jiayi li / ECE4180LAB3

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Fork of wave_player by Steve Ravet

wave_player.cpp@2:fe95c7574400, 2016-02-24 (annotated)

Committer:
conantina
Date:
Wed Feb 24 16:43:33 2016 +0000
Revision:
2:fe95c7574400
Parent:
0:62c18ade9a60 
ECE4180 Lab3

Who changed what in which revision?

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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
sravet 0:62c18ade9a60 21 wave_player::wave_player(AnalogOut *_dac)
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
sravet 0:62c18ade9a60 25 verbosity=0;
sravet 0:62c18ade9a60 26 }
sravet 0:62c18ade9a60 27
sravet 0:62c18ade9a60 28 //-----------------------------------------------------------------------------
sravet 0:62c18ade9a60 29 // if verbosity is set then wave player enters a mode where the wave file
sravet 0:62c18ade9a60 30 // is decoded and displayed to the screen, including sample values put into
sravet 0:62c18ade9a60 31 // the DAC FIFO, and values read out of the DAC FIFO by the ISR. The DAC output
sravet 0:62c18ade9a60 32 // itself is so slow as to be unusable, but this might be handy for debugging
sravet 0:62c18ade9a60 33 // wave files that don't play
sravet 0:62c18ade9a60 34 //-----------------------------------------------------------------------------
sravet 0:62c18ade9a60 35 void wave_player::set_verbosity(int v)
sravet 0:62c18ade9a60 36 {
sravet 0:62c18ade9a60 37 verbosity=v;
sravet 0:62c18ade9a60 38 }
sravet 0:62c18ade9a60 39
sravet 0:62c18ade9a60 40 //-----------------------------------------------------------------------------
sravet 0:62c18ade9a60 41 // player function. Takes a pointer to an opened wave file. The file needs
sravet 0:62c18ade9a60 42 // to be stored in a filesystem with enough bandwidth to feed the wave data.
sravet 0:62c18ade9a60 43 // LocalFileSystem isn't, but the SDcard is, at least for 22kHz files. The
sravet 0:62c18ade9a60 44 // SDcard filesystem can be hotrodded by increasing the SPI frequency it uses
sravet 0:62c18ade9a60 45 // internally.
sravet 0:62c18ade9a60 46 //-----------------------------------------------------------------------------
sravet 0:62c18ade9a60 47 void wave_player::play(FILE *wavefile)
sravet 0:62c18ade9a60 48 {
sravet 0:62c18ade9a60 49 unsigned chunk_id,chunk_size,channel;
sravet 0:62c18ade9a60 50 unsigned data,samp_int,i;
sravet 0:62c18ade9a60 51 short unsigned dac_data;
sravet 0:62c18ade9a60 52 long long slice_value;
sravet 0:62c18ade9a60 53 char *slice_buf;
sravet 0:62c18ade9a60 54 short *data_sptr;
sravet 0:62c18ade9a60 55 unsigned char *data_bptr;
sravet 0:62c18ade9a60 56 int *data_wptr;
sravet 0:62c18ade9a60 57 FMT_STRUCT wav_format;
sravet 0:62c18ade9a60 58 long slice,num_slices;
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 }
sravet 0:62c18ade9a60 137 data_sptr=(short *)slice_buf; // 16 bit samples
sravet 0:62c18ade9a60 138 data_bptr=(unsigned char *)slice_buf; // 8 bit samples
sravet 0:62c18ade9a60 139 data_wptr=(int *)slice_buf; // 32 bit samples
sravet 0:62c18ade9a60 140 slice_value=0;
sravet 0:62c18ade9a60 141 for (channel=0;channel<wav_format.num_channels;channel++) {
sravet 0:62c18ade9a60 142 switch (wav_format.sig_bps) {
sravet 0:62c18ade9a60 143 case 16:
sravet 0:62c18ade9a60 144 if (verbosity)
