Jay Balar / Mbed 2 deprecated 4180_Project_3

Important changes to repositories hosted on mbed.com

Mbed hosted mercurial repositories are deprecated and are due to be permanently deleted in July 2026.

To keep a copy of this software download the repository Zip archive or clone locally using Mercurial.

It is also possible to export all your personal repositories from the account settings page.

Dependencies:   4DGL-uLCD-SE Physac-MBED PinDetect SDFileSystem mbed-rtos mbed

wave_player_appbd/wave_player.cpp@21:df9e8f45e14c, 2022-12-06 (annotated)

Committer:
jstephens78
Date:
Tue Dec 06 22:09:51 2022 +0000
Revision:
21:df9e8f45e14c
Parent:
6:fc95af217f01 
Uncomment audio thread

Who changed what in which revision?

UserRevisionLine numberNew contents of line
dangulo7 6:fc95af217f01 1 //-----------------------------------------------------------------------------
dangulo7 6:fc95af217f01 2 // a sample mbed library to play back wave files.
dangulo7 6:fc95af217f01 3 //
dangulo7 6:fc95af217f01 4 // explanation of wave file format.
dangulo7 6:fc95af217f01 5 // https://ccrma.stanford.edu/courses/422/projects/WaveFormat/
dangulo7 6:fc95af217f01 6
dangulo7 6:fc95af217f01 7 // if VERBOSE is uncommented then the wave player will enter a verbose
dangulo7 6:fc95af217f01 8 // mode that displays all data values as it reads them from the file
dangulo7 6:fc95af217f01 9 // and writes them to the DAC. Very slow and unusable output on the DAC,
dangulo7 6:fc95af217f01 10 // but useful for debugging wave files that don't work.
dangulo7 6:fc95af217f01 11 //#define VERBOSE
dangulo7 6:fc95af217f01 12
dangulo7 6:fc95af217f01 13
dangulo7 6:fc95af217f01 14 #include <mbed.h>
dangulo7 6:fc95af217f01 15 #include <stdio.h>
dangulo7 6:fc95af217f01 16 #include <wave_player.h>
dangulo7 6:fc95af217f01 17
dangulo7 6:fc95af217f01 18
dangulo7 6:fc95af217f01 19 //-----------------------------------------------------------------------------
dangulo7 6:fc95af217f01 20 // constructor -- accepts an mbed pin to use for AnalogOut. Only p18 will work
dangulo7 6:fc95af217f01 21 wave_player::wave_player(AnalogOut *_dac)
dangulo7 6:fc95af217f01 22 {
jstephens78 21:df9e8f45e14c 23 wave_DAC=_dac;
jstephens78 21:df9e8f45e14c 24 wave_DAC->write_u16(32768); //DAC is 0-3.3V, so idles at ~1.6V
jstephens78 21:df9e8f45e14c 25 verbosity=0;
dangulo7 6:fc95af217f01 26 }
dangulo7 6:fc95af217f01 27
dangulo7 6:fc95af217f01 28 //-----------------------------------------------------------------------------
dangulo7 6:fc95af217f01 29 // if verbosity is set then wave player enters a mode where the wave file
dangulo7 6:fc95af217f01 30 // is decoded and displayed to the screen, including sample values put into
dangulo7 6:fc95af217f01 31 // the DAC FIFO, and values read out of the DAC FIFO by the ISR. The DAC output
dangulo7 6:fc95af217f01 32 // itself is so slow as to be unusable, but this might be handy for debugging
dangulo7 6:fc95af217f01 33 // wave files that don't play
dangulo7 6:fc95af217f01 34 //-----------------------------------------------------------------------------
dangulo7 6:fc95af217f01 35 void wave_player::set_verbosity(int v)
dangulo7 6:fc95af217f01 36 {
jstephens78 21:df9e8f45e14c 37 verbosity=v;
dangulo7 6:fc95af217f01 38 }
dangulo7 6:fc95af217f01 39
dangulo7 6:fc95af217f01 40 //-----------------------------------------------------------------------------
dangulo7 6:fc95af217f01 41 // player function. Takes a pointer to an opened wave file. The file needs
