ECE 2035 TA / wave_player

wave_player library

Dependents:   ECE2035_SUM17_Project wav_player USBHostMSD_WavePlayer

wave_player.cpp@0:910a7c3c9b24, 2017-07-14 (annotated)

Committer:
kennyainny
Date:
Fri Jul 14 21:42:27 2017 +0000
Revision:
0:910a7c3c9b24
no changes;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
kennyainny 0:910a7c3c9b24 1 //-----------------------------------------------------------------------------
kennyainny 0:910a7c3c9b24 2 // a sample mbed library to play back wave files.
kennyainny 0:910a7c3c9b24 3 //
kennyainny 0:910a7c3c9b24 4 // explanation of wave file format.
kennyainny 0:910a7c3c9b24 5 // https://ccrma.stanford.edu/courses/422/projects/WaveFormat/
kennyainny 0:910a7c3c9b24 6
kennyainny 0:910a7c3c9b24 7 // if VERBOSE is uncommented then the wave player will enter a verbose
kennyainny 0:910a7c3c9b24 8 // mode that displays all data values as it reads them from the file
kennyainny 0:910a7c3c9b24 9 // and writes them to the DAC. Very slow and unusable output on the DAC,
kennyainny 0:910a7c3c9b24 10 // but useful for debugging wave files that don't work.
kennyainny 0:910a7c3c9b24 11 //#define VERBOSE
kennyainny 0:910a7c3c9b24 12
kennyainny 0:910a7c3c9b24 13
kennyainny 0:910a7c3c9b24 14 #include <mbed.h>
kennyainny 0:910a7c3c9b24 15 #include <stdio.h>
kennyainny 0:910a7c3c9b24 16 #include <wave_player.h>
kennyainny 0:910a7c3c9b24 17
kennyainny 0:910a7c3c9b24 18
kennyainny 0:910a7c3c9b24 19 //-----------------------------------------------------------------------------
kennyainny 0:910a7c3c9b24 20 // constructor -- accepts an mbed pin to use for AnalogOut. Only p18 will work
kennyainny 0:910a7c3c9b24 21 wave_player::wave_player(AnalogOut *_dac)
kennyainny 0:910a7c3c9b24 22 {
kennyainny 0:910a7c3c9b24 23 wave_DAC=_dac;
kennyainny 0:910a7c3c9b24 24 wave_DAC->write_u16(32768); //DAC is 0-3.3V, so idles at ~1.6V
kennyainny 0:910a7c3c9b24 25 verbosity=0;
kennyainny 0:910a7c3c9b24 26 }
kennyainny 0:910a7c3c9b24 27
kennyainny 0:910a7c3c9b24 28 //-----------------------------------------------------------------------------
kennyainny 0:910a7c3c9b24 29 // if verbosity is set then wave player enters a mode where the wave file
kennyainny 0:910a7c3c9b24 30 // is decoded and displayed to the screen, including sample values put into
kennyainny 0:910a7c3c9b24 31 // the DAC FIFO, and values read out of the DAC FIFO by the ISR. The DAC output
kennyainny 0:910a7c3c9b24 32 // itself is so slow as to be unusable, but this might be handy for debugging
kennyainny 0:910a7c3c9b24 33 // wave files that don't play
kennyainny 0:910a7c3c9b24 34 //-----------------------------------------------------------------------------
kennyainny 0:910a7c3c9b24 35 void wave_player::set_verbosity(int v)
kennyainny 0:910a7c3c9b24 36 {
kennyainny 0:910a7c3c9b24 37 verbosity=v;
kennyainny 0:910a7c3c9b24 38 }
kennyainny 0:910a7c3c9b24 39
kennyainny 0:910a7c3c9b24 40 //-----------------------------------------------------------------------------
kennyainny 0:910a7c3c9b24 41 // player function. Takes a pointer to an opened wave file. The file needs
kennyainny 0:910a7c3c9b24 42 // to be stored in a filesystem with enough bandwidth to feed the wave data.
kennyainny 0:910a7c3c9b24 43 // LocalFileSystem isn't, but the SDcard is, at least for 22kHz files. The
kennyainny 0:910a7c3c9b24 44 // SDcard filesystem can be hotrodded by increasing the SPI frequency it uses
kennyainny 0:910a7c3c9b24 45 // internally.
