waveplayer with play pause
Dependents: WavePlayer_HelloWorld_RTOS5
wave_player.cpp
00001 //----------------------------------------------------------------------------- 00002 // a sample mbed library to play back wave files. 00003 // 00004 // explanation of wave file format. 00005 // https://ccrma.stanford.edu/courses/422/projects/WaveFormat/ 00006 00007 // if VERBOSE is uncommented then the wave player will enter a verbose 00008 // mode that displays all data values as it reads them from the file 00009 // and writes them to the DAC. Very slow and unusable output on the DAC, 00010 // but useful for debugging wave files that don't work. 00011 //#define VERBOSE 00012 00013 00014 #include <mbed.h> 00015 #include <stdio.h> 00016 #include <wave_player.h> 00017 00018 extern bool playing; 00019 short unsigned dac_data; 00020 00021 00022 //----------------------------------------------------------------------------- 00023 // constructor -- accepts an mbed pin to use for AnalogOut. Only p18 will work 00024 wave_player::wave_player(AnalogOut *_dac) 00025 { 00026 wave_DAC=_dac; 00027 wave_DAC->write_u16(32768); //DAC is 0-3.3V, so idles at ~1.6V 00028 verbosity=0; 00029 } 00030 00031 //----------------------------------------------------------------------------- 00032 // if verbosity is set then wave player enters a mode where the wave file 00033 // is decoded and displayed to the screen, including sample values put into 00034 // the DAC FIFO, and values read out of the DAC FIFO by the ISR. The DAC output 00035 // itself is so slow as to be unusable, but this might be handy for debugging 00036 // wave files that don't play 00037 //----------------------------------------------------------------------------- 00038 void wave_player::set_verbosity(int v) 00039 { 00040 verbosity=v; 00041 } 00042 00043 //----------------------------------------------------------------------------- 00044 // player function. Takes a pointer to an opened wave file. The file needs 00045 // to be stored in a filesystem with enough bandwidth to feed the wave data. 00046 // LocalFileSystem isn't, but the SDcard is, at least for 22kHz files. The 00047 // SDcard filesystem can be hotrodded by increasing the SPI frequency it uses 00048 // internally. 00049 //----------------------------------------------------------------------------- 00050 void wave_player::play(FILE *wavefile) 00051 { 00052 unsigned chunk_id,chunk_size,channel; 00053 unsigned data,samp_int,i; 00054 //short unsigned dac_data; 00055 long long slice_value; 00056 char *slice_buf; 00057 short *data_sptr; 00058 unsigned char *data_bptr; 00059 int *data_wptr; 00060 FMT_STRUCT wav_format; 00061 long slice,num_slices; 00062 DAC_wptr=0; 00063 DAC_rptr=0; 00064 for (i=0;i<256;i+=2) { 00065 DAC_fifo[i]=0; 00066 DAC_fifo[i+1]=3000; 00067 } 00068 DAC_wptr=4; 00069 DAC_on=0; 00070 00071 fread(&chunk_id,4,1,wavefile); 00072 fread(&chunk_size,4,1,wavefile); 00073 while (!feof(wavefile)) { 00074 if (verbosity) 00075 printf("Read chunk ID 0x%x, size 0x%x\n",chunk_id,chunk_size); 00076 switch (chunk_id) { 00077 case 0x46464952: 00078 fread(&data,4,1,wavefile); 00079 if (verbosity) { 00080 printf("RIFF chunk\n"); 00081 printf(" chunk size %d (0x%x)\n",chunk_size,chunk_size); 00082 printf(" RIFF type 0x%x\n",data); 00083 } 00084 break; 00085 case 0x20746d66: 00086 fread(&wav_format,sizeof(wav_format),1,wavefile); 00087 if (verbosity) { 00088 printf("FORMAT chunk\n"); 00089 printf(" chunk size %d (0x%x)\n",chunk_size,chunk_size); 00090 printf(" compression code %d\n",wav_format.comp_code); 00091 printf(" %d channels\n",wav_format.num_channels); 00092 printf(" %d samples/sec\n",wav_format.sample_rate); 00093 printf(" %d bytes/sec\n",wav_format.avg_Bps); 00094 printf(" block align %d\n",wav_format.block_align); 00095 printf(" %d bits per sample\n",wav_format.sig_bps); 00096 } 00097 if (chunk_size > sizeof(wav_format)) 00098 fseek(wavefile,chunk_size-sizeof(wav_format),SEEK_CUR); 00099 break; 00100 case 0x61746164: 00101 // allocate a buffer big enough to hold a slice 00102 slice_buf=(char *)malloc(wav_format.block_align); 