Getting lossless images from mjpeg

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Varsha Nataraj
Varsha Nataraj 2019-1-16
评论： Varsha Nataraj 2019-1-31
I am learning with video to image conversion and vice versa.
I had a mjpeg of 3 sec, when i converted to jpeg images i got 55 images.
then i used all 55 images to make a mjpeg video but the video is not of 3 sec anymore
Please tell me correct way of video to image conversion and vice versa. i am not getting where i am going wrong.

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采纳的回答

Varsha Nataraj
Varsha Nataraj 2019-1-30
hello iqra,
i am very sorry for not replying so long.
i cleared my issue after refering to this link below
https://in.mathworks.com/help/matlab/examples/convert-between-image-sequences-and-video.html
go through this
hope it helps
  2 个评论
Iqra Saleem
Iqra Saleem 2019-1-30
Can you tell me from where you get motion jpeg video.
I tried to convert using Oxelon media Converter but that .mjpg video is not playing in matlab.

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更多回答（2 个）

Walter Roberson
Walter Roberson 2019-1-16
It is impossible to get lossless images from Motion JPEG. mjpeg inherently uses lossy jpeg compression .
However it sounds to me as if you did not tell the video writer that the frame rate should be 55/3 frames per second. (I suspect your real frame rate is either 18 or 20 fps and that 3 seconds is an approximation )
Iqra Saleem
Iqra Saleem 2019-1-27
Hey;
Varsha Natraj , can you tell me please how you convert motion jpeg to jpeg images?
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Iqra Saleem
Iqra Saleem 2019-1-30
My matlab code is :
clc
close all
clear all
info = mmfileinfo('akiyo_CIF.mjpg');
xyloObj = VideoReader('akiyo_CIF.mjpg');
get(xyloObj)
nFrames = xyloObj.NumberOfFrames;
vidHeight = xyloObj.Height;
vidWidth = xyloObj.Width;
% Preallocate movie structure.
mov(1:nFrames) = ...
struct('cdata', zeros(vidHeight, vidWidth, 3, 'uint8'),...
'colormap', []);
% Read one frame at a time.
for k = 1 : 3
mov(k).cdata = read(xyloObj, k);
end
% Size a figure based on the video's width and height.
hf = figure;
set(hf, 'position', [150 150 vidWidth vidHeight])
% Play back the movie once at the video's frame rate.
movie(hf, mov, 1, xyloObj.FrameRate);
Walter Roberson
Walter Roberson 2019-1-30
Except possibly on Linux, .mpeg or .mjpg is not a supported video format. Motion JPEG is supported inside of .avi
https://www.mathworks.com/help/matlab/import_export/supported-video-file-formats.html

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