kennyainny 0:910a7c3c9b24 46 //-----------------------------------------------------------------------------
kennyainny 0:910a7c3c9b24 47 void wave_player::play(FILE *wavefile)
kennyainny 0:910a7c3c9b24 48 {
kennyainny 0:910a7c3c9b24 49 unsigned chunk_id,chunk_size,channel;
kennyainny 0:910a7c3c9b24 50 unsigned data,samp_int,i;
kennyainny 0:910a7c3c9b24 51 short unsigned dac_data;
kennyainny 0:910a7c3c9b24 52 long long slice_value;
kennyainny 0:910a7c3c9b24 53 char *slice_buf;
kennyainny 0:910a7c3c9b24 54 short *data_sptr;
kennyainny 0:910a7c3c9b24 55 unsigned char *data_bptr;
kennyainny 0:910a7c3c9b24 56 int *data_wptr;
kennyainny 0:910a7c3c9b24 57 FMT_STRUCT wav_format;
kennyainny 0:910a7c3c9b24 58 long slice,num_slices;
kennyainny 0:910a7c3c9b24 59 DAC_wptr=0;
kennyainny 0:910a7c3c9b24 60 DAC_rptr=0;
kennyainny 0:910a7c3c9b24 61 for (i=0;i<256;i+=2) {
kennyainny 0:910a7c3c9b24 62 DAC_fifo[i]=0;
kennyainny 0:910a7c3c9b24 63 DAC_fifo[i+1]=3000;
kennyainny 0:910a7c3c9b24 64 }
kennyainny 0:910a7c3c9b24 65 DAC_wptr=4;
kennyainny 0:910a7c3c9b24 66 DAC_on=0;
kennyainny 0:910a7c3c9b24 67
kennyainny 0:910a7c3c9b24 68 fread(&chunk_id,4,1,wavefile);
kennyainny 0:910a7c3c9b24 69 fread(&chunk_size,4,1,wavefile);
kennyainny 0:910a7c3c9b24 70 while (!feof(wavefile)) {
kennyainny 0:910a7c3c9b24 71 if (verbosity)
kennyainny 0:910a7c3c9b24 72 printf("Read chunk ID 0x%x, size 0x%x\n",chunk_id,chunk_size);
kennyainny 0:910a7c3c9b24 73 switch (chunk_id) {
kennyainny 0:910a7c3c9b24 74 case 0x46464952:
kennyainny 0:910a7c3c9b24 75 fread(&data,4,1,wavefile);
kennyainny 0:910a7c3c9b24 76 if (verbosity) {
kennyainny 0:910a7c3c9b24 77 printf("RIFF chunk\n");
kennyainny 0:910a7c3c9b24 78 printf(" chunk size %d (0x%x)\n",chunk_size,chunk_size);
kennyainny 0:910a7c3c9b24 79 printf(" RIFF type 0x%x\n",data);
kennyainny 0:910a7c3c9b24 80 }
kennyainny 0:910a7c3c9b24 81 break;
kennyainny 0:910a7c3c9b24 82 case 0x20746d66:
kennyainny 0:910a7c3c9b24 83 fread(&wav_format,sizeof(wav_format),1,wavefile);
kennyainny 0:910a7c3c9b24 84 if (verbosity) {
kennyainny 0:910a7c3c9b24 85 printf("FORMAT chunk\n");
kennyainny 0:910a7c3c9b24 86 printf(" chunk size %d (0x%x)\n",chunk_size,chunk_size);
kennyainny 0:910a7c3c9b24 87 printf(" compression code %d\n",wav_format.comp_code);
kennyainny 0:910a7c3c9b24 88 printf(" %d channels\n",wav_format.num_channels);
kennyainny 0:910a7c3c9b24 89 printf(" %d samples/sec\n",wav_format.sample_rate);
kennyainny 0:910a7c3c9b24 90 printf(" %d bytes/sec\n",wav_format.avg_Bps);
kennyainny 0:910a7c3c9b24 91 printf(" block align %d\n",wav_format.block_align);
kennyainny 0:910a7c3c9b24 92 printf(" %d bits per sample\n",wav_format.sig_bps);
kennyainny 0:910a7c3c9b24 93 }
kennyainny 0:910a7c3c9b24 94 if (chunk_size > sizeof(wav_format))
kennyainny 0:910a7c3c9b24 95 fseek(wavefile,chunk_size-sizeof(wav_format),SEEK_CUR);
kennyainny 0:910a7c3c9b24 96 break;
kennyainny 0:910a7c3c9b24 97 case 0x61746164:
kennyainny 0:910a7c3c9b24 98 // allocate a buffer big enough to hold a slice
kennyainny 0:910a7c3c9b24 99 slice_buf=(char *)malloc(wav_format.block_align);
kennyainny 0:910a7c3c9b24 100 if (!slice_buf) {
kennyainny 0:910a7c3c9b24 101 printf("Unable to malloc slice buffer");
kennyainny 0:910a7c3c9b24 102 exit(1);
kennyainny 0:910a7c3c9b24 103 }
kennyainny 0:910a7c3c9b24 104 num_slices=chunk_size/wav_format.block_align;
kennyainny 0:910a7c3c9b24 105 samp_int=1000000/(wav_format.sample_rate);
kennyainny 0:910a7c3c9b24 106 if (verbosity) {
kennyainny 0:910a7c3c9b24 107 printf("DATA chunk\n");
kennyainny 0:910a7c3c9b24 108 printf(" chunk size %d (0x%x)\n",chunk_size,chunk_size);
