ffplay代码播放pcm数据

摘抄雷兄

http://blog.csdn.net/leixiaohua1020/article/details/46890259

/**
* 最简单的SDL2播放音频的例子（SDL2播放PCM）
* Simplest Audio Play SDL2 (SDL2 play PCM)
*
* 雷霄骅 Lei Xiaohua
* leixiaohua1020@126.com
* 中国传媒大学/数字电视技术
* Communication University of China / Digital TV Technology
* http://blog.csdn.net/leixiaohua1020 *
* 本程序使用SDL2播放PCM音频采样数据。SDL实际上是对底层绘图
* API（Direct3D，OpenGL）的封装，使用起来明显简单于直接调用底层
* API。
*
* 函数调用步骤如下:
*
* [初始化]
* SDL_Init(): 初始化SDL。
* SDL_OpenAudio(): 根据参数（存储于SDL_AudioSpec）打开音频设备。
* SDL_PauseAudio(): 播放音频数据。
*
* [循环播放数据]
* SDL_Delay(): 延时等待播放完成。
*
* This software plays PCM raw audio data using SDL2.
* SDL is a wrapper of low-level API (DirectSound).
* Use SDL is much easier than directly call these low-level API.
*
* The process is shown as follows:
*
* [Init]
* SDL_Init(): Init SDL.
* SDL_OpenAudio(): Opens the audio device with the desired
*                  parameters (In SDL_AudioSpec).
* SDL_PauseAudio(): Play Audio.
*
* [Loop to play data]
* SDL_Delay(): Wait for completetion of playback.
*/

#include <stdio.h>
#include "SDL2/SDL.h"

//Buffer:
//|-----------|-------------|
//chunk-------pos---len-----|
static  unsigned char *audio_chunk;
static  unsigned int audio_len;
static  unsigned char *audio_pos;

/* Audio Callback
* The audio function callback takes the following parameters:
* stream: A pointer to the audio buffer to be filled
* len: The length (in bytes) of the audio buffer
*
*/
void  fill_audio(void *udata,unsigned char *stream,int len){
//SDL 2.0
SDL_memset(stream, 0, len);
if(audio_len==0)        /*  Only  play  if  we  have  data  left  */
return;
len=(len>audio_len?audio_len:len);   /*  Mix  as  much  data  as  possible  */

SDL_MixAudio(stream,audio_pos,len,SDL_MIX_MAXVOLUME);
audio_pos += len;
audio_len -= len;
}

int main(int argc, char* argv[])
{
//Init
if(SDL_Init(SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
printf( "Could not initialize SDL - %s\n", SDL_GetError());
return -1;
}
//SDL_AudioSpec
SDL_AudioSpec wanted_spec;
wanted_spec.freq = 44100;
wanted_spec.format = AUDIO_S16SYS;
wanted_spec.channels = 2;
wanted_spec.silence = 0;
wanted_spec.samples = 1024;
wanted_spec.callback = fill_audio;

if (SDL_OpenAudio(&wanted_spec, NULL)<0){
printf("can't open audio.\n");
return -1;
}

FILE *fp=fopen("audio_play_48K.pcm","rb+");
if(fp==NULL){
printf("cannot open this file\n");
return -1;
}

int pcm_buffer_size=4096;
char *pcm_buffer=(char *)malloc(pcm_buffer_size);
int data_count=0;

//Play
SDL_PauseAudio(0);

while(1){
if (fread(pcm_buffer, 1, pcm_buffer_size, fp) != pcm_buffer_size){
// Loop
fseek(fp, 0, SEEK_SET);
fread(pcm_buffer, 1, pcm_buffer_size, fp);
data_count=0;
}
printf("Now Playing %10d Bytes data.\n",data_count);
data_count+=pcm_buffer_size;
//Set audio buffer (PCM data)
audio_chunk = (unsigned char*) pcm_buffer;
//Audio buffer length
audio_len =pcm_buffer_size;
audio_pos = audio_chunk;

while(audio_len>0)//Wait until finish
SDL_Delay(1);
}
free(pcm_buffer);
SDL_Quit();
return 0;
}

一、环境搭建

（1）安装sdl

http://www.cnblogs.com/chencesc/p/5759850.html

在安装前为了能在 ubuntu pc上播放 sudo apt-get install libasound2-dev

然后在编译sdl2.0是configure支持pc设备驱动

（2）安装ffmpeg

各版本下载

https://github.com/FFmpeg/FFmpeg/tree/n2.5.2

下载源码编译安装

一、编译运行

1 #Makefile
2
3 GCC=gcc # GCC编译器命令
4 OUTPUT=a.out
5 CFLAGS=-g # 程序优化选项
6 LDFLAGS=-lSDL2main -lSDL2  -lavformat -lavcodec -lavutil -lswscale -lswresample -lm -lpthread -lz -llzma# 链接库
7 EXEC=sdl_audio.c# 程序的名字，由你决定
8
9 all: ${EXEC}
10     ${GCC} $(CFLAGS) -o ${OUTPUT} ${EXEC} ${LDFLAGS}
11 clean:
12     rm -rf ${OUTPUT}

运行要注意linux用pc播放需要以下代码

SDL_AUDIODRIVER=alsa ./a.out

播放效果不错哦