Kevin Lee / wave_player

s

Fork of wave_player by Steve Ravet

wave_player.cpp@2:44a41c9ff2d4, 2016-05-02 (annotated)

Committer:
kthlee
Date:
Mon May 02 08:00:12 2016 +0000
Revision:
2:44a41c9ff2d4
Parent:
0:62c18ade9a60 
changes;

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/
kthlee 2:44a41c9ff2d4 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
kthlee 2:44a41c9ff2d4 12
kthlee 2:44a41c9ff2d4 13
sravet 0:62c18ade9a60 14 #include <mbed.h>
sravet 0:62c18ade9a60 15 #include <stdio.h>
sravet 0:62c18ade9a60 16 #include <wave_player.h>
kthlee 2:44a41c9ff2d4 17
kthlee 2:44a41c9ff2d4 18
sravet 0:62c18ade9a60 19 //-----------------------------------------------------------------------------
sravet 0:62c18ade9a60 20 // constructor -- accepts an mbed pin to use for AnalogOut. Only p18 will work
kthlee 2:44a41c9ff2d4 21 wave_player::wave_player(AnalogOut *_dac, PwmOut *_pwm)
kthlee 2:44a41c9ff2d4 22 {
kthlee 2:44a41c9ff2d4 23
kthlee 2:44a41c9ff2d4 24
kthlee 2:44a41c9ff2d4 25 wave_PWM= _pwm;
sravet 0:62c18ade9a60 26 wave_DAC=_dac;
sravet 0:62c18ade9a60 27 wave_DAC->write_u16(32768); //DAC is 0-3.3V, so idles at ~1.6V
kthlee 2:44a41c9ff2d4 28 *wave_PWM=32768;
sravet 0:62c18ade9a60 29 verbosity=0;
sravet 0:62c18ade9a60 30 }
kthlee 2:44a41c9ff2d4 31
sravet 0:62c18ade9a60 32 //-----------------------------------------------------------------------------
sravet 0:62c18ade9a60 33 // if verbosity is set then wave player enters a mode where the wave file
sravet 0:62c18ade9a60 34 // is decoded and displayed to the screen, including sample values put into
sravet 0:62c18ade9a60 35 // the DAC FIFO, and values read out of the DAC FIFO by the ISR. The DAC output
sravet 0:62c18ade9a60 36 // itself is so slow as to be unusable, but this might be handy for debugging
sravet 0:62c18ade9a60 37 // wave files that don't play
sravet 0:62c18ade9a60 38 //-----------------------------------------------------------------------------
sravet 0:62c18ade9a60 39 void wave_player::set_verbosity(int v)
sravet 0:62c18ade9a60 40 {
sravet 0:62c18ade9a60 41 verbosity=v;
sravet 0:62c18ade9a60 42 }
kthlee 2:44a41c9ff2d4 43
sravet 0:62c18ade9a60 44 //-----------------------------------------------------------------------------
sravet 0:62c18ade9a60 45 // player function. Takes a pointer to an opened wave file. The file needs
sravet 0:62c18ade9a60 46 // to be stored in a filesystem with enough bandwidth to feed the wave data.
sravet 0:62c18ade9a60 47 // LocalFileSystem isn't, but the SDcard is, at least for 22kHz files. The
sravet 0:62c18ade9a60 48 // SDcard filesystem can be hotrodded by increasing the SPI frequency it uses
sravet 0:62c18ade9a60 49 // internally.