kennyainny 0:910a7c3c9b24 109 printf(" %d slices\n",num_slices);
kennyainny 0:910a7c3c9b24 110 printf(" Ideal sample interval=%d\n",(unsigned)(1000000.0/wav_format.sample_rate));
kennyainny 0:910a7c3c9b24 111 printf(" programmed interrupt tick interval=%d\n",samp_int);
kennyainny 0:910a7c3c9b24 112 }
kennyainny 0:910a7c3c9b24 113
kennyainny 0:910a7c3c9b24 114 // starting up ticker to write samples out -- no printfs until tick.detach is called
kennyainny 0:910a7c3c9b24 115 if (verbosity)
kennyainny 0:910a7c3c9b24 116 tick.attach_us(this,&wave_player::dac_out, 500000);
kennyainny 0:910a7c3c9b24 117 else
kennyainny 0:910a7c3c9b24 118 tick.attach_us(this,&wave_player::dac_out, samp_int);
kennyainny 0:910a7c3c9b24 119 DAC_on=1;
kennyainny 0:910a7c3c9b24 120
kennyainny 0:910a7c3c9b24 121 // start reading slices, which contain one sample each for however many channels
kennyainny 0:910a7c3c9b24 122 // are in the wave file. one channel=mono, two channels=stereo, etc. Since
kennyainny 0:910a7c3c9b24 123 // mbed only has a single AnalogOut, all of the channels present are averaged
kennyainny 0:910a7c3c9b24 124 // to produce a single sample value. This summing and averaging happens in
kennyainny 0:910a7c3c9b24 125 // a variable of type signed long long, to make sure that the data doesn't
kennyainny 0:910a7c3c9b24 126 // overflow regardless of sample size (8 bits, 16 bits, 32 bits).
kennyainny 0:910a7c3c9b24 127 //
kennyainny 0:910a7c3c9b24 128 // note that from what I can find that 8 bit wave files use unsigned data,
kennyainny 0:910a7c3c9b24 129 // while 16 and 32 bit wave files use signed data
kennyainny 0:910a7c3c9b24 130 //
kennyainny 0:910a7c3c9b24 131 for (slice=0;slice<num_slices;slice+=1) {
kennyainny 0:910a7c3c9b24 132 fread(slice_buf,wav_format.block_align,1,wavefile);
kennyainny 0:910a7c3c9b24 133 if (feof(wavefile)) {
kennyainny 0:910a7c3c9b24 134 printf("Oops -- not enough slices in the wave file\n");
kennyainny 0:910a7c3c9b24 135 exit(1);
kennyainny 0:910a7c3c9b24 136 }
kennyainny 0:910a7c3c9b24 137 data_sptr=(short *)slice_buf; // 16 bit samples
kennyainny 0:910a7c3c9b24 138 data_bptr=(unsigned char *)slice_buf; // 8 bit samples
kennyainny 0:910a7c3c9b24 139 data_wptr=(int *)slice_buf; // 32 bit samples
kennyainny 0:910a7c3c9b24 140 slice_value=0;
kennyainny 0:910a7c3c9b24 141 for (channel=0;channel<wav_format.num_channels;channel++) {
kennyainny 0:910a7c3c9b24 142 switch (wav_format.sig_bps) {
kennyainny 0:910a7c3c9b24 143 case 16:
kennyainny 0:910a7c3c9b24 144 if (verbosity)
kennyainny 0:910a7c3c9b24 145 printf("16 bit channel %d data=%d ",channel,data_sptr[channel]);
kennyainny 0:910a7c3c9b24 146 slice_value+=data_sptr[channel];
kennyainny 0:910a7c3c9b24 147 break;
kennyainny 0:910a7c3c9b24 148 case 32:
kennyainny 0:910a7c3c9b24 149 if (verbosity)
kennyainny 0:910a7c3c9b24 150 printf("32 bit channel %d data=%d ",channel,data_wptr[channel]);
kennyainny 0:910a7c3c9b24 151 slice_value+=data_wptr[channel];
kennyainny 0:910a7c3c9b24 152 break;
kennyainny 0:910a7c3c9b24 153 case 8:
kennyainny 0:910a7c3c9b24 154 if (verbosity)
kennyainny 0:910a7c3c9b24 155 printf("8 bit channel %d data=%d ",channel,(int)data_bptr[channel]);
kennyainny 0:910a7c3c9b24 156 slice_value+=data_bptr[channel];
kennyainny 0:910a7c3c9b24 157 break;
kennyainny 0:910a7c3c9b24 158 }
kennyainny 0:910a7c3c9b24 159 }
kennyainny 0:910a7c3c9b24 160 slice_value/=wav_format.num_channels;
kennyainny 0:910a7c3c9b24 161
kennyainny 0:910a7c3c9b24 162 // slice_value is now averaged. Next it needs to be scaled to an unsigned 16 bit value
kennyainny 0:910a7c3c9b24 163 // with DC offset so it can be written to the DAC.
