Jered Tupik / wave_player

Wave playing code based of sravet/wave_player, but with mbed-os v5 support and additional PWM output

Dependents:   waveplayer_mbedOS_v5_helloworld

wave_player.cpp@2:106018dd7db9, 2019-10-01 (annotated)

Committer:
HighTide
Date:
Tue Oct 01 00:41:24 2019 +0000
Revision:
2:106018dd7db9
Parent:
0:62c18ade9a60 
Added PWM output and mbed-os v5 support

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>
sravet 0:62c18ade9a60 17
sravet 0:62c18ade9a60 18
sravet 0:62c18ade9a60 19 //-----------------------------------------------------------------------------
sravet 0:62c18ade9a60 20 // constructor -- accepts an mbed pin to use for AnalogOut. Only p18 will work
HighTide 2:106018dd7db9 21 wave_player::wave_player(AnalogOut *_dac, PwmOut *_pwm)
sravet 0:62c18ade9a60 22 {
sravet 0:62c18ade9a60 23 wave_DAC=_dac;
sravet 0:62c18ade9a60 24 wave_DAC->write_u16(32768); //DAC is 0-3.3V, so idles at ~1.6V
HighTide 2:106018dd7db9 25 wave_PWM=_pwm;
HighTide 2:106018dd7db9 26 wave_PWM->write(0.0f);
sravet 0:62c18ade9a60 27 verbosity=0;
sravet 0:62c18ade9a60 28 }
sravet 0:62c18ade9a60 29
sravet 0:62c18ade9a60 30 //-----------------------------------------------------------------------------
sravet 0:62c18ade9a60 31 // if verbosity is set then wave player enters a mode where the wave file
sravet 0:62c18ade9a60 32 // is decoded and displayed to the screen, including sample values put into
sravet 0:62c18ade9a60 33 // the DAC FIFO, and values read out of the DAC FIFO by the ISR. The DAC output
sravet 0:62c18ade9a60 34 // itself is so slow as to be unusable, but this might be handy for debugging
sravet 0:62c18ade9a60 35 // wave files that don't play
sravet 0:62c18ade9a60 36 //-----------------------------------------------------------------------------
sravet 0:62c18ade9a60 37 void wave_player::set_verbosity(int v)
sravet 0:62c18ade9a60 38 {
sravet 0:62c18ade9a60 39 verbosity=v;
sravet 0:62c18ade9a60 40 }
sravet 0:62c18ade9a60 41
sravet 0:62c18ade9a60 42 //-----------------------------------------------------------------------------
sravet 0:62c18ade9a60 43 // player function. Takes a pointer to an opened wave file. The file needs
sravet 0:62c18ade9a60 44 // to be stored in a filesystem with enough bandwidth to feed the wave data.
sravet 0:62c18ade9a60 45 // LocalFileSystem isn't, but the SDcard is, at least for 22kHz files. The
sravet 0:62c18ade9a60 46 // SDcard filesystem can be hotrodded by increasing the SPI frequency it uses
sravet 0:62c18ade9a60 47 // internally.