dangulo7 6:fc95af217f01 42 // to be stored in a filesystem with enough bandwidth to feed the wave data.
dangulo7 6:fc95af217f01 43 // LocalFileSystem isn't, but the SDcard is, at least for 22kHz files. The
dangulo7 6:fc95af217f01 44 // SDcard filesystem can be hotrodded by increasing the SPI frequency it uses
dangulo7 6:fc95af217f01 45 // internally.
dangulo7 6:fc95af217f01 46 //-----------------------------------------------------------------------------
dangulo7 6:fc95af217f01 47 void wave_player::play(FILE *wavefile)
dangulo7 6:fc95af217f01 48 {
jstephens78 21:df9e8f45e14c 49 unsigned chunk_id,chunk_size,channel;
jstephens78 21:df9e8f45e14c 50 unsigned data,samp_int,i;
jstephens78 21:df9e8f45e14c 51 short unsigned dac_data;
jstephens78 21:df9e8f45e14c 52 long long slice_value;
jstephens78 21:df9e8f45e14c 53 char *slice_buf;
jstephens78 21:df9e8f45e14c 54 short *data_sptr;
jstephens78 21:df9e8f45e14c 55 unsigned char *data_bptr;
jstephens78 21:df9e8f45e14c 56 int *data_wptr;
jstephens78 21:df9e8f45e14c 57 FMT_STRUCT wav_format;
jstephens78 21:df9e8f45e14c 58 long slice,num_slices;
jstephens78 21:df9e8f45e14c 59 DAC_wptr=0;
jstephens78 21:df9e8f45e14c 60 DAC_rptr=0;
jstephens78 21:df9e8f45e14c 61 for (i=0; i<256; i+=2) {
jstephens78 21:df9e8f45e14c 62 DAC_fifo[i]=0;
jstephens78 21:df9e8f45e14c 63 DAC_fifo[i+1]=3000;
jstephens78 21:df9e8f45e14c 64 }
jstephens78 21:df9e8f45e14c 65 DAC_wptr=4;
jstephens78 21:df9e8f45e14c 66 DAC_on=0;
dangulo7 6:fc95af217f01 67
jstephens78 21:df9e8f45e14c 68 fread(&chunk_id,4,1,wavefile);
jstephens78 21:df9e8f45e14c 69 fread(&chunk_size,4,1,wavefile);
jstephens78 21:df9e8f45e14c 70 while (!feof(wavefile)) {
jstephens78 21:df9e8f45e14c 71 if (verbosity)
jstephens78 21:df9e8f45e14c 72 printf("Read chunk ID 0x%x, size 0x%x\n",chunk_id,chunk_size);
jstephens78 21:df9e8f45e14c 73 switch (chunk_id) {
jstephens78 21:df9e8f45e14c 74 case 0x46464952:
jstephens78 21:df9e8f45e14c 75 fread(&data,4,1,wavefile);
jstephens78 21:df9e8f45e14c 76 if (verbosity) {
jstephens78 21:df9e8f45e14c 77 printf("RIFF chunk\n");
jstephens78 21:df9e8f45e14c 78 printf(" chunk size %d (0x%x)\n",chunk_size,chunk_size);
jstephens78 21:df9e8f45e14c 79 printf(" RIFF type 0x%x\n",data);
jstephens78 21:df9e8f45e14c 80 }
jstephens78 21:df9e8f45e14c 81 break;
jstephens78 21:df9e8f45e14c 82 case 0x20746d66:
jstephens78 21:df9e8f45e14c 83 fread(&wav_format,sizeof(wav_format),1,wavefile);
jstephens78 21:df9e8f45e14c 84 if (verbosity) {
jstephens78 21:df9e8f45e14c 85 printf("FORMAT chunk\n");
jstephens78 21:df9e8f45e14c 86 printf(" chunk size %d (0x%x)\n",chunk_size,chunk_size);
jstephens78 21:df9e8f45e14c 87 printf(" compression code %d\n",wav_format.comp_code);
jstephens78 21:df9e8f45e14c 88 printf(" %d channels\n",wav_format.num_channels);
jstephens78 21:df9e8f45e14c 89 printf(" %d samples/sec\n",wav_format.sample_rate);
jstephens78 21:df9e8f45e14c 90 printf(" %d bytes/sec\n",wav_format.avg_Bps);
jstephens78 21:df9e8f45e14c 91 printf(" block align %d\n",wav_format.block_align);
jstephens78 21:df9e8f45e14c 92 printf(" %d bits per sample\n",wav_format.sig_bps);
jstephens78 21:df9e8f45e14c 93 }
jstephens78 21:df9e8f45e14c 94 if (chunk_size > sizeof(wav_format))
jstephens78 21:df9e8f45e14c 95 fseek(wavefile,chunk_size-sizeof(wav_format),SEEK_CUR);
jstephens78 21:df9e8f45e14c 96 break;
jstephens78 21:df9e8f45e14c 97 case 0x61746164:
dangulo7 6:fc95af217f01 98 // allocate a buffer big enough to hold a slice