sravet 0:62c18ade9a60 50 //-----------------------------------------------------------------------------
sravet 0:62c18ade9a60 51 void wave_player::play(FILE *wavefile)
sravet 0:62c18ade9a60 52 {
kthlee 2:44a41c9ff2d4 53 extern float volume_change;
kthlee 2:44a41c9ff2d4 54 extern bool playing;
sravet 0:62c18ade9a60 55 unsigned chunk_id,chunk_size,channel;
sravet 0:62c18ade9a60 56 unsigned data,samp_int,i;
sravet 0:62c18ade9a60 57 short unsigned dac_data;
sravet 0:62c18ade9a60 58 long long slice_value;
sravet 0:62c18ade9a60 59 char *slice_buf;
sravet 0:62c18ade9a60 60 short *data_sptr;
sravet 0:62c18ade9a60 61 unsigned char *data_bptr;
sravet 0:62c18ade9a60 62 int *data_wptr;
sravet 0:62c18ade9a60 63 FMT_STRUCT wav_format;
sravet 0:62c18ade9a60 64 long slice,num_slices;
sravet 0:62c18ade9a60 65 DAC_wptr=0;
sravet 0:62c18ade9a60 66 DAC_rptr=0;
sravet 0:62c18ade9a60 67 for (i=0;i<256;i+=2) {
sravet 0:62c18ade9a60 68 DAC_fifo[i]=0;
sravet 0:62c18ade9a60 69 DAC_fifo[i+1]=3000;
sravet 0:62c18ade9a60 70 }
sravet 0:62c18ade9a60 71 DAC_wptr=4;
sravet 0:62c18ade9a60 72 DAC_on=0;
kthlee 2:44a41c9ff2d4 73
sravet 0:62c18ade9a60 74 fread(&chunk_id,4,1,wavefile);
sravet 0:62c18ade9a60 75 fread(&chunk_size,4,1,wavefile);
sravet 0:62c18ade9a60 76 while (!feof(wavefile)) {
sravet 0:62c18ade9a60 77 if (verbosity)
sravet 0:62c18ade9a60 78 printf("Read chunk ID 0x%x, size 0x%x\n",chunk_id,chunk_size);
sravet 0:62c18ade9a60 79 switch (chunk_id) {
sravet 0:62c18ade9a60 80 case 0x46464952:
sravet 0:62c18ade9a60 81 fread(&data,4,1,wavefile);
sravet 0:62c18ade9a60 82 if (verbosity) {
sravet 0:62c18ade9a60 83 printf("RIFF chunk\n");
sravet 0:62c18ade9a60 84 printf(" chunk size %d (0x%x)\n",chunk_size,chunk_size);
sravet 0:62c18ade9a60 85 printf(" RIFF type 0x%x\n",data);
sravet 0:62c18ade9a60 86 }
sravet 0:62c18ade9a60 87 break;
sravet 0:62c18ade9a60 88 case 0x20746d66:
sravet 0:62c18ade9a60 89 fread(&wav_format,sizeof(wav_format),1,wavefile);
sravet 0:62c18ade9a60 90 if (verbosity) {
sravet 0:62c18ade9a60 91 printf("FORMAT chunk\n");
sravet 0:62c18ade9a60 92 printf(" chunk size %d (0x%x)\n",chunk_size,chunk_size);
sravet 0:62c18ade9a60 93 printf(" compression code %d\n",wav_format.comp_code);
sravet 0:62c18ade9a60 94 printf(" %d channels\n",wav_format.num_channels);
sravet 0:62c18ade9a60 95 printf(" %d samples/sec\n",wav_format.sample_rate);
sravet 0:62c18ade9a60 96 printf(" %d bytes/sec\n",wav_format.avg_Bps);
sravet 0:62c18ade9a60 97 printf(" block align %d\n",wav_format.block_align);
sravet 0:62c18ade9a60 98 printf(" %d bits per sample\n",wav_format.sig_bps);
sravet 0:62c18ade9a60 99 }
sravet 0:62c18ade9a60 100 if (chunk_size > sizeof(wav_format))
sravet 0:62c18ade9a60 101 fseek(wavefile,chunk_size-sizeof(wav_format),SEEK_CUR);
sravet 0:62c18ade9a60 102 break;
sravet 0:62c18ade9a60 103 case 0x61746164:
sravet 0:62c18ade9a60 104 // allocate a buffer big enough to hold a slice
sravet 0:62c18ade9a60 105 slice_buf=(char *)malloc(wav_format.block_align);
sravet 0:62c18ade9a60 106 if (!slice_buf) {
sravet 0:62c18ade9a60 107 printf("Unable to malloc slice buffer");
sravet 0:62c18ade9a60 108 exit(1);
sravet 0:62c18ade9a60 109 }
sravet 0:62c18ade9a60 110 num_slices=chunk_size/wav_format.block_align;
sravet 0:62c18ade9a60 111 samp_int=1000000/(wav_format.sample_rate);
sravet 0:62c18ade9a60 112 if (verbosity) {
sravet 0:62c18ade9a60 113 printf("DATA chunk\n");
sravet 0:62c18ade9a60 114 printf(" chunk size %d (0x%x)\n",chunk_size,chunk_size);
