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Trouble: 24/96KHz FLAC -> ALAC

Posted: Mon Oct 06, 2008 7:06 pm
by krmathis
I ran into the following issues, and am unsure if its known.
Transcoding 24-bit/96KHz FLAC files to Apple Lossless (ALAC) result in 16-bit/96KHz output.

Here is how to reproduce:
1. Download one of the HDTT samples ->
2. Set MAX to output ALAC files.
3. Transcode FLAC to ALAC.
4. Playback and observe...

Decoding the FLAC file using the flac binary, then encode to ALAC using iTunes result in 24-bit/96KHz files as expected. But Max is different...

Re: Trouble: 24/96KHz FLAC -> ALAC

Posted: Tue Oct 07, 2008 12:28 am
by sbooth
Is this with 0.8.1 or the latest svn? I believe I fixed this bug already, but it could be a different one.

Re: Trouble: 24/96KHz FLAC -> ALAC

Posted: Tue Oct 07, 2008 6:12 am
by krmathis
Using latest SVN code (rev. 1381)

Re: Trouble: 24/96KHz FLAC -> ALAC

Posted: Mon Oct 13, 2008 3:40 pm
by sbooth
I am not able to reproduce this- I grabbed the Dvorak violin concerto and converted to ALAC with the r1381 unstable build I posted the other day. afinfo says:

Code: Select all

File:           00 Unknown Track.m4a
File type ID:   m4af
Data format:     2 ch,  96000 Hz, 'alac' (0x00000003) from 24-bit source, 4096 frames/packet
Channel layout: Stereo (L R)
estimated duration: 323.413 sec
audio bytes: 111267891
audio packets: 7580
audio 31047680 valid frames + 0 priming + 0 remainder = 31047680
bit rate: 2752338 bits per second
packet size upper bound: 17299
audio data file offset: 61561
What are you using to play/determine the file's bit depth?

Re: Trouble: 24/96KHz FLAC -> ALAC

Posted: Tue Oct 14, 2008 1:34 pm
by krmathis
Strange! I am not even longer able to reproduce...
..and I am sure I have not updated Max.

Oh well, until I run (if ever) into the issue again consider it a non-issue.
Sorry for the trouble. :wink:

Re: Trouble: 24/96KHz FLAC -> ALAC

Posted: Thu Oct 16, 2008 8:01 am
by Athoss
Hi, I think I am finding a similar or related problem. I have been able to recreate it NUMEROUS times.
I am starting with the Delta-Q-Delta OCRemix project and am trying to convert the FLAC files to ALAC. They seem to be 24-bit/44.1K.
Quicktime and iTunes play the resultant ALAC files just fine locally. I noticed something was wrong when my Roku SoundBridge would not play them.
VLC will LOOK like it is playing them but nothing is coming out. It spouts tons of messages about errors with the frames in the file and when I look a the file info in VLC it claims that is a 16-bit audio file. Ordinarily I would suspect that this is a problem with VLC except there is the problem with the SoundBridge...

To try and get around this I tried exporting FLAC -> AIFF-16bit -> ALAC. It plays in everything but I lose the Tag info at the -> AIFF-16bit step...

oh, and I am using the 1381 svn build.