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Questions tagged [video-processing]

Video processing deals mostly with filtering video frames. Most common filters are noise removal, contrast and color modifications. For questions related to trimming and modifying videos use [video-editing], and [video-encoding] for questions related to editing videos into any format.

Video processing is a particular case of signal processing, which often employs video filters and where the input and output signals are video files or video streams. Video processing techniques are used in television sets, VCRs, DVDs, video codecs, video players, video scalers and other devices.

Most common filters are noise removal, contrast and color modifications. Relevant questions should include specific filters.

See also:

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Select the camera while using navigate.getUserMedia()

I am using navigate.getUserMedia() method to capture video on my mobile and do further processing on it. But as of now it is capturing the video using the front camera. How do i make it to access the rear facing camera?? Below is some sample code…
Vinay C
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How to create videos from images with php?

Let's say I have 10 images and I want to combine those images in a video like a slideshow. For example I want to show each image for 5 seconds and then continue with next image for another 5 seconds. If it's possible, it will be perfect to include…
mirza
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FFMPEG: Extracting 20 images from a video of variable length

I've browsed the internet for this very intensively, but I didn't find what I needed, only variations of it which are not quite the thing I want to use. I've got several videos in different lengths and I want to extract 20 images out of every video…
Vapire
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How to Add Font size in subtitles in ffmpeg video filter

I'm using this command to crop,scale, and then add subtitles as overlay ffmpeg -i input.avi -vf "[in]crop=in_w:in_h-20:0:0 [crop]; [crop]scale=320:240 [scale];[scale]subtitles=srt.srt" -aspect 16:9 -vcodec libx264 -crf 23 oq.mp4 how can we set…
khizar ansari
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How to expose a virtual camera on macOS?

I want to write my own camera filters for videochat, and ideally apply them in any/all of the popular videochat applications (Zoom, Hangouts, Skype, etc.). The way I imagine this working is to write a macOS application that reads the camera feed,…
user18184
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Decode video frames on iPhone GPU

I'm looking for the fastest way to decode a local mpeg-4 video's frames on the iPhone. I'm simply interested in the luminance values of the pixels in every 10th frame. I don't need to render the video anywhere. I've tried ffmpeg, AVAssetReader,…
simon.d
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How to seek in FFmpeg C/C++

Does anyone know how to implement seeking by seconds (or milliseconds) in FFmpeg. I currently have a loop running through the frames of a video using av_read_frame() and I want to determine what time this frame should be at in seconds. If it gets to…
DRiFTy
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ffmpeg in python script

I would like to run the following command in a python script, I also want to make it loop over several videos in a folder. This is the command I want to run. ffmpeg -i mymovie.avi -f image2 -vf fps=fps=1 output%d.png I want to fit it in something…
jawwe
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why DCT transform is preferred over other transforms in video/image compression

I went through how DCT (discrete cosine transform) is used in image and video compression standards. But why DCT only is preferred over other transforms like dft or dst?
mrsatish
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Android: Alternative to the deprecated Context.MODE_WORLD_READABLE?

From here I know a way to write a file and be accessible to other app and other intent, but now that the Context.MODE_WORLD_READABLE is deprecated how can I safely accomplish this? FileOutputStream out = myActivity.openFileOutput(fileTo,…
Marl
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OpenCV doesn't report accurate frame rate/count

I have a 33 second video that I'm trying to process with OpenCV. My goal is to determine what instance in time (relative to the start of the video) each frame corresponds to. I'm doing this in order to be able to compare frames from videos of the…
mpenkov
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Reverse video in android

I have recorded a video from camera in my app and saved in device storage.Now I want to reverse the video such that it plays from backwards.i.e. if video is of 10 seconds then the last frame at 10th second will become first frame and it starts…
Android Developer
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Why does video resolution change when streaming from Android via WebRTC

I'm trying to stream at 640x480 from Chrome on Android using WebRTC, and the video starts off at that, but then the resolution drops to 320x240. Here are the getUserMedia parameters that are sent: "getUserMedia": [ { "origin":…
Jay P.
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How to read a frame from YUV file in OpenCV?

How to read a frame from YUV file in OpenCV?
Jason
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Concatenate mp4 files in Android using halfninja ffmpeg

I've manage to compile halfninja ffmpeg scripts for Android NDK using NDK version r5c. (Unfortunately any attempt to compile with earlier NDK generated some error), also I'm not very knowledgeable on the whole NDK process, so it's a bit hit-n-miss…
Budius
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