what the container is and what the compression tool is?

[Selur]

I hope so (no clue since I don't use iTunes)

[Foxman50]

Well after much research i'm going to keep my music mainly in FLAC on my NAS drive. I will use Fluke, thanks Selur for the link, to import the FLAC files into itunes. This will only work for standard CD rips as Fluke wont support any hi res formats. Then ill use dbpoweramp to convert any hi res albums into AIFF format, container ? and import those. This way hopefully it will be minimal time required to convert the few hi res albums i have.

All i need to do now is research how to make sure that itunes sends out what it reads in bit for bit without any interference. Think there is an app called bit perfect for this. More reading required

Anyway thanks to all for all the help and knowledge ive half picked up. Very much appreciated. What would we do without the web. Hmm enjoy life a whole lot more i suspect

Regards