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