kennyainny 0:910a7c3c9b24 164 switch (wav_format.sig_bps) {
kennyainny 0:910a7c3c9b24 165 case 8: slice_value<<=8;
kennyainny 0:910a7c3c9b24 166 break;
kennyainny 0:910a7c3c9b24 167 case 16: slice_value+=32768;
kennyainny 0:910a7c3c9b24 168 break;
kennyainny 0:910a7c3c9b24 169 case 32: slice_value>>=16;
kennyainny 0:910a7c3c9b24 170 slice_value+=32768;
kennyainny 0:910a7c3c9b24 171 break;
kennyainny 0:910a7c3c9b24 172 }
kennyainny 0:910a7c3c9b24 173 dac_data=(short unsigned)slice_value;
kennyainny 0:910a7c3c9b24 174 if (verbosity)
kennyainny 0:910a7c3c9b24 175 printf("sample %d wptr %d slice_value %d dac_data %u\n",slice,DAC_wptr,(int)slice_value,dac_data);
kennyainny 0:910a7c3c9b24 176 DAC_fifo[DAC_wptr]=dac_data;
kennyainny 0:910a7c3c9b24 177 DAC_wptr=(DAC_wptr+1) & 0xff;
kennyainny 0:910a7c3c9b24 178 while (DAC_wptr==DAC_rptr) {
kennyainny 0:910a7c3c9b24 179 }
kennyainny 0:910a7c3c9b24 180 }
kennyainny 0:910a7c3c9b24 181 DAC_on=0;
kennyainny 0:910a7c3c9b24 182 tick.detach();
kennyainny 0:910a7c3c9b24 183 free(slice_buf);
kennyainny 0:910a7c3c9b24 184 break;
kennyainny 0:910a7c3c9b24 185 case 0x5453494c:
kennyainny 0:910a7c3c9b24 186 if (verbosity)
kennyainny 0:910a7c3c9b24 187 printf("INFO chunk, size %d\n",chunk_size);
kennyainny 0:910a7c3c9b24 188 fseek(wavefile,chunk_size,SEEK_CUR);
kennyainny 0:910a7c3c9b24 189 break;
kennyainny 0:910a7c3c9b24 190 default:
kennyainny 0:910a7c3c9b24 191 printf("unknown chunk type 0x%x, size %d\n",chunk_id,chunk_size);
kennyainny 0:910a7c3c9b24 192 data=fseek(wavefile,chunk_size,SEEK_CUR);
kennyainny 0:910a7c3c9b24 193 break;
kennyainny 0:910a7c3c9b24 194 }
kennyainny 0:910a7c3c9b24 195 fread(&chunk_id,4,1,wavefile);
kennyainny 0:910a7c3c9b24 196 fread(&chunk_size,4,1,wavefile);
kennyainny 0:910a7c3c9b24 197 }
kennyainny 0:910a7c3c9b24 198 }
kennyainny 0:910a7c3c9b24 199
kennyainny 0:910a7c3c9b24 200
kennyainny 0:910a7c3c9b24 201 void wave_player::dac_out()
kennyainny 0:910a7c3c9b24 202 {
kennyainny 0:910a7c3c9b24 203 if (DAC_on) {
kennyainny 0:910a7c3c9b24 204 #ifdef VERBOSE
kennyainny 0:910a7c3c9b24 205 printf("ISR rdptr %d got %u\n",DAC_rptr,DAC_fifo[DAC_rptr]);
kennyainny 0:910a7c3c9b24 206 #endif
kennyainny 0:910a7c3c9b24 207 wave_DAC->write_u16(DAC_fifo[DAC_rptr]);
kennyainny 0:910a7c3c9b24 208 DAC_rptr=(DAC_rptr+1) & 0xff;
kennyainny 0:910a7c3c9b24 209 }
kennyainny 0:910a7c3c9b24 210 }
kennyainny 0:910a7c3c9b24 211