sravet 0:62c18ade9a60 48 //-----------------------------------------------------------------------------
sravet 0:62c18ade9a60 49 void wave_player::play(FILE *wavefile)
sravet 0:62c18ade9a60 50 {
sravet 0:62c18ade9a60 51 unsigned chunk_id,chunk_size,channel;
sravet 0:62c18ade9a60 52 unsigned data,samp_int,i;
sravet 0:62c18ade9a60 53 short unsigned dac_data;
sravet 0:62c18ade9a60 54 long long slice_value;
sravet 0:62c18ade9a60 55 char *slice_buf;
sravet 0:62c18ade9a60 56 short *data_sptr;
sravet 0:62c18ade9a60 57 unsigned char *data_bptr;
sravet 0:62c18ade9a60 58 int *data_wptr;
sravet 0:62c18ade9a60 59 FMT_STRUCT wav_format;
sravet 0:62c18ade9a60 60 long slice,num_slices;
sravet 0:62c18ade9a60 61 DAC_wptr=0;
sravet 0:62c18ade9a60 62 DAC_rptr=0;
sravet 0:62c18ade9a60 63 for (i=0;i<256;i+=2) {
sravet 0:62c18ade9a60 64 DAC_fifo[i]=0;
sravet 0:62c18ade9a60 65 DAC_fifo[i+1]=3000;
sravet 0:62c18ade9a60 66 }
sravet 0:62c18ade9a60 67 DAC_wptr=4;
sravet 0:62c18ade9a60 68 DAC_on=0;
sravet 0:62c18ade9a60 69
sravet 0:62c18ade9a60 70 fread(&chunk_id,4,1,wavefile);
sravet 0:62c18ade9a60 71 fread(&chunk_size,4,1,wavefile);
sravet 0:62c18ade9a60 72 while (!feof(wavefile)) {
sravet 0:62c18ade9a60 73 if (verbosity)
HighTide 2:106018dd7db9 74 printf("Read chunk ID 0x%x, size 0x%x\r\n",chunk_id,chunk_size);
sravet 0:62c18ade9a60 75 switch (chunk_id) {
sravet 0:62c18ade9a60 76 case 0x46464952:
sravet 0:62c18ade9a60 77 fread(&data,4,1,wavefile);
sravet 0:62c18ade9a60 78 if (verbosity) {
HighTide 2:106018dd7db9 79 printf("RIFF chunk\r\n");
HighTide 2:106018dd7db9 80 printf(" chunk size %d (0x%x)\r\n",chunk_size,chunk_size);
HighTide 2:106018dd7db9 81 printf(" RIFF type 0x%x\r\n",data);
sravet 0:62c18ade9a60 82 }
sravet 0:62c18ade9a60 83 break;
sravet 0:62c18ade9a60 84 case 0x20746d66:
sravet 0:62c18ade9a60 85 fread(&wav_format,sizeof(wav_format),1,wavefile);
sravet 0:62c18ade9a60 86 if (verbosity) {
HighTide 2:106018dd7db9 87 printf("FORMAT chunk\r\n");
HighTide 2:106018dd7db9 88 printf(" chunk size %d (0x%x)\r\n",chunk_size,chunk_size);
HighTide 2:106018dd7db9 89 printf(" compression code %d\r\n",wav_format.comp_code);
HighTide 2:106018dd7db9 90 printf(" %d channels\r\n",wav_format.num_channels);
HighTide 2:106018dd7db9 91 printf(" %d samples/sec\r\n",wav_format.sample_rate);
HighTide 2:106018dd7db9 92 printf(" %d bytes/sec\r\n",wav_format.avg_Bps);
HighTide 2:106018dd7db9 93 printf(" block align %d\r\n",wav_format.block_align);
HighTide 2:106018dd7db9 94 printf(" %d bits per sample\r\n",wav_format.sig_bps);
sravet 0:62c18ade9a60 95 }
sravet 0:62c18ade9a60 96 if (chunk_size > sizeof(wav_format))
sravet 0:62c18ade9a60 97 fseek(wavefile,chunk_size-sizeof(wav_format),SEEK_CUR);
sravet 0:62c18ade9a60 98 break;
sravet 0:62c18ade9a60 99 case 0x61746164:
sravet 0:62c18ade9a60 100 // allocate a buffer big enough to hold a slice
sravet 0:62c18ade9a60 101 slice_buf=(char *)malloc(wav_format.block_align);
sravet 0:62c18ade9a60 102 if (!slice_buf) {
HighTide 2:106018dd7db9 103 printf("Unable to malloc slice buffer\r\n");
sravet 0:62c18ade9a60 104 exit(1);
sravet 0:62c18ade9a60 105 }
sravet 0:62c18ade9a60 106 num_slices=chunk_size/wav_format.block_align;
sravet 0:62c18ade9a60 107 samp_int=1000000/(wav_format.sample_rate);
sravet 0:62c18ade9a60 108 if (verbosity) {
HighTide 2:106018dd7db9 109 printf("DATA chunk\r\n");
HighTide 2:106018dd7db9 110 printf(" chunk size %d (0x%x)\r\n",chunk_size,chunk_size);
