<pre name="code" class="cpp">/*
* libmad - MPEG audio decoder library
* Copyright (C) 2000-2004 Underbit Technologies, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* $Id: minimad.c,v 1.4 2004/01/23 09:41:32 rob Exp $
*/
#include <stdio.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <pthread.h>
#include "alsa/asoundlib.h"
#include "mad.h"
#include "player_ipc_interface.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 DEBUG(x,y...) //{printf("[ %s : %s : %d] ",__FILE__, __func__, __LINE__); printf(x,##y); printf("\n");}
#define ERROR(x,y...) {printf("[ %s : %s : %d] ",__FILE__, __func__, __LINE__); printf(x,##y); printf("\n");}
typedef struct mad_decoder_s {
struct mad_synth synth;
struct mad_stream stream;
struct mad_frame frame;
} mad_decoder_t;
extern player_shm_t *shm_buff;
static int to_stop_play = 0;
static inline void play_frame(mad_decoder_t *mad_decoder);
static inline signed int scale(mad_fixed_t sample);
static int set_pcm();
static snd_pcm_t *handle = NULL; //PCI设备句柄
static snd_pcm_hw_params_t* params = NULL;//硬件信息和PCM流配置
static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
int libmad_play_mp3(char *mp3_file, res_type_t type)
{
struct stat stat;
int fd;
int count;
char *buff = NULL;
mad_decoder_t *this;
int buf_size = 1152;
int buf_len = 0;
this = calloc(1, sizeof(mad_decoder_t));
buff = malloc(buf_size);
if(buff)
memset(buff,0,buf_size);
mad_synth_init (&this->synth);
mad_stream_init (&this->stream);
mad_frame_init (&this->frame);
if(NULL == mp3_file || strlen(mp3_file) == 0){
ERROR("mp3_file is NULL of empty.");
return -1;
}
if(shm_buff){
strcpy(shm_buff->url, mp3_file);
shm_buff->type = type;
shm_buff->is_playing = 1;
}else{
ERROR("player share memory shm_buff is NULL\n");
return -2;
}
fd = open(mp3_file, O_RDONLY);
if(fd < 0){
perror("open file failed:");
return -2;
}
if (fstat(fd, &stat) == -1 || stat.st_size == 0){
ERROR("fstat failed:\n");
return -3;
}
if(set_pcm(fd, this)!=0){ //设置pcm 参数
ERROR("set_pcm fialed:\n");
return -4;
}
while((count = read(fd, buff+buf_len, buf_size-buf_len)) > 0){
buf_len += count;
if(count < 0){
ERROR("read mp3_file error:%s", strerror(errno));
return -5;
}
if(to_stop_play){
break;
}
while(1){
int ret;
mad_stream_buffer (&this->stream, (unsigned char *)buff, buf_len);
ret=mad_frame_decode (&this->frame, &this->stream);
if (this->stream.next_frame) {
int num_bytes =
(char*)buff+buf_len - (char*)this->stream.next_frame;
memmove(buff, this->stream.next_frame, num_bytes);
buf_len = num_bytes;
}
if (ret == 0)
play_frame(this);
// error! try to resync!
if(this->stream.error==MAD_ERROR_BUFLEN) break;
}
}
if(shm_buff){
memset(shm_buff->url, 0, URL_SIZE);
shm_buff->type = UNKNOWN_TYPE;
shm_buff->is_playing = 0;
pthread_mutex_lock(&mutex);
to_stop_play = 0;
pthread_mutex_unlock(&mutex);
}
mad_synth_finish (&this->synth);
mad_frame_finish (&this->frame);
mad_stream_finish(&this->stream);
free(this);
free(buff);
close(fd);
snd_pcm_drain(handle);
snd_pcm_close(handle);
return 0;
}
static inline void play_frame(mad_decoder_t *this)
{
mad_synth_frame (&this->synth, &this->frame);
unsigned int nchannels, nsamples,n;
mad_fixed_t const *left_ch, *right_ch;
struct mad_pcm *pcm = &this->synth.pcm;
/* pcm->samplerate contains the sampling frequency */
nchannels = pcm->channels;
n=nsamples = pcm->length;
left_ch = pcm->samples[0];
right_ch = pcm->samples[1];
unsigned char Output[6912], *OutputPtr;
