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FLAC to ALAC
paperskyline
post May 5 2012, 15:08
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What if I convert FLAC files to ALAC and then convert it to AAC using iTunes?
Will there be any degradation of quality when I convert the FLAC to ALAC?
I want iTunes to convert my files to AAC. I don't want to use any other AAC codec (like Nero).
So is it OK if I convert FLAC to ALAC?
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polemon
post May 5 2012, 15:14
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Both are lossless, there is no quality degradation whatsoever. You might as well decode them into WAV and then use iTunes to convert them into AAC.

However, since headers are slightly different, the resulting files will not have the exact same size, but don't let that freak you out.

When your FLAC files are tagged, you might lose some of that tagging data, but you can add them afterwards, of course.

This post has been edited by polemon: May 5 2012, 15:14


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db1989
post May 5 2012, 15:32
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Please feel free to do your own research about such basic questions as this and those in your other recent posts. Information is freely available on Hydrogenaudio’s forums and Knowledgebase, on Wikipedia, and from many other sources.

Ah, if only the type of site from which people obtain files such as these were to provide more information, we wouldn’t have to deal with the fallout from their lack of guidance/verifiability. rolleyes.gif
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Dario
post May 5 2012, 19:13
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If you're on a Windows machine, consider using qaac and transcode the FLAC files directly to AAC. It's the same as transcoding them with iTunes or QuickTime.

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polemon
post May 5 2012, 20:38
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Actually, I just did some testing on Windows in a VM. I have qaac, flac, lame, oggenc, etc installed so that I can use them from commandline.

All I need to do, is this:
CODE
flac -d --force-raw-format --endian=little --sign=signed <file>.flac -c | qaac -R -o <file>.m4a -

As you can see, I omitted all options for encoding, like -V100, etc. Also, I made a habit of using pcm (raw) format, since I use very large and long files from live recording, and WAV cannot be bigger than 4GB. all this is circumvented when using raw data.


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greynol
post May 5 2012, 23:05
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I have a script somewhere that encodes and copies tags over using Nero (to encode and tag). I imagine it would be fairly trivial to modify it to use qaac. I think it also prescales in order to apply RG album gain info using sox. I think I posted it to the forum at one point in time.


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newman079
post May 5 2012, 23:16
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Fast and painless way to convert flac to alac preserving audio tags smile.gif

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tev777
post May 6 2012, 05:30
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Give this a try. You can go directly to AAC or you can convert to AAC and ALAC at the same time.

http://sbooth.org/Max/


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smok3
post May 6 2012, 19:24
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ffmpeg -i file.flac -acodec alac -vn out.m4a
(seems to be working, metadata travels as well)

p.s. i have an OS X droplet for that, but if you want recursive directory stuff, it would need some modifications, currently it takes bunch of files as input only. http://forum.doom9.org/showthread.php?p=1528488 (check /audio folder: audioToAlacInternal.app)

This post has been edited by smok3: May 6 2012, 19:28


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polemon
post May 7 2012, 00:30
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QUOTE (smok3 @ May 6 2012, 20:24) *
ffmpeg -i file.flac -acodec alac -vn out.m4a


I tend to avoid FFmpeg when possible. I much rather use the the encoders/decoders directly. Saving the metadata to JSON should be no problem, for putting it back into the new format later.

As a matter of fact, there is no decent raw format available. As I said in my earlier post, I use it quite often, since I do live recordings. Something like a PCM file with an accompanying JSON would be nice.

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smok3
post May 7 2012, 08:18
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polemon: and what exactly would you use to put an external db back into any metadatable format? (hint: ffmpeg)

btw, I did some experimenting yesterday, it is possible to use ffmpeg to say convert alac to pcm+external_meta and later pcm+external_meta into say mp3. (This saves one from using lots of different metatagging tools and hopefully has some sort of abstraction layer, so that "standard" fields will land into correct locations..., need more experimenting)

p.s. Would you think JSON is human enough to be hand-written?

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p.s.2. oh and it is not hard to use ffmpeg in a way that it works only as decoder, piping (or tmp file) to say lame.

This post has been edited by smok3: May 7 2012, 08:24


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Porcus
post May 7 2012, 11:59
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QUOTE (polemon @ May 7 2012, 01:30) *
I tend to avoid FFmpeg when possible. I much rather use the the encoders/decoders directly.


I understand that point in the cases where there is actual transcoding taking place (and the reference encoders/decoders might be more reliable than ffmpeg's), but the -acodec copy or -vcodec copy will move the stream without transcoding.


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polemon
post May 7 2012, 12:18
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QUOTE (Porcus @ May 7 2012, 12:59) *
QUOTE (polemon @ May 7 2012, 01:30) *
I tend to avoid FFmpeg when possible. I much rather use the the encoders/decoders directly.


I understand that point in the cases where there is actual transcoding taking place (and the reference encoders/decoders might be more reliable than ffmpeg's), but the -acodec copy or -vcodec copy will move the stream without transcoding.


This is a given, of course. I use FFmpeg with -acodec copy or -vcodec copy quite a lot, when composing MKV or MP4. But when it comes to audio encoding, where transcoding is involved, I tend not to use FFmpeg. This probably, is due to the fact that I was involved in audio streaming technologies for a couple of years. I had bad experiences with FFmpeg, back then...


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polemon
post May 7 2012, 12:29
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QUOTE (smok3 @ May 7 2012, 09:18) *
polemon: and what exactly would you use to put an external db back into any metadatable format? (hint: ffmpeg)

btw, I did some experimenting yesterday, it is possible to use ffmpeg to say convert alac to pcm+external_meta and later pcm+external_meta into say mp3. (This saves one from using lots of different metatagging tools and hopefully has some sort of abstraction layer, so that "standard" fields will land into correct locations..., need more experimenting)

p.s. Would you think JSON is human enough to be hand-written?

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p.s.2. oh and it is not hard to use ffmpeg in a way that it works only as decoder, piping (or tmp file) to say lame.


I think you misunderstood my intentions. I don't want an external db for meta information generally, I just need it where it is otherwise unprovided, as it is with PCM files. Things like MP3 or M4A don't need external meta info dbs.

Now, I'm quite a fan of JSON, for two or three reasons: It is easy to edit, and it is widely supported. And where it is not supported, it is easy to implement. I've been editing quite a lot of JSON files manually, and I don't see any hardships in that. Now, the meta info goes beyond tagging. The data needed for PCM files is things like sampling rate, bits per sample, endianess, signed or not, etc. Not things like track title, artist, or album name. Those would also go well into the JSON, but it is not necessary. For instance, when you rip a CD, you have a dump.bin and a dump.cue, I'd re-use that idea.


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smok3
post May 7 2012, 21:04
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right, i was thinking strictly about "container" level metadata, my example was about metadata traveling across formats, like:

a. alac (1 file)
b. pcm or something that doesn't have any internal possibilities (2 files)
c. mp3 (1 file)

yes, i have my own intentions as well wink.gif

This post has been edited by smok3: May 7 2012, 21:05


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