Video Streaming: Bitrate & Lag

You are watching a 4K movie. Suddenly, the image turns into blocky mush. Your internet slowed down. To keep the movie playing without stopping, Netflix lowered the Bitrate.

The Firehose of Data

Raw video is huge.

• 1920x1080 pixels x 3 colors x 60 frames/sec = 373 Megabytes per second.
• Average Internet Speed: 10-20 Megabytes per second. You physically cannot stream raw video. You must Compress it.

Compression (MJPEG vs. H.264)

1. Intra-frame (MJPEG): Squeezes each photo individually (like a JPEG).
   • Pros: Low latency. Simple.
   • Cons: High bandwidth.
2. Inter-frame (H.264): Only saves what changed.
   • “The background stayed the same; only the guy’s mouth moved.”
   • Pros: Tiny file size.
   • Cons: The computer has to think hard to reconstruct the image (Lag).

The Robot Bottleneck

In FTC, we stream the camera view to the driver’s phone. But we are limited to a specialized Wi-Fi channel with low bandwidth.

• If we stream 1080p, the Wi-Fi chokes. The robot controls lag. You crash.
• The Fix:
  • Resolution: Drop to 320x240 (Potato quality).
  • Bitrate: Cap it at 1Mbps.
  • Format: Raw or MJPEG (because we care about latency more than quality).

We don’t need to see the game in 4K. We just need to see the yellow blob of the game piece. Engineering is knowing when “Potato Quality” is the correct technical choice.