Encoding Video

ENCODING VIDEO FILES

Here's where things start to get a little complicated. Let's review the parameters that you need to consider when encoding video for the web:

Broadband or Dialup - Since broadband connections download at about 10 times the speed of dialup, you may have to create two versions of the same video.

Movie (frame) size - broadband is generally 320x240 pixels up to 640x480. Dialup is generally 160x120 up to 320x240. Unless you are working with a wide-screen format, the ratio should be 4 x 3. The larger the frame size, the larger the resulting file.

Codec  - how much and how well the movie is compressed. There are frequent new or updated Codecs. The question is whether you want your viewers to go through the hassle of downloading a codec to watch your video.

Frame rate - A normal video is 30 frames per second (fps). Desktop videos can use 5 - 10 fps, head shots 10 - 15 fps and full motion video 15 - 30 fps. The frame rate should be divisible into the original frame rate (30 fps can be lowered to 15, 10, 7.5 or 5 fps)

Streaming rate in kilobits per second (kbps) - for video you want to stream at the lowest common denominator while still maintaining decent quality. Dial-up users on a 28.8K are pretty much out of luck. 56K modems can view small videos of generally poor quality at 37 kbps, or slightly higher when using a buffer (see below). A safe range for broadband is 300 - 500 kbps.

CBR or VBR?  Your other option is whether to use a Constant Bitrate (CBR) or Variable Bitrate (VBR). With CBR the rate stays the same and the picture quality varies and it's the opposite for VBR, which actually produces an average bitrate with higher motion at a higher bitrate and slower motion at a slower bitrate.

Interlacing.  If you have imported video from a video camera it will normally be interlaced for viewing on a TV (NTSC for N. America or PAL for Europe). For web viewing you should deinterlace the video.

There are two more parameters that we can add to this list. The first is the keyframe rate. In between keyframes the video stream just sends the difference, or 'delta' from the keyframe. So, slower action can get by with less frequent keyframes (usually specified as a keyframe every so many seconds or frames) and faster action video needs more frequent keyframes, creating larger file sizes.

The second is the size of the buffer. By buffering you allow a certain portion of the file to be downloaded before playing. That way if the receive rate is slower than your streaming rate there won't be any interruption if the buffer is large enough. I go into more detail in the video below.

What I  do in the video is give you very good guidelines to achieve the desired result. You may still have to do some experimenting but the trial and error process will be greatly reduced, since I have spent weeks "trialing and erroring" to come up with these guidelines.
 

How to Encode Video Using Media Encoder

Tip: If you are on broadband, a handy tool for testing your streaming video or your whole site at dial-up speeds is a program called Sloppy available from http://www.dallaway.com/sloppy/

DOWNLOADABLE VIDEO FILES 

Consider adding a downloadable .wmv and/or .mov file to your site to allow dial-up users the option of downloading a higher quality or broadband quality video rather than streaming a poor-quality video to them.

To allow the downloading of a Flash video with its controller you will have to Zip the .swf file with the controller files plus an html interface.