Convert to Apple Lossless in Itunes is not ALAC

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Level 1

8 points

Convert to Apple Lossless in Itunes is not ALAC

Itunes propose an option to convert to Apple Lossless Format.

I assumed it was ALAC but apparently not exactly.

Assuming an ALAC file ripped from CD with an external converter (16bits, 44,100 kHz, Stéréo) this gives 1411 kbit/S (16*44100*2).

If i import this ALAC file in ITUNES, i effectively get a file with 1411 kbit/s. The file size is 42,7 Mbytes.

Now, on this file i create an Apple Lossless version with iTunes just to check what happens and i gat the following result: The file size is 43 Mbytes, 16 bits, 44,100 kHz but the is 921 kbit/s !

How is this possible since 16*44100*2 cannot give 921 kbit/s ?

Is there 2 different versions of Apple Lossless Format.

I am really confused...

MacBook Pro (13-inch Early 2011), macOS Sierra (10.12.1)

Posted on Nov 9, 2016 12:40 AM

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Answer 1

Nov 9, 2016 1:01 AM in response to Lacarbre

HI,

1411 Kbps suggests that you have not ripped the CD as ALAC. This is what you get when the file is AIFF.

When you rip as ALAC you get a variable bit rate depending on the complexity of track. So it is possible for on track to be 921 Kbps whilst others are much higher or lower rate.

Jim

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Answer 2

Lacarbre Author

Level 1

8 points

Nov 9, 2016 1:18 AM in response to Jimzgoldfinch

Thanks Jim for your answer.

I agree the difference should come from VBR but i don't agree on the fact my initial file is not ALAC because it is and recognized as such in Itunes and It's a compressed file. It's probably ALAC CBR if this exists?

Surprisingly the ALAC VBR generated by Itunes is a bit bigger than the initial ALAC file ?

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Answer 3

Nov 9, 2016 4:34 AM in response to Lacarbre

Hi,

What external converter are you using?

As well as iTunes, I use XLD to convert CD imports. Conversion does not have and option to chose CBR or VBR.

As mentioned in previous post, if you are seeing 1411kbps, this is bit rate that standard CD will show if they are copied directly onto you hard drive.

Jim

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Answer 4

Lacarbre Author

Level 1

8 points

Nov 9, 2016 5:58 AM in response to Jimzgoldfinch

Hi,

I used "MediaHuman Audio Converter". Input file beeing FLAC (Hotel California - Eagles) and output file beeing ALAC 44,1 KHz.

There is no option for CBR or VBR but since before using Itunes the bitrate was 1411bps i made this assumption.

Again both files in Itunes are recognized as ALAC respectively with bitrates of 1411 kbps and 921 kbps and a size of 42,7 Mbit for the 1411 kbps file and 43 Mbit for the 921 kbps file.

One assumption could be that before processed by Itunes the bitrate displayed is the theoretical bitrate (2*16*44,1) and after Itunes gives the real bitrate?

PS: Sorry for approximative English (not first language as you could notice)

Jacky

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Answer 5

Lacarbre Author

Level 1

8 points

Nov 9, 2016 6:14 AM in response to Jimzgoldfinch

New test even more surprising !

Itunes seems capable to convert an AAC 256 kpbs to an ALAC 921 kbps ?

You can try with one of you files in Itunes

Does it mean Itunes is capable te recreate the missing information destroyed in the destructive AAC format ?

I am even more lost. It looks like a miracle or maybe Itunes doesn't convert the file but has all music in ALAC and when asking for conversion it is going to fetch the ALA file file in a hidden library ?

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Answer 6

ed2345

Level 9

63,608 points

Nov 9, 2016 6:36 AM in response to Lacarbre

Lacarbe,

Apple Lossless Audio Codec (ALAC) is a compressed lossless format. It makes a PCM-encoded file smaller but keeps the same sample rate (usually 44.1 kHz) and does not lose any audio information. If you are interested in the technicalities, see:

https://en.wikipedia.org/wiki/Apple_Lossless

New test even more surprising !

Itunes seems capable to convert an AAC 256 kpbs to an ALAC 921 kbps ?

You can try with one of you files in Itunes

Does it mean Itunes is capable te recreate the missing information destroyed in the destructive AAC format ?

I am even more lost. It looks like a miracle or maybe Itunes doesn't convert the file but has all music in ALAC and when asking for conversion it is going to fetch the ALA file file in a hidden library ?

Yes, of course. iTunes will do that conversion if your settings request it to do so. Some people do that conversion thinking it will give them better audio quality (it does not), but the output will indeed be in ALAC format.

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Answer 7

Lacarbre Author

Level 1

8 points

Nov 9, 2016 6:57 AM in response to ed2345

Thanks,

In this case, i am really suspicious since the two files i get from an AAC 256 kbps and from an ALAC 1411 kbps are giving after conversion with Itunes almost the same file size (one is 42,8 Mbit and the other is 43 Mbit).

The file issued from AAC being built upon a destructive format it's not lossless (if we refer to inital FLAC format for example). Maybe the other one issued from ALAC 1411 kbps is lossless but you don't really know since both files have same format and almost same size ...

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Answer 8

ed2345

Level 9

63,608 points

Nov 9, 2016 7:14 AM in response to Lacarbre

Lacarbre,

ALAC is optimized to do its lossless compression on PCM-encoded files, which are ubiquitous due to being used as the audio CD standard. That is what the 40-60% compression number applies to.

Since it is a lossless format, the ALAC file that you got from the conversion should have the exact audio content of the AAC you started with. It is bigger, so there is no reason to convert an AAC to ALAC except as part of your natural zeal for experimentation. 🙂

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