Calculation error
Tim Dylla <[email protected]> Fri, 24 Aug 2007 12:16:12 +0200
| Newsgroups | gmane.comp.audio.mad.devel |
|---|---|
| Message-ID | <[email protected]> |
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