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Chris Benoit
29th June 2005, 22:03
Is it possible to mux he-aac (m4a) audio into an avi container?
bond
29th June 2005, 22:11
yes with avimuxgui

:search:
Chris Benoit
29th June 2005, 22:22
No it doesn't support it!It supports .acc but not .m4a.I tried opening an .m4a but it displayed a dialogue where it says it's not supported.
bond
29th June 2005, 22:25
demux the aac stream from .m4a to .aac with mp4ui, mp4box, mp4creator or whatever tool you like
eb
29th June 2005, 22:27
rename to .aac
bond
29th June 2005, 22:29
rename to .aac
nonsense
Chris Benoit
29th June 2005, 22:31
right renaming doesn't wrong,it was the first thing i tried!

Ok i will demux tha aac stream as advised.thanx!
Chris Benoit
29th June 2005, 22:43
Ok i did it and it now opens in avimux gui but it recognizes it as 22050 LC but it's HE 44k,y'that?

http://briefcase.pathfinder.gr/download/therock69/35541/448067/0/untitled.JPG
bond
29th June 2005, 22:50
thats correct, there is a special sbr/he-aac switch you have to tick to tell avimuxgui that the stream is he-aac
SeeMoreDigital
29th June 2005, 23:17
thats correct, there is a special sbr/he-aac switch you have to tick to tell avimuxgui that the stream is he-aacYep... You get to the "SBR" option by right clicking over the audio file, like this: -

http://img87.echo.cx/img87/236/avimux5mc.png


Cheers
Chris Benoit
29th June 2005, 23:48
Ok that's coveres as for the frequency thing why is it recognized as 22k rather than 44?
SeeMoreDigital
29th June 2005, 23:52
Ok that's coveres as for the frequency thing why is it recognized as 22k rather than 44?Because an AAC-HE (SBR) stream uses exactly half the sample rate as a comparable AAC-LC stream.

Therefore if you have say a WAV source at 44.1kHz your AAC-HE stream will become 22.05kHz. Or if you have an AC3 source at 48kHz your AAC-HE stream will become 24kHz!


Cheers
Chris Benoit
30th June 2005, 01:33
no but the aac is already 44.It's in the picture i've posted above!

In foobar properties it's recognized as 44 in avi mux as 22.
celtic_druid
30th June 2005, 01:59
A he aac file will be 44 with the SBR part, but 22 if treated as a lc aac stream and therefor without the SBR part. When it is in a mp4 container it has a header telling it that it is he aac, as just a raw stream it is upto the decoder or in the case of AVIMuxGUI the user to specify.
Chris Benoit
30th June 2005, 02:11
so bottom line if i enable sbr and mux it it will remain 44?
KpeX
30th June 2005, 02:42
so bottom line if i enable sbr and mux it it will remain 44?
It's not 44 right now, it's 22 khz. As mentioned SBR audio stands for spectral band replication, not reproduction. With the SBR extension your audio will simulate 44 khz samplerate but you ultimately have 22 khz audio. If you have a problem with this, don't use HE, it's not intended for high quality audio.
Chris Benoit
30th June 2005, 04:19
What is it intended for then?I chose it for that reason!

I can't understand one thing.Is it the avi that doesn't support he-aac 22k?
celtic_druid
30th June 2005, 04:24
As already said, avi does support he-aac.
It is intended to give better quality at lower bitrates. For higher quality, you would use a higher bitrate and lc aac.

The point is that 24KHz+SBC @ 64k should give better quality than 48KHz @ 64k.
Chris Benoit
30th June 2005, 06:54
ok i get it,thanx a lot everyone.