用matlab提取视频帧

Question

我正在尝试使用此代码提取某些视频的所有帧（每个视频包含大约 13000 帧），但提取所有帧所需的时间太长。有没有更快捷的方法？

    filename = 'S.avi';
mov = VideoReader(filename);

% Output folder

outputFolder = fullfile(cd, 'S');
mkdir(outputFolder);


%getting no of frames
framee=100000;
numberOfFrames = mov.NumberOfFrames;
numberOfFramesWritten = 0;
for frame =       1:12525

    thisFrame = read(mov, frame);
    framee=framee+1;
    outputBaseFileName = sprintf('%3.3d.png', framee);
    outputFullFileName = fullfile(outputFolder, outputBaseFileName);
    imwrite(thisFrame, outputFullFileName, 'png');
%     progressIndication = sprintf('Wrote frame %4d of %d.', frame,numberOfFrames);
%     disp(progressIndication);
    numberOfFramesWritten = numberOfFramesWritten + 1;

end
progressIndication = sprintf('Wrote %d frames to folder "%s"',numberOfFramesWritten, outputFolder);
disp(progressIndication);

Answer 1

从概念上讲，这与您所做的并没有太大不同，但是您的代码中有许多迂回步骤。

大概你可以这样做：

mov = VideoReader(filename);
vidFrames = read(mov);

将您的电影收集为 4D 数组，然后就可以了

for frame = 1 : size(vidFrames, 4)
    outputBaseFileName = sprintf('%3.3d.png', frame);
    outputFullFileName = fullfile(outputFolder, outputBaseFileName);
    imwrite( vidFrames(:,:,:,frame), outputFullFileName, 'png');
end

而且它可能会更快。此外，您可能会使用 parfor（或使用计数器函数句柄的 spmd）来进一步并行化

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