sravet 0:62c18ade9a60 115 printf(" %d slices\n",num_slices);
sravet 0:62c18ade9a60 116 printf(" Ideal sample interval=%d\n",(unsigned)(1000000.0/wav_format.sample_rate));
sravet 0:62c18ade9a60 117 printf(" programmed interrupt tick interval=%d\n",samp_int);
sravet 0:62c18ade9a60 118 }
kthlee 2:44a41c9ff2d4 119
sravet 0:62c18ade9a60 120 // starting up ticker to write samples out -- no printfs until tick.detach is called
sravet 0:62c18ade9a60 121 if (verbosity)
sravet 0:62c18ade9a60 122 tick.attach_us(this,&wave_player::dac_out, 500000);
sravet 0:62c18ade9a60 123 else
sravet 0:62c18ade9a60 124 tick.attach_us(this,&wave_player::dac_out, samp_int);
sravet 0:62c18ade9a60 125 DAC_on=1;
kthlee 2:44a41c9ff2d4 126
sravet 0:62c18ade9a60 127 // start reading slices, which contain one sample each for however many channels
sravet 0:62c18ade9a60 128 // are in the wave file. one channel=mono, two channels=stereo, etc. Since
sravet 0:62c18ade9a60 129 // mbed only has a single AnalogOut, all of the channels present are averaged
sravet 0:62c18ade9a60 130 // to produce a single sample value. This summing and averaging happens in
sravet 0:62c18ade9a60 131 // a variable of type signed long long, to make sure that the data doesn't
sravet 0:62c18ade9a60 132 // overflow regardless of sample size (8 bits, 16 bits, 32 bits).
sravet 0:62c18ade9a60 133 //
sravet 0:62c18ade9a60 134 // note that from what I can find that 8 bit wave files use unsigned data,
sravet 0:62c18ade9a60 135 // while 16 and 32 bit wave files use signed data
sravet 0:62c18ade9a60 136 //
sravet 0:62c18ade9a60 137 for (slice=0;slice<num_slices;slice+=1) {
kthlee 2:44a41c9ff2d4 138 if (playing == false){
kthlee 2:44a41c9ff2d4 139 break;
kthlee 2:44a41c9ff2d4 140 }
sravet 0:62c18ade9a60 141 fread(slice_buf,wav_format.block_align,1,wavefile);
sravet 0:62c18ade9a60 142 if (feof(wavefile)) {
sravet 0:62c18ade9a60 143 printf("Oops -- not enough slices in the wave file\n");
sravet 0:62c18ade9a60 144 exit(1);
sravet 0:62c18ade9a60 145 }
sravet 0:62c18ade9a60 146 data_sptr=(short *)slice_buf; // 16 bit samples
sravet 0:62c18ade9a60 147 data_bptr=(unsigned char *)slice_buf; // 8 bit samples
sravet 0:62c18ade9a60 148 data_wptr=(int *)slice_buf; // 32 bit samples
sravet 0:62c18ade9a60 149 slice_value=0;
sravet 0:62c18ade9a60 150 for (channel=0;channel<wav_format.num_channels;channel++) {
sravet 0:62c18ade9a60 151 switch (wav_format.sig_bps) {
sravet 0:62c18ade9a60 152 case 16:
sravet 0:62c18ade9a60 153 if (verbosity)
sravet 0:62c18ade9a60 154 printf("16 bit channel %d data=%d ",channel,data_sptr[channel]);
sravet 0:62c18ade9a60 155 slice_value+=data_sptr[channel];
sravet 0:62c18ade9a60 156 break;
sravet 0:62c18ade9a60 157 case 32:
sravet 0:62c18ade9a60 158 if (verbosity)
sravet 0:62c18ade9a60 159 printf("32 bit channel %d data=%d ",channel,data_wptr[channel]);
sravet 0:62c18ade9a60 160 slice_value+=data_wptr[channel];
sravet 0:62c18ade9a60 161 break;
sravet 0:62c18ade9a60 162 case 8:
sravet 0:62c18ade9a60 163 if (verbosity)
sravet 0:62c18ade9a60 164 printf("8 bit channel %d data=%d ",channel,(int)data_bptr[channel]);
sravet 0:62c18ade9a60 165 slice_value+=data_bptr[channel];
sravet 0:62c18ade9a60 166 break;
sravet 0:62c18ade9a60 167 }
sravet 0:62c18ade9a60 168 }
sravet 0:62c18ade9a60 169 slice_value/=wav_format.num_channels;
sravet 0:62c18ade9a60 170
sravet 0:62c18ade9a60 171 // slice_value is now averaged. Next it needs to be scaled to an unsigned 16 bit value
sravet 0:62c18ade9a60 172 // with DC offset so it can be written to the DAC.
