Does anybody know of a simple dll that has like 3 main functions, i.e.
1. Start_recording_mpeg(<encoding>, <fps>, <file>, <etc>)
2. Encode_frame(<raw rgb data>)
3. Finish()
Convert your RGB frames to YUV and then pipe them to ffmpeg as described in this blog entry.
Related
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 have the code for computing the histogram for hsv and yuv images. As am trying to obtain values corresponding to brightness alone, I want the 'v' channel value from hsv image and luma ('y') channel value from yuv image. this is the code I have used.
int channels[] = {0};
calcHist(&src_yuv,1,channels,Mat(),hist,1,histSize,ranges,true,false);
This sample code is for yuv. I just change {0} to {2} to obtain 'v' channel values from HSV. I am getting certain results, but am not sure if am choosing the right channels. could you please help me, to know if those numbers choose the exact channels I want to? Thanks in advance
To be absolute sure that the channel number X corresponds to the channel you are after, consult the channelSeq attribute of the IPL Image structure. If channelSeq[X] gives the name (a character) of the channel you are after, then you found it.
But, given how this attribute is documented (along other interesting ones), even if you were always using IPLImage, there is no guarantee that the information contained there would be accurate. Thus, to be absolutely sure about the channel sequence in your image you have to trust the conversion specification and remember that yourself. So, if you start with an image in BGR and convert using BGR2YUV, then you trust that the Y channel is the first one, and so on. If OpenCV ever changes BGR2YUV to mean that Y goes to the last channel, and so on, then too bad for you.
what is the proper way of using cvSplit function? I saw different version of it.
should it be
cvSplit(oriImg, r,g,b, NULL);
or
cvSplit(oriImg, b,g,r, NULL);
Both of them are ok, it depends on the channel ordering. By default OpenCV uses BGR, so in this case it would be cvSplit(oriImg, b,g,r, NULL);, but you can convert it to RGB and then use the other one.
It is exactly the same thing I was puzzled by when I started using OpenCV. OpenCV uses BGR instead of RGB so you should use
cvSplit(img,b,g,r,NULL);
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