What equipment do I need to do a Live stream?

Part 2b. - The details

There are two primary methods for encoding video:

Capturing and encoding from a live stream directly to a Windows Media broadcast as a real time process.

Capturing to an uncompressed AVI file, and then encoding a Windows Media file from the AVI file in non-real time.

Live event broadcasting requires real-time encoding. Two-step or two-pass (note: these are not the same) encoding is generally used for creating On-Demand content.

There are also several items you need to consider when building a high quality workstation:

Source quality.

The final product can be no better than the source. Make sure to use as high a quality digital input format as possible. With the proper digital interface, such as the IEEE 1394 (sometimes called FireWire) interface or the professional Serial Digital Interface (SDI), you can skip the analog-to-digital conversion that reduces quality. If you must convert from analog, make sure your video source is high quality, and use S-Video connectors if possible.

If you are capturing from a tuner, demodulator, film scanner, mixing board, or router, make sure the cables and connections are professional quality and working properly, and the radio frequency (RF) connections to the tuner or demodulator are properly adjusted and terminated. Not only does poor source quality result in a poor quality product, any noise, glitches, or instability in the picture can increase the bit rate and size of the final file.

Fast CPU, PCI bus, and more RAM.

A fast CPU enables a computer to keep up with the demand imposed by the continuous stream of bits, while a fast PCI bus moves those bits easily between the capture device and the processor. A large amount of RAM eases the load on the CPU by enabling bits to be cached as they are converted. If your CPU usage often hits 100 percent, there is a very good chance the capture quality will be impaired. If necessary, use a computer with dual PCI buses to improve performance.

High-quality capture cards.

A capture card is responsible for properly inputting and processing the audio and video signals, and then converting them into a digital stream of bits. For this reason, the video capture card is the most important link in the chain. A low-quality or outdated capture card can greatly reduce the quality of the video. After the video has been converted to digital form, the data can be stored, transferred, and copied without affecting quality.