Creating a 4 channel AAC file in Quicktime Pro

Using Quicktime Pro (v7.1.3), it is possible to export multi-channel audio (up to 5.1 surround sound) in AIFF and MOV formats.

I decoded a short 3-channel ambisonic file from ambisonicbootlegs.net by John Leonard to Quad (4.0-channel audio) using Bruce Wiggins’ Wigware Ambisonic Decoder (WAD) version 0.4 alpha (30-11-2006) running in AudioMulch v1.0.  WAD settings were: Use Spatial EQ: Yes-BothF; Low F Pattern: 1.33; High F Pattern: 1.15; Cut off F: 500 Hz; Layout: Quad; Distance Comp: None.

I then exported the resulting 4-channel WAV file (approx 37 MB in size) to a Quicktime MOV file containing only a 4-channel AAC encoded soundtrack.

The resultant file, Applause.mov is 8.2 MB (640 kbps total bitrate), encoded at the highest available settings (quadraphonic, best quality and constant bit rate of 160 kbps per channel at the original sample rate of 44.1 kHz).

UPDATE:
A new smaller 4-channel AAC test file is available, along with the 4ch wav file used to create it:
test4ch_1234.mov (96kbps per channel, 24.5 KB)
test4ch_1234.wav (246.4 KB)

The process to encode a 4-channel WAV to Quicktime Movie containing a 4-channel AAC sound track takes two easy steps, described below, with screenshots (click for full size):

  1. Open the 4-channel WAV and examine the sound track within the “movie properties”.  Ensure that each channel is correctly assigned to the desired speaker output channel.  (When you originally open the file it will probably show all channels assigned as mono, which will prevent the second step of exporting the multi-channel AAC file).


  2. Export the file (menu File>Export) as “Movie to Quicktime Movie”, select “Options” then in “Sound Settings”, select AAC format and other desired settings.