tool/mbed/mbed-sdk/libraries/tests/usb/device/audio/main.cpp

   1 // Playback example with the USBAUDIO library
   2
   3 #include "mbed.h"
   4 #include "USBAudio.h"
   5
   6 // frequency: 48 kHz
   7 #define FREQ_SPK 48000
   8 #define FREQ_MIC 48000
   9
  10 // 2channels: stereo
  11 #define NB_CHA_SPK 2
  12 #define NB_CHA_MIC 2
  13
  14 // length computed: each ms, we receive 48 * 16bits ->48 * 2 bytes. as there are two channels, the length will be 48 * 2 * 2
  15 #define LENGTH_AUDIO_PACKET_SPK (FREQ_SPK / 500) * NB_CHA_SPK
  16 #define LENGTH_AUDIO_PACKET_MIC (FREQ_MIC / 500) * NB_CHA_MIC
  17
  18 // USBAudio object
  19 USBAudio audio(FREQ_SPK, NB_CHA_SPK, FREQ_MIC, NB_CHA_MIC, 0xab45, 0x0378);
  20
  21 int main() {
  22     // buffer of int
  23     int buf_in[LENGTH_AUDIO_PACKET_SPK/sizeof(int)];
  24     int buf_out[LENGTH_AUDIO_PACKET_MIC/sizeof(int)];
  25     int * stream_out = buf_in;
  26     int * stream_in = buf_out;
  27     int * tmp = NULL;
  28
  29     while (1) {
  30         // read and write one audio packet each frame
  31         audio.readWrite((uint8_t *)stream_in, (uint8_t *)stream_out);
  32
  33         // swap the buffers
  34         tmp = stream_in;
  35         stream_in = stream_out;
  36         stream_out = tmp;
  37     }
  38 }
  39
  40