Decoding the Inner Workings of Television Encoding Schemes

  • Thread starter mearvk
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In summary: TV industry from people who wanted to hack them to change the programming or make unauthorized broadcasts. In summary, the TV encoding process changes a lot from NTSC to ATSC. TVs can now be controlled from the broadcast station, and there are laws against blocking commercials.
  • #1
mearvk
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Hi guys/gals.

Enjoying the Superbowl here on the east coast. Hope you guys are having a good evening too.

My question is how is the encoding for TVs done? I've read the NTSC link below. I didn't see how exactly the signal is created but rather more about where the different data are stored in the encoding. Does anyone on this forum have this knowledge?

http://en.wikipedia.org/wiki/NTSC

Thanks.
 
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  • #2
i don't have the knowledge. But i once looked for it.

Since TV went digital it changed a LOT from NTSC.

I think you want to look into ATSC standards
http://www.atsc.org/cms/index.php/standards/standards/50-atsc-a53-standard

google on "digital tv standards"
you will be amazed at what is possible. Your TV can be controlled from the broadcast station; commands exist to change channel..
I'm surprised there's not hackers yet.

my intent when looking was to decode the frame information and make a gizmo to turn way down both the volume and brightness during viagra commercials.
There are law aginst blocking them, but knocking them both down about 20db might be legal.
If so, can you imagine how that device would sell?

But it's too complex for this old analog guy.

Good luck !
 
  • #3
jim hardy said:
...my intent when looking was to decode the frame information and make a gizmo to turn way down both the volume and brightness during viagra commercials.
:rofl:

BTW IIRC there was a FCC law to keep the dB level within some range years ago. This one, ‘‘Commercial Advertisement Loudness
Mitigation Act’’ or the ‘‘CALM Act’’
, is probably new due to the change to digital.

And from their Guid "Loud Commercials and the CALM Act"...

Effective December 13, 2012, the FCC's rules require television commercial advertisements to have the same average volume as the programs that they accompany.
 
  • #4
Interesting notion. Are commercials framed in somehow so they can be detected? In other words how would your device know when to start working and when to stop?
 
  • #5
mearvk said:
Interesting notion. Are commercials framed in somehow so they can be detected? In other words how would your device know when to start working and when to stop?

The standards are absolutely amazing to read.
Everything is preceded by a frame saying what is its content. I think once every seven seconds the program's name, episode number, etc is sent, and immediately prior to a change eg from program to commercial A to commercial B...

Your TV is now a computer. It could easily be made to do anything by somebody with intimate knowledge of how today's TV's work.

I too thought they still used the old NTSC intervals of flyback and vertical blanking for such information. But your TV signal is a cacophonous bitstream now.
This new digital world has left me in the dust. I had to get one of these handsets in order to use the wife's cellphone.
http://www.bedbathandbeyond.com/assets/product_images/230/21442140088358p.jpg [Broken]


I would love to crack the TV computers, and am still competent with logic analyser and oscilloscope. But i just didnt keep up with the software world. All i can fix in today's TV's is power supply problems.

old jim
 
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1. What is a television encoding scheme and how does it work?

A television encoding scheme is a method used to convert visual and audio information into a format that can be transmitted and displayed on a television screen. It involves breaking down the information into digital data and compressing it for efficient transmission. This data is then decoded by the television set to recreate the original image and sound.

2. What are the different types of television encoding schemes?

There are several types of television encoding schemes, including analog encoding, which uses electromagnetic signals to transmit information, and digital encoding, which converts information into binary code for transmission. Other types include MPEG, H.264, and HEVC, which are commonly used for video compression in digital broadcasting.

3. How does a television encoding scheme affect video quality?

The type of television encoding scheme used can greatly impact the quality of the video being transmitted. Some encoding schemes, such as analog, have lower quality and may result in lower resolution and poorer image and sound quality. Digital encoding schemes, on the other hand, offer higher quality and can transmit high-definition videos with better clarity and sound.

4. Can television encoding schemes be changed or upgraded?

Yes, television encoding schemes can be changed or upgraded to improve the quality of transmission. This is often done as technology advances and new and more efficient encoding schemes are developed. However, upgrading may require both the broadcasting station and television sets to be compatible with the new encoding scheme.

5. Are there any limitations or drawbacks to television encoding schemes?

One limitation of television encoding schemes is the potential loss of quality during compression, which can result in lower resolution and clarity of the video. Additionally, not all encoding schemes are compatible with each other, which can make it difficult to transmit and receive videos across different systems. Lastly, some encoding schemes may require more bandwidth and data storage, making it more expensive to broadcast and store videos.

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