[Mp4-tech] Re: [audio] Regarding conformance testing of HE-AAC

[Ralph Sperschneider]

sakthi narayanan wrote:
> Hi,
>
>   Presently,Iam working in MPEG4 AAC-LC Decoder.I had the standard 
> bitstreams.Iam having small doubt in the profile.
>
> In Adts file,we will get the profile information from the header 
> itself.So,I come to know the bitstream is whether LC,Main or SSR.
> But,for raw how can we know whether the bitstream is LC,Main or SSR.
> Whether profile information is needed for the raw file format.So,how 
> can to differentiate the LC & main profile bitstreams in MPEG4 AAC for
> raw file format.
>
There is no such thing as a "raw file format", but only a 
raw_data_stream() is defined in the standard. When feeding such 
raw_data_stream() into any decoder, such decoder needs to be provided 
with the meta information like profile information and sampling rate 
from another source. It is the same problem when you store raw pcm data; 
any player needs to know the meta information like the number of 
channels, the number of bits per sample, the bit order and the kind of 
quantization.
>
> And also,where can i get Erroneous bitsream & required documents for 
> the error conformace test.
>
Which "error conformance test" do you refer to?
Best regards,
Ralph
-- 
Dipl.-Ing. Ralph Sperschneider  | Phone: +49 9131 776 344
Fraunhofer IIS                  | Fax:   +49 9131 776 398
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