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    基于alsa驱动架构的pcm播放

    /*modify by hfl 2014-2-16*/ /* Use the newer ALSA API */ #define ALSA_PCM_NEW_HW_PARAMS_API #include <alsa/asoundlib.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <fcntl.h> int main(int argc, char *argv[]) {   long loops;   int rc;   int size;   snd_pcm_t *handle;   snd_pcm_hw_params_t *params;   unsigned int val;   int dir;   snd_pcm_uframes_t frames;   printf("222133\n");  char buffer[20*2];/*size=frame*channles*byte persaple*/  int fd,i; if (argc != 2) { fprintf (stderr, "usage: %s <filename>!\n", argv[0]); exit ( -1 ) ; } if ( ( fd = open (argv[1],O_RDONLY))<0) { fprintf ( stderr, " Can't open sound file!\n"); exit (-1 ); }   /* Open PCM device for playback. */   rc = snd_pcm_open(&handle, "default",                     SND_PCM_STREAM_PLAYBACK, 0);   if (rc < 0) {     fprintf(stderr,             "unable to open pcm device: %s\n",             snd_strerror(rc));     exit(1);   }   /* Allocate a hardware parameters object. */   snd_pcm_hw_params_alloca(¶ms);   /* Fill it in with default values. */   snd_pcm_hw_params_any(handle, params);   /* Set the desired hardware parameters. */   /* Interleaved mode */   snd_pcm_hw_params_set_access(handle, params,                       SND_PCM_ACCESS_RW_INTERLEAVED);   /* Signed 16-bit little-endian format */   snd_pcm_hw_params_set_format(handle, params,                               SND_PCM_FORMAT_S16_LE);   /* Two channels (stereo) */   snd_pcm_hw_params_set_channels(handle, params, 1);   /* 44100 bits/second sampling rate (CD quality) */   val = 16000;   snd_pcm_hw_params_set_rate_near(handle, params,                                   &val, &dir);   /* Set period size to 32 frames. */   frames =20;/*一次送人的帧太少，会下溢冲（至少15帧)*/  // snd_pcm_hw_params_set_period_size_near(handle,  params, &frames, &dir);   /* Write the parameters to the driver */   rc = snd_pc

    03

    libmad学习进阶4 -----基于atlas音频驱动架构的MP3播放器

    /*modify by hfl 20140216*/ #define ALSA_PCM_NEW_HW_PARAMS_API # include <stdio.h> # include <unistd.h> # include <sys/stat.h> # include <sys/mman.h> # include "mad.h" #include<sys/types.h> #include<sys/stat.h> #include<fcntl.h> #include<stdlib.h> #include <sys/ioctl.h> #include <sys/soundcard.h> #include <alsa/asoundlib.h> /*  * This is perhaps the simplest example use of the MAD high-level API.  * Standard input is mapped into memory via mmap(), then the high-level API  * is invoked with three callbacks: input, output, and error. The output  * callback converts MAD's high-resolution PCM samples to 16 bits, then  * writes them to standard output in little-endian, stereo-interleaved  * format.  */  //#define printf     static Get_file_length(char *PATH); static int init_dsp(); static int Uninit_dsp(); static int decode(unsigned char const *, unsigned long); static enum mad_flow outputplay(void *data,     struct mad_header const *header,     struct mad_pcm *pcm); int main(int argc, char *argv[]) { printf("The main is start!\n");   struct stat stat;   void *fdm;   int  fd;   //char buffer1[80000];   printf("###The input file is %s  ! the arc=%d###\n",argv[1],argc);   if (argc == 1)    {    printf("The argc is wrong!\n");     return 1;  } #if 0   if (fstat(STDIN_FILENO, &stat) == -1 ||       stat.st_size == 0)     return 2; #endif  fd =open(argv[1],O_RDWR); if(-1==fd) {    printf("sorry,The file open is faild!\n"); } else {  printf("The file open is sucessed!\n"); } //read(fd,buffer1,sizeof(buffer1)); //printf("%s", buffer1); stat.st_size = Get_file_length(argv[1]); printf("The file size is %d\n",stat.st_size ); printf("The Map is begin ok!\n"); fdm = mmap(0, stat.st_size, PROT_READ, MAP_SHARED, fd, 0);   if (fdm == MAP_FAILED) { printf("mmap is failed\n");     return 3; }   decode(fdm, stat.st_size);   if (munmap(fdm, stat.st

    02

    libmad学习进阶2----利用libmad将mp3转码成pcm

    # include <stdio.h> # include <unistd.h> # include <sys/stat.h> # include <sys/mman.h> # include "mad.h" #include<sys/types.h> #include<sys/stat.h> #include<fcntl.h> #include<stdlib.h> /* * This is perhaps the simplest example use of the MAD high-level API. * Standard input is mapped into memory via mmap(), then the high-level API * is invoked with three callbacks: input, output, and error. The output * callback converts MAD's high-resolution PCM samples to 16 bits, then * writes them to standard output in little-endian, stereo-interleaved * format. */ #define printf static Get_file_length(char *PATH); static int decode(unsigned char const *, unsigned long); int main(int argc, char *argv[]) { printf("The main is start!\n"); struct stat stat; void *fdm; int fd; //char buffer1[80000]; printf("###The input file is %s ! the arc=%d###\n",argv[1],argc); if (argc == 1) { printf("The argc is wrong!\n"); return 1; } #if 0 if (fstat(STDIN_FILENO, &stat) == -1 || stat.st_size == 0) return 2; #endif fd =open(argv[1],O_RDWR); if(-1==fd) { printf("sorry,The file open is faild!\n"); } else { printf("The file open is sucessed!\n"); } //read(fd,buffer1,sizeof(buffer1)); //printf("%s", buffer1); stat.st_size = Get_file_length(argv[1]); printf("The file size is %d\n",stat.st_size ); printf("The Map is begin!\n"); fdm = mmap(0, stat.st_size, PROT_READ, MAP_SHARED, fd, 0); if (fdm == MAP_FAILED) { printf("mmap is failed\n"); return 3; } decode(fdm, stat.st_size); if (munmap(fdm, stat.st_size) == -1) return 4; return 0; } /* * This is a private message structure. A generic pointer to this structure * is passed to each of the callback functions. Put here any data you need * to access from within the callbacks. */ struct buffer { unsigned char const *start; unsigned long length; }; /* * This is the input callback. The purpose of this callback is to

    05

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