# Tag Info

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 ...
• 42.4k
Accepted

### Difference Between monocular video and stereo video?

Monocular video is taken using a single camera. Stereo video is taken using two cameras side-by-side, producing two video streams. That's pretty much it. A stereo video pair allows depth ...
• 517
Accepted

### Make a Movie from Multiple Images in MATLAB

It is easy to do using the VideoWriter class. You easily add frame (Image) using the proper method which is writeVideo. After creating a video object, ...
• 42.4k
Accepted

### How to Increase the Resolution of a Video from a Sequence of Photos?

One way to do it is to solve a MAP problem of the up scaled video and using the High Resolution images as a prior. Try looking at the articles - Super Resolution MAP.
• 42.4k

### How to Reduce Noise in a Video Stream?

Usually, Salt and Pepper Noise is done using Median Filter. There are variations of the Non Local Means to deal with Salt and Pepper but it might be overkill so I'd start with the above. The tricky ...
• 42.4k
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 ...
• 42.4k

### 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 ...
• 13.9k

### Pixel Wise Write into a Video File in MATLAB

I assume your matrix is 3D where the first 2 dimensions are Width and Height and the third is time (Gray Scale Video). If you can write your processing as a Filter you can use MATLAB's ...
• 42.4k
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 ...
• 26.9k
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 ...
• 30.5k
Accepted

### How to Find the Probability of Kalman Filter States?

The idea of Kalman is it fuses the data with the optimal weighing to get results. Optimal requires definition and in the case of Kalman it means that if your model is right this is the optimal. Since ...
• 42.4k
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 ...
• 30.5k

### 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 ...
• 12.5k

### Map time difference between two similar videos

To compute an offset between the two signals in the first image, I think that phase-correlation will give you much better results, than simply the basic correlation. You can reuse your fft code but ...
• 1,720
Accepted

### Video: Detecting a digital timer and when it ticks

To OCR or not? If the timer is about $h$ pixels height, you could segment each frame into lines of height $h/2$, run an OCR on each line, and scan the result with a regexp for anything that looks ...

### How are video thumbnails chosen?

There are many ways to skin this cat. I'll explain one way that I know is used in industry. Create candidate frames algorithmically using the image features; e.g., the histogram, sharpness, presence ...
• 2,837

### 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-...
• 33.8k

### Map time difference between two similar videos

Naive question: is it very common for the relationship between the two sequences of timestamps (the "warping function") to be something else than a linear function? I assume it'll be almost always ...
• 19.1k
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 ...
• 1,211

### 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 ...
• 30.5k

### Find large distinctions in Video

Implement a low pass 2D filter that will reduce greatly the noise. Following an example that you could complete yourself. You could subtract the filter bias to keep an average of 0 "addition" by the ...
• 322
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

### 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

### 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 ...
• 1,306

### 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 ...
• 3,887

### 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 ...
• 34.1k

### 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 ...
• 34.1k

### 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. ...
• 26.9k