5
votes
What is difference between the terms bit rate,baud rate and data rate?
Bit rate and data rate are somewhat ambiguous, and their exact definitions vary from one field or application to another.
Bit rate is often used to measure the information rate, since information is ...
- 14.9k
5
votes
Accepted
When a face collapses into a swirling black hole on a video conference call like this is it due to some advanced AI-based error-correction gone wrong?
This looks like what pretty "classical" video compression does when facing severe data loss – notice the very MPEG-typical square blocks, and how some of the probably more changing blocks ...
- 29.6k
4
votes
Accepted
Can deep learning be applied to video compression?
[EDIT: addition of a March 2017 preprint]
Deep learning already has many applications in video, like enhancement (Deep Convolutional Neural Network for Decompressed Video Enhancement) or semantic ...
- 31.7k
4
votes
Accepted
Identifying license plate number of a thief's car from a video
Averaging may not be the best option, due to motion compensation in video frames: one number (say $8$) may be extrapolated for another (say $3$) on a different JPEG block. It might be interesting to ...
- 31.7k
3
votes
What is the state-of-the-art of using signal-processing for "cleaning-up" videos?
Entertainment industry greatly exaggerates what video enhancement can do.
2016 answer:
Spatial and temporal noise reduction
Noise reduction by Neat Video and MSU Denoiser Filter, which are somewhere ...
- 13.5k
3
votes
My fft gives always gives the correct frequency or double the correct frequency
The 'beat' that you are looking for is a periodic signal but NOT a sine wave. So it can be represented as a sum of sine waves: the fundamental and multiples of it (harmonics).
$$
x[t] = \sum_{n=0}^{P-...
- 42.7k
3
votes
Difference between frame and image?
Frame is the element in the time index of a video.
For 2D videos, each frame is an image.
Frame Rate is just the sampling frequency of the time index of the video.
- 19.3k
2
votes
Accepted
Detect ending of frame in H.264 video stream
I think Technically speaking the only way to detect when a frame ends is to see where the next one begins. That means, you should search for the next start prefix code 0x000001. If you go to the ...
- 1,241
2
votes
Identifying license plate number of a thief's car from a video
There is a company named Signalscape who has a line of products called StarWitness (http://www.starwitnessinfo.com/) that do forensic video analysis that are available to law enforcement agencies (...
- 21
2
votes
What is the state-of-the-art of using signal-processing for "cleaning-up" videos?
I have recently discussed image restoration with a team of one of the French forensics police departments. They have issues related to dirty/spider web nested lens, wrong illumation, occlusions ...
- 31.7k
2
votes
Accepted
How to sync audio and video signals in MATLAB?
Thanks to helpful comments from @MBaz, I managed to come up with a solution:
we can associate multiple audio samples with a single frame using the VideoFileWriter object. This fact and use-case is ...
- 180
2
votes
Accepted
How Can an Object Move by Less Than a Pixel Between Two Consecutive Frames?
The frame is 2D Grid which samples the continuous world in Discrete way.
Leave alone video for a second.
Let's talk about taking a photo of a white paper laid on a black surface.
The photo is taken ...
- 19.3k
2
votes
Video stitching for static scene (infinite loop video)
Lets assume your camera axis has polar and azimuthal angles and you want to align your frames only regarding the azimuthal angle and set the polar angle free.
First you have to find the geometric ...
- 1,328
2
votes
Accepted
How Can I Remove Flickering Background in a Video?
For those classic Video Processing operations there is nothing better than the Plug In's of AviSynth.
Specifically for De Flickering look at:
LMFlicker.
ReduceFlicker.
DeFlicker.
The source code of ...
- 19.3k
2
votes
How Can I Remove Flickering Background in a Video?
I've used in the past Julie Delon's flickering removal (pdf) approach which is based on midway image equalization. It's not hard to implement, and the parameters are easy enough to tune.
Since it ...
- 3,937
2
votes
Interpolation of audio for new frames
When upsampling the number video frames to allow playing a video in slow motion, rather than for a frame rate increase for smoothness, you will likely need to modify the audio using a time-pitch ...
- 35.2k
2
votes
RF demodulation for dummies
A good answer might constitute a few chapters in a good DSP text, making this question overly broad. So I'll sketch an over-simplified skeleton, where you will need to seek a decent rationale ...
- 35.2k
2
votes
Is it possible to calculate/estimate the storage space a certain duration of .mp4 video files will take up?
No.
The MPEG4 video codec allows for a large ranges (easily a dynamic range of 50 for "useful" quality) of compression ratios for the same raw video material. The same applies to audio compressors.
...
- 29.6k
2
votes
2D to 3D view conversion
It seems to be at a stadium which uses 12 cameras and Replay-Technologies special signal processing called FreeD: https://www.youtube.com/watch?v=N1kgt2VDjdM
The image you show seems to use 2-3 ...
- 459
2
votes
Difference H264 and H265 algorithms
The high-level picture is that h.265 allows lower bandwidth at the same visual quality (or more visual quality at the same bandwidth). It achieves this by using more advanced techniques that require ...
- 3,310
2
votes
Accepted
What's the purpose of dividing the light and combining back in TV Cameras?
This is the process of using dichroic prisms for color separation in high end camcorders and digital cameras. The other approach used is with color filters directly on a single CCD photosensor in a ...
- 48.9k
1
vote
Video stabilization using Lucas-Kanade method
For video stabilization, you need to estimate motion vector with respect to a reference frame $F_{reference}$ (which let's assume it to be the first frame). Then your motion model should be determined,...
- 1,976
1
vote
Accepted
How to use optical character recognition program to read coins?
Without seeing the coins it's not easy to give a unique solution. A possibility would be: Use the Hough transform to detect circles (the coin). Then do some open/close operations to get blocks of text,...
- 701
1
vote
How to recognize for small video sequence with a large sequence?
The most intuitive approach here would simply be taking every pixel's color values, and finding peaks in the individual pixels' reference video/short video cross correlation function. That's basically ...
- 29.6k
1
vote
temporal high-pass filtering to approximate phase derivative
I am not familiar with the algorithm you have proposed, but I believe I can answer the question you asked.
Once you have computed the DFT of your image, what you get is a 2D array of complex number. ...
1
vote
Accepted
Video processing to detect a logo in frames
If you know where the logo is then you can detect its presence, fairly quickly, with cross-correlation...with a little bit more work.
Detecting the presence of "things" using cross-correlation is a ...
- 10.6k
1
vote
Does the cv2.waitKey argument determine the frame-rate while capturing a video?
It does not determine the framerate, but it has an influence on the framerate.
The first caveat is that although you're only waiting 1ms between frames, the program has other work to do in order to ...
1
vote
Measure the amount of drift in video and audio frames
the two cameras are not genlocked and as a result I expect there to be some drifting between the frames of the two video/audio signals.
Drifting would imply that ...
- 10.6k
1
vote
Video compression - why not just sending the changed parts?
Video codecs tries to find apparent movement (akin to optical flow) first. Bits have to be allocated to describe that motion. Then the residual is coded using a lossy transform/quantazation that tends ...
- 3,310
1
vote
Accepted
Video compression - why not just sending the changed parts?
You could do that, in theory, if you knew "what are the parts" (or objects) frame-to-frame in a video. But:
objects move, change scale, rotate, have color changes, they even can be occluded.
the ...
- 31.7k
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