What is Videocasting?
Videocasts allow people to view a presentation over the internet either live by watching the real-time streaming video, or on-demand as a pre-recorded video. Streaming files are not downloaded, but rather are broadcast in a manner similar to television broadcasts. While content is being viewed, the streaming server machine and software continues to "stream" data in such a manner that the viewer experiences no break in the content.
Videocasting Services Available to the NIH Community
CTIVS can broadcast your seminar, conference or meeting live to a world-wide audience over the internet. The event can be recorded and made available for viewers to watch at their convenience. Existing recordings can also be converted and published as videocasts or podcasts. In addition, captioning is available for Videocasts.
Introduction to Videocasting
The videos are processed by a compression program into a streaming format and delivered in a staggered fashion to minimize impact upon the network and maximize the experience of the content for the viewer. When users request a streaming file they will receive an initial burst of data after a short delay ("file latency").
Multicasts are single data streams read by any number of clients with the appropriate decoder. Multicasting is a unidirectional communication. Clients simply listen to a data stream. Multicasting conserves bandwidth (one 350kb stream viewed by 100 clients uses only 350kb of bandwidth), however, clients cannot determine when the data stream starts, pause the stream without losing data, or move forward or backward in the data stream. A client that connects in the middle of a multicast misses half of the data stream.
Unicasts are data streams decoded on a one-to-one basis. Unicasting is a bidirectional communication. Clients send requests to the server and each connection from client to server uses bandwidth. A 350kb data stream unicast to 100 clients uses 35,000kb (35Mb) of bandwidth. When unicasting is deployed for a past event (not a live web cast), clients can determine when the data starts, move forward or backward in the data stream, or pause the stream without missing any data.
Most of the NIH network is multicast enabled. Live events streamed to computers on the NIHnet are mostly multicast, thus saving considerable bandwidth. However, the same live event streamed to computers on the Internet or to non-multicast enabled segments of the NIH network are unicast. On-demand viewing of past events, whether on the NIH network or the Internet are always unicast.
Directory of NIH Videocasts
A complete schedule of current and future events, plus an archive of past events, is available at http://videocast.nih.gov.
Requirements to watch NIH Videocasts
To View World-Accessible NIH Videocasts:
Windows RealPlayer (available as a free download) - RealPlayer for Windows - NIH Staff Only download
- RealPlayer for Windows - Public
- RealPlayer for Macintosh - Public
Internet connection with minimum of 350kbps. Dial-up is not supported. Firewall Settings: Port 554 for RTSP unicasting must be allowed through your firewall
To View HHS-Only Videocasts:
- You must access the videocast from a computer logged into the HHS network which includes the following agencies: ACF, AoA, AHRQ, ATSDR, CDC, CMS, FDA, HHS, HRSA, IHS, NIH, PSC, and SAMHSA.
OR
- You will need an NIH Virtual Private Network (VPN) account and software to watch NIH-only or HHS-only VideoCasts from a private computer. VPN allows NIH employees to access the NIH network and Institute computing resources over a third-party Internet Service Provider (ISP) such as that from Verizon, AOL, or Comcast. You will need to contact your ISP to verify that the ISP allows VPN over their network.
To View NIH-Only Videocasts:
- You must access the videocast from a computer logged into the NIH network.
OR
- You will need an NIH Virtual Private Network (VPN) account and software to watch NIH-only or HHS-only VideoCasts from a private computer. VPN allows NIH employees to access the NIH network and Institute computing resources over a third-party Internet Service Provider (ISP) such as that from Verizon, AOL, or Comcast. You will need to contact your ISP to verify that the ISP allows VPN over their network.
