24-bit 176.4kHz m4a problem

[Talos2000]

I have a weird problem. If I ask dBpoweramp to inspect the ID tags of a 24-bit 176.4kHz Apple Lossless (.m4a) file created by another app it thinks the file is 16-bit 176.4kHz. If I then ask it to convert that file to flac, the resultant flac file is garbled.

On the other hand, if I take a 24-bit 176.4kHz flac file and ask dBpoweramp to convert it to Apple Lossless, I get a m4a file that plays fine in all apps and if I ask dBpoweramp to inspect its ID tags, they all say 24-bit.

Can anybody else replicate this?

[Spoon]

Re: 24-bit 176.4kHz m4a problem

I believe a program called MAX was creating invalid labelled Apple Lossless files (24 bit), was this program used?

[Talos2000]

Re: 24-bit 176.4kHz m4a problem

No it wasn't. It was Apple's CoreAudio.

[Spoon]

Re: 24-bit 176.4kHz m4a problem

Send the file over please:

http://www.dbpoweramp.com/email.htm

[Talos2000]

Re: 24-bit 176.4kHz m4a problem

OK. I just sent the e-mail.

[Spoon]

Re: 24-bit 176.4kHz m4a problem

Thank you I have it...looking

          stsd: Atom Size: 88  Version: 0  Flag 0: 0  Flag 1: 0  Flag 2: 0  NumEntries: 1
              entry 0:  SampleDescriptionSize: 72  DataReferenceIndex: 1  DataFormat: alac:  Version: 0  Revision: 0  Vendor:   Channels: 2  Bits: 16  CompressionID:   PacketSize: 0  SampleRate: 44100
                 alac entry 0  SubSize: 36  SubType: alac  SubVersion: 0  SubFlag 0: 0  SubFlag 1: 0  SubFlag 2: 0  SubSampleDuration: 4096  SubBits: 24  Sub_a: 10250  Sub_b: 14  Sub_Channels: 2  Sub_c: 255  SubMaxSampleSize: 14015  SubBitRate: 4322368  SubRate: 176400

The issue is in the file, it is signalled as both 16 bit and 24 bit, other software must use the 2nd entry, we shall swap over to ensure compatibility, the R15 beta will update with this fix.

[Spoon]

Re: 24-bit 176.4kHz m4a problem

R15 updated with fix.

[Talos2000]

Re: 24-bit 176.4kHz m4a problem

Great news - Thanks