00103 if (!slice_buf) { 00104 printf("Unable to malloc slice buffer"); 00105 exit(1); 00106 } 00107 num_slices=chunk_size/wav_format.block_align; 00108 samp_int=1000000/(wav_format.sample_rate); 00109 if (verbosity) { 00110 printf("DATA chunk\n"); 00111 printf(" chunk size %d (0x%x)\n",chunk_size,chunk_size); 00112 printf(" %d slices\n",num_slices); 00113 printf(" Ideal sample interval=%d\n",(unsigned)(1000000.0/wav_format.sample_rate)); 00114 printf(" programmed interrupt tick interval=%d\n",samp_int); 00115 } 00116 00117 // starting up ticker to write samples out -- no printfs until tick.detach is called 00118 if (verbosity) 00119 tick.attach_us(this,&wave_player::dac_out, 500000); 00120 else 00121 tick.attach_us(this,&wave_player::dac_out, samp_int); 00122 DAC_on=1; 00123 00124 // start reading slices, which contain one sample each for however many channels 00125 // are in the wave file. one channel=mono, two channels=stereo, etc. Since 00126 // mbed only has a single AnalogOut, all of the channels present are averaged 00127 // to produce a single sample value. This summing and averaging happens in 00128 // a variable of type signed long long, to make sure that the data doesn't 00129 // overflow regardless of sample size (8 bits, 16 bits, 32 bits). 00130 // 00131 // note that from what I can find that 8 bit wave files use unsigned data, 00132 // while 16 and 32 bit wave files use signed data 00133 // 00134 for (slice=0;slice<num_slices;slice+=1) { 00135 if (playing == false){ 00136 00137 break; 00138 } 00139 fread(slice_buf,wav_format.block_align,1,wavefile); 00140 if (feof(wavefile)) { 00141 printf("Oops -- not enough slices in the wave file\n"); 00142 exit(1); 00143 } 00144 data_sptr=(short *)slice_buf; // 16 bit samples 00145 data_bptr=(unsigned char *)slice_buf; // 8 bit samples 00146 data_wptr=(int *)slice_buf; // 32 bit samples 00147 slice_value=0; 00148 for (channel=0;channel<wav_format.num_channels;channel++) { 00149 switch (wav_format.sig_bps) { 00150 case 16: 00151 if (verbosity) 00152 printf("16 bit channel %d data=%d ",channel,data_sptr[channel]); 00153 slice_value+=data_sptr[channel]; 00154 break; 00155 case 32: 00156 if (verbosity) 00157 printf("32 bit channel %d data=%d ",channel,data_wptr[channel]); 00158 slice_value+=data_wptr[channel]; 00159 break; 00160 case 8: 00161 if (verbosity) 00162 printf("8 bit channel %d data=%d ",channel,(int)data_bptr[channel]); 00163 slice_value+=data_bptr[channel]; 00164 break; 00165 } 00166 } 00167 slice_value/=wav_format.num_channels; 00168 00169 // slice_value is now averaged. Next it needs to be scaled to an unsigned 16 bit value 00170 // with DC offset so it can be written to the DAC. 00171 switch (wav_format.sig_bps) { 00172 case 8: slice_value<<=8; 00173 break; 00174 case 16: slice_value+=32768; 00175 break; 00176 case 32: slice_value>>=16; 00177 slice_value+=32768; 00178 break; 00179 } 00180 dac_data=(short unsigned)slice_value; 00181 if (verbosity) 00182 printf("sample %d wptr %d slice_value %d dac_data %u\n",slice,DAC_wptr,(int)slice_value,dac_data); 00183 DAC_fifo[DAC_wptr]=dac_data; 00184 DAC_wptr=(DAC_wptr+1) & 0xff; 00185 while (DAC_wptr==DAC_rptr) { 00186 } 00187 } 00188 DAC_on=0; 00189 tick.detach(); 00190 free(slice_buf); 00191 break; 00192 case 0x5453494c: 00193 if (verbosity) 00194 printf("INFO chunk, size %d\n",chunk_size); 00195 fseek(wavefile,chunk_size,SEEK_CUR); 00196 break; 00197 default: 00198 printf("unknown chunk type 0x%x, size %d\n",chunk_id,chunk_size); 00199 data=fseek(wavefile,chunk_size,SEEK_CUR); 00200 break; 00201 } 00202 fread(&chunk_id,4,1,wavefile); 00203 fread(&chunk_size,4,1,wavefile); 00204 } 00205 } 00206 00207 00208 void wave_player::dac_out() 00209 { 00210 if (DAC_on) { 00211 #ifdef VERBOSE 00212 printf("ISR rdptr %d got %u\n",DAC_rptr,DAC_fifo[DAC_rptr]); 00213 #endif 00214 wave_DAC->write_u16(DAC_fifo[DAC_rptr]); 00215 DAC_rptr=(DAC_rptr+1) & 0xff; 00216 } 00217 } 00218 void wave_player::update_level() 00219 { 00220 dac_data_pub=dac_data; 00221 } 00222
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