YUV序列下采样以及彩色4:2:0与灰度4:0:0转换---基于matlab实现

1、YUV序列（4:2:0）下采样

matlab代码：

yuvDownSample.m

clear
clc

%% Read yuv from file
yuvseq = 'kendo0.yuv';        % 输入yuv序列名称
fid = fopen(yuvseq, 'r');

row=1024;col=768;             % 输入yuv序列尺寸
fnum=300;                     % 要转换的帧数

Y=zeros(row,col,fnum);
U=zeros(row/2,col/2,fnum);
V=zeros(row/2,col/2,fnum);

YY=zeros(row/4,col/4,fnum);   % 4倍下采样（除以4）
UU=zeros(row/8,col/8,fnum);
VV=zeros(row/8,col/8,fnum);

for frame=1:fnum
    [Y(:,:,frame),count] = fread(fid,[row,col],'uchar');
    [U(:,:,frame),count1]=fread(fid,[row/2,col/2],'uchar');
    [V(:,:,frame),count2]=fread(fid,[row/2,col/2],'uchar');
    
     YY(:,:,frame) = Y(1:4:row,1:4:col,frame);
     UU(:,:,frame) = U(1:4:row/2,1:4:col/2,frame);
     VV(:,:,frame) = V(1:4:row/2,1:4:col/2,frame);
end

filename=sprintf('%s%s','downSample_',yuvseq);      % 下采样后输出yuv序列名称
outfid=fopen(filename,'wb');

for frame=1:fnum
    fwrite(outfid,YY(:,:,frame), 'uchar');
    fwrite(outfid,UU(:,:,frame), 'uchar');
    fwrite(outfid,VV(:,:,frame), 'uchar');
end
fclose(fid);
fclose(outfid);

2、YUV序列（4:2:0）转换为灰度YUV序列（4:0:0）

主函数：main_color2gray.m

function main_color2gary()

% 帧数
f=300;    
% 参数downSample_kendo0.yuv为输入视频（4:2:0），
% 参数downSample_kendo0_gray.yuv为转换输出的视频（4:0:0）
% 参数f为转换帧数
% 参数'downSample'表示输入视频的尺寸，可以进入color2gary内查看及设置。
color2gary('downSample_kendo0.yuv','kendo0_gray.yuv',f,'downSample');

子函数：color2gray.m

function color2gary(fin,fout,fnum,frmsz)
if isequal(frmsz,'qcif')
    fwid=176;
    fhei=144;
elseif isequal(frmsz,'cif')
    fwid=352;
    fhei=288;
elseif isequal(frmsz,'downSample')
    fwid=256;
    fhei=192;
elseif isequal(frmsz,'1024x768')
    fwid=1024;
    fhei=768;
elseif isequal(frmsz,'1280x720')
    fwid=1280;
    fhei=720;
elseif isequal(frmsz,'1920x1080')
    fwid=1920;
    fhei=1080;
elseif isequal(frmsz,'832x480')
    fwid=832;
    fhei=480;
elseif isequal(frmsz,'roi')
    fwid=128;
    fhei=192;
end
rec=zeros(fhei,fwid,fnum);
for f=1:fnum
    rec(:,:,f)=open420Y(fin,fwid,fhei,f);
end
saveY(rec,fout);
    

子函数：open420Y.m

function img=open420Y(fname,width,height,frame_idx)

fid=fopen(fname,'r');
fsize=width*height;
frame_no=length(frame_idx);
img=zeros(height,width,frame_no);
for i=1:frame_no
    fseek(fid,(frame_idx(i)-1)*fsize*3/2,'bof');
    buf=fread(fid,fsize,'uint8');
    img(:,:,i)=double(reshape(buf,width,height).');
end
fclose(fid);

子函数： saveY .m

function saveY(img,fname)

fid=fopen(fname,'w');
[row,col,frm]=size(img);
for i=1:frm
    buf=uint8(img(:,:,i).');
    count=fwrite(fid,buf,'uint8');
end
fclose(fid);

多视点视频序列下载地址： http://www.tanimoto.nuee.nagoya-u.ac.jp/~fukushima/mpegftv/