HighTide 2:106018dd7db9 111 printf(" %d slices\r\n",num_slices);
HighTide 2:106018dd7db9 112 printf(" Ideal sample interval=%d\r\n",(unsigned)(1000000.0/wav_format.sample_rate));
HighTide 2:106018dd7db9 113 printf(" programmed interrupt tick interval=%d\r\n",samp_int);
sravet 0:62c18ade9a60 114 }
sravet 0:62c18ade9a60 115
sravet 0:62c18ade9a60 116 // starting up ticker to write samples out -- no printfs until tick.detach is called
sravet 0:62c18ade9a60 117 if (verbosity)
HighTide 2:106018dd7db9 118 tick.attach_us(callback(this, &wave_player::dac_out), 500000);
sravet 0:62c18ade9a60 119 else
HighTide 2:106018dd7db9 120 tick.attach_us(callback(this, &wave_player::dac_out), samp_int);
sravet 0:62c18ade9a60 121 DAC_on=1;
sravet 0:62c18ade9a60 122
sravet 0:62c18ade9a60 123 // start reading slices, which contain one sample each for however many channels
sravet 0:62c18ade9a60 124 // are in the wave file. one channel=mono, two channels=stereo, etc. Since
sravet 0:62c18ade9a60 125 // mbed only has a single AnalogOut, all of the channels present are averaged
sravet 0:62c18ade9a60 126 // to produce a single sample value. This summing and averaging happens in
sravet 0:62c18ade9a60 127 // a variable of type signed long long, to make sure that the data doesn't
sravet 0:62c18ade9a60 128 // overflow regardless of sample size (8 bits, 16 bits, 32 bits).
sravet 0:62c18ade9a60 129 //
sravet 0:62c18ade9a60 130 // note that from what I can find that 8 bit wave files use unsigned data,
sravet 0:62c18ade9a60 131 // while 16 and 32 bit wave files use signed data
sravet 0:62c18ade9a60 132 //
sravet 0:62c18ade9a60 133 for (slice=0;slice<num_slices;slice+=1) {
sravet 0:62c18ade9a60 134 fread(slice_buf,wav_format.block_align,1,wavefile);
sravet 0:62c18ade9a60 135 if (feof(wavefile)) {
HighTide 2:106018dd7db9 136 printf("Oops -- not enough slices in the wave file\r\n");
sravet 0:62c18ade9a60 137 exit(1);
sravet 0:62c18ade9a60 138 }
sravet 0:62c18ade9a60 139 data_sptr=(short *)slice_buf; // 16 bit samples
sravet 0:62c18ade9a60 140 data_bptr=(unsigned char *)slice_buf; // 8 bit samples
sravet 0:62c18ade9a60 141 data_wptr=(int *)slice_buf; // 32 bit samples
sravet 0:62c18ade9a60 142 slice_value=0;
sravet 0:62c18ade9a60 143 for (channel=0;channel<wav_format.num_channels;channel++) {
sravet 0:62c18ade9a60 144 switch (wav_format.sig_bps) {
sravet 0:62c18ade9a60 145 case 16:
sravet 0:62c18ade9a60 146 if (verbosity)
HighTide 2:106018dd7db9 147 printf("16 bit channel %d data=%d \r\n",channel,data_sptr[channel]);
sravet 0:62c18ade9a60 148 slice_value+=data_sptr[channel];
sravet 0:62c18ade9a60 149 break;
sravet 0:62c18ade9a60 150 case 32:
sravet 0:62c18ade9a60 151 if (verbosity)
HighTide 2:106018dd7db9 152 printf("32 bit channel %d data=%d \r\n",channel,data_wptr[channel]);
sravet 0:62c18ade9a60 153 slice_value+=data_wptr[channel];
sravet 0:62c18ade9a60 154 break;
sravet 0:62c18ade9a60 155 case 8:
sravet 0:62c18ade9a60 156 if (verbosity)
HighTide 2:106018dd7db9 157 printf("8 bit channel %d data=%d \r\n",channel,(int)data_bptr[channel]);
sravet 0:62c18ade9a60 158 slice_value+=data_bptr[channel];
sravet 0:62c18ade9a60 159 break;
sravet 0:62c18ade9a60 160 }
sravet 0:62c18ade9a60 161 }
sravet 0:62c18ade9a60 162 slice_value/=wav_format.num_channels;
sravet 0:62c18ade9a60 163
sravet 0:62c18ade9a60 164 // slice_value is now averaged. Next it needs to be scaled to an unsigned 16 bit value
sravet 0:62c18ade9a60 165 // with DC offset so it can be written to the DAC.
