Parabolic antennas do more than just pick up signals. They receive a highly processed data stream that is extracted, encrypted and sent across space. To display this image on the screen, the broadcast center uses a high-quality video signal via an MPEG encoder. This device converts programming to MPEG-4 video and formats it specifically for home receivers.
Encoding and compression happen simultaneously. The encoder analyzes each video frame to find unnecessary or irrelevant data. We then remove this bloat and extrapolate the data from other frames. The result is a noticeable reduction in file size.
Each frame is encoded in one of three ways.
- Intra: This contains complete image information. It achieves minimal packaging.
- Predicted Frame: Only information needed to update the image based on the last internal or predicted frame is stored here. It explains “how” the image changes.
- Bidirectional Frame: This uses information from surrounding frames. The receiver interpolates the position and color of each pixel.
This process can cause malfunctions. Macroblocks may appear. The fluid image is divided into blocks. People often call this “pixelation”. This is technically incorrect. Graphic artists use “pixelation” to describe the intentional distortion of an image. There are pixels on the television screen, but they are too small to display individually. These are just small squares of video data.
“Graphics and video editors use “pixelation” to more accurately describe image distortion.
Compression speeds vary depending on the program. News broadcasts use many predicted frames. The scene hardly changes. Competitions change quickly. The encoder must also generate intraframes. News broadcasts are small compared to fast-paced games.
Encryption and transfer
After compression, the service provider encrypts the data. This prevents free access. Encryption scrambles the digital bits. In order to decrypt the signal, the correct algorithm and security key must be used.
The transmission center sends this encrypted signal to the satellite. The satellite receives it through its internal antenna. It strengthens the signal. It uses another antenna to transmit to the ground. The receiver captures it from there.
Intentional pixelation
Sometimes pixelation isn’t a mistake. This is a tool.
A law passed in 2006 gave the Federal Communications Commission (FCC) the authority to fine television stations $325,000 for violating integrity standards. Broadcasters avoid these fines by using clear language. In addition, the screen is used digitally. It pixelates the speaker’s mouth. This prevents the viewer from lip-reading the words.
PBS is faced with a dilemma. They must avoid fines. They also wanted to preserve the authenticity of the documentary. How can we protect ourselves without losing the truth about programming? The answer is still confusing.
