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你知道 Apple 的带有CameraRipple效果的示例代码吗?好吧,在openGL完成了水的所有凉爽效果之后,我正试图将相机输出记录在一个文件中。

我已经用 glReadPixels 完成了,我在其中读取了 void * buffer 中的所有像素,创建 CVPixelBufferRef 并将其附加到 AVAssetWriterInputPixelBufferAdaptor,但它太慢了,因为 readPixels 需要大量时间。我发现使用 FBO 和纹理现金你可以做同样的事情,但速度更快。这是我在 Apple 使用的 drawInRect 方法中的代码:

CVReturn err = CVOpenGLESTextureCacheCreate(kCFAllocatorDefault, NULL, (__bridge void *)_context, NULL, &coreVideoTextureCashe);
if (err) 
{
    NSAssert(NO, @"Error at CVOpenGLESTextureCacheCreate %d");
}


CFDictionaryRef empty; // empty value for attr value.
CFMutableDictionaryRef attrs2;
empty = CFDictionaryCreate(kCFAllocatorDefault, // our empty IOSurface properties dictionary
                           NULL,
                           NULL,
                           0,
                           &kCFTypeDictionaryKeyCallBacks,
                           &kCFTypeDictionaryValueCallBacks);
attrs2 = CFDictionaryCreateMutable(kCFAllocatorDefault,
                                  1,
                                  &kCFTypeDictionaryKeyCallBacks,
                                  &kCFTypeDictionaryValueCallBacks);

CFDictionarySetValue(attrs2,
                     kCVPixelBufferIOSurfacePropertiesKey,
                     empty);

//CVPixelBufferPoolCreatePixelBuffer (NULL, [assetWriterPixelBufferInput pixelBufferPool], &renderTarget);
CVPixelBufferRef pixiel_bufer4e = NULL;

CVPixelBufferCreate(kCFAllocatorDefault, 
                    (int)_screenWidth, 
                    (int)_screenHeight,
                    kCVPixelFormatType_32BGRA,
                    attrs2,
                    &pixiel_bufer4e);
CVOpenGLESTextureRef renderTexture;
CVOpenGLESTextureCacheCreateTextureFromImage (kCFAllocatorDefault,
                                              coreVideoTextureCashe, pixiel_bufer4e,
                                              NULL, // texture attributes
                                              GL_TEXTURE_2D,
                                              GL_RGBA, // opengl format
                                              (int)_screenWidth, 
                                              (int)_screenHeight,
                                              GL_BGRA, // native iOS format
                                              GL_UNSIGNED_BYTE,
                                              0,
                                              &renderTexture);
CFRelease(attrs2);
CFRelease(empty);
glBindTexture(CVOpenGLESTextureGetTarget(renderTexture), CVOpenGLESTextureGetName(renderTexture));
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, CVOpenGLESTextureGetName(renderTexture), 0);

CVPixelBufferLockBaseAddress(pixiel_bufer4e, 0);

if([pixelAdapter appendPixelBuffer:pixiel_bufer4e withPresentationTime:currentTime]) {
                float result = currentTime.value;
            NSLog(@"\n\n\4eta danni i current time e : %f \n\n",result);
                currentTime = CMTimeAdd(currentTime, frameLength);
        }

CVPixelBufferUnlockBaseAddress(pixiel_bufer4e, 0);
CVPixelBufferRelease(pixiel_bufer4e);
CFRelease(renderTexture);
CFRelease(coreVideoTextureCashe);

它录制了一段视频,而且速度很快,但视频只是黑色的,我认为 textureCashRef 不是正确的,还是我填错了。

作为更新,这是我尝试过的另一种方式。我肯定错过了什么。在 viewDidLoad 中,设置 openGL 上下文后,我执行以下操作:

CVOpenGLESTextureCacheCreate(kCFAllocatorDefault, NULL, (__bridge   void *)_context, NULL, &coreVideoTextureCashe);

    if (err) 
    {
        NSAssert(NO, @"Error at CVOpenGLESTextureCacheCreate %d");
    }

    //creats the pixel buffer

    pixel_buffer = NULL;
    CVPixelBufferPoolCreatePixelBuffer (NULL, [pixelAdapter pixelBufferPool], &pixel_buffer);

    CVOpenGLESTextureRef renderTexture;
    CVOpenGLESTextureCacheCreateTextureFromImage (kCFAllocatorDefault, coreVideoTextureCashe, pixel_buffer,
                                                  NULL, // texture attributes
                                                  GL_TEXTURE_2D,
                                                  GL_RGBA, //  opengl format
                                                   (int)screenWidth,
                                                  (int)screenHeight,
                                                  GL_BGRA, // native iOS format
                                                  GL_UNSIGNED_BYTE,
                                                  0,
                                                  &renderTexture);

    glBindTexture(CVOpenGLESTextureGetTarget(renderTexture), CVOpenGLESTextureGetName(renderTexture));
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, CVOpenGLESTextureGetName(renderTexture), 0);

