[M4IF Technotes] Re: Confirmance BitStreams

Tue Jul 1 20:41:31 EDT 2003

Apoorva Ankad wrote:
> Dear Mr.Ralph,
> 
> 	I am testing my MPEG4 AAC LC decoder. The standard tells that we
> have the test sequences from ftp.research.att.com .But, in that FTP
> there are only .mp4 files and no corresponding .wav files. So I checked
> the FTP 
>        ftp://[email protected]/mpeg4audio-conformance
> Here I got both .mp4 and the corresponding .wav files. I downloaded the
> Mp4 file al06_96.mp4 and its three corresponding Wave files
> al06_96_f00.wav, al06_96_f01.wav and al06_96_f02.wav. But, what I felt
> was, all the three .Wav files have a background noise. I used CoolEdit
> for opening and playing them. Can you kindly tell me, whether to use
> these files itself, as the references?  
> 
> Apoorva M. Ankad
> Scanned by SecureSynergy VirusScreen Service. 
> For more information log on to : http://www.securesynergyonline.com or http://www.securesynergy.com
> 

Dear Apoorva,
I hereby confirm that the files on 
ftp://[email protected]/mpeg4audio-conformance are the most recent 
conformance test sequences (both compressed and uncompressed representation). 
The files on ftp.research.att.com are outdated and shall not be used anymore.
The occurance of background noise or similar effects might be due to a badly 
tuned encoder or to a noisy input signal. However, this is irrelavant since it 
does not affect the decoder conformance testing.
Best regards,
Ralph
-- 
Dipl.-Ing. Ralph Sperschneider  | Phone: +49 9131 776 344
FhG IIS                         | Fax:   +49 9131 776 398
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