如何使用MATLAB从给定的YUV文件中提取Y,U和V组件?每个组件用于进一步的像素级操作
题
大家好。我目前正在玩YUV文件。您对如何从YUV视频中提取y,u,v组件有什么建议?一世 成立 一种 程序 如下所示。但是我不知道我想要的有效组件是哪个部分。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);
解决方案
不确定我是否对YUV文件有一些基本的误解,但是如果您像下面一样编辑函数,则您的每个帧中的YUV组件都在一个称为单个变量中 imgYUV
. 。请注意,您可能会在过程中用完内存,也许您不想一次加载电影的所有帧。
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);
其他提示
我只会更改函数定义:
function [mov,imgYuv] = loadFileYuv(fileName, width, height, idxFrame)
无需返回imgrgb,因为它与 mov(numel(idxFrame)).cdata
.
指定两个输出变量,您将在第二个变量中获得最后一个帧的YUV组件。
我将更改功能以检查缓冲区是否为空,以免出现与文件所包含更多的帧有关的错误。
...
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
...
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