Indeed, it's possible to encode ALS stored in MP4 now, but there is no way of playing them. The Winamp ALS plugin that they released was crippled and didn't support the decoding of all of the features; also it does not read ALS in MP4.
However some semi good news. Haali's splitter seems relatively happy to parse the file already (the explorer extensions and tooltips etc. report the correct duration and samplerate), and seems to think it is an AAC file. Obviously the only thing missing is a directshow decoder, but I reckon that if we had a directshow decoder, these files would work fine with the combination of that decoder and Haali's MP4 splitter.
So if any devs out there are reading; there is some reference software available (which obviously has decoder components). Perhaps some kind soul cares to whip up a basic directshow decoder or library? Something that could be usable and a part of FFDShow would be awesome, but really just _something_ so that we can listen to the files in our favourite players would be nice ;p
Ah well, can only ask