sravet 0:62c18ade9a60 145 printf("16 bit channel %d data=%d ",channel,data_sptr[channel]);
sravet 0:62c18ade9a60 146 slice_value+=data_sptr[channel];
sravet 0:62c18ade9a60 147 break;
sravet 0:62c18ade9a60 148 case 32:
sravet 0:62c18ade9a60 149 if (verbosity)
sravet 0:62c18ade9a60 150 printf("32 bit channel %d data=%d ",channel,data_wptr[channel]);
sravet 0:62c18ade9a60 151 slice_value+=data_wptr[channel];
sravet 0:62c18ade9a60 152 break;
sravet 0:62c18ade9a60 153 case 8:
sravet 0:62c18ade9a60 154 if (verbosity)
sravet 0:62c18ade9a60 155 printf("8 bit channel %d data=%d ",channel,(int)data_bptr[channel]);
sravet 0:62c18ade9a60 156 slice_value+=data_bptr[channel];
sravet 0:62c18ade9a60 157 break;
sravet 0:62c18ade9a60 158 }
sravet 0:62c18ade9a60 159 }
sravet 0:62c18ade9a60 160 slice_value/=wav_format.num_channels;
sravet 0:62c18ade9a60 161
sravet 0:62c18ade9a60 162 // slice_value is now averaged. Next it needs to be scaled to an unsigned 16 bit value
sravet 0:62c18ade9a60 163 // with DC offset so it can be written to the DAC.
sravet 0:62c18ade9a60 164 switch (wav_format.sig_bps) {
sravet 0:62c18ade9a60 165 case 8: slice_value<<=8;
sravet 0:62c18ade9a60 166 break;
sravet 0:62c18ade9a60 167 case 16: slice_value+=32768;
sravet 0:62c18ade9a60 168 break;
sravet 0:62c18ade9a60 169 case 32: slice_value>>=16;
sravet 0:62c18ade9a60 170 slice_value+=32768;
sravet 0:62c18ade9a60 171 break;
sravet 0:62c18ade9a60 172 }
sravet 0:62c18ade9a60 173 dac_data=(short unsigned)slice_value;
sravet 0:62c18ade9a60 174 if (verbosity)
sravet 0:62c18ade9a60 175 printf("sample %d wptr %d slice_value %d dac_data %u\n",slice,DAC_wptr,(int)slice_value,dac_data);
sravet 0:62c18ade9a60 176 DAC_fifo[DAC_wptr]=dac_data;
sravet 0:62c18ade9a60 177 DAC_wptr=(DAC_wptr+1) & 0xff;
sravet 0:62c18ade9a60 178 while (DAC_wptr==DAC_rptr) {
sravet 0:62c18ade9a60 179 }
sravet 0:62c18ade9a60 180 }
sravet 0:62c18ade9a60 181 DAC_on=0;
sravet 0:62c18ade9a60 182 tick.detach();
sravet 0:62c18ade9a60 183 free(slice_buf);
sravet 0:62c18ade9a60 184 break;
sravet 0:62c18ade9a60 185 case 0x5453494c:
sravet 0:62c18ade9a60 186 if (verbosity)
sravet 0:62c18ade9a60 187 printf("INFO chunk, size %d\n",chunk_size);
sravet 0:62c18ade9a60 188 fseek(wavefile,chunk_size,SEEK_CUR);
sravet 0:62c18ade9a60 189 break;
sravet 0:62c18ade9a60 190 default:
sravet 0:62c18ade9a60 191 printf("unknown chunk type 0x%x, size %d\n",chunk_id,chunk_size);
sravet 0:62c18ade9a60 192 data=fseek(wavefile,chunk_size,SEEK_CUR);
sravet 0:62c18ade9a60 193 break;
sravet 0:62c18ade9a60 194 }
sravet 0:62c18ade9a60 195 fread(&chunk_id,4,1,wavefile);
sravet 0:62c18ade9a60 196 fread(&chunk_size,4,1,wavefile);
sravet 0:62c18ade9a60 197 }
sravet 0:62c18ade9a60 198 }
sravet 0:62c18ade9a60 199
sravet 0:62c18ade9a60 200
sravet 0:62c18ade9a60 201 void wave_player::dac_out()
sravet 0:62c18ade9a60 202 {
sravet 0:62c18ade9a60 203 if (DAC_on) {
sravet 0:62c18ade9a60 204 #ifdef VERBOSE
sravet 0:62c18ade9a60 205 printf("ISR rdptr %d got %u\n",DAC_rptr,DAC_fifo[DAC_rptr]);
sravet 0:62c18ade9a60 206 #endif
sravet 0:62c18ade9a60 207 wave_DAC->write_u16(DAC_fifo[DAC_rptr]);
sravet 0:62c18ade9a60 208 DAC_rptr=(DAC_rptr+1) & 0xff;
sravet 0:62c18ade9a60 209 }
sravet 0:62c18ade9a60 210 }
sravet 0:62c18ade9a60 211