jstephens78 21:df9e8f45e14c 99 slice_buf=(char *)malloc(wav_format.block_align);
jstephens78 21:df9e8f45e14c 100 if (!slice_buf) {
jstephens78 21:df9e8f45e14c 101 printf("Unable to malloc slice buffer");
jstephens78 21:df9e8f45e14c 102 exit(1);
jstephens78 21:df9e8f45e14c 103 }
jstephens78 21:df9e8f45e14c 104 num_slices=chunk_size/wav_format.block_align;
jstephens78 21:df9e8f45e14c 105 samp_int=1000000/(wav_format.sample_rate);
jstephens78 21:df9e8f45e14c 106 if (verbosity) {
jstephens78 21:df9e8f45e14c 107 printf("DATA chunk\n");
jstephens78 21:df9e8f45e14c 108 printf(" chunk size %d (0x%x)\n",chunk_size,chunk_size);
jstephens78 21:df9e8f45e14c 109 printf(" %d slices\n",num_slices);
jstephens78 21:df9e8f45e14c 110 printf(" Ideal sample interval=%d\n",(unsigned)(1000000.0/wav_format.sample_rate));
jstephens78 21:df9e8f45e14c 111 printf(" programmed interrupt tick interval=%d\n",samp_int);
jstephens78 21:df9e8f45e14c 112 }
dangulo7 6:fc95af217f01 113
dangulo7 6:fc95af217f01 114 // starting up ticker to write samples out -- no printfs until tick.detach is called
jstephens78 21:df9e8f45e14c 115 if (verbosity)
jstephens78 21:df9e8f45e14c 116 tick.attach_us(this,&wave_player::dac_out, 500000);
jstephens78 21:df9e8f45e14c 117 else
jstephens78 21:df9e8f45e14c 118 tick.attach_us(this,&wave_player::dac_out, samp_int);
jstephens78 21:df9e8f45e14c 119 DAC_on=1;
dangulo7 6:fc95af217f01 120
dangulo7 6:fc95af217f01 121 // start reading slices, which contain one sample each for however many channels
dangulo7 6:fc95af217f01 122 // are in the wave file. one channel=mono, two channels=stereo, etc. Since
dangulo7 6:fc95af217f01 123 // mbed only has a single AnalogOut, all of the channels present are averaged
dangulo7 6:fc95af217f01 124 // to produce a single sample value. This summing and averaging happens in
dangulo7 6:fc95af217f01 125 // a variable of type signed long long, to make sure that the data doesn't
dangulo7 6:fc95af217f01 126 // overflow regardless of sample size (8 bits, 16 bits, 32 bits).
dangulo7 6:fc95af217f01 127 //
dangulo7 6:fc95af217f01 128 // note that from what I can find that 8 bit wave files use unsigned data,
dangulo7 6:fc95af217f01 129 // while 16 and 32 bit wave files use signed data
dangulo7 6:fc95af217f01 130 //
jstephens78 21:df9e8f45e14c 131 for (slice=0; slice<num_slices; slice+=1) {
jstephens78 21:df9e8f45e14c 132 fread(slice_buf,wav_format.block_align,1,wavefile);
jstephens78 21:df9e8f45e14c 133 if (feof(wavefile)) {
jstephens78 21:df9e8f45e14c 134 printf("Oops -- not enough slices in the wave file\n");
jstephens78 21:df9e8f45e14c 135 exit(1);
jstephens78 21:df9e8f45e14c 136 }
jstephens78 21:df9e8f45e14c 137 data_sptr=(short *)slice_buf; // 16 bit samples
jstephens78 21:df9e8f45e14c 138 data_bptr=(unsigned char *)slice_buf; // 8 bit samples
jstephens78 21:df9e8f45e14c 139 data_wptr=(int *)slice_buf; // 32 bit samples
jstephens78 21:df9e8f45e14c 140 slice_value=0;
jstephens78 21:df9e8f45e14c 141 for (channel=0; channel<wav_format.num_channels; channel++) {
jstephens78 21:df9e8f45e14c 142 switch (wav_format.sig_bps) {
jstephens78 21:df9e8f45e14c 143 case 16:
jstephens78 21:df9e8f45e14c 144 if (verbosity)
jstephens78 21:df9e8f45e14c 145 printf("16 bit channel %d data=%d ",channel,data_sptr[channel]);
jstephens78 21:df9e8f45e14c 146 slice_value+=data_sptr[channel];
jstephens78 21:df9e8f45e14c 147 break;
jstephens78 21:df9e8f45e14c 148 case 32:
