Philips Philips
This is early stages of my project, the idea of this project is to be able to mix a guitar with windows sounds in reverse such as instrumental background music or trance music perhaps or maybe another fellow guitarist you may have downloaded from the internet. Microphone or guitar pin is p19 I would use a microphone for drums:) and that it for the moment, the code makes the mbed act as usb speaker that excepts a guitar or microphone input, but with a twist it all in reverse like a guitar reverse effects pedal but only you can mix anything you can get from the internet or any windows sound.
main.cpp@0:7610d342c76e, 2012-01-08 (annotated)
- Committer:
- mbed2f
- Date:
- Sun Jan 08 17:28:24 2012 +0000
- Revision:
- 0:7610d342c76e
Who changed what in which revision?
| User | Revision | Line number | New contents of line |
|---|---|---|---|
| mbed2f | 0:7610d342c76e | 1 | // Hello World example for the USBMIDI library (circular buffer) |
| mbed2f | 0:7610d342c76e | 2 | |
| mbed2f | 0:7610d342c76e | 3 | #include "mbed.h" |
| mbed2f | 0:7610d342c76e | 4 | #include "USBAudio.h" |
| mbed2f | 0:7610d342c76e | 5 | #include "CircBuffer.h" |
| mbed2f | 0:7610d342c76e | 6 | |
| mbed2f | 0:7610d342c76e | 7 | Serial pc(USBTX, USBRX); |
| mbed2f | 0:7610d342c76e | 8 | |
| mbed2f | 0:7610d342c76e | 9 | // frequency: 48 kHz |
| mbed2f | 0:7610d342c76e | 10 | #define FREQ 32000 |
| mbed2f | 0:7610d342c76e | 11 | |
| mbed2f | 0:7610d342c76e | 12 | // 1 channel: mono |
| mbed2f | 0:7610d342c76e | 13 | #define NB_CHA 1 |
| mbed2f | 0:7610d342c76e | 14 | |
| mbed2f | 0:7610d342c76e | 15 | // length computed: each ms, we receive 48 * 16bits ->48 * 2 bytes. as there is one channel, the length will be 48 * 2 * 1 |
| mbed2f | 0:7610d342c76e | 16 | #define LENGTH_AUDIO_PACKET 32 * 2 * 1 |
| mbed2f | 0:7610d342c76e | 17 | |
| mbed2f | 0:7610d342c76e | 18 | #define USR_POWERDOWN (0x104) |
| mbed2f | 0:7610d342c76e | 19 | |
| mbed2f | 0:7610d342c76e | 20 | int semihost_powerdown() { |
| mbed2f | 0:7610d342c76e | 21 | uint32_t arg; |
| mbed2f | 0:7610d342c76e | 22 | return __semihost(USR_POWERDOWN, &arg); |
| mbed2f | 0:7610d342c76e | 23 | } |
| mbed2f | 0:7610d342c76e | 24 | |
| mbed2f | 0:7610d342c76e | 25 | |
| mbed2f | 0:7610d342c76e | 26 | // USBAudio |
| mbed2f | 0:7610d342c76e | 27 | USBAudio USBaudio(FREQ, NB_CHA, 0x7186, 0x7507); |
| mbed2f | 0:7610d342c76e | 28 | |
| mbed2f | 0:7610d342c76e | 29 | // speaker connected to the AnalogOut output. The audio stream received over USb will be sent to the speaker |
| mbed2f | 0:7610d342c76e | 30 | AnalogOut speaker(p18); |
| mbed2f | 0:7610d342c76e | 31 | |
| mbed2f | 0:7610d342c76e | 32 | AnalogIn mic(p19); |
| mbed2f | 0:7610d342c76e | 33 | |
| mbed2f | 0:7610d342c76e | 34 | // ticker to send data to the speaker at the good frequency |
| mbed2f | 0:7610d342c76e | 35 | Ticker tic; |
| mbed2f | 0:7610d342c76e | 36 | |
| mbed2f | 0:7610d342c76e | 37 | // circular buffer where will be stored data to be sent to the speaker |
| mbed2f | 0:7610d342c76e | 38 | CircBuffer<int16_t> cbuf(LENGTH_AUDIO_PACKET); |
| mbed2f | 0:7610d342c76e | 39 | |
| mbed2f | 0:7610d342c76e | 40 | // previous value sent to the speaker |
| mbed2f | 0:7610d342c76e | 41 | uint16_t p_val = 0; |
| mbed2f | 0:7610d342c76e | 42 | |
| mbed2f | 0:7610d342c76e | 43 | // function executed each 1/FREQ s |
| mbed2f | 0:7610d342c76e | 44 | void tic_handler() { |
| mbed2f | 0:7610d342c76e | 45 | int16_t val; |
| mbed2f | 0:7610d342c76e | 46 | float speaker_value; |
| mbed2f | 0:7610d342c76e | 47 | unsigned short PlaySample; |
| mbed2f | 0:7610d342c76e | 48 | |
| mbed2f | 0:7610d342c76e | 49 | |
| mbed2f | 0:7610d342c76e | 50 | if (cbuf.available() >= 1) { |
| mbed2f | 0:7610d342c76e | 51 | cbuf.dequeue(&val); |
| mbed2f | 0:7610d342c76e | 52 | speaker_value = (float)val; |
| mbed2f | 0:7610d342c76e | 53 | |
| mbed2f | 0:7610d342c76e | 54 | // speaker_value between 0 and 65535 |
| mbed2f | 0:7610d342c76e | 55 | speaker_value += 32768.0; |
| mbed2f | 0:7610d342c76e | 56 | |
| mbed2f | 0:7610d342c76e | 57 | // adjust according to current volume |
| mbed2f | 0:7610d342c76e | 58 | speaker_value *= USBaudio.getVolume(); |
| mbed2f | 0:7610d342c76e | 59 | } else { |
| mbed2f | 0:7610d342c76e | 60 | speaker_value = p_val; |
| mbed2f | 0:7610d342c76e | 61 | } |
| mbed2f | 0:7610d342c76e | 62 | p_val = speaker_value; |
| mbed2f | 0:7610d342c76e | 63 | |
| mbed2f | 0:7610d342c76e | 64 | /* ADAMGR: Inserting my May 30th reversing code here!!! */ |
| mbed2f | 0:7610d342c76e | 65 | { |
| mbed2f | 0:7610d342c76e | 66 | static const unsigned int BufferSize = 20 * 640; |
| mbed2f | 0:7610d342c76e | 67 | static unsigned short Buffer[BufferSize]; |
| mbed2f | 0:7610d342c76e | 68 | |
| mbed2f | 0:7610d342c76e | 69 | static int Index = 0; |
| mbed2f | 0:7610d342c76e | 70 | static int Direction = 1; |
| mbed2f | 0:7610d342c76e | 71 | static int Playback = false; |
| mbed2f | 0:7610d342c76e | 72 | static int ChunkSize = BufferSize; |
| mbed2f | 0:7610d342c76e | 73 | |
| mbed2f | 0:7610d342c76e | 74 | unsigned short ReadSample; |
| mbed2f | 0:7610d342c76e | 75 | |
| mbed2f | 0:7610d342c76e | 76 | /* Default PlaySample to the current sample from USB buffer. */ |
| mbed2f | 0:7610d342c76e | 77 | PlaySample = speaker_value; |
| mbed2f | 0:7610d342c76e | 78 | |
| mbed2f | 0:7610d342c76e | 79 | |
| mbed2f | 0:7610d342c76e | 80 | |
| mbed2f | 0:7610d342c76e | 81 | /* Read out the sample from the buffer to be played back */ |
| mbed2f | 0:7610d342c76e | 82 | if (Playback) |
| mbed2f | 0:7610d342c76e | 83 | { |
| mbed2f | 0:7610d342c76e | 84 | PlaySample = Buffer[Index]; |
| mbed2f | 0:7610d342c76e | 85 | } |
| mbed2f | 0:7610d342c76e | 86 | |
| mbed2f | 0:7610d342c76e | 87 | /* Obtain current audio sample from the USB buffer. */ |
| mbed2f | 0:7610d342c76e | 88 | ReadSample = (unsigned short)speaker_value; |
