demux/remux AAC

[bassgoonist]

I demuxed the aac stream from an m4a, and I want to put it back into an m4a container. How can I mux it back up?

[patul]

MP4Box or MP4Mux

[bassgoonist]

So, I muxed it with mp4box and yamb, but now it lists a different bit rate...
I'm trying to ensure that no transcoding takes place, and that the quality is preserved, how can I be sure of this?

[Inspector.Gadget]

MP4box is not an AAC encoder. No transcoding took place.

[bassgoonist]

And I need to make the itunes m4a container...how do I do that...

[Inspector.Gadget]

Simply rename them.

[bassgoonist]

Yeah, that does seem to work. Gspot still knows the difference, but itunes and ipods don't. Thanks.

[magic144]

hi there - hope this is a good place to ask this one - I too have some burning questions about .aac, .m4a and iTunes interactions

if I use mp4box to mux .aac into an .m4a container (e.g. for use in iTunes), it seems I have to use something like this

mp4box -add source.aac:mpeg4 -sbr -ipod target.m4a

my questions about this are:
1) if the source.aac is only AAC-LC and not HE-AACv1/2, will the inclusion of the -sbr flag here screw anything up
2) how can I tell unambiguously whether the .aac source is or is not HE-AAC if mp4box says it would be unable to without the provision of this (-sbr) flag? - btw, MediaInfo seems to be able to report the difference.
3) is there any other reliable tool to achieve the same goal (.aac to .m4a with full iTunes compatibility)

thanks in advance!

m