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Hopefully this page will give you a little insight about bit rates!



Bit Rates and Camstreams
Bit rates determine the quality of your stream, both video and audio. In this day and age, bit rates can be found everywhere - from mp3s to digital TV, the higher the number the better the quality. Generally you will hear bit rates referred to as Kbps (Kilobits per second) or Mbps (Megabits per second). Camstreams generally talks in terms of Kbps.

You can't just use an incredibly high bit rate though - there are always considerations:
  • Your 'upstream' bandwidth may only be in the few hundred Kbps range (test it at speedtest.net, paying attention to the 'upload' result)
  • The network fluctuations that exist between your ISP and Camstreams may mean the effective upload rate you can handle is lower than expected
  • Encoding at higher bit rates requires more CPU time, so it is possible your stream wouldn't encode properly resulting in jitteryness/cutouts

When you installed the Camstreams Encoder, it was set to use the default bitrate of 64Kbps.This means that when you are Encoding and a viewer connects, we pull 64Kbps of data continuously from your Encoder and send 64Kbps of data out to each individual viewer. As you can imagine this can mount up with many viewers.

Whilst Camstreams allows for unlimited viewers/bandwidth, we have an upper limit on the bit rate of an individual stream of around 500Kbps. If you try and broadcast above this rate, it will not work. We recommend you stay at the 64Kbps rate, or select the 'Camstreams High Bandwidth' option in the encoder.

Here's how to select a new bit rate:

Changing your bit rate in the Camstreams Encoder
  • Make sure the Camstreams Encoder is running but not broadcasting
  • Click 'Options', then 'Compression' - see 'Select and configure compression profile'
  • Pull down the drop down box and select the compression profile you wish to use.
  • Click Ok. You can now start broadcasting at the new bit rate.

Dial-up user? - Select 'Camstreams Dial-up' within the compression profiles before clicking OK and you will be able to broadcast on your dial-up connection.


Changing bit rate in Microsoft Windows Media Encoder 9
  • Launch the Encoder as usual with the broadcast.wme file
  • Click 'Properties'
  • Click the 'Compression' tab
  • Click 'Edit...'
  • Select '64Kbps (64000 bps)' and click 'Edit'
  • Change the 'Video Bit Rate' field to something between 48K and 300K, for example 180K
  • Click 'Ok'
  • Click 'Apply'
  • Go to File > Save As... and save your file as a new settings file so you can switch between 64Kbps and the new bit rate if you want to, in the future.

Dial-up user? - You will need to lower your bit rate to something around 28K in total, so 'video bit rate' should be set to about 20k. You will then be able to broadcast a fluid stream to Camstreams and we can rebroadcast it. Your viewers will be shocked you're on dial-up when you see how good it can look at lower bit rates!


Multiple Bit Rates
In this age of broadband, it's easy to forget that some people in the world still use dial-up modems to connect to the Internet. To them, a 64Kbps stream will appear as one new frame every 30 seconds, if they're lucky, and possibly some major breakup in audio. Not good.

In order to cater for your dial-up viewers, at the same time as keeping quality high for your broadband viewers, you can set up a multiple bit rate stream. It's fairly simple - just be aware that multiple bit rates means multiple processes and could tie up your computer's processor more noticably than before.

When you set up a multiple bit rate stream, you push out one big stream containing both bit rates to our server (so you must be on broadband to do this) and the technology at Camstreams determines which bit rate to send to the viewer, based on what the viewer's media player believes it can receive.

Setting up a Multiple bit rate Stream in the Camstreams Media Encoder 3.0
  • Make sure the Camstreams Encoder is running but not broadcasting
  • Click 'Options', then 'Compression' - see 'Select and configure compression profile'
  • Pull down the drop down box until 'Camstreams Multi-bit rate' is selected.
  • Click Ok. You can now start a Live or Archived broadcast with a multiple bit rate stream.
Please note - For simplicity the Camstreams Encoder only contains one Multi-bit rate profile and you cannot add your own. If you wish to use custom multi-bit rate streams, please use a Microsoft Encoder (see here for download/setup instructions)


Setting up a Multiple bit rate Stream in Microsoft Windows Media Encoder 9
  • Launch the Encoder as usual with the broadcast.wme file
  • Click 'Properties'
  • Click the 'Compression' tab
  • Click 'Edit...'
  • Click 'Add', in the 'Target bit rates' area.
  • Enter the extra bit rate in the new window. A good example is 28K (include the 'K'), Click OK.
  • You'll notice you're now in a tabbed screen with the new bit rate selected.
  • The default settings the Encoder chooses usually suit the bit rate quite well, feel free to alter them though.
  • Click 'OK' or you will lose the new bit rate, and then 'Apply'.
  • Go to File > Save As... and save your file as a new settings file so you can switch between your existing bit rate and the new multi-bit rate setting if you want to, in the future.
Test your multi-bit rate stream
To do this, you will have to force your Windows Media Player to believe you don't have much bandwidth:
  • Open Windows Media Player from Start > Programs > Accessories > Entertainment
  • Go to the 'Tools' Menu, and 'Options'.
  • Select the 'Performance' tab
  • Select "Choose Connection Speed" and pull down "Modem (28.8Kbps)", click OK.
Now refresh your broadcast page when you are broadcasting the multi-bit rate stream and you should see the 28Kbps version, as if you were on dialup!