video-processing

问题 In my app I am rendering a Video generated from images I retrieve from the users photos. I have set up an AVAssetwriter with a AVAssetwriterInput has an AVAssetWriterInputPixelBufferAdaptor. I'm able to transform the ALAsset objects I retrieve from the users library to CVPixelBuffers and add them to the Video, which then is saved as an mp4. Adding all the images to the video is done on a background thread which sends a Notification to the main thread every frame, so the interface can be

问题 I want to destroy all i-frames of a video. Doing this I want to check if encrypting only the i-frames of a video would be sufficient for making it unwatchable. How can I do this? Only removing them and recompressing the video would not be the same as really overwriting the i-frame in the stream without recalculating b-frames etc. 回答1: Using libavformat (library from ffmpeg), you can demultiplex the video into packets that represent a single frame. You can then encrypt data in the packets that

问题 I want to extract frames from a video and apply some filters on it such as gabor/hough etc. Which Java library would be perfect for handling all kinds of video encodings? I have been looking at GStreamer, JMF, Xuggler etc. but am unable to decide which one would be the best. I'm also looking to edit the frames and make the video with the new frames. 回答1: If you're looking to do low level operations such as extracting frames and manipulating them, then Xuggler would be the best choice, because

问题 I want to extract frames from a video and apply some filters on it such as gabor/hough etc. Which Java library would be perfect for handling all kinds of video encodings? I have been looking at GStreamer, JMF, Xuggler etc. but am unable to decide which one would be the best. I'm also looking to edit the frames and make the video with the new frames. 回答1: If you're looking to do low level operations such as extracting frames and manipulating them, then Xuggler would be the best choice, because

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed last year . I am making a app which supports video calls and I am looking for a tutorial/doc explaining the structure of the h.264 codec. I want to be able to package the stream, wrap it in datagrams, send and unpack on the receiving side. Any suggestions/reading materials? 回答1: What do you mean by structure? If you are

问题 I want to cut a sub-purt of an image (or crop it) using Emgu CV (or OpenCV) and calculate average color of that part; looking for changes. Thanks 回答1: Set the ROI (Region of Interest) of the image you are working with this will mean any calculation is only done over this area. image.ROI = new Rectangle(x,Y,Width,Height); Calculate the Average of the ROI where "TYPE" is image dependant Bgr for colour Gray for Grayscale TYPE average = image.GetAverage(image); When youve finished reset your

问题 I am trying to do some operations on color video in MATLAB however, I am facing 2 problems: I am getting an error while converting color video to grayscale video. I mean I need to convert color video to grayscale video and write it back to .avi file How can I perform some operation (say edge detection) on grayscale frames (extracted from color video) and then can write back the result of edge detection in .avi video format? My incomplete code (which consist of color format conversion) is as

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 4 years ago . Is there any framework or open source project for Java that does video conversion from any video format to any video format. Something similar to Panda Video Conversion framework. 回答1: Do you Mean JMF? - ( Java Media FrameWork ) Check this out. 回答2: Along the lines of JMF - perhaps this will become to be better

问题 How do I extract the frames from a yuv 420 video? Let's say i want to store them as still images. How? 回答1: Here's a submission from the MathWorks File Exchange that should do what you want: Convert YUV CIF 4:2:0 video file to image files by Da Yu The function loadFileYuv from the above submission will load a YUV file and return an array of movie frames. Each movie frame is a structure with the following fields: cdata : A matrix of uint8 values. The dimensions are height-by-width-by-3.

问题 Modern graphics cards have hardware video scalers, for example as part of AMD Avivo, NVIDIA PureVideo or Intel ClearVideo. For example, AMD's Avivo whitepaper says: "The image output scalers support up to 6 vertical filter taps and up to 10 horizontal filter taps. These scalers are high-precision polyphase scalers that are highly programmable; they are suitable for upscaling by practically any ratio, or for downscaling by up to 4:1." The question: How can the video scaler hardware be used