然后在 drawInRect: 我这样做:

 if(isRecording&&writerInput.readyForMoreMediaData) {
    CVPixelBufferLockBaseAddress(pixel_buffer, 0);

    if([pixelAdapter appendPixelBuffer:pixel_buffer withPresentationTime:currentTime]) {
        currentTime = CMTimeAdd(currentTime, frameLength);
    }
    CVPixelBufferLockBaseAddress(pixel_buffer, 0);
    CVPixelBufferRelease(pixel_buffer);
}

然而它在渲染纹理上因 bad_acsess 而崩溃,它不是零,而是 0x000000001。

更新

使用下面的代码,我实际上设法提取了视频文件,但有一些绿色和红色闪烁。我使用 BGRA pixelFormatType。

这里我创建了纹理缓存:

CVReturn err2 = CVOpenGLESTextureCacheCreate(kCFAllocatorDefault, NULL, (__bridge void *)_context, NULL, &coreVideoTextureCashe);
if (err2) 
{
    NSLog(@"Error at CVOpenGLESTextureCacheCreate %d", err);
    return;
}

然后在 drawInRect 我称之为:

if(isRecording&&writerInput.readyForMoreMediaData) {
    [self cleanUpTextures];



    CFDictionaryRef empty; // empty value for attr value.
    CFMutableDictionaryRef attrs2;
    empty = CFDictionaryCreate(kCFAllocatorDefault, // our empty IOSurface properties dictionary
                           NULL,
                           NULL,
                           0,
                           &kCFTypeDictionaryKeyCallBacks,
                           &kCFTypeDictionaryValueCallBacks);
    attrs2 = CFDictionaryCreateMutable(kCFAllocatorDefault,
                                   1,
                                   &kCFTypeDictionaryKeyCallBacks,
                                   &kCFTypeDictionaryValueCallBacks);

    CFDictionarySetValue(attrs2,
                     kCVPixelBufferIOSurfacePropertiesKey,
                     empty);

//CVPixelBufferPoolCreatePixelBuffer (NULL, [assetWriterPixelBufferInput pixelBufferPool], &renderTarget);
    CVPixelBufferRef pixiel_bufer4e = NULL;

    CVPixelBufferCreate(kCFAllocatorDefault, 
                    (int)_screenWidth, 
                    (int)_screenHeight,
                    kCVPixelFormatType_32BGRA,
                    attrs2,
                    &pixiel_bufer4e);
    CVOpenGLESTextureRef renderTexture;
    CVOpenGLESTextureCacheCreateTextureFromImage (kCFAllocatorDefault,
                                              coreVideoTextureCashe, pixiel_bufer4e,
                                              NULL, // texture attributes
                                              GL_TEXTURE_2D,
                                              GL_RGBA, // opengl format
                                              (int)_screenWidth, 
                                              (int)_screenHeight,
                                              GL_BGRA, // native iOS format
                                              GL_UNSIGNED_BYTE,
                                              0,
                                              &renderTexture);
    CFRelease(attrs2);
    CFRelease(empty);
    glBindTexture(CVOpenGLESTextureGetTarget(renderTexture), CVOpenGLESTextureGetName(renderTexture));
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, CVOpenGLESTextureGetName(renderTexture), 0);

    CVPixelBufferLockBaseAddress(pixiel_bufer4e, 0);

    if([pixelAdapter appendPixelBuffer:pixiel_bufer4e withPresentationTime:currentTime]) {
        float result = currentTime.value;
        NSLog(@"\n\n\4eta danni i current time e : %f \n\n",result);
        currentTime = CMTimeAdd(currentTime, frameLength);
    }

    CVPixelBufferUnlockBaseAddress(pixiel_bufer4e, 0);
    CVPixelBufferRelease(pixiel_bufer4e);
    CFRelease(renderTexture);
  //  CFRelease(coreVideoTextureCashe);
}

我知道我可以通过不在这里做所有这些事情来优化它,但我一直想让它工作。在 cleanUpTextures 中,我使用以下命令刷新 textureCache:

 CVOpenGLESTextureCacheFlush(coreVideoTextureCashe, 0);

RGBA 的东西可能有问题,或者我不知道,但它似乎仍然有点错误的缓存。

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1 回答 1

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对于录制视频,这不是我会使用的方法。您正在为每个渲染帧创建一个新的像素缓冲区,这会很慢,而且您永远不会释放它,因此收到内存警告也就不足为奇了。

相反,请遵循我在此答案中描述的内容。我为缓存的纹理创建了一个像素缓冲区,将该纹理分配给我要渲染到的 FBO,然后在每一帧上使用 AVAssetWriter 的像素缓冲区输入附加该像素缓冲区。使用单个像素缓冲区比每帧重新创建一个像素缓冲区要快得多。您还希望保留与 FBO 的纹理目标关联的像素缓冲区,而不是在每一帧上关联它。

如果你想看看它在实践中是如何工作的,我将这个录制代码封装在我的开源GPUImage框架中的 GPUImageMovieWriter 中。正如我在上面链接的答案中指出的那样,以这种方式进行录制会导致极快的编码。

于 2012-07-30T14:25:07.387 回答