使用openal與mpg123播放MP3，(轉)

使用openal與mpg123播放MP3，附帶工程文件(轉)

2013-12-09 01:47 本站整理 瀏覽(5)

使用openal與mpg123播放MP3，附帶工程文件

使用openal和mpg123播放MP3文件
使用靜態編譯，相關文件都在附件裏
相關工程文件：openal_mpg123_player.7z
使用visual studio 2010編譯，理論上是跨平臺的
相關說明請看源代碼註釋以及mpg123.h和openal文檔

/*AUTHOR bowman han
* NOTE  this is a test program for mpg123 basic usage
* EMAIL  [email protected]
* DATA　６／２　２０１２
* Please DO NOT REMOVE THIS
*/

#include "openal\include\al.h"
#include "openal\include\alc.h"
#include <stdio.h>
#include <Windows.h>
#define NUM_BUFFERS 4
#include "mpg123\mpg123.h"
#include <conio.h>

#pragma comment (lib, "./mpg123/libmpg123.lib")
#pragma comment (lib, "./openal/lib/OpenAL32.lib")
int main()
{
    ALuint g_Buffers[NUM_BUFFERS];
    ALuint uiSource;
    ALuint uiBuffer;
    ALCdevice * pDevice = NULL;
    ALCcontext *pContext = NULL;
    ALboolean g_bEAX;
    ALenum error, eBufferFormat;
    ALint iDataSize, iFrequency;
    ALuint ulFormat;
    int iLoop,iBuffersProcessed, iTotalBuffersProcessed;
    unsigned long ulDataSize = 0;
    unsigned long ulFrequency = 0;
    unsigned long ulBufferSize;
    unsigned long ulBytesWritten;
    long lRate;
    int iEncoding, iChannels;
    int encoding;
    void *        pData = NULL;
    WAVEFORMATEX *pwfex;
    int iState, iQueuedBuffers;
    mpg123_handle *mpg123 ;
    int iMpg123_error;
    //init mpg123 library
    if(MPG123_OK != (iMpg123_error = mpg123_init()))
    {
        printf("failed to init mpg123\n");
        return -1;
    }

    //open a default mpg123 decoder
    mpg123 = mpg123_new(mpg123_decoders()[0], &iMpg123_error);

    //open a openal default device
    pDevice = alcOpenDevice(NULL); //select the perfered device
    
    if(pDevice){
        pContext = alcCreateContext(pDevice, NULL);
        alcMakeContextCurrent(pContext);
    }else
    {
        printf("failed to get a openal decice\n");
        return -2;
    }

    g_bEAX = alIsExtensionPresent("EAX2.0");

    //Generate openal  Buffers
    alGetError();  //clear all error code
    
    alGenBuffers(NUM_BUFFERS, g_Buffers);

    if((error = alGetError()) != AL_NO_ERROR)
    {
        fprintf(stderr, "alGenBuffers :%s", error);
    }

    alGenSources(1, &uiSource);

    //try to open a mp3 file, modify to your own mp3 files
    if(MPG123_OK != (iMpg123_error = mpg123_open(mpg123,"D:\\sound\\320k.mp3")))
    {
        fprintf(stderr,"error in open mp3 file\n");
        return -1;
    }
    //get mp3 format infomation
    mpg123_getformat(mpg123, &lRate, &iChannels,  &iEncoding);

    //there only parse stereo mp3 file
    if(iChannels ==2)
    {
        ulFormat = alGetEnumValue("AL_FORMAT_STEREO16");
        ulBufferSize = lRate;  //set buffer to 250ms
        ulBufferSize -= (ulBufferSize % 4);  //set pcm Block align
        ulFrequency = lRate;  //set pcm sample rate

    }
    else
    {
        printf("channels info%i\n", iChannels);
        return -3;
    }

    pData = malloc(ulBufferSize);
    //feed data to openal buffer
    for(iLoop= 0; iLoop < 4; iLoop++)
    {
        mpg123_read(mpg123, (char *)pData, ulBufferSize,&ulBytesWritten);
        alBufferData(g_Buffers[iLoop], ulFormat, pData, ulBytesWritten, ulFrequency);
        alSourceQueueBuffers(uiSource, 1, &g_Buffers[iLoop]);
    }
    alSourcePlay(uiSource);
    iTotalBuffersProcessed = 0;
    printf("playing\n");
    //wait for key press
    while(!_kbhit())
    {
        Sleep(20);
        iBuffersProcessed = 0;
        alGetSourcei(uiSource, AL_BUFFERS_PROCESSED, &iBuffersProcessed);

        iTotalBuffersProcessed += iBuffersProcessed;
        printf("Buffers total Processed %d\r", iTotalBuffersProcessed);
        while(iBuffersProcessed)
        {
            uiBuffer = 0;
            alSourceUnqueueBuffers(uiSource, 1, &uiBuffer);

            mpg123_read(mpg123, (char *)pData, ulBufferSize, &ulBytesWritten);
            if(ulBytesWritten)
            {
                alBufferData(uiBuffer, ulFormat, pData, ulBytesWritten, ulFrequency);
                alSourceQueueBuffers(uiSource, 1, &uiBuffer);
            }                iBuffersProcessed--;

        }
        alGetSourcei(uiSource, AL_SOURCE_STATE, &iState);
        if(iState != AL_PLAYING)
        {
            alGetSourcei(uiSource, AL_BUFFERS_QUEUED, &iQueuedBuffers);
            
            if(iQueuedBuffers)
            {
                alSourcePlay(uiSource);//buffers have data, play it
            }
            else
            {
                //there is no data any more
                break;
            }
        }
    }
    //close mpg123
    mpg123_close(mpg123);
    //stop the source and clear the queue
    alSourceStop(uiSource);
    alSourcei(uiSource, AL_BUFFER, 0);

    free(pData);
    pData = NULL;

    

    return 0;
}