sravet 0:62c18ade9a60 173 switch (wav_format.sig_bps) {
sravet 0:62c18ade9a60 174 case 8: slice_value<<=8;
sravet 0:62c18ade9a60 175 break;
sravet 0:62c18ade9a60 176 case 16: slice_value+=32768;
sravet 0:62c18ade9a60 177 break;
sravet 0:62c18ade9a60 178 case 32: slice_value>>=16;
sravet 0:62c18ade9a60 179 slice_value+=32768;
sravet 0:62c18ade9a60 180 break;
sravet 0:62c18ade9a60 181 }
sravet 0:62c18ade9a60 182 dac_data=(short unsigned)slice_value;
sravet 0:62c18ade9a60 183 if (verbosity)
sravet 0:62c18ade9a60 184 printf("sample %d wptr %d slice_value %d dac_data %u\n",slice,DAC_wptr,(int)slice_value,dac_data);
kthlee 2:44a41c9ff2d4 185 DAC_fifo[DAC_wptr]=((volume_change) * dac_data);
sravet 0:62c18ade9a60 186 DAC_wptr=(DAC_wptr+1) & 0xff;
sravet 0:62c18ade9a60 187 while (DAC_wptr==DAC_rptr) {
sravet 0:62c18ade9a60 188 }
sravet 0:62c18ade9a60 189 }
sravet 0:62c18ade9a60 190 DAC_on=0;
sravet 0:62c18ade9a60 191 tick.detach();
sravet 0:62c18ade9a60 192 free(slice_buf);
sravet 0:62c18ade9a60 193 break;
sravet 0:62c18ade9a60 194 case 0x5453494c:
sravet 0:62c18ade9a60 195 if (verbosity)
sravet 0:62c18ade9a60 196 printf("INFO chunk, size %d\n",chunk_size);
sravet 0:62c18ade9a60 197 fseek(wavefile,chunk_size,SEEK_CUR);
sravet 0:62c18ade9a60 198 break;
sravet 0:62c18ade9a60 199 default:
sravet 0:62c18ade9a60 200 printf("unknown chunk type 0x%x, size %d\n",chunk_id,chunk_size);
sravet 0:62c18ade9a60 201 data=fseek(wavefile,chunk_size,SEEK_CUR);
sravet 0:62c18ade9a60 202 break;
sravet 0:62c18ade9a60 203 }
sravet 0:62c18ade9a60 204 fread(&chunk_id,4,1,wavefile);
sravet 0:62c18ade9a60 205 fread(&chunk_size,4,1,wavefile);
sravet 0:62c18ade9a60 206 }
sravet 0:62c18ade9a60 207 }
kthlee 2:44a41c9ff2d4 208
kthlee 2:44a41c9ff2d4 209
sravet 0:62c18ade9a60 210 void wave_player::dac_out()
sravet 0:62c18ade9a60 211 {
sravet 0:62c18ade9a60 212 if (DAC_on) {
sravet 0:62c18ade9a60 213 #ifdef VERBOSE
sravet 0:62c18ade9a60 214 printf("ISR rdptr %d got %u\n",DAC_rptr,DAC_fifo[DAC_rptr]);
sravet 0:62c18ade9a60 215 #endif
kthlee 2:44a41c9ff2d4 216 //scale down Analog voltage by 8 for PC speakers
kthlee 2:44a41c9ff2d4 217 wave_DAC->write_u16(DAC_fifo[DAC_rptr]>>3);
kthlee 2:44a41c9ff2d4 218 //Output to onboard speaker using PWM (Class D Audio Amp!)
kthlee 2:44a41c9ff2d4 219 wave_PWM->write(float(DAC_fifo[DAC_rptr]/65536.0));
sravet 0:62c18ade9a60 220 DAC_rptr=(DAC_rptr+1) & 0xff;
sravet 0:62c18ade9a60 221 }
kthlee 2:44a41c9ff2d4 222 }