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Hello Alteraforum,
I am searching for help, with the libMAD, because it drives me mad. :) I am working on an easy example to decode a MP3-file from flash, decode it into sram and output the PCM from there. I have verified, that the output is working. So when I read an PCM (16bit, 44.1kHz) from the flash and output it, it plays nice. I then tried to write and read from sram, no problem. I then tried the same with a MP3 and libMAD. As codebase I tried to adept the minimad.c example, but I do not get it working and I even can't really determine where the error occurs. There is audio output, but just plain noise. Has someone here an easy example for the DE2-Family that he would share with me, where you decode an MP3 with libMAD and use the Wolfson to output the data? (please don't refer to the Neek-Example, because there they do so much more to output the id-tags and read the files, I have looked quite deep into that example already). I think my problem lies somewhere in the scale function or I get mixed up with the endians. Any example code would be really appreciated. Yours, Peter.Link Copied
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Ok, I got it running now. The problem was the output method of the minimad.c example. I have now written some new code for it, see below.
//j is a global variable, that i use to count the length of the pcm.
//I use it to output from the sram in another method
while (nsamples--) {
unsigned int sample;
//i am sure, that i only decode stereo, so I don't check nsamples == 2
unsigned int audioausgabe = 0;
//sample = scale(*left_ch++);
sample = (*left_ch++);
audioausgabe = sample&0xFFFF;
audioausgabe = audioausgabe << 16;
//sample = scale(*right_ch++);
sample = (*right_ch++);
audioausgabe = audioausgabe|(sample & 0xFFFF);
//write to sram the resulting 32bit word
IOWR(SRAM_BASE,j,audioausgabe);
j++;
}
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Could you provide me with the working project?
Jeff Goeders jeffrey.goeders (GMAIL)
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