[FFmpeg-soc] AAC integration

[Andreas Öman]

Mike Melanson wrote:

> Just curious, what have you done for testing and validation? Does it
> "pass" the conformance suite (to within reasonable PSNR)?

Just conducted some tests, on some streams it seems ok, on others
not. These are al00_48 to al05_48.

stddev:  0.70 PSNR:99.34 bytes:716800
stddev:  0.69 PSNR:99.43 bytes:786432
stddev:  0.69 PSNR:99.42 bytes:786432
stddev:  0.69 PSNR:99.43 bytes:786432
stddev: 19.86 PSNR:70.36 bytes:786432
stddev: 30.43 PSNR:66.65 bytes:1417216

So, there seem to be some kind of issue still lingering.
I've also discovered that it outputs the samples inverted.
This should be as well fixed I guess.

I've only tested the last one with FAAD (there seems to be
some kind of bug in faad/ffmpeg integrations making it always
output stereo, the first 5 streams are mono)

stddev:  0.70 PSNR:99.36 bytes:1417216

Apparently FAAD does the right thing.

OTOH, if I compare the output from FAAD and aac.c using an AAC
stream from iTunes (this is what i've been used previously),
it looks ok:

stddev:  0.05 PSNR:122.12 bytes:38842368

Probably, the reference streams is exercising some tool which is
not commonly used and where it might be some bug lurking.
I cannot tell any difference by just listening on the streams though.

Either way, I'll have a look at it and come back when I know
whats going on ..