Credit: Mulchaey et al (ST Sci/UMD/NASA)
What is Streaming Media
Streaming media refers to a technology in which small amounts of video and
audio are accumulated in a buffer, and then played out on the Web while
the buffer is being filled with the following segment. There are two main
types of streaming media:
- Real time streaming media in which the buffer is filled with input
coming directly from an online camera or microphone, and
- File based streaming media in which the buffer is repeatedly filled
from an existing computer file
See
Streaming Media for an article on streaming media at this University
which includes examples
What is the Current State of the Art?
At the present time, streaming media is greatly limited by the
communication bandwidth that is commonly available, as well as the
computational and storage power of most PCs. As a result, streaming
videos are greatly inferior to live TV, and the pictures tend to be small,
low resolution, jerky, and the sound quality limited. However, these
limitations will surely be overcome in the near future. If Moore's law,
which states that computing power doubles every 18 months and which has
held steady for over 30 years, remains valid for another 10 years, we will
see computing/storage power 100 times greater than at present, as well as
ever faster communication bandwidth through DSL and fiber optic links. So
the future looks very bright for this technology.
How Do You Create Streaming Media
See Streaming Media
Services for an overview of how you create streaming media in the
University of Washington environment
A Streaming Media Example
I created a simple streaming video by:
- using a Sony CamCorder with a mini Digital Video (DV) tape to record
a session
- connecting the CamCorder (with the DV tape inside)
via a small cable to an Apple iMac computer
- invoking the Apple iMovie software to upload the video
- selecting another option in iMovie to edit the video to add
captions, music, and imported GIF files
- exporting the iMovie file as a Quicktime file optimized for the Web.
The original movie was 670 Megabytes, but the exported QT file was
only 6 Megabytes. Note that QuickTime movies have the suffix ".mov"
- using FETCH in "raw binary" mode to transport the QT file to a
C&C computer (Homer)
- using SSH FTP to transport the QT file from Homer to
a Windows 98 PC
- testing the QT file on the PC using File > Import in QuickTime
and playing it
At this time you have at least two options: you can play the movie
directly from your public_html directory, or you can
create a compressed file and place it in your public_media
directory.
To compress the file I:
- Processed the imported QT file with QuickTimePro to make a
what is called a "hinted" movie that provides "hint" tracks for
efficient processing. The steps in Quicktime Pro are:
- click File > Export
- supply a File name, such as "hinted.mov"
- Save as type: "All files"
- set Export: as "Movie to Hinted Movie"
- set Use: to "Default Settings"
- click Save
The "hinted" file was about 3 Megabytes long
- Used SSH FTP to transfer it to my public_media
directory
- Created a "reference" movie as follows:
- invoke MakRefMovie on the Windows PC
- select a file name, "ref.mov", then click "Save"
- click Movie > Add URL and type in:
rtsp://qtmedia.XXX.washington.edu/YYY/hinted.mov
where XXX is either "student", "staff", or "Faculty", and
YYY is a UW NetID
- select the speed
- click File > Save and File > Quit
The "reference" movie was less than 1 Kilobyte
- Uploaded the "ref.mov" file to your public_html
directory
- Included the line
<a href="ref.mov"<My Movie </>
in an HTML file
These
movies show you the difference between the uncompressed (that is,
"unhinted") movie and the hinted version. You may need to
manipulate the sound controls in your PC to get the proper sounds.
These controls are found by clicking on
Start > Settings > Control Panel > MultiMedia > Playback (the
little icon that looks like a horn), and then manipulating the sound
controls in the menu that opens up.
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