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copied!<p>I'm a java-guy in heart, but this task (especially on a cpu constrained device, like a handheld) is crying for C. I would suggest simply using the libsamplerate. It has a simple API, and even if you're new to C you'll find plenty of examples by just googling around.</p> <p><em>of course the java based solution could and would work, it just doesn't seem polite to the users to eat up their batteries just because your new to C :)</em></p> <p>EDIT: I might contradict myself a bit, but even though performance is a serious issue, I would avoid doing <em>anything</em> in kernel-space, unless I know the kernel and the hardware <strong>really</strong> well. In light of this I would go with a user-space program linked to libsamplerate. After a bit of googling around I've found this example (<em>note that the output is the jack interface, obviously it has to be different for you</em>)</p> <pre><code>#include <jack/jack.h> #include <samplerate.h> int channels; float data_samplerate; ///////////////////////////////////////////////////// ///////////////////////////////////////////////////// void getDasData(float **dst,int num_frames){ /* Provide sound data here, and only here. */ } ///////////////////////////////////////////////////// ///////////////////////////////////////////////////// long getDasResampledData_callback(void *cb_data, float **data){ static float ret[1024]; static float ret3[1024]; static float *ret2[2]={&ret[0],&ret[512]}; getDasData(ret2,512); for(int i=0;i<512;i++){ ret3[i*2]=ret2[0][i]; ret3[i*2+1]=ret2[1][i]; } *data=&ret3[0]; return 512; } void getDasResampledData(float **dst,int num_frames){ double ratio=samplerate/getSourceRate(); float outsound[num_frames*2]; long read=src_callback_read(dassrc_state,ratio,num_frames,outsound); //fprintf(stderr,"read: %d, num_frames: %d\n",read,num_frames); for(int i=0;i<read;i++){ dst[0][i]=outsound[i*2]; dst[1][i]=outsound[i*2+1]; } if(read<num_frames){ float *newdst[2]={dst[0]+read,dst[1]+read}; getDasResampledData(newdst,num_frames-read); } } static int process (jack_nframes_t nframes, void *arg){ int ch; sample_t *out[channels]; for(ch=0;ch<channels;ch++){ out[ch]=(sample_t*)jack_port_get_buffer(ports[ch],nframes); } if( (fabs(data_samplerate - jack_samplerate)) > 0.1) getDasResampledData(out,numSamples); else getDasData(outputChannelData,numSamples); return; audioCallback(NULL,0,out,channels,nframes); } int main(){ dassrc_state=src_callback_new(getDasResampledData_callback,SRC_QUALITY,2,NULL,NULL); jack_set_process_callback(client, process,NULL); } </code></pre> <blockquote> <p>from <a href="http://old.nabble.com/Example-of-using-libresample-with-jack-td8795847.html" rel="nofollow">http://old.nabble.com/Example-of-using-libresample-with-jack-td8795847.html</a></p> </blockquote> <p>This example seems pretty straightforward, I hope you can use it.</p>

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