Skip to main content


Please be aware that much of the software linked to or mentioned on this forum is niche and therefore infrequently downloaded. Lots of anti-virus scanners and so-called malware detectors like to flag infrequently downloaded software as bad until it is either downloaded enough times, or its developer actually bothers with getting each individual release allow listed by every single AV vendor. You can do many people a great favor when encountering such a "problem" example by submitting them to your AV vendor for examination. For almost everything on this forum, it is a false positive.
Topic: qaac error with 7.1-channel ALAC/MP4 (Read 2216 times) previous topic - next topic
0 Members and 1 Guest are viewing this topic.

qaac error with 7.1-channel ALAC/MP4


I have an 7.1-channel audio file (ALAC/MP4) from ffmpeg (Lavf58.12.100) and want it to convert to the same but with Apple Encoder.

I use this command:
Code: [Select]
qaac64.exe --verbose -A audio2.m4a -o iTunes\audio2.m4a

qaac 2.67, CoreAudioToolbox

ERROR: Channel layout not supported

Unfortunately I get the error message above.

Here are the meta-information from audio2.m4a:
Code: [Select]
Complete name                            : C:\Users\Felix\Downloads\Lossless\Tools\qaac_2.67\x64\audio2.m4a
Format                                   : MPEG-4
Format profile                           : Apple audio with iTunes info
Codec ID                                 : M4A  (isom/iso2)
File size                                : 4.30 GiB
Duration                                 : 2 h 24 min
Overall bit rate mode                    : Variable
Overall bit rate                         : 4 263 kb/s
Writing application                      : Lavf58.12.100

ID                                       : 1
Format                                   : ALAC
Codec ID                                 : alac
Codec ID/Info                            : Apple Lossless Audio Codec
Duration                                 : 2 h 24 min
Duration_LastFrame                       : -74 ms
Bit rate mode                            : Variable
Bit rate                                 : 4 262 kb/s
Nominal bit rate                         : 9 216 kb/s
Channel(s)                               : 8 channels
Sampling rate                            : 48.0 kHz
Bit depth                                : 24 bits
Stream size                              : 4.30 GiB (100%)
Default                                  : Yes
Alternate group                          : 1

The format should be supported:
Code: [Select]
qaac64.exe --format

LC 48000Hz 7.1 (C Lc Rc L R Ls Rs LFE) -- 224,256,288,320,384,448,512,576,640,768,960

Afconvert (v2.0) on my Mac is doing fine:
Code: [Select]
afconvert -v -d 0 -f m4af audio2.m4a

  Input file     8 ch,  48000 Hz, 'alac' (0x00000003) from 24-bit source, 4096 frames/packet
  Output file    8 ch,  48000 Hz, 'alac' (0x00000003) from 24-bit source, 4096 frames/packet
Optimizing ./audio2-1.m4a... done
Output file: audio2-1.m4a, 416137760 frames

I thought qaac and afconvert are using the same encoder?

So I don't understand what I see.

Can you help me.

Best regards,

Re: qaac error with 7.1-channel ALAC/MP4

Reply #1
Fixed in 2.68:

This was due to:
  • ffmpeg doesn't write channel layout info in ALACSpecificConfig in MP4 file.
  • The spec doesn't specify channel layout when the info is absent
  • When channel layout is absent in the input file, qaac guesses some default channel layout, which is only relevant for WAV-like channel order.

(The following is what ALAC spec says: )
If the channel layout is absent from the cookie, then the following assumptions are made:
1 channel - mono
2 channels - stereo in left, right order
> 2 channels - no specific channel designation or role.

In v2.68, qaac picks up more appropriate channel layout for ALAC in MP4 when it is absent in the input.

Re: qaac error with 7.1-channel ALAC/MP4

Reply #2
Thank you, works like a charm :)

SimplePortal 1.0.0 RC1 © 2008-2021