[Mp4-tech] Encoding AAC stereo using the reference software (was: One query Sir,)

[Ralph Sperschneider]

sumit thatte wrote:
> 
> Hello Sir,
> Pls help me for one query. I want to test stereo on my version of AAC. I 
> tried all the things which are given it in the read me. I have attached 
> the readme with this mail.
> First ly I have changed the MP4_RAWAUDIOFILE to
> "integer16, 0, 48000.0, big-endian, 2, default"
> 
> and i tried
> 
> -r 96000 -lf -cp AL05_96000_f01.pcm -cpn 1 AL05_96000_f02.pcm -o test.aac
> 
> Can you please tell me ,
> 
> How to test streo for left , right and center.
> 
> Thanks and Regs
> 
> Sumit Thatte
> 

Dear Summit,
al05_96000_f01.pcm is a single channel (i.e. mono) file, output by the aac 
decoder. This is the left stereo channel encoded in al05_96000.aac.
There should be another file al05_96000_f02.pcm, which is the right stereo 
channel encoded in al05_96000.aac.
There is no center channel.
Up to my knowledge you cannot input several mono files into the encoder, but you 
need a stereo file. You e.g. can use CopyAudio to perform the multiplex.
Beside this, it should be possible to encode the file you tried, simply by 
treating it as a stereo file (its raw, so you can treat it as whatever you want, 
as long as you don´t rely on the audio output). If you want to treat the input 
file as having a sampling rate of 96000 Hz and being two channel stereo, you 
would have to specifiy MP4_RAWAUDIOFILE as follows: "integer16, 0, 96000.0, 
big-endian, 2, default".
You are furthermore using the wrong command line. So I have e.g. no idea about 
your intention to use the switches '-cp' and '-cpn', which all deal with 
coupling and at the same time not to specify the profile with e.g '-c "-lc"'. 
Why don´t you simply use the command line e-mailed before and just enter another 
input file, leading to something like:
enc AL_96000_f01.pcm -r 96000 -c "-lc" -o AL5_96000_f01.aac
where I was able to successfully decode the raw-aac output as follows:
aacdec_mc -s 96000 -Dn -p LC AL5_96000_f01.aac AL5_96000_f01.wav
BTW:
1. Is there no way to convice you not to use the outdated conformance data? If 
you prefer raw-pcm over wav-pcm (I don´t know about any advantage, but you 
might), you can convert the new (24 bit) wav-pcm data into raw-pcm data using 
CopyAudio.
2. In the future please send your requests to the mp4-tech reflector. I tend to 
not answering personal e-mails regarding those topics anymore.
3. Don´t send any files anymore which can someone download on its own (even no 
README files).
4. Please use subjects which identify your request.
Best regards,
Ralph
-- 
Dipl.-Ing. Ralph Sperschneider  | Phone: +49 9131 776 344
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