NewTek TriCaster 8000 - Manual (Page 326)

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You could think of this as being like water flowing through a hose. You control the
‘faucet’, because you get to choose the Stream Profile in TriCaster’s Stream
Configuration panel. However, you don’t own the ‘hose’ – or at least, not the entire
hose.
Once the stream leaves your immediate environment, even if you can supply good
throughput locally, bandwidth may be constricted elsewhere along the transmission
path. The level of Internet traffic can impose limits, but another major factor is the
sort of connection your viewing audience may have.
Consider an example scenario:
Even though you know that most of your audience is going to connect to your program
using (relatively slow) wireless devices, you use a very high outgoing bitrate
– thinking
that this will surely be enough to fill the need. The fact is, though, a high bitrate actually
ensures their experience will be poor!
The client player tries to play the stream at the bitrate you specified, but (in this example)
the wireless bottleneck impedes flow. It is as if you connected a fire hose on your end,
giving them a suitable high capacity nozzle for their end
– but in the last stage of flow, the
stream must pass through a small garden hose. Sadly, the stream will be quite
insufficient, and output from the ‘nozzle’ (the client player) will falter badly.
For reliable performance, try to ensure the potential upload bandwidth from your
system to the net is around twice the bitrate you choose. You can broadcast at a rate
closer to your actual ceiling, but reliable performance cherishes headroom.
Also consider the expected download abilities of your viewers. Ideally, a safety
margin 1.5 times the stream’s bitrate is desirable. This may mean you need to
consider using a lower resolution, or lower framerate for your stream – but doing so
when required will generally deliver a smooth result, and is the wise course.
(Nothing inclines viewers to turn away quicker than a stuttering, start and stop
stream. See “Speed Tests” in Section 18.8.1 for some useful resources.)
18.6.2 STREAMING PROTOCOLS
Additionally, there are two primary streaming methods, known as Pull and Push.
Choosing the best method for your needs is important. Let’s review each, and
consider what is best for your needs.