//int fmt, wrote, speed, exact_rate, err, dir;
// printf("This is output\n");
OutputPtr = Output;
while (nsamples--)
{
signed int sample;
/* output sample(s) in 16-bit signed little-endian PCM */
sample = scale(*left_ch++);
*(OutputPtr++) = sample >> 0;
*(OutputPtr++) = sample >> 8;
if (nchannels == 2)
{
sample = scale (*right_ch++);
*(OutputPtr++) = sample >> 0;
*(OutputPtr++) = sample >> 8;
}
}
snd_pcm_writei (handle, Output, n);
}
void libmad_stop_play_mp3()
{
DEBUG("url:%s, type:%d, is_playing:%d\n", shm_buff->url, shm_buff->type, shm_buff->is_playing);
if(shm_buff && shm_buff->type == CAN_STOP && shm_buff->is_playing){
memset(shm_buff->url, 0, URL_SIZE);
shm_buff->type = UNKNOWN_TYPE;
shm_buff->is_playing = 0;
pthread_mutex_lock(&mutex);
to_stop_play = 1;
pthread_mutex_unlock(&mutex);
}
}
static int set_pcm(int fd, mad_decoder_t *this)
{
int rc;
int dir=0;
unsigned int rate = 44100;; /* 采样频率 44.1KHz*/
//int format = SND_PCM_FORMAT_S16_LE; /* 量化位数 16 */
int channels = 2; /* 声道数 2 */
char *buff = NULL;
int buf_size = 1152;
int buf_len = 0;
int count;
int flag = 0;
buff = malloc(buf_size);
if(buff)
memset(buff,0,buf_size);
while((count = read(fd, buff+buf_len, buf_size-buf_len)) > 0){
buf_len += count;
if(count < 0){
ERROR("read mp3_file error:%s", strerror(errno));
return -5;
}
while(1){
int ret;
mad_stream_buffer (&this->stream, (unsigned char *)buff, buf_len);
ret=mad_frame_decode (&this->frame, &this->stream);
if (this->stream.next_frame) {
int num_bytes =
(char*)buff+buf_len - (char*)this->stream.next_frame;
memmove(buff, this->stream.next_frame, num_bytes);
buf_len = num_bytes;
}
if (ret == 0){
channels = MAD_NCHANNELS(&(this->frame.header)); //动态设置通道数，采样率
rate = this->frame.header.samplerate;
flag = 1;
break;
}
}
if(flag)
break;
}
lseek(fd, 0, SEEK_SET);
free(buff);
rc=snd_pcm_open(&handle, "default", SND_PCM_STREAM_PLAYBACK, 0);
if(rc<0){
perror("\nopen PCM device failed:");
exit(1);
}
snd_pcm_hw_params_alloca(¶ms); //分配params结构体
rc=snd_pcm_hw_params_any(handle, params);//初始化params
if(rc<0){
perror("\nsnd_pcm_hw_params_any:");
exit(1);
}
rc=snd_pcm_hw_params_set_access(handle, params, SND_PCM_ACCESS_RW_INTERLEAVED); //初始化访问权限
if(rc<0){
perror("\nsed_pcm_hw_set_access:");
exit(1);
}
rc=snd_pcm_hw_params_set_format(handle, params, SND_PCM_FORMAT_S16_LE); //设置16位采样精度
if(rc<0){
perror("snd_pcm_hw_params_set_format failed:");
exit(1);
}
rc=snd_pcm_hw_params_set_channels(handle, params, channels); //设置声道,1表示单声>道，2表示立体声
if(rc<0){
perror("\nsnd_pcm_hw_params_set_channels:");
exit(1);
}
rc=snd_pcm_hw_params_set_rate_near(handle, params, &rate, &dir); //设置>频率
if(rc<0){
perror("\nsnd_pcm_hw_params_set_rate_near:");
exit(1);
}
rc = snd_pcm_hw_params(handle, params);
if(rc<0){
perror("\nsnd_pcm_hw_params: ");
exit(1);
}
return 0;
}
/*
* The following utility routine performs simple rounding, clipping, and
* scaling of MAD's high-resolution samples down to 16 bits. It does not
* perform any dithering or noise shaping, which would be recommended to
* obtain any exceptional audio quality. It is therefore not recommended to
* use this routine if high-quality output is desired.
*/
static inline
signed int scale(mad_fixed_t sample)
{
/* round */
sample += (1L << (MAD_F_FRACBITS - 16));
/* clip */
if (sample >= MAD_F_ONE)
sample = MAD_F_ONE - 1;
else if (sample < -MAD_F_ONE)
sample = -MAD_F_ONE;
/* quantize */
return sample >> (MAD_F_FRACBITS + 1 - 16);
}
