Key-Frame | 这是用opencv以颜色直方图法进行的关键帧提取 和 用Python以流光分析写的关键帧提取

It's about live video streaming to STEAM... with ffmpeg

I have this command

i want to change font color for part of text every second using react and javascript.

this is my string "good morning"

i want the text "morning" to change colors

below are the colors i want to change

red, green, blue, yellow, purple, pink, black

below is what i have tried,

This is an issue in a Java Android application with a very simple custom draggable drawer in MainActivity.

This is how it behaves when it runs on Android 10 (API level 29) emulator, and it is the expected behavior.

But the problem is, when it runs on Android L (API level 21) emulator, it behaves unexpectedly as follows :

During the animation, UI components are not visible. But when app goes to background and comes back, they become visible.

Implementation details of app :

To detect fling / drag touch gesture, GestureDetectorCompat was used. When a fling gesture is detected, the custom drawer open animation is being initiated. Animation is implemented using ConstraintSet, ConstraintLayout and TransitionManager.

This is the implementation of touch gesture detections and TransitionManager animations.

MainActivity.java

I am trying to make it so that the H2 and the span text has a bit of a bounce effect towards the end of the hover animation I've created. What I am trying to do can be seen in the following example. Just to be clear in that example, SCSS is being used. I am not using SCSS so I am not 100% sure what I am trying to do is possible with just plain CSS but I sure hope it is because that is what I am using for my project. So the code below shows you what I was able to do. The H2 and span text have a basic start point and end point animation on hover. I want it to have a little bounce towards the end(like in the linked example I shared) something I feel I need to add key-frames to in order to achieve. But I don't know if its even possible to add a key-frame animation on hover especially if I want it to animate back to its original position on mouse out. Am I wrong about this? I appreciate any solutions you guys might have. thank you.

I'm trying to use ffmpeg to output all key-frames from a video file and scale them down to 320px wide while maintaining aspect ratio. I know I could do this with two separate commands but I am trying to find a way to do it tidily in one.

I've already succeeded in each of the steps individually using the following commands.

Output the keyframes:

.\ffmpeg -i input.mp4 -q:v 2 -vf select="eq(pict_type\,PICT_TYPE_I)" -vsync 0 thumb%07d.png

Scale images:

.\ffmpeg -i input.mp4 -vf scale=320:-1 thumb%07d.png

I won't share everything i've tried, but here's three failures at combining them.

//fail, not just keyframes, scaled .\ffmpeg -i input.mp4 -q:v 2 -vf select="eq(pict_type\,PICT_TYPE_I)" -vsync 0 -vf scale=320:-1 thumb%07d.png -hide_banner

//fail, can't find suitable output format for scale command, invalid argument .\ffmpeg -i input.mp4 -q:v 2 -vf select="eq(pict_type\,PICT_TYPE_I)" -vsync 0, scale=320:-1 thumb%07d.png -hide_banner

//fail .\ffmpeg -i input.mp4 -q:v 2 -vf scale=320:-1, -vf select="eq(pict_type\,PICT_TYPE_I)" -vsync 0 thumb%07d.png -hide_banner

I've tried many different things, moving commands, combining using commas etc... But I have not had any success at combining the get key-frames and scale commands. So how would I go about combining the get key-frames and scale commands so that it works?

thanks.

I simply declare a key-frames:

I'm trying to live stream the desktop that's captured through Desktop duplication API. H264 encoding works fine, except the fact that the Desktop duplication API delivers frames only when there is a screen change, but video encoders expect the frames to be delivered at a constant frame rate. So, I'm forced to save the previous sample to feed the encoder at a constant rate when there is no screen change triggered. This works, I could see live output at the other end.

One problem though, the encoder produces a large sample equal to the size of a fresh full-screen sample (which is probably a key-frame) at a constant rate. I have also noticed that an I frame (That large sample) is produced exactly once every 1 second (I guess, it could possibly the default GOP size) even when there is no screen change and I'm providing only the sample that I previously created and literally no diff between them except the sample time I'm setting. This is costly for a live stream, I'm not expecting the decoder to be able to seek or join the stream at the midst of the stream (At least, I have control over it), is there a way to get around this by setting a larger GOP?

I tried all the below settings, but nothing seems to be changing.

I'm very new to image processing and OpenCV. I'm working on a helper-function to assist in tuning some key-frame detection parameters.

I'd like to be able to apply a (dramatic) color cast to a video frame if that frame is a member of a set of detected frames, so that I can play back the video with this function and see which frames were detected as members of each class.

The code below will breifly "hold" a frame if it's a member of one of the classes, and I used a simple method from the getting started with video OpenCV-python tutorial to display members of one class in grayscale, but as I have multiple classes, I need to be able to tell one class from another, so I'd like to be able to apply striking color casts to signal members of the other classes.

I haven't seen anything that teaches simple color adjustment using OpenCV, any help would be greatly appreciated!

Basically, video size is calculated: