Max Brown / wave_player

Wave Player

Dependents:   Capacitive_Touch_Sensor_MP3_Player

Fork of wave_player by Steve Ravet

wave_player.cpp@2:87acbc2d0023, 2016-11-21 (annotated)

Committer:
maxmbrown
Date:
Mon Nov 21 21:13:54 2016 +0000
Revision:
2:87acbc2d0023
Parent:
0:62c18ade9a60 
First Draft

Who changed what in which revision?

UserRevisionLine numberNew contents of line
sravet 0:62c18ade9a60 1 //-----------------------------------------------------------------------------
sravet 0:62c18ade9a60 2 // a sample mbed library to play back wave files.
sravet 0:62c18ade9a60 3 //
sravet 0:62c18ade9a60 4 // explanation of wave file format.
sravet 0:62c18ade9a60 5 // https://ccrma.stanford.edu/courses/422/projects/WaveFormat/
sravet 0:62c18ade9a60 6
sravet 0:62c18ade9a60 7 // if VERBOSE is uncommented then the wave player will enter a verbose
sravet 0:62c18ade9a60 8 // mode that displays all data values as it reads them from the file
sravet 0:62c18ade9a60 9 // and writes them to the DAC. Very slow and unusable output on the DAC,
sravet 0:62c18ade9a60 10 // but useful for debugging wave files that don't work.
sravet 0:62c18ade9a60 11 //#define VERBOSE
sravet 0:62c18ade9a60 12
sravet 0:62c18ade9a60 13
sravet 0:62c18ade9a60 14 #include <mbed.h>
sravet 0:62c18ade9a60 15 #include <stdio.h>
sravet 0:62c18ade9a60 16 #include <wave_player.h>
maxmbrown 2:87acbc2d0023 17 int g_volume = 0;
sravet 0:62c18ade9a60 18 //-----------------------------------------------------------------------------
sravet 0:62c18ade9a60 19 // constructor -- accepts an mbed pin to use for AnalogOut. Only p18 will work
sravet 0:62c18ade9a60 20 wave_player::wave_player(AnalogOut *_dac)
sravet 0:62c18ade9a60 21 {
sravet 0:62c18ade9a60 22 wave_DAC=_dac;
sravet 0:62c18ade9a60 23 wave_DAC->write_u16(32768); //DAC is 0-3.3V, so idles at ~1.6V
sravet 0:62c18ade9a60 24 verbosity=0;
sravet 0:62c18ade9a60 25 }
sravet 0:62c18ade9a60 26
sravet 0:62c18ade9a60 27 //-----------------------------------------------------------------------------
sravet 0:62c18ade9a60 28 // if verbosity is set then wave player enters a mode where the wave file
sravet 0:62c18ade9a60 29 // is decoded and displayed to the screen, including sample values put into
sravet 0:62c18ade9a60 30 // the DAC FIFO, and values read out of the DAC FIFO by the ISR. The DAC output
sravet 0:62c18ade9a60 31 // itself is so slow as to be unusable, but this might be handy for debugging
sravet 0:62c18ade9a60 32 // wave files that don't play
sravet 0:62c18ade9a60 33 //-----------------------------------------------------------------------------
sravet 0:62c18ade9a60 34 void wave_player::set_verbosity(int v)
sravet 0:62c18ade9a60 35 {
sravet 0:62c18ade9a60 36 verbosity=v;
sravet 0:62c18ade9a60 37 }
sravet 0:62c18ade9a60 38
sravet 0:62c18ade9a60 39 //-----------------------------------------------------------------------------
sravet 0:62c18ade9a60 40 // player function. Takes a pointer to an opened wave file. The file needs
sravet 0:62c18ade9a60 41 // to be stored in a filesystem with enough bandwidth to feed the wave data.
sravet 0:62c18ade9a60 42 // LocalFileSystem isn't, but the SDcard is, at least for 22kHz files. The
sravet 0:62c18ade9a60 43 // SDcard filesystem can be hotrodded by increasing the SPI frequency it uses
sravet 0:62c18ade9a60 44 // internally.
sravet 0:62c18ade9a60 45 //-----------------------------------------------------------------------------
maxmbrown 2:87acbc2d0023 46 void wave_player::play(FILE *wavefile, int *startStop, int *volume)
sravet 0:62c18ade9a60 47 {
sravet 0:62c18ade9a60 48 unsigned chunk_id,chunk_size,channel;
sravet 0:62c18ade9a60 49 unsigned data,samp_int,i;
sravet 0:62c18ade9a60 50 short unsigned dac_data;
sravet 0:62c18ade9a60 51 long long slice_value;
sravet 0:62c18ade9a60 52 char *slice_buf;
sravet 0:62c18ade9a60 53 short *data_sptr;
sravet 0:62c18ade9a60 54 unsigned char *data_bptr;
sravet 0:62c18ade9a60 55 int *data_wptr;
sravet 0:62c18ade9a60 56 FMT_STRUCT wav_format;
sravet 0:62c18ade9a60 57 long slice,num_slices;
maxmbrown 2:87acbc2d0023 58
sravet 0:62c18ade9a60 59 DAC_wptr=0;
sravet 0:62c18ade9a60 60 DAC_rptr=0;
sravet 0:62c18ade9a60 61 for (i=0;i<256;i+=2) {
sravet 0:62c18ade9a60 62 DAC_fifo[i]=0;
sravet 0:62c18ade9a60 63 DAC_fifo[i+1]=3000;
sravet 0:62c18ade9a60 64 }
sravet 0:62c18ade9a60 65 DAC_wptr=4;
sravet 0:62c18ade9a60 66 DAC_on=0;
sravet 0:62c18ade9a60 67
sravet 0:62c18ade9a60 68 fread(&chunk_id,4,1,wavefile);
sravet 0:62c18ade9a60 69 fread(&chunk_size,4,1,wavefile);
sravet 0:62c18ade9a60 70 while (!feof(wavefile)) {
sravet 0:62c18ade9a60 71 if (verbosity)
sravet 0:62c18ade9a60 72 printf("Read chunk ID 0x%x, size 0x%x\n",chunk_id,chunk_size);
sravet 0:62c18ade9a60 73 switch (chunk_id) {
sravet 0:62c18ade9a60 74 case 0x46464952:
sravet 0:62c18ade9a60 75 fread(&data,4,1,wavefile);
sravet 0:62c18ade9a60 76 if (verbosity) {
sravet 0:62c18ade9a60 77 printf("RIFF chunk\n");
sravet 0:62c18ade9a60 78 printf(" chunk size %d (0x%x)\n",chunk_size,chunk_size);
sravet 0:62c18ade9a60 79 printf(" RIFF type 0x%x\n",data);
sravet 0:62c18ade9a60 80 }
sravet 0:62c18ade9a60 81 break;
sravet 0:62c18ade9a60 82 case 0x20746d66:
sravet 0:62c18ade9a60 83 fread(&wav_format,sizeof(wav_format),1,wavefile);
sravet 0:62c18ade9a60 84 if (verbosity) {
sravet 0:62c18ade9a60 85 printf("FORMAT chunk\n");
sravet 0:62c18ade9a60 86 printf(" chunk size %d (0x%x)\n",chunk_size,chunk_size);
sravet 0:62c18ade9a60 87 printf(" compression code %d\n",wav_format.comp_code);
sravet 0:62c18ade9a60 88 printf(" %d channels\n",wav_format.num_channels);
sravet 0:62c18ade9a60 89 printf(" %d samples/sec\n",wav_format.sample_rate);
sravet 0:62c18ade9a60 90 printf(" %d bytes/sec\n",wav_format.avg_Bps);
sravet 0:62c18ade9a60 91 printf(" block align %d\n",wav_format.block_align);
sravet 0:62c18ade9a60 92 printf(" %d bits per sample\n",wav_format.sig_bps);
sravet 0:62c18ade9a60 93 }
sravet 0:62c18ade9a60 94 if (chunk_size > sizeof(wav_format))
sravet 0:62c18ade9a60 95 fseek(wavefile,chunk_size-sizeof(wav_format),SEEK_CUR);
sravet 0:62c18ade9a60 96 break;
sravet 0:62c18ade9a60 97 case 0x61746164:
sravet 0:62c18ade9a60 98 // allocate a buffer big enough to hold a slice
sravet 0:62c18ade9a60 99 slice_buf=(char *)malloc(wav_format.block_align);
sravet 0:62c18ade9a60 100 if (!slice_buf) {
sravet 0:62c18ade9a60 101 printf("Unable to malloc slice buffer");
sravet 0:62c18ade9a60 102 exit(1);
sravet 0:62c18ade9a60 103 }
sravet 0:62c18ade9a60 104 num_slices=chunk_size/wav_format.block_align;
sravet 0:62c18ade9a60 105 samp_int=1000000/(wav_format.sample_rate);
sravet 0:62c18ade9a60 106 if (verbosity) {
sravet 0:62c18ade9a60 107 printf("DATA chunk\n");
sravet 0:62c18ade9a60 108 printf(" chunk size %d (0x%x)\n",chunk_size,chunk_size);
sravet 0:62c18ade9a60 109 printf(" %d slices\n",num_slices);
sravet 0:62c18ade9a60 110 printf(" Ideal sample interval=%d\n",(unsigned)(1000000.0/wav_format.sample_rate));
sravet 0:62c18ade9a60 111 printf(" programmed interrupt tick interval=%d\n",samp_int);
sravet 0:62c18ade9a60 112 }
sravet 0:62c18ade9a60 113
sravet 0:62c18ade9a60 114 // starting up ticker to write samples out -- no printfs until tick.detach is called
sravet 0:62c18ade9a60 115 if (verbosity)
sravet 0:62c18ade9a60 116 tick.attach_us(this,&wave_player::dac_out, 500000);
sravet 0:62c18ade9a60 117 else
sravet 0:62c18ade9a60 118 tick.attach_us(this,&wave_player::dac_out, samp_int);
sravet 0:62c18ade9a60 119 DAC_on=1;
sravet 0:62c18ade9a60 120
sravet 0:62c18ade9a60 121 // start reading slices, which contain one sample each for however many channels
sravet 0:62c18ade9a60 122 // are in the wave file. one channel=mono, two channels=stereo, etc. Since
sravet 0:62c18ade9a60 123 // mbed only has a single AnalogOut, all of the channels present are averaged
sravet 0:62c18ade9a60 124 // to produce a single sample value. This summing and averaging happens in
sravet 0:62c18ade9a60 125 // a variable of type signed long long, to make sure that the data doesn't
sravet 0:62c18ade9a60 126 // overflow regardless of sample size (8 bits, 16 bits, 32 bits).
sravet 0:62c18ade9a60 127 //
sravet 0:62c18ade9a60 128 // note that from what I can find that 8 bit wave files use unsigned data,
sravet 0:62c18ade9a60 129 // while 16 and 32 bit wave files use signed data
sravet 0:62c18ade9a60 130 //
sravet 0:62c18ade9a60 131 for (slice=0;slice<num_slices;slice+=1) {
sravet 0:62c18ade9a60 132 fread(slice_buf,wav_format.block_align,1,wavefile);
sravet 0:62c18ade9a60 133 if (feof(wavefile)) {
sravet 0:62c18ade9a60 134 printf("Oops -- not enough slices in the wave file\n");
sravet 0:62c18ade9a60 135 exit(1);
sravet 0:62c18ade9a60 136 }
maxmbrown 2:87acbc2d0023 137 //exit when user stops song
maxmbrown 2:87acbc2d0023 138 if (*startStop == 0){
maxmbrown 2:87acbc2d0023 139 break;
maxmbrown 2:87acbc2d0023 140 }
maxmbrown 2:87acbc2d0023 141 //pass volume to dac_out
maxmbrown 2:87acbc2d0023 142 g_volume = *volume;
maxmbrown 2:87acbc2d0023 143
sravet 0:62c18ade9a60 144 data_sptr=(short *)slice_buf; // 16 bit samples
sravet 0:62c18ade9a60 145 data_bptr=(unsigned char *)slice_buf; // 8 bit samples
sravet 0:62c18ade9a60 146 data_wptr=(int *)slice_buf; // 32 bit samples
sravet 0:62c18ade9a60 147 slice_value=0;
sravet 0:62c18ade9a60 148 for (channel=0;channel<wav_format.num_channels;channel++) {
sravet 0:62c18ade9a60 149 switch (wav_format.sig_bps) {
sravet 0:62c18ade9a60 150 case 16:
sravet 0:62c18ade9a60 151 if (verbosity)
sravet 0:62c18ade9a60 152 printf("16 bit channel %d data=%d ",channel,data_sptr[channel]);
sravet 0:62c18ade9a60 153 slice_value+=data_sptr[channel];
