[mad-dev] Calculation error

[Tim Dylla]

Hi List,

   I did some testing on my own implementation of mp3, and used MAD as 
reference.
Therefore I generated a sine-sweep from 0Hz to 22kHz ( as far as this is 
possible ;) ) at 0dBFS, and 48kHz Samplerate. Then I encoded it with 
Lame for a single Channel MPEG-1 Layer III Bitstream, 48kHz Samplerate, 
320kbps Bitrate. (I don't know the exact Lame-version and optionstring 
anymore, but I didn't use anything weird)
As expected, the resulting bitstream can be decoded without any obvious 
error with my Decoder and also with the dist10 decoder.
MAD in contrast introduces a perceivable error right on the first half 
wave of the sine sweep. I think, it's an overflow in the requantization 
or the IMDCT (when I remember right, the huffman decoder produces very 
high output at this moment).
I used MAD 0.15.2b in conjunction with MADFrontend on a 
32bit-Windoze-machine. The option string was -b24 -d

I'm not a friend of posting large files on a mailing list without any 
agreement with the moderator, so if someone is interested in the 
bitstream and the resulting raw file, pleas feel free to send me a message.

With regards,

	Tim Dylla