I have a problem with a RAW YUB video load in OpenCV. I can play it in mplayer with the following command:
mplayer myvideo.raw -rawvideo w=1280:h=1024:fps=30:y8 -demuxer rawvideo
My code for load in OpenCV is:
CvCapture* capture=cvCaptureFromFile("C:\\myvideo.raw");
cvCaptureFromFile always return NULL. But if I try with a normal avi file, the code runs normally (capture is not null).
I'm working with the lastest version of OpenCV under Windows 7.
EDIT: Output messages are
[IMGUTILS # 0036f724] Picture size 0x0 is invalid
[image2 # 009f3300] Could not find codec parameters (Video: rawvideo, yuv420p)
Thanks
OpenCV uses ffmpeg as back-end, however, it includes only a subset of ffmpeg functions. What you can try is to install some codecs. (K-lite helped me some time ago)
But, if your aim is to obtain raw YUV in OpenCV, the answer is "not possible".
OpenCV is hardcoded to convert every input format to BGR, so even if you will be able to open the raw input, it will automatically convery it to BGR before passing it. No chance to solve that, the only way is to use a different capture library or hack into OpenCV.
What you can do (to simulate YUV input) is to capture the avi, convert to YUV
cvtColor(...,CV_BGR2YCBCR /* or CV_BGR2YUV */ );
and then process it
Related
Are there any good examples that show how to render the IMFSample output from the H.264 decoder? My scenario uses a 4K resolution H.264 stream and the PC that I am targeting will only accept 1080p using the DXGI buffers. But the H.264 decoder will handle 4K so I need to find a way to feed that NV12 IMFSample directly to the DirectX 11 renderer. I have already tried using the DX11VideoRenderer sample but it fails due to this particular IMFSample not having an IMFDXGIBuffer interface.
It looks like in the DX11VideoRenderer the input IMFDXGIBuffer is NV12 type and that can be rendered successfully in hardware. So it seems logical that a non-DXGI buffer of NV12 type should be acceptable too?
Perhaps I need to create a ID3D11Texture2D texture or resource with an NV12 type? I found examples for how to create a texture from a file but none for how to create a texture from a sample, which would seem to be even more useful. And if I can create a NV12 texture, how to figure out the SysMemPitch and SysMemSlicePitch values in the D3D11_SUBRESOURCE_DATA structure for NV12?
Any help would be really appreciated! Thank you.
I was able to find a complete example that renders an NV12 sample to the screen. Although there are some simple stride calculation errors in how it renders it's own example image, the actual rendering code does work correctly. It appears to be an old Microsoft sample that I cannot find any other information about.
D3D11NV12Rendering
OpenCV 2.4 VideoWriter couldn't save video files larger than 2GB, since it only accepts .avi files, I am wondering if this is still the case in OpenCV 3.0, or if it can save other kind of video files that doesn't have this limitations.
I tried to find any documentations pointing to a limit of 2GB or a release note saying it's capable to handle larger files, but I can't find none.
Even though the OpenCV 3.0-beta documentation states otherwise, OpenCV 3.0's VideoWriter seems to handle other file formats, such as mkv, as shown in this issue.
I adapted the code from the above issue to generate a 4GB mkv video (4096 frames of random 2048x2048).
The things to be aware is that the image size should be passed as width then height in the VideoWriter whereas the numpy array should be initialized with height then width. VideoWriter will fail silently otherwise.
You will also require a recent OpenCV 3.0 source to handle uncompressed streams.
This is not OpenCV limitation. AVI file size cannot be larger than 2 GB due to format limitations (4-byte size signed integer has max value 2,147,483,647).
Is it possible to pack video in another container with OpenCV (mkv etc)?
the RIFF header has the following form:
'RIFF' fileSize fileType (data)
where 'RIFF' is the literal FOURCC code 'RIFF',
fileSize is a 4-byte value giving the size of the data in the file,
and fileType is a FOURCC that identifies the specific file type.
For a specific purpose I am trying to convert an AVI video to a kind of Moving JPEG format using OpenCV. In order to do so I read images from the source video, convert them to JPEG using imEncode, and write these JPEG images to the target video.
After several hundreds of frames suddenly the size of the resulting JPEG image nearly doubles. Here's a list of sizes:
68045
68145
68139
67885
67521
67461
67537
67420
67578
67573
67577
67635
67700
67751
127800
127899
127508
127302
126990
126904
Anybody got a clue what's going on here?
By the way: I'm using OpenCV.Net as a wrapper for OpenCV.
Thanks a lot in advance,
Paul
I found the solution. If I explicitly enter the third parameter to imEncode (for JPEG encoding this indicates the quality of the encoding, ranging from 0 to 100) instead of using the default (95) the problem disappears. It's likely this is a bug in OpenCV.Net, but it could also be a bug in OpenCV itself.
Is there any way to generate a 16-bits per channel(RGBA) PNG file using D3DX11SaveTextureToFile?
Or any version of DirectX, any image library(C++), any image format
I tried to use the sample code here:
http://msdn.microsoft.com/en-us/library/windows/desktop/bb205131(v=vs.85).aspx
and modified the function names to D3D11 version.
The program works perfectly when I set the desc.Format to DXGI_FORMAT_R8G8B8A8_UNORM .
But the D3DX11SaveTextureToFile returns E_FAIL when I changed the desc.Format to DXGI_FORMAT_R16G16B16A16_UNORM .
I've tried to use DevIL (developer's image library) but it doesn't support 16-bits per channel png file.
The only format which can save all texture-formats is D3DX11_IFF_DDS. It seems that D3DX11SaveTextureToFile can't save 16Bit pngs. One possibility is to extract the imagedata of your texture and save it manually with one of the possibilities (e.g. OpenCV or libpng) discussed here: Writing 16 bit uncompressed image using OpenCV.
I've got a V4L2 camera that can grab frame in JPEG format or YUV422 or BGR24. I'd like to set camera to BGR24#640x480 by OpenCV. To do this, I did the following settings:
capture = cvCreateCameraCapture(0);
cvSetCaptureProperty( capture, CV_CAP_PROP_FRAME_WIDTH, 640 );
cvSetCaptureProperty( capture, CV_CAP_PROP_FRAME_HEIGHT, 480 );
cvSetCaptureProperty( capture, CV_CAP_PROP_FOURCC, CV_FOURCC('B', 'G', 'R', '3'));
but opencv gives me back the following error message:
HIGHGUI ERROR: V4L: Property <unknown property string>(6) not supported by device
So, openCV set JPEG#640x480 format instead of BGR24.
How can I fix it?
NOTE: BGR24 format was tested with the following gstreamer pipeline and it works properly:
gst-launch-0.10 v4l2src num-buffers=10 device=/dev/video0 ! 'video/x-raw-rgb,width=640,height=480,bpp=24,depth=24,red_mask=255,green_mask=65280,blue_mask=16711680,endianness=4321' ! filesink location=/tmp/output10.rgb24
Kind regards
I'd check that you are accessing the correct camera
If you have multiple cameras varying N in cvCreateCameraCapture(N) should cycle through them.
Other than that I would check that the webcam itself conforms to the UVC specification. V4L might be having trouble querying the parameters of the cam.
Just because the Camera supports the capture of a certain format, if it doesn't strictly comply with the Usb Video Class, OpenCV is not guaranteed to be able to detect that it can capture in that format and, to the best of my knowledge, cannot be forced to.