FLV files can be played back with the Macromedia Flash plugin. As of flash 8, there are two supported formats available: the newer VP6 codec and the Sorenson H.263 codec. In this article, we compare three software packages that can be used to create FLV files.
Software packages for creating flash video files
Riva FLV Encoder
Riva FLV encoder is a free software packages available from the Riva website. This tool was able to read and compress all three video files that we used for testing. It has a simple user interface and is easy to use.
The compression from the Riva FLV encoder may not be as good as other options (see the comparison table below), and it lacks any progress information when compressing files. Another consideration is that the VP6 codec is not supported.
Flash 8 Video Encoder
High hopes were placed on the Flash 8 video encoder as it is part of the Flash Professional suite (and was naturally assumed to support flash formats well). The user interface is simple to use and unlike the other products reviewed, supports the VP6 codec out-of-the-box. But alas, the flash 8 video encoder failed to produce correct output from any of the three video files tested.
Macromedia Flash 8 professional starts at about $420 including GST for the academic version.Sorenson Squeeze
Another alternative is Sorenson Squeeze for Flash. This is specifically designed for creating flash video and it claims to provide the best compression. It sells for about $299 including GST. Note that you need to purchase a seperate plugin to encode using the VP6 codec.
Sorenson squeeze was able to compress two of the three video files tested, with smaller output files than the Riva FLV encoder.Comparisons
The compression software packages were compared by encoding three different video sources. The test video sources were chosen to represent the type of video that would be used in a training situation. One video was recorded from a digital video camera (video 1) of a person speaking. The second video was of an interview and was obtained obtained from video.google.com. Finally, a Mpeg 1 version of the first video was created (video 3).
| Video 1 | Video 2 | Video 3 | |
| File Type | PAL DV AVI | Mpeg4 AVI | Mpeg1 |
| Play time | 1m 04s | 1m 01s | 1m 04s |
| Frame Size | 720 x 576 | 480 x 360 | 352 x 288 |
| Frame rate | 25 (interlaced, 2 fields/frame) fps | 30 fps | 25 fps |
| File size | 220 MB | 5.3 MB | 10.7 MB |
These videos were then compressed using the following parameters in the respective video encoding software packages:
- Video: 320 x 240 @ 48 kb/s
- Audio: MP3 audio @ 24 kb/s
Comparison Results
| Riva FLV Encoder | Sorenson Squeeze 4.2 | |
|---|---|---|
| Cost | Free | $299 |
| Video 1 - Raw DV file from PAL video camera. Duration 1:04 minute, file size 220 MB | ||
| Time to encode | 1m 20s | 2m 04s |
| File size | 806 kB | 629 kB |
| Video detail sample |  |
 |
| Video 2 - Video from video.google.com, mpeg4 480x360 avi, audio codec: mp3. Duration 60.6 File size 5.3 MB | ||
| Time to encode | 21s | Unable to import video, so no comparison could be
made |
| File size | 751 kB | |
| Video 3 - Mpeg 1 file created from Video 1 | ||
| Time to encode | 21s | 1m 49s |
| File size | 797 kB | 624 kB |
| Video detail sample |
 |
 |
Conclusions
It is clear that the free Riva FLV encoder tool is a worthy competitor (if not superior) to the commercial software packages as it was able to quickly encode all of the video files that were tested. The resulting file size may be bigger, but the video detail samples show that the resulting quality was about the same or better the the Sorenson software package.Further Information
Using video in online training.
The Riva FLV encoder is built on free software tools that can be
run directly from the command line and work under linux. Fore more
information, see http://klaus.geekserver.net/flash/streaming.html.
You might also find some items of interest on the Open source flash tools website.
There is some information about creating FLV files for use with the flowplayer (a flash video player) at http://flowplayer.sourceforge.net/encoding.html
A document that was found useful when making use of the free MJPEG-tools is available on sourceforge.
Article by Russell Kliese
