I'm editing all frames of an existing mp4 video in MATLAB (doing it in a for loop).
After I'm done editing, I want to save the new set of frames to a new output video file, but in mp4 rather than .avi (that seems to be the default).
I thought changing the filename extension is sufficient, but apparently it's not.
Any ideas?
newVid = VideoWriter(outputfilename);
newVid.FrameRate = fps;
newVid.Quality = 100;
open(newVid)
for...
writeVideo(newVid,imgs{i})%within the for loop saving one frame at a time
end
close(newVid)
Renaming the file is not sufficient. You also need to specify the codec you want. In your case, you need to include an additional parameter into the VideoWriter constructor that consists of the codec you want to use as a MATLAB
string. In your case, specify 'MPEG-4':
newVid = VideoWriter(outputfilename, 'MPEG-4'); % New
newVid.FrameRate = fps;
newVid.Quality = 100;
open(newVid);
for ...
% Rest of your code here
BTW, have a look at the documentation in the future. It clearly shows you what to do if you want to save to a new format, and not AVI: https://www.mathworks.com/help/matlab/ref/videowriter.html#input_argument_d0e1094625
You need to pass a profile argument to matlab's videowriter.
From Matlab Help, VideoWriter(filename,profile) creates a VideoWriter object and applies a set of properties tailored to a specific file format (such as 'MPEG-4' or 'Uncompressed AVI').
In your case, you need to pass the string MPEG-4 to the profile argument.
Related
I have a ".mat" file supposedly containing a [30720000x4 double] matrix (values from accelerometers). When I try to open this file with "Import data" in Matlab I get the following error:
Error using load
Can't read file F:\vibration_exp_2\GR_UB50n\bearing1\GR_UB50n_1_2.mat.
Error using load
Unknown text on line number 1 of ASCII file
F:\vibration_exp_2\GR_UB50n\bearing1\GR_UB50n_1_2.mat
"MATLAB".
Error in uiimport/runImportdata (line 456)
datastruct = load('-ascii', fileAbsolutePath);
Error in uiimport/gatherFilePreviewData (line 424)
[datastruct, textDelimiter, headerLines]= runImportdata(fileAbsolutePath,
type);
Error in uiimport (line 240)
[ctorPreviewText, ctorHeaderLines, ctorDelim] = ...
The filesize is 921MB which is the same as my other files that do open. I also tried opening the file using python, but no success. Any suggestions? I use MATLAB R2013b .
More info:
How the file was create:
%% acquisition of vibration data
% input:
% sample rate in Hz (max. 51200 Hz, should be used as bearing
% faults are high-frequent)
% time in seconds, stating the duration of the measurement
% (e.g. 600 seconds = 10 minutes)
% filename for the file to be saved
%
% examples:
% data = DAQ(51200, 600, 'NF1_1.mat');
% data = DAQ(51200, 600, 'NF1_2.mat');
function data = DAQ(samplerate,time,filename)
s = daq.createSession('ni'); % Creates the DAQ session
%%% Add the channels as accelerometer channels (meaning IEPE is turned on)
s.addAnalogInputChannel('cDAQ1Mod1','ai0','Accelerometer');
s.addAnalogInputChannel('cDAQ1Mod1','ai1','Accelerometer');
s.addAnalogInputChannel('cDAQ1Mod1','ai2','Accelerometer');
s.addAnalogInputChannel('cDAQ1Mod1','ai3','Accelerometer');
%s.addAnalogInputChannel('cDAQ1Mod2','ai0','Accelerometer');
s.Rate = samplerate;
s.NumberOfScans = samplerate*time;
%%% Defining the Sensitivities in V/g
s.Channels(1).Sensitivity = 0.09478; %31965, top outer
s.Channels(2).Sensitivity = 0.09531; %31966, back outer
s.Channels(3).Sensitivity = 0.09275; %31964, top inner
s.Channels(4).Sensitivity = 0.09363; %31963, back inner
data = s.startForeground(); %Acquiring the data
save(filename, 'data');
More info:
When I open the file using a simple text editor I can see a lot of characters that do not make sense but also the first line:
MATLAB 5.0 MAT-FILE, Platform: PCWIN64, Created on: Thu Apr 30
16:29:07 2015
More info:
The file itself: https://www.dropbox.com/s/r7mavil79j47xa2/GR_UB50n_1_2.mat?dl=0
It is 921MB.
EDIT:
How can I recover my data?
I've tried this, but got memory errors.
I've also tried this, but it did not work.
I fear I can't add many good news to what you know already, but it hasn't been mentioned yet.