| mbed2f | 0:7610d342c76e | 89 | |
| mbed2f | 0:7610d342c76e | 90 | /* Record the sample into the buffer right where a space was freed up from the PlaySample read above */ |
| mbed2f | 0:7610d342c76e | 91 | Buffer[Index] = ReadSample += mic.read_u16(); |
| mbed2f | 0:7610d342c76e | 92 | |
| mbed2f | 0:7610d342c76e | 93 | /* Increment the buffer pointer */ |
| mbed2f | 0:7610d342c76e | 94 | Index += Direction; |
| mbed2f | 0:7610d342c76e | 95 | |
| mbed2f | 0:7610d342c76e | 96 | /* Check to see if the chunk has been filled */ |
| mbed2f | 0:7610d342c76e | 97 | if (Index < 0) |
| mbed2f | 0:7610d342c76e | 98 | { |
| mbed2f | 0:7610d342c76e | 99 | /* Now have a chunk to be played back */ |
| mbed2f | 0:7610d342c76e | 100 | Playback = true; |
| mbed2f | 0:7610d342c76e | 101 | /* Reverse the direction of playback and recording */ |
| mbed2f | 0:7610d342c76e | 102 | Direction *= -1;//Direction; |
| mbed2f | 0:7610d342c76e | 103 | Index = 0; |
| mbed2f | 0:7610d342c76e | 104 | } |
| mbed2f | 0:7610d342c76e | 105 | else if (Index >= ChunkSize) |
| mbed2f | 0:7610d342c76e | 106 | |
| mbed2f | 0:7610d342c76e | 107 | |
| mbed2f | 0:7610d342c76e | 108 | |
| mbed2f | 0:7610d342c76e | 109 | { |
| mbed2f | 0:7610d342c76e | 110 | /* Now have a chunk to be played back */ |
| mbed2f | 0:7610d342c76e | 111 | Playback = true; |
| mbed2f | 0:7610d342c76e | 112 | /* Reverse the direction of playback and recording */ |
| mbed2f | 0:7610d342c76e | 113 | Direction *= -1;//Direction; |
| mbed2f | 0:7610d342c76e | 114 | Index = ChunkSize - 1; |
| mbed2f | 0:7610d342c76e | 115 | } |
| mbed2f | 0:7610d342c76e | 116 | } |
| mbed2f | 0:7610d342c76e | 117 | |
| mbed2f | 0:7610d342c76e | 118 | |
| mbed2f | 0:7610d342c76e | 119 | // send value to the speaker |
| mbed2f | 0:7610d342c76e | 120 | speaker.write_u16((uint16_t)PlaySample); |
| mbed2f | 0:7610d342c76e | 121 | } |
| mbed2f | 0:7610d342c76e | 122 | |
| mbed2f | 0:7610d342c76e | 123 | int main() { |
| mbed2f | 0:7610d342c76e | 124 | int16_t buf[LENGTH_AUDIO_PACKET/2]; |
| mbed2f | 0:7610d342c76e | 125 | |
| mbed2f | 0:7610d342c76e | 126 | semihost_powerdown(); |
| mbed2f | 0:7610d342c76e | 127 | |
| mbed2f | 0:7610d342c76e | 128 | // attach a function executed each 1/FREQ s |
| mbed2f | 0:7610d342c76e | 129 | tic.attach_us(tic_handler, 1000000.0/(float)FREQ); |
| mbed2f | 0:7610d342c76e | 130 | |
| mbed2f | 0:7610d342c76e | 131 | while (1) { |
| mbed2f | 0:7610d342c76e | 132 | // read an audio packet |
| mbed2f | 0:7610d342c76e | 133 | USBaudio.read((uint8_t *)buf); |
| mbed2f | 0:7610d342c76e | 134 | |
| mbed2f | 0:7610d342c76e | 135 | // put buffer in the circ buffer |
| mbed2f | 0:7610d342c76e | 136 | for(int i = 0; i < LENGTH_AUDIO_PACKET/2; i++) { |
| mbed2f | 0:7610d342c76e | 137 | cbuf.queue(buf[i]); |
| mbed2f | 0:7610d342c76e | 138 | } |
| mbed2f | 0:7610d342c76e | 139 | } |
| mbed2f | 0:7610d342c76e | 140 | } |