如何使用Matlab从给定的yuv文件中提取Y、U和V分量？每个组件用于进一步的像素级操作

嘿，伙计们。我现在正在玩YUV文件。对于如何从yuv视频中提取y、u、v分量，您有什么建议吗？下面显示了一个示例。但我不知道哪一部分是我想要的有效组件。谢谢

% function mov = loadFileYuv(fileName, width, height, idxFrame)

function [mov,imgRgb] = loadFileYuv(fileName, width, height, idxFrame)
% load RGB movie [0, 255] from YUV 4:2:0 file

fileId = fopen(fileName, 'r');

subSampleMat = [1, 1; 1, 1];
nrFrame = length(idxFrame);


for f = 1 : 1 : nrFrame

    % search fileId position
    sizeFrame = 1.5 * width * height;
    fseek(fileId, (idxFrame(f) - 1) * sizeFrame, 'bof');

    % read Y component
    buf = fread(fileId, width * height, 'uchar');
    imgYuv(:, :, 1) = reshape(buf, width, height).'; % reshape RESHAPE(X,M,N) returns the M-by-N matrix 
                                                     %whose elements are taken columnwise from X.  
                                                     %An error results if X does not have M*N elements

    % read U component
    buf = fread(fileId, width / 2 * height / 2, 'uchar');
    imgYuv(:, :, 2) = kron(reshape(buf, width / 2, height / 2).', subSampleMat); % reshape and upsample

    % read V component
    buf = fread(fileId, width / 2 * height / 2, 'uchar');
    imgYuv(:, :, 3) = kron(reshape(buf, width / 2, height / 2).', subSampleMat); % reshape and upsample

    % normalize YUV values
    % imgYuv = imgYuv / 255;

    % convert YUV to RGB
    imgRgb = reshape(convertYuvToRgb(reshape(imgYuv, height * width, 3)), height, width, 3);
    % imgRgb = ycbcr2rgb(imgYuv);
    %imwrite(imgRgb,'ActualBackground.bmp','bmp');
    mov(f) = im2frame(imgRgb);
    %   mov(f).cdata = uint8(imgRgb);
    %   mov(f).colormap =  [];
    %     imwrite(imgRgb,'ActualBackground.bmp','bmp');

    %figure, imshow(imgRgb);
    %name = 'ActualBackground.bmp';
    %Image = imread(name, 'bmp');
    %figure, imshow(Image);
end
fclose(fileId);

---

不确定我是否对YUV文件有一些基本的误解，但是如果你像我下面所做的那样编辑函数，你会在一个名为imgYUV的变量中为每一帧设置YUV组件。请注意，在此过程中可能会耗尽内存，您可能不希望一次性加载电影的所有帧

function imgYUV = loadFileYuv(fileName, width, height, idxFrame)
% load YUV data from YUV 4:2:0 file

fileId = fopen(fileName, 'r');

subSampleMat = [1, 1; 1, 1];
nrFrame = length(idxFrame);

%# preassign imgYUV. In case we can't keep everything in RAM,
%# it is better that the function crashes here, rather than after
%# having wasted time slowly filling up the memory.
%# Since the images are likely to be of class 'uint8', 
%# you can save on a lot of memory by initializing
%# imgYUV as zeros(width/2,height/2,3,nrFrame,'uint8');
imgYUV = zeros(width/2 height/2, 3, nrFrame);

for f = 1 : 1 : nrFrame

    %# search fileId position
    sizeFrame = 1.5 * width * height;
    fseek(fileId, (idxFrame(f) - 1) * sizeFrame, 'bof');

    %# read Y component
    buf = fread(fileId, width * height, 'uchar');
    imgYuv(:, :, 1, f) = reshape(buf, width, height).'; 

    %# read U component
    buf = fread(fileId, width / 2 * height / 2, 'uchar');
    imgYuv(:, :, 2, f) = kron(reshape(buf, width / 2, height / 2).', subSampleMat); % reshape and upsample

    % read V component
    buf = fread(fileId, width / 2 * height / 2, 'uchar');
    imgYuv(:, :, 3, f) = kron(reshape(buf, width / 2, height / 2).', subSampleMat); % reshape and upsample

end
fclose(fileId);

---

我只想更改函数定义：

function [mov,imgYuv] = loadFileYuv(fileName, width, height, idxFrame)

不需要返回imgRgb，因为它与movnumelidxFrame.cdata相同

指定两个输出变量，您将在第二个变量中获得最后一帧的YUV组件

我会将函数更改为检查缓冲区是否为空，以避免在请求的帧数超过文件包含的帧数时出错

    ...
    status = fseek(fileId, (idxFrame(f) - 1) * sizeFrame, 'bof');
    if status == -1
        error('Cannot read frame %d',idxFrame(f));
    end

    % read Y component
    buf = fread(fileId, width * height, 'uchar');
    if isempty(buf)
        error('Cannot read frame %d',idxFrame(f));
    end
    imgYuv(:, :, 1) = reshape(buf, width, height).'; % reshape

    % read U component
    buf = fread(fileId, width / 2 * height / 2, 'uchar');
    if isempty(buf)
        error('Cannot read frame %d',idxFrame(f));
    end
    imgYuv(:, :, 2) = kron(reshape(buf, width / 2, height / 2).', subSampleMat); % reshape and upsample

    % read V component
    buf = fread(fileId, width / 2 * height / 2, 'uchar');
    if isempty(buf)
        error('Cannot read frame %d',idxFrame(f));
    end
    ...

---

我使用以下代码来触发loadFileYuv函数。你认为这是正确的吗？nFrames=2000；mov1:nFrames=struct'cdata'，zeros352288,3，'uint8'，'colormap'，[]；对于k=1:n帧movk.cdata=loadFileYuv。。。；end@yoursclark：只要将k作为第四个输入参数传递，看起来是正确的。行吗？嗨，乔纳斯。谢谢你的快速回复。我将k作为loadFileYuv函数的第四个输入参数。但是，当我试图通过键入“mov1.cdata”来显示cdata的内容时，像素结果都是零，这意味着帧数据没有存储在cdata字段中，不是吗？@yoursclark:看起来确实如此。我建议您在文件loadFileYuv中放置一个断点，单击编辑器中第一行数字旁边的破折号，应该会出现一个红点；当函数停止执行时，可以使用工具栏中的“步骤”按钮单步执行。这将让您了解loadFileYUV是否正常工作。将鼠标悬停在变量名上或在数组编辑器中查看它们是否都为零。谢谢Jonas。根据您的建议，我成功地获得了我想要的YUV组件。谢谢你的解释！谢谢你！你是对的。没有必要返回imgRgb，因为它不是我想要的。谢谢你指出这一点！