67
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Accepted
Why is TV static noise always black and white?
The color burst is also an indicator that there is a color signal.
This is for compatibility with black and white signals. No color burst means B&W signal, so only decode the luminance signal (no ...
- 5,016
27
votes
Why is TV static noise always black and white?
In the absence of a valid color burst signal, the "color killer" circuit disables the color difference signals, otherwise you would indeed see colored noise. This is mainly intended for displaying ...
- 371
5
votes
Converting speech audio to telephone audio
Band-pass filtering with cut-off frequencies of 300 Hz and 3400 Hz should result in a good approximation. Try with a Chebychev filter or order not more than 6.
Then you may need to downsample your ...
- 5,016
4
votes
Why is TV static noise always black and white?
In PAL, the colour information (chrominance or chroma) is modulated onto the black and white (luminance or luma) baseband signal. The chroma is at ~4.4MHz offset from DC and is about 1.3 MHz wide.
...
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3
votes
Is there any relation between QAM and streaming?
QAM is a digital modulation scheme. As such it is one way of implementing a physical layer that allows to convey digital information over a given medium. QAM is frequently used in all kinds of systems,...
- 2,463
3
votes
Accepted
How to remove wind noise from video file
Extracting Audio from Video
There is a simple cross-platform tool for manipulating / accessing video & audio files called ffmpeg. I've linked you the documentation available for the whole toolkit,...
- 212
2
votes
Why is TV static noise always black and white?
To add to the existing answers, PAL corrects for color errors by reversing the color component of each line in the next one, which cancels out color errors and should also reduce the color component ...
- 121
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 ...
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2
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Converting speech audio to telephone audio
I did this once using two phones and by making and actual call. The calling phone had a good quality headset pushed against its microphone, and the audio was played through the headset. The audio was ...
- 13.5k
2
votes
Why do we need motion vectors in MPEG?
Because that's way more efficient at encoding a lot of typical scenes.
Imagine this: you're filming a complex scene with lots of different objects. The camera shifts ten pixels to the right; with your ...
- 30.7k
2
votes
Accepted
Combining Analog Video Signals for Diversity Receiver System
(or maximal gain combining if a simple circuit exists to variably attenuator each signal).
Nobody does maximum gain combining in analog circuitry (at least as far as I know). That would require ...
- 30.7k
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
Codec for forensic video
Don't discount the contribution of physics to the blur in your pictures: Especially in low light, you need to have long exposure times, to get a picture that isn't completely dominated by grain. ...
- 30.7k
2
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Can I get audio version of UCSD dataset?
The DCASE community has since 2020 had a compoetition on Unsupervised Detection of Anomalous Sounds, with acommanying datasets. Here is the 2021 edition.
- 277
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 ...
- 3,394
2
votes
Detecting & tracking an arbitrary object in a video
If all you want to do is to isolate* and track objects that have some contrast against the background, then the key phrase you want to search on is "object tracking", "video tracking&...
- 12.7k
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 ...
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1
vote
Alternate Octave Commands for Matlab
I am not an Octave user, but the Video package appears to do these things.
Good luck!
- 111
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vote
Video-Encoding planes
The question might be more about code written in a specific context. However, the Y, U, V letters refer to YUV formats, a transformation of an image in RGB format into three other planes, one of ...
- 31.9k
1
vote
Confusions regarding frame rate?
The vision centre of the brain retains an image for $\frac{1}{15}^{th}$ of a second and any image added in that time frame gives a sense of continuity. 24 FPS is mostly used in movies and TV.
Also, ...
- 480
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vote
Accepted
Confusions regarding frame rate?
In this case, images/frames are moving horizontally or vertically?
Neither. They just appear; usually, they stand still for as long as a frame is displayed.
But what is the minimum rate of frame/...
- 30.7k
1
vote
Does Gamma Correction Interfere with Sub Pixel Motion Estimation?
It is a matter of "getting away with it".
The multi-tap algorithm is not doing a perfect job either because it's not a brick-wall sinc filter, giving some error even for linear color space input. ...
- 13.5k
1
vote
Accepted
Does Gamma Correction Interfere with Sub Pixel Motion Estimation?
When one does an operation Wrong / Right aren't strictly defined.
In most cases the questions are:
What's the model?
Is the model reasonable?
When you do sub pixel motion estimation on frames which ...
- 19.6k
1
vote
How to extract pixel-specific time-stream from mp4 video
In video, pixels are not usually encoded independently; you will need to decode full frames. If you are going to run several experiments on a single video, I would suggest that you decode the video ...
- 13.5k
1
vote
Accepted
What is Typical RTP Packet size for H.264 video transmission
RTP Payload Format for H.264 Video
...
1
vote
Accepted
How to calculate transfer rate and needed bandwidth
First of all, you mistakenly assume that those multimedia source files are sent as raw bits (or bytes); no but instead in compressed form. Hence you shall not compute the raw bitrates of those file ...
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How to calculate transfer rate and needed bandwidth
Your calculations are wrong. You have misunderstood the concept. The files may contain an amount of bits as you calculated but transferring that information is a bit different.
First of all, you send ...
- 195
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 ...
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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
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 ...
- 3,394
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