how to write a MP4 video using vision toolbox ?
2 vues (au cours des 30 derniers jours)
Afficher commentaires plus anciens
hello , I have been trying to use
vision.VideoFileWriter('output.mp4','FileFormat', '???' ); but the help cant really tell me the strings for format types.
tnx to Dima for the help so far.
i still have a problem ( still trying to output a MP4 to a file) i get a "On Windows, frame must be between 64 by 64 and 1920 by 1088 when writing MPEG4 files." error when my frame to write is 1920X1080
my code :
hVideoSrc_Color = vision.VideoFileReader('swipeCut.mp4'); hReffVideoOut = vision.VideoFileWriter('diff.mp4','FrameRate',hVideoSrc_Color.info.VideoFrameRate,'FileFormat','MPEG4'); counter=0; while ~isDone(hVideoSrc_Color) frame=step(hVideoSrc_Color); step(hReffVideoOut,frame); counter=counter+1; end
release(hVideoSrc_gray); release(hReffVideoOut);
0 commentaires
Réponse acceptée
Dinesh Iyer
le 24 Juil 2014
Modifié(e) : Dinesh Iyer
le 24 Juil 2014
Lirian,
I see the confusion. It is common to refer to image dimensions in terms of Width x Height. So a full HD video is said to have dimensions 1920x1080. But an array storing that frame has 1080 rows and 1920 columns.
However, the variable "frame" that you have contains 1920 rows and 1080 columns. If you look at the example code I posted earlier, the data array was 1080x1920.
I am surprised that step( vision.VideoFileReader('swipeCut.mp4') ) returns 1920x1080x3 frames. I tried reading HD video from an MP4 file at my end and it returned a 1080x1920x3 matrix.
Hope this helps. Try to transpose "frame" and write it. I agree that the error message issued is confusing.
Dinesh
2 commentaires
Dinesh Iyer
le 28 Juil 2014
Hi Lirian, You can try to write the transpose of the frame to an MP4 file.
if true
vfw = vision.VideoFileWriter('Filename', 'myfile.mp4', 'FileFormat', 'MPEG-4');
vfr = vision.VideoFileReader('swipeCut.mp4');
while ~isDone(vfr)
frame = step(vfr);
step(vfw, frame');
end
release(vfr);
release(vfw);
end
Hope this helps.
Dinesh
Plus de réponses (2)
Dima Lisin
le 23 Juil 2014
Modifié(e) : Dima Lisin
le 23 Juil 2014
If you do
>> help vision.VideoFileWriter
and then click on FileFormat you should see this:
FileFormat Format of created file
Specify the format of the video file.
On Windows (R) platforms, this may be one of:
[{'AVI'} | 'WMV' | 'MJ2000' | 'MPEG4'].
On Linux (R) platforms, this may be one of:
[{'AVI'} | 'MJ2000'].
On Mac OS X (R) platforms, this may be one of:
[{'AVI'} | 'MJ2000' | 'MPEG4']
These abbreviations
correspond to the following file formats:
WMV: Windows Media Video
AVI: Audio-Video Interleave
MJ2000: Motion JPEG 2000
MPEG4: MPEG-4/H.264 Video
Dinesh Iyer
le 23 Juil 2014
Liran, I tried the following code to write one frame of HD video on Windows 7 using R2014a:
if true
data = single(rand(1080, 1920, 3));
vfw = vision.VideoFileWriter('Filename', 'hdoutput.mp4', 'FileFormat', 'MPEG4')
step(vfw, data);
end
and it worked fine without any errors. Can you verify the dimensions of the video in swipeCut.mp4?
Voir également
Produits
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!