sravet 0:62c18ade9a60 166 switch (wav_format.sig_bps) {
sravet 0:62c18ade9a60 167 case 8: slice_value<<=8;
sravet 0:62c18ade9a60 168 break;
sravet 0:62c18ade9a60 169 case 16: slice_value+=32768;
sravet 0:62c18ade9a60 170 break;
sravet 0:62c18ade9a60 171 case 32: slice_value>>=16;
sravet 0:62c18ade9a60 172 slice_value+=32768;
sravet 0:62c18ade9a60 173 break;
sravet 0:62c18ade9a60 174 }
sravet 0:62c18ade9a60 175 dac_data=(short unsigned)slice_value;
sravet 0:62c18ade9a60 176 if (verbosity)
HighTide 2:106018dd7db9 177 printf("sample %d wptr %d slice_value %d dac_data %u\r\n",slice,DAC_wptr,(int)slice_value,dac_data);
sravet 0:62c18ade9a60 178 DAC_fifo[DAC_wptr]=dac_data;
sravet 0:62c18ade9a60 179 DAC_wptr=(DAC_wptr+1) & 0xff;
sravet 0:62c18ade9a60 180 while (DAC_wptr==DAC_rptr) {
sravet 0:62c18ade9a60 181 }
sravet 0:62c18ade9a60 182 }
sravet 0:62c18ade9a60 183 DAC_on=0;
sravet 0:62c18ade9a60 184 tick.detach();
sravet 0:62c18ade9a60 185 free(slice_buf);
sravet 0:62c18ade9a60 186 break;
sravet 0:62c18ade9a60 187 case 0x5453494c:
sravet 0:62c18ade9a60 188 if (verbosity)
HighTide 2:106018dd7db9 189 printf("INFO chunk, size %d\r\n",chunk_size);
sravet 0:62c18ade9a60 190 fseek(wavefile,chunk_size,SEEK_CUR);
sravet 0:62c18ade9a60 191 break;
sravet 0:62c18ade9a60 192 default:
HighTide 2:106018dd7db9 193 printf("unknown chunk type 0x%x, size %d\r\n",chunk_id,chunk_size);
sravet 0:62c18ade9a60 194 data=fseek(wavefile,chunk_size,SEEK_CUR);
sravet 0:62c18ade9a60 195 break;
sravet 0:62c18ade9a60 196 }
sravet 0:62c18ade9a60 197 fread(&chunk_id,4,1,wavefile);
sravet 0:62c18ade9a60 198 fread(&chunk_size,4,1,wavefile);
sravet 0:62c18ade9a60 199 }
sravet 0:62c18ade9a60 200 }
sravet 0:62c18ade9a60 201
sravet 0:62c18ade9a60 202
sravet 0:62c18ade9a60 203 void wave_player::dac_out()
sravet 0:62c18ade9a60 204 {
sravet 0:62c18ade9a60 205 if (DAC_on) {
HighTide 2:106018dd7db9 206 LPC_DAC->DACR = DAC_fifo[DAC_rptr] & 0XFFC0;
HighTide 2:106018dd7db9 207 wave_PWM->write(float(DAC_fifo[DAC_rptr]/65536.0));
sravet 0:62c18ade9a60 208 DAC_rptr=(DAC_rptr+1) & 0xff;
HighTide 2:106018dd7db9 209 }
HighTide 2:106018dd7db9 210 }