Formula for Live Video Streaming Bitrate

Question

I am simply looking for the formula that should be used here. All the results I've found base "finding the bitrate" off of already existing video. I'm talking about LIVE streaming. (indeterminate length)

So, I know some basic parts of it, but I just need to know if I'm right or missing anything.

For Kbps:

Resolution * Framerate / 1024

Is it really that simple? Audio would be a separate element for our purposes here. Am I missing anything from this formula?

(Coming up with a proposal of what amount of bandwidth would be required, relative to possible resolution options, so I just need to be sure that I'm not missing anything or inaccurate about it)

Answer 1

There are two different bit rates in question when talking about video:

• bit rate of the rendered video (for which your equation is almost there on)
• bit rate of the networking 'stream' from server to client (which I suspect you are after)

The bit rate value for the network stream has many, many variables. These are dependent upon not just the resolution and frame rate, but also...

• the video CODEC,
• the CODEC configuration (key frame rate, use of advanced compression techniques, etc),
• streaming and network protocols (RTMP?, RTP?, RTSP?, HTTP?, etc),
• audio CODEC (MP3, AAC, etc.), source & quality (8-bit 11KHz mono? 16-bit 44.1KHz stereo?),
• expectations and requirements regarding end user viewing quality,
• and more!

Even the video source's characteristics can impact the bit rate. (No motion with a compressed stream means a lower bit rate.)

Because of all this, streaming live video is more of an art and less of a science.