jstephens78 21:df9e8f45e14c 149 if (verbosity)
jstephens78 21:df9e8f45e14c 150 printf("32 bit channel %d data=%d ",channel,data_wptr[channel]);
jstephens78 21:df9e8f45e14c 151 slice_value+=data_wptr[channel];
jstephens78 21:df9e8f45e14c 152 break;
jstephens78 21:df9e8f45e14c 153 case 8:
jstephens78 21:df9e8f45e14c 154 if (verbosity)
jstephens78 21:df9e8f45e14c 155 printf("8 bit channel %d data=%d ",channel,(int)data_bptr[channel]);
jstephens78 21:df9e8f45e14c 156 slice_value+=data_bptr[channel];
jstephens78 21:df9e8f45e14c 157 break;
jstephens78 21:df9e8f45e14c 158 }
jstephens78 21:df9e8f45e14c 159 }
jstephens78 21:df9e8f45e14c 160 slice_value/=wav_format.num_channels;
jstephens78 21:df9e8f45e14c 161
dangulo7 6:fc95af217f01 162 // slice_value is now averaged. Next it needs to be scaled to an unsigned 16 bit value
dangulo7 6:fc95af217f01 163 // with DC offset so it can be written to the DAC.
jstephens78 21:df9e8f45e14c 164 switch (wav_format.sig_bps) {
jstephens78 21:df9e8f45e14c 165 case 8:
jstephens78 21:df9e8f45e14c 166 slice_value<<=8;
jstephens78 21:df9e8f45e14c 167 break;
jstephens78 21:df9e8f45e14c 168 case 16:
jstephens78 21:df9e8f45e14c 169 slice_value+=32768;
jstephens78 21:df9e8f45e14c 170 break;
jstephens78 21:df9e8f45e14c 171 case 32:
jstephens78 21:df9e8f45e14c 172 slice_value>>=16;
jstephens78 21:df9e8f45e14c 173 slice_value+=32768;
jstephens78 21:df9e8f45e14c 174 break;
jstephens78 21:df9e8f45e14c 175 }
jstephens78 21:df9e8f45e14c 176 dac_data=(short unsigned)slice_value;
jstephens78 21:df9e8f45e14c 177 if (verbosity)
jstephens78 21:df9e8f45e14c 178 printf("sample %d wptr %d slice_value %d dac_data %u\n",slice,DAC_wptr,(int)slice_value,dac_data);
jstephens78 21:df9e8f45e14c 179 DAC_fifo[DAC_wptr]=dac_data;
jstephens78 21:df9e8f45e14c 180 DAC_wptr=(DAC_wptr+1) & 0xff;
jstephens78 21:df9e8f45e14c 181 while (DAC_wptr==DAC_rptr) {
jstephens78 21:df9e8f45e14c 182 }
jstephens78 21:df9e8f45e14c 183 }
jstephens78 21:df9e8f45e14c 184 DAC_on=0;
jstephens78 21:df9e8f45e14c 185 tick.detach();
jstephens78 21:df9e8f45e14c 186 free(slice_buf);
jstephens78 21:df9e8f45e14c 187 break;
jstephens78 21:df9e8f45e14c 188 case 0x5453494c:
jstephens78 21:df9e8f45e14c 189 if (verbosity)
jstephens78 21:df9e8f45e14c 190 printf("INFO chunk, size %d\n",chunk_size);
jstephens78 21:df9e8f45e14c 191 fseek(wavefile,chunk_size,SEEK_CUR);
jstephens78 21:df9e8f45e14c 192 break;
jstephens78 21:df9e8f45e14c 193 default:
jstephens78 21:df9e8f45e14c 194 printf("unknown chunk type 0x%x, size %d\n",chunk_id,chunk_size);
jstephens78 21:df9e8f45e14c 195 data=fseek(wavefile,chunk_size,SEEK_CUR);
jstephens78 21:df9e8f45e14c 196 break;
dangulo7 6:fc95af217f01 197 }
jstephens78 21:df9e8f45e14c 198 fread(&chunk_id,4,1,wavefile);
jstephens78 21:df9e8f45e14c 199 fread(&chunk_size,4,1,wavefile);
dangulo7 6:fc95af217f01 200 }
dangulo7 6:fc95af217f01 201 }
dangulo7 6:fc95af217f01 202
dangulo7 6:fc95af217f01 203
dangulo7 6:fc95af217f01 204 void wave_player::dac_out()
dangulo7 6:fc95af217f01 205 {
jstephens78 21:df9e8f45e14c 206 if (DAC_on) {
dangulo7 6:fc95af217f01 207 #ifdef VERBOSE
jstephens78 21:df9e8f45e14c 208 printf("ISR rdptr %d got %u\n",DAC_rptr,DAC_fifo[DAC_rptr]);
dangulo7 6:fc95af217f01 209 #endif
jstephens78 21:df9e8f45e14c 210 wave_DAC->write_u16(DAC_fifo[DAC_rptr]);
jstephens78 21:df9e8f45e14c 211 DAC_rptr=(DAC_rptr+1) & 0xff;
jstephens78 21:df9e8f45e14c 212 }
dangulo7 6:fc95af217f01 213 }
dangulo7 6:fc95af217f01 214