Dmitriy Startsev wrote:
Hello, Grzegorz! You wrote to "MP3 Encoder" <[EMAIL PROTECTED]> on Tue, 01 Jun 2004 21:24:29 +0000:
GK> In the function 'compute_ffts()' there is a loop computing total energy GK> of 1024-point FFT. The loop is placed in line 305 and looks as follows:
GK> for (j=11; j < HBLKSIZE; j++) totalenergy += fftenergy[j];
GK> I'm wondering why 'j' (being a number of spectrum component) starts GK> from 11. It seems first 10 spectrum components are ignored for some GK> reason. Or it is just some typo and 'j' should start from 1?
It is not a bug but psychoacoustic model specifics. It was so in all lame versions, even in original ISO code some components are ignored.
It effects a highpass filter at about 200 Hz which doesn't surprise me too much since the energy at low frequencies can easily dominate the total energy but not the psychoacoustical sensitivity.
Bob --
"Things should be described as simply as possible, but no simpler."
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