Question

我是Objective-C的新手......

我找到了源代码如何使用OpenAl，复制它然后进行测试，但声音是干扰播放的。你能看一下代码并告诉我有什么问题吗？

ALCcontext *context = NULL;
ALCdevice *device = alcOpenDevice(NULL);
if (device)
{
    context = alcCreateContext(device, NULL);
    alcMakeContextCurrent(context);
}
NSString *path = [[NSBundle mainBundle] pathForResource:@"sound" ofType:@"caf"];

AudioFileID fileID = 0;
NSURL *url = [NSURL fileURLWithPath:path];

OSStatus result = AudioFileOpenURL((CFURLRef)url, kAudioFileReadPermission, 0, &fileID);
if (result != 0)
    NSLog(@"Faild to load file at path:%@",path);

UInt32 fileSize = 0;
UInt32 propSize = sizeof(UInt64);

OSStatus result1 = AudioFileGetProperty(fileID, kAudioFilePropertyAudioDataByteCount, &propSize, &fileSize);
if (result1 != 0)
    NSLog(@"Cannot get size of file!");

unsigned char *buffer = malloc(fileSize);
OSStatus result2 = noErr;
result2 = AudioFileReadBytes(fileID, false, 0, &fileSize, buffer);
AudioFileClose(fileID);
if (result2 != 0)
    NSLog(@"Cannot load data from file!");

ALuint bufferId = 0;
alGenBuffers(1, &bufferId);
alBufferData(bufferId, AL_FORMAT_STEREO16,  buffer, fileSize, 44100);

free(buffer); 

ALuint sourceId = 0;
alGenSources(1, &sourceId);
alSourcei(sourceId, AL_BUFFER, bufferId);
alSourcef(sourceId, AL_PITCH, 1.0f);
alSourcef(sourceId, AL_GAIN, 1.0f); 
alSourcei(sourceId, AL_LOOPING, AL_TRUE);

alSourcePlay(sourceId);

Answer 1

如果声音数据未存储在内存中，则无法播放声音。

free(buffer);

您的声音数据从内存中擦除，alBufferData（）仅将OpenAL绑定到声音数据。我建议将缓冲区指针存储在其他位置，以便在您希望从内存中删除声音时释放它。

Answer 2

您对磁盘上的源数据做了很多假设（字节序，通道数，交错，格式）。您应该在加载文件时查看ASBD并为您转换音频服务。

以下是加载用于OpenAL的音频数据的示例：https://github.com/kstenerud/ObjectAL-for-iPhone/blob/master/libs/ObjectAL/Support/OALAudioFile.m

IOS / OpenAl声音干扰

2 个答案: