AAC audio as an .aac file / in an .mp4 container

[SeeMoreDigital]

Strange...

I've just had a go at using dbpowerAMP (v10.1) with Nero's AAC (v1.1) plug-in.

It's really quite good, as it's able to generate AAC LC and HE streams at bitrates between 16-448kbps!

It will put AAC streams in an mp4 container and exports them as ISO 13818-7 AAC streams (.aac)

The weird thing is the .aac files are 1% larger than the .mp4 files!

Is this correct. I thought they would have been slightly smaller?

That said, MP4UI (v1.0) Beta 1 seems to like them.

Cheers

[KpeX]

Nope, seeing as how MP4 is AAC's native container, it actually gets smaller when you mux it into MP4; this is actually a sign it has been muxed correctly. If I recall correctly it has to do with ADTS headers being removed when muxing.

What you're doing is also possible with Besweet or Foobar2000.

[bond]

in contrary to adif headers, which are only stored at the beginning of the .aac files, the adts headers are stored throughout the whole file and can change from frame to frame
i guess thats why adts headers cause this overhead

when muxing into mp4 this header is stripped