sravet 0:62c18ade9a60 154 break;
sravet 0:62c18ade9a60 155 case 32:
sravet 0:62c18ade9a60 156 if (verbosity)
sravet 0:62c18ade9a60 157 printf("32 bit channel %d data=%d ",channel,data_wptr[channel]);
sravet 0:62c18ade9a60 158 slice_value+=data_wptr[channel];
sravet 0:62c18ade9a60 159 break;
sravet 0:62c18ade9a60 160 case 8:
sravet 0:62c18ade9a60 161 if (verbosity)
sravet 0:62c18ade9a60 162 printf("8 bit channel %d data=%d ",channel,(int)data_bptr[channel]);
sravet 0:62c18ade9a60 163 slice_value+=data_bptr[channel];
sravet 0:62c18ade9a60 164 break;
sravet 0:62c18ade9a60 165 }
sravet 0:62c18ade9a60 166 }
sravet 0:62c18ade9a60 167 slice_value/=wav_format.num_channels;
sravet 0:62c18ade9a60 168
sravet 0:62c18ade9a60 169 // slice_value is now averaged. Next it needs to be scaled to an unsigned 16 bit value
sravet 0:62c18ade9a60 170 // with DC offset so it can be written to the DAC.
sravet 0:62c18ade9a60 171 switch (wav_format.sig_bps) {
sravet 0:62c18ade9a60 172 case 8: slice_value<<=8;
sravet 0:62c18ade9a60 173 break;
sravet 0:62c18ade9a60 174 case 16: slice_value+=32768;
sravet 0:62c18ade9a60 175 break;
sravet 0:62c18ade9a60 176 case 32: slice_value>>=16;
sravet 0:62c18ade9a60 177 slice_value+=32768;
sravet 0:62c18ade9a60 178 break;
sravet 0:62c18ade9a60 179 }
sravet 0:62c18ade9a60 180 dac_data=(short unsigned)slice_value;
sravet 0:62c18ade9a60 181 if (verbosity)
sravet 0:62c18ade9a60 182 printf("sample %d wptr %d slice_value %d dac_data %u\n",slice,DAC_wptr,(int)slice_value,dac_data);
sravet 0:62c18ade9a60 183 DAC_fifo[DAC_wptr]=dac_data;
sravet 0:62c18ade9a60 184 DAC_wptr=(DAC_wptr+1) & 0xff;
sravet 0:62c18ade9a60 185 while (DAC_wptr==DAC_rptr) {
sravet 0:62c18ade9a60 186 }
sravet 0:62c18ade9a60 187 }
sravet 0:62c18ade9a60 188 DAC_on=0;
sravet 0:62c18ade9a60 189 tick.detach();
sravet 0:62c18ade9a60 190 free(slice_buf);
sravet 0:62c18ade9a60 191 break;
sravet 0:62c18ade9a60 192 case 0x5453494c:
sravet 0:62c18ade9a60 193 if (verbosity)
sravet 0:62c18ade9a60 194 printf("INFO chunk, size %d\n",chunk_size);
sravet 0:62c18ade9a60 195 fseek(wavefile,chunk_size,SEEK_CUR);
sravet 0:62c18ade9a60 196 break;
sravet 0:62c18ade9a60 197 default:
sravet 0:62c18ade9a60 198 printf("unknown chunk type 0x%x, size %d\n",chunk_id,chunk_size);
sravet 0:62c18ade9a60 199 data=fseek(wavefile,chunk_size,SEEK_CUR);
sravet 0:62c18ade9a60 200 break;
sravet 0:62c18ade9a60 201 }
sravet 0:62c18ade9a60 202 fread(&chunk_id,4,1,wavefile);
sravet 0:62c18ade9a60 203 fread(&chunk_size,4,1,wavefile);
maxmbrown 2:87acbc2d0023 204
sravet 0:62c18ade9a60 205 }
sravet 0:62c18ade9a60 206 }
sravet 0:62c18ade9a60 207
sravet 0:62c18ade9a60 208
sravet 0:62c18ade9a60 209 void wave_player::dac_out()
sravet 0:62c18ade9a60 210 {
sravet 0:62c18ade9a60 211 if (DAC_on) {
sravet 0:62c18ade9a60 212 #ifdef VERBOSE
sravet 0:62c18ade9a60 213 printf("ISR rdptr %d got %u\n",DAC_rptr,DAC_fifo[DAC_rptr]);
sravet 0:62c18ade9a60 214 #endif
maxmbrown 2:87acbc2d0023 215
maxmbrown 2:87acbc2d0023 216 wave_DAC->write_u16((DAC_fifo[DAC_rptr]*(16 - g_volume))>>4);
sravet 0:62c18ade9a60 217 DAC_rptr=(DAC_rptr+1) & 0xff;
sravet 0:62c18ade9a60 218 }
sravet 0:62c18ade9a60 219 }
sravet 0:62c18ade9a60 220