alDeleteBuffers函数的“'Invalid”错误

Question

在此程序中，函数alDeleteBuffers在几秒钟后生成Invalid Name错误：

#include <stdio.h>
#include <math.h>


#ifdef __APPLE__
#include <OpenAL/al.h>
#include <OpenAL/alc.h>
#elif __linux
#include <AL/al.h>
#include <AL/alut.h>
#include <AL/alc.h>
#endif


#include <iostream>
#include <thread>
using namespace std;


class Sound
{
public:
    ALCdevice* openal_output_device;
    ALCcontext* openal_output_context;


    int al_check_error(const char * given_label)
    {
        ALenum al_error = alGetError();

        if(al_error != AL_NO_ERROR)
        {
            printf("ERROR - %s  (%s)\n", alGetString(al_error), given_label);
            return al_error;
        }
        return 0;
    }

    void StartAl()
    {
        const char* defname = alcGetString(0,ALC_DEFAULT_DEVICE_SPECIFIER);
        openal_output_device  = alcOpenDevice(defname);
        openal_output_context = alcCreateContext(openal_output_device,0);
        alcMakeContextCurrent(openal_output_context);
    }

    void EndAl()
    {
        alcMakeContextCurrent(0);
        al_check_error("EndAl1");
        alcDestroyContext(openal_output_context);
        al_check_error("EndAl2");
        alcCloseDevice(openal_output_device);
        al_check_error("EndAl3");
    }

    void Beep(float frequency, float seconds)
    {
        seconds *= 2;

        ALuint internal_buffer;
        ALuint streaming_source[1];

        alGenBuffers(1,&internal_buffer);
        al_check_error("failed call to alGenBuffers");

        /* Fill buffer with Sine-Wave */
        unsigned sample_rate = 10000;

        size_t buf_size = seconds*sample_rate;

        // allocate PCM audio buffer
        short* samples = new short[buf_size];

        for(int i = 0; i < buf_size; i++)
            samples[i] = 32760*sin(2*M_PI*i*frequency/sample_rate);


        /* upload buffer to OpenAL */
        alBufferData(internal_buffer, AL_FORMAT_MONO16, samples, buf_size, sample_rate);
        al_check_error("alBufferData Failed");

        delete[] samples;//free(samples);

        /* Set-up sound source and play buffer */

        alGenSources(1,&streaming_source[0]);
        alSourcei(streaming_source[0], AL_BUFFER, internal_buffer);
        alSourcePlay(streaming_source[0]);


        ALenum current_playing_state;
        alGetSourcei(streaming_source[0],AL_SOURCE_STATE,&current_playing_state);
        al_check_error("alGetSourcei Failed");

        alutSleep(seconds);
        while(current_playing_state == AL_PLAYING)
        {
            alGetSourcei(streaming_source[0], AL_SOURCE_STATE, &current_playing_state);
            if(al_check_error("alGetSourcei in while loop") != 0)
                break;
            alutSleep(0.1);
        }

        alSourceStopv(1,&streaming_source[0]);
        al_check_error("alSourceStopv");
        alSourcei(streaming_source[0],AL_BUFFER,0);
        al_check_error("alSourcei");
        alDeleteSources(1,&streaming_source[0]);
        al_check_error("alDeleteSources");

        alDeleteBuffers(16,&streaming_source[0]); // HERE HERE HERE HERE
        al_check_error("alDeleteBuffers");
    }

    Sound()
    {
        StartAl();
    }
    ~Sound()
    {
        EndAl();
    }
};


void Beep(float frequency = 440, float seconds = 1)
{
    static Sound s;
    s.Beep(frequency,seconds);
}


int main()
{
   for(int i = 0; i < 1000; i++)
   {
        thread t(Beep, 840,0.5);
        t.detach();
        alutSleep(0.01);
        cout<< i << "\n";
   }
    cin.get();
}     

此外，EndAl方法中的所有OpenAl函数都会产生(null)错误。

为什么会发生这种情况，有没有办法解决它？

就是这条线

alDeleteBuffers(16,&streaming_source[0]);

是否需要释放缓冲区和占用的内存？

Answer 1

我建议你改变

alDeleteBuffers(16,&streaming_source[0]); // HERE HERE HERE HERE

至

alDeleteBuffers(1,&internal_buffer); // HERE HERE HERE HERE

因为这个函数似乎是一个缓冲区删除器。

此外，您也不需要使用数组：

ALuint streaming_source[1];

使用变量代替，以获得更简单的代码。

关于(null)错误，我不知道，可能不是错误，因为OpenAl已经结束了，alGetError在这种情况下可能不能使用。