A S t r e a m i n g M e d i a P r i m e r :
H O W D O I M A K E ( G O O D ) S T R E A M I N G M E D I A ?
Compared to the fi nal fi les you would output for other mediums, such as
SOME CAPTURE POINTERS
DVD ROM or VHS tape, the fi nal fi les you'll output for the Web will be
FOR STREAMING MEDIA
small a smaller frame size, a lower frame rate, and more heavily compressed.
However, it is recommended that you capture your source material (both video
Use AV hard drives
SCSI or RAID
and audio) at the highest quality settings your system can handle 30 fps is
Research your video capture card
Test it, if
recommended for video; 16 bit for audio. You'll be using up lots of hard disk
possible, before making a fi nal decision.
space, but it's better to start with high quality (i.e., more data) and, therefore,
Conserve CPU power
Disable all anti virus
have more choices about what information to discard when you reach the
programs, screen savers, and extensions during the
encoding stage, than to start with low quality (less data) and potentially
regret having fewer options down the road.
Optimize your hard drive
hard drive before capturing.
Frames per second
Capture high quality
Capture your source
material (both video and audio) at the highest
640 x 480
quality settings your system can handle 30 fps
is recommended for video; 16 bit for audio.
640 x 480
Avoid dropped frames
Test and improve your
320 x 240
system until you reach a zero dropped frames
160 x 120
Capture mono audio
Unless you really, truly
Make sure your system has adequate capacity. A 3.46 MB per second data
need stereo output.
rate is standard for DV. In terms of disk space, you'll probably want at least
Keep an archive of your raw video fi le
a 30 GB hard drive. The larger your resolution (video window size), the
future use, and because accidents happen.
more colors, and the higher the frame rate captured the bigger your
captured fi le will be.
Dropped frames, during capture, are something you want to avoid. You can't recover dropped frames
after capture, so you'll want to test and improve your system until you reach a zero dropped frames
standard. If you are using Adobe Premiere to control capture, make sure to select the Report Dropped
Frames option, so you'll know when frames are dropped. You can also set Adobe Premiere to auto
matically abort capture when frames are dropped. Dropped frames are usually the result of a
confi guration problem, or are caused by trying to capture video that exceeds the capture rate for
your system. DV requires a hard disk capable of sustaining a 3.6 MB per second data rate.
Capture cards for streaming
You'll fi nd there are capture cards designed specifi cally for streaming media. Your decisions will depend
on your needs and your budget. But the industry is now mature enough that there is, indeed, something
that's right for every requirement.
The most basic capture cards are for input only. Some popular, inexpensive ones (under $200) let
you hook up a variety of sources at once (although only one of those devices can be used at a time)
including S video and full duplex audio input. Such cards provide basic capture software. But in order
to stream, you'll need a solid video editing package, such as Adobe Premiere, and streaming software like
Real Producer Plus, to refi ne and process the video before broadcasting from a site, reports Joel Strauch
in his article for Streaming Media.com, Video Capture on a Shoestring.
More expensive capture cards may have input and output capabilities, and may perform a variety of
ancillary tasks such as scaling (resizing), color conversion, de interlacing, closed captioning and more.
namic Medianamic Media
One popular capture card priced under $2,500 has such on board pre processing capabilities, leaving
the bulk of your CPU power for creating higher quality video streams. These specialized streaming
cards enable real time (live) streaming from a DV source, with the ability to transfer the digital video
directly to the host.
obe Dobe D
41 Video Capture on a Shoestring, by Joel Strauch, Streaming Media.com, http://www.streamingmedia.com/article.asp?id=6794