Bandwidth requirements for video streaming

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Some calculations ...

Example 1: Webcam streaming

  • 640x480 @ 1 fps produces an unencoded video stream of 523.6 kbit/s
  • encoded as MJPEG @ q=1 (maximum quality) using ffmpeg: CPU usage = 40% @ 1 GHz single-core (no GPU)
  • ifstat reports:

$$ 18.5 \mathrm{\frac{KB}{s}} = 150 \mathrm{\frac{kbit}{s}} $$

Example 2: Continuum, season 1, episode 3

  • broadcasted via DVB in high-definition quality
  • 1280 × 720 (720p) @ 24 fps, encoded as H.264/AVC Video
  • 44.1 kHz stereo audio, encoded as MPEG-4 AAC audio
  • transmission of 296 MB lasts 44:09 min

$$ \frac{ 296 \cdot 10^3 \mathrm{KB}}{44 \cdot 60 \mathrm{s} + 09 \mathrm{s}} = 112 \mathrm{\frac{KB}{s}} $$ $$ 112 \mathrm{\frac{KB}{s}} = 894 \mathrm{\frac{kbit}{s}} $$

  • note: playback on dual-core 1.60 GHz + GPU (used by mplayer) scratches the limits of the hardware: stutters from time to time

Example 2: Continuum, season 1, episode 4

  • broadcasted via DVB in good quality
  • 720 x 404 @ 24 fps, encoded as H.264/AVC Video
  • 44.1 kHz stereo audio, encoded as MPEG-4 AAC audio
  • transmission of 124 MB lasts 44:24 min

$$ \frac{ 124 \cdot 10^3 \mathrm{KB}}{44 \cdot 60 \mathrm{s} + 24 \mathrm{s}} = 46.55 \mathrm{\frac{KB}{s}} $$ $$ 46.55 \mathrm{\frac{KB}{s}} = 372 \mathrm{\frac{kbit}{s}} $$

  • note: plays back smoothly on dual-core 800 MHz, without GPU

Internet speed

Telekom DSL-6000

  • nominal downrate: 6.016 kbit/s
  • nominal uprate: 576 kbit/s
  • realistic: about 80% of these values = 461 kbit/s

Telekom DSL-16000

  • nominal downrate: 16.000 kbit/s
  • nominal uprate: 1.024 kbit/s
  • 80% = 819 kbit/s
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