The reason the .mat-file can't be load is due to the data beeing corrupted. What makes it 'unrecoverable' is the way it is stored internally. The exact format is specified in the MAT-File Format Documentation. So I decided to manually construct a simple reader to specifically read your .mat file.
It makes sense, that the splitmat.m can't recover anything, as it will basicly split the data into chunks, one stored variable per chunk, however in this case there is only 1 variable stored and thus only one chunk, which happens to be the corrupted one.
In this case, the data is stored as a miCOMPRESSED, which is a normal matlab array compressed using gzip. (Which, as a side note, doesn't seem like a good fit for 'random' vibration data.) This might explain previous comments about the smaller file size then the full data, as the filesize matches exatly with the internally stored value.
I extracted the compressed archive and tried to uncompress it in a variety of ways. Basicly it is a '.gz' without the header, that can be appended manually. Unfortunatly there seems to be a corrupted block near the start of the dataset. I am by no means an expert on gzip, but as far as I know the dictionary (or decryption key) is stored dynamicly which makes all data useless from the point the block is corrupted. If you are really eager, there seems to be a way to recover data even behind the point where data is corrupted, but that method is massively timeconsuming. Also the only way to validate data of those sections is manual inspection, which in your case might proof very difficult.
Below is the code, that I used to extract the .gz-file, so if you want to give it a try, this might get you started. If you manage to decrypt the data, you can read it as described in the MAT-File Format, 13f.
corrupted_file_id = fopen('corrupt.mat','r');
%% some header data
% can be skipped replacing this block with
% fread(id,132);
%header of .mat file
header_text = char(fread(corrupted_file_id,116,'char')');
subsystem_data_offset = fread(corrupted_file_id,8,'uint8');
version = fread(corrupted_file_id,1,'int16');
endian_indicator = char(fread(corrupted_file_id,2,'int8')');
data_type = fread(corrupted_file_id,4,'uint8');
%data_type is 15, so it is a compressed matlab array
%% save te content
data_size = fread(corrupted_file_id,1,'uint32');
gz_file_id = fopen('compressed_array.gz','w');
% first write a valid gzip head
fwrite(gz_file_id,hex2dec('1f8b080000000000'),'uint64',0,'b');
% then write the data sequentialy
step = 1:1e3:data_size;% 1MB steps
for idx = step
fwrite(gz_file_id,fread(corrupted_file_id,1e3,'uint8'));
end
step = step(end):data_size;% 1B steps
for idx = step
fwrite(gz_file_id,fread(corrupted_file_id,1,'uint8'));
end
fclose(gz_file_id);
fclose(corrupted_file_id);
To answer literally to the question, my suggestion would be to make sure first that the file is okay. This tool on File Exchange apparently knows how to diagnose corrupted .MAT files starting with version V5 (R8):
http://www.mathworks.com/matlabcentral/fileexchange/6893-matcat-mat-file-corruption-analysis-tool
The file's size (indices going out of range) seems to be a problem. Octave, which should read .mat files, gives the error
memory exhausted or requested size too large for range of Octave's index type
To find out what is wrong you may need to write a test program outside MatLab, where you have more control over memory management. Examples are here, including instructions on how to build them on your own platform. These stand-alone programs may not have the same memory issues. The program matdgns.c is specifically made to check .mat files for errors.
I'm looking for an easy way too save the current state of my GUI and be able to load this saved state again. I know there is a video for this (http://blogs.mathworks.com/videos/2010/12/10/how-to-save-and-restore-state-of-a-gui-in-matlab/) but somehow it doesn't work on my computer.
I thought of something like this: (I used gcf because I didn't know the "mainhandle" for my entire GUI)
%Save Data
currentdata = getappdata(gcf);
uisave('currentdata',date);
%Load Data
[filename,pathname]=uigetfile({'*.mat'},'Select input file');
load([pathname,filename]);
The problem with this way is, that the saved Data is opened in a new figure and not the current one from which I chose to open it.
I was also wondering if it is possible to set a folder(which is added to the matlab path) as the deault folder for saving/loading.
Thank you for your help! Klaus
Since your currentdata keeps the whole handles of your GUI, including the handle to the GUI's main figure, so when you load it, there will be a new figure opened.
What one did in the mentioned video is: just save the fields/data that you need to be remained/reloaded in later session.
So either you save these specific fields in the GUI's handles and reload them one by one, or you can use the exchange functions mentioned in the comment under the video.
How can i do the same math function(eg:average) for a folder containing large number of data files using matlab(2010) and store them in one output?
This is the code I have, but it was unsuccessful.
function A = RepeatForAll()
A = 0;
% audio is the folder name where audio files are saved
path = fullfile(pwd,'audio');
files = dir(path);
for fileIndex=3:length(files)
if (files(fileIndex).isdir == 0)
if (~isempty(strfind(files(fileIndex).name,'wav')))
fullfile(path,files(fileIndex).name)
result = wavread(fullfile(path,files(fileIndex).name));
% Any thing you have to for each audio file
inputz=wavread(result);
outx = mfccx(result);
A(count,:) = mean(outx,2);
count=count+1;
end;
end;
end;
You need to set
count=0;
before going into the for loop, now count is undefined.
Also the line inputz=wavread(result); is both unused and wrong. you don't use inputz anywhere, and you are calling wavread on result, which is not a filename (see the line above). This would generate an error.
Please be more clear next time, at least give us error messages. Describing what you think should happen is also useful.
Last, correctly format your code. In matlab, select al your code (control+a) then press control+i to format it.
I am having a problem when creating an avi file using Matlab. My aim is to use an edge filter on an entire video and save the file as an avi. The filter works fine, my problem is the writing of the avi file.
My code:
vidFile = VideoReader('video.avi');
edgeMov = avifile('edges','fps',30);
for i = 1:vidFile.numberofframes
frameI = read(vidFile,i);
frameIgray = rgb2gray(frameI);
edgeI = edge(frameIgray,'canny',0.6);
edgeIuint8 = im2uint8(edgeI);
edgeIuint8(:,:,2) = edgeIuint8(:,:,1);
edgeIuint8(:,:,3) = edgeIuint8(:,:,1);
edgeMov = addframe(edgeMov,edgeIuint8);
end
edgeMov = close(edgeMov)
When the loop finishes and the avifile is closed, I go to play the video and it says "Windows Media Player encountered a problem while playing this file". I've also tried, without success, Media Player Classic and VLC which lead me to believe that the problem must be the file itself. Using GSpot I checked the file and it said that the AVI header is corrupt.
Retrying the loop again returned exactly the same problem. What's confusing me is when I run the loop for a smaller number of frames, 30 for example, the video writes fine and I can watch it. The size of the video I am trying to convert is in excess of 1000 frames so I don't know if size is a problem?
Any help would be greatly appreciated, thank you.
I've used the following to create AVI
edgeMov = avifile('video.avi','compression','Indeo5','fps',15,'quality',95);
Give it a try.
I'm looking for some sample code to show me how to add metadata to the wav files we create.
Anyone?
One option is to add your own chunk with a unique id. Most WAV players will ignore it.
Another idea would to be use a labl chunk, associated with a que set at the beginning or end of the file. You'd also need a que chunk. See here for a reference
How to write the data is simple
Write "RIFF".
save the file position.
Write 4 bytes of 0's
Write all the existing chunks. Keep count of bytes written.
Add your chunk. Be sure to get the chunksize right. Keep
count of bytes written.
rewind to the saved position. Write the new size (as a 32-bit
number).
Close the file.
It's slightly more complicated if you are adding things to an existing list chunk, but the same principle applies.
Maybe the nist file format will give you what you want:
NIST
Here is a lib that could help, but im afraid it looks old. NIST Lib
Cant find more useful information right now how exactly to use it, and im afraid the information papers from my company must stay there. :L/
Try code below
private void WaveTag()
{
string fileName = "in.wav";
WaveReadWriter wrw = new WaveReadWriter(File.Open(fileName, FileMode.Open, FileAccess.ReadWrite));
//removes INFO tags from audio stream
wrw.WriteInfoTag(null);
//writes INFO tags into audio stream
Dictionary<WaveInfo, string> tag = new Dictionary<WaveInfo, string>();
tag[WaveInfo.Comments] = "Comments...";
wrw.WriteInfoTag(tag);
wrw.Close();
//reads INFO tags from audio stream
WaveReader wr = new WaveReader(File.OpenRead(fileName));
Dictionary<WaveInfo, string> dir = wr.ReadInfoTag();
wr.Close();
if (dir.Count > 0)
{
foreach (string val in dir.Values)
{
Console.WriteLine(val);
}
}
}
from http://alvas.net/alvas.audio,articles.aspx#id3-tags-for-wave-files
If you examine the wave file spec you'll see that there does not seem to be room for annotations of any kind. An option would be to wrap the wave file with your own format that includes custom information but you would in effect be creating a whole new format that would not be readable by users who do not have your app. But you might be ok with that.