Module 2: additional information about data transmission

Encoding

Encoding is the process whereby a videofile is processed in order for it to be used in the application you envisage (streamed, burned on a DVD, saved on a PC hard disk etc.) When you want to publish your video by streaming it to your target audience, you should take into account at the encoding stage the technical conditions of your audience.

Encoding consists basically of two parts:

  • video compression (this means adapting the overall size of the video, resulting in smaller file size, which means by consequence less data storage capacity needed and faster transmission).
  • storage in the correct format. Video files can be stored in many different formats (avi, wmf, mpeg etc). Depending on the player that you expect the audience to use for playback, you should store the video in the appropriate format.

More information:

Encoding software

There are many software programmes that can be installed to do the job:

Real Producer

Windows Media Encoder


(A concise overview of the encoding process of the Windows Media Encoder can be found in this short explanation.)

QuickTime Encoder

Sorensen

Formats

The encoder converts media into a suitable format for streaming.
There are many formats for the encoding of media for streaming. Competition between the major format backing vendors (Apple, RealNetworks, Microsoft, Adobe) has pushed streaming technology towards higher levels of quality and performance. The downside of this is that the same competition has resulted in a large number of encoding formats that are not always compatible with each other or with some of the media players. Therefore it is advisable to check the compatibility of player and encoding format.

Most important media formats:

  • Motion Pictures expert group (MPEG)
  • Digital Video (dv)
  • Microsoft Advanced Streaming Format (asf)
  • Realnetworks (rm, ram, ra)
  • Macromedia Flash MX Video (flv)
  • Apple Quicktime movie (mov)

Input to the encoder

What do you send to the encoder for processing?

  • A file

    • Media files that are residing on your computer (most often of the type .avi,.wav,.mov of.mpg).

    The transmission of these files happens in two steps:
    1. Upload
    2. Encode into multi media

  • A live source

    • The images coming from the digital camera, video tape, tv or any other broadcast are loaded directly into the encoder software.