avcodecmap: Increase max AAC channels to 16
FFmpeg's aacenc
supports up to 16 now, so let's enable this in our elements too.
8 channel output works perfectly fine, I tested 7.1 and 8.0 layouts.
16 channel encoding also works correctly, but codec-utils
can't yet parse its channel config, so level
won't be set in output caps. Needs GASpecificConfig parsing for that to work. Aside from that, also seems correct, I tested it with the AV_CH_LAYOUT_HEXADECAGONAL
layout (0x3137D37
channel mask in GStreamer).
Small fix regarding >16ch is also included, as a double-free would happen in that scenario, resulting in a crash and malloc complaining.