Streaming audio/video
An excellent executive overview of seven streaming video products by NewMedia.
and a more in-depth look at each streaming video solution.
RealSystem G2 is the next generation streaming software from RealNetworks, that will be released in May '98.
Summary
Streaming media using Vxtreme's WebTheatre by Bernd Gillhoff of ANSPAG
Microsoft
NetShow Streaming Server for all types of media - relies on Windows
NT as a server, and windows 95/NT codecs (also has a Mac client) for decoding
the content. Effectively Netshow uses ASF (advanced streaming format) to
wrap around the multimedia content (which can use any audio or video coder)
which is then delivered in a bandwidth controlled packet delivery system.
A sample of Microsoft Netshow streaming
A technical note on Microsoft Netshow
Download free player software
Samples
RealVideo by Real Networks (The company formerly known as Progressive Networks)
Real Video is a player that plays as it downloads, either from a web-page or via server-side streaming software. It uses
UDP and it maintains the audio without dropping content. The video may
drop frames if there is network congestion. If the audio cannot be
satisfied, the player stops and lets the buffer fill up. Playing videos across the internet
from various sites, using a shared ethernet LAN connected PC, considerable delays and many instances
of frames frozen for periods of up to ten seconds or more were experienced.
Many of the frames also suffered from a 'smudging' artefact where a line of pixels seemed
to be replicated down the screen a number of times. (Later player version fixes this, I believe) When the network allowed it, however, the video
quality was quite good.
Free downloadable player offered.
It is a complete streaming solution based on open standards that
blends multiple media types into one presentation. Supported media
types are video, audio, high resolution stills with transition effects.
There is also support for extensions to MPEG, VRML and other types.
Using a system called SmartStream, the bitrate of the delivered presentation
is dynamically altered to suit the current network capabilities, thus reducing
pauses due to buffer underflow.
The open standards that RealSystem G2 is based on are RTSP(Real Time Streaming Protocol)
which is a client/server transport protocol and SMIL (Synchronised Multimedia Integration Language) proposed by W3C.
Xing
Streamworks player This plays on the fly. It uses UDP and plays at
"best effort", not pausing if there is network congestion. This player
simply drops frames and drops segments of audio. Lip synch is almost
non-existant. Local samples for
Streamworks from Filmlink.com
Vosaic Corp
According to the Vosaic company's product description
"Vosaic uses Video Datagram Protocol (VDP), an adaptive protocol
that is net friendly and uses only available bandwidth. Running over IP, it adjusts its data rates to accommodate other users while maintaining the best possible delivery of video and audio, compressed using standard techniques such as MPEG1, MPEG2, GSM audio, and H.263.
Vosaic currently supports four different sound formats at various bit rates and qualities from low 3.3 kbps half-rate 723 format, suitable for transmission over 28.8 kbps modem lines, to high-quality MPEG audio for the best possible sound over high-speed networks.
Vosaic adaptively streams MPEG1, MPEG2, and H.263 video over a wide range of transmission bandwidths.
Vosaic also supports a non-adaptive video streaming protocol, served by http servers.
This allows you to stream videos through users’ firewalls." ---endquote
The Vosaic player doesn't need plug-in software for
the browser, as it uses Just-In-Time compiled Java, although there is a
Downloadable MediaClient available
that (I think) sends information back to the server to allow it to adapt to network performance.
Requires a browser that has JIT Java. Recent versions of Netscape and Internet Explorer
can handle it. (As of 7/7/97)
The Vosaic MediaStudio can convert the following multimedia file formats into a format
that the Vosaic MediaServer can distribute:
VXtreme home page VXtreme provide
a dedicated video server which uses RTP with UDP, thus ensuring lip
synch as well as server rate control based on available transmission
resources. In addition, they provide a serverless configuration as an
entry level. This does not provide rate control.
A sample of Microsoft VXtreme streaming
Net Toob MPEG-1 software-only player
VivoActive video streamer
Vivo uses H.263 Video and G.723 Audio coding through their Vivo Producer. Vivo
Producer only accepts AVI and QuickTime file formats as input. Because these two
formats can have their own compression systems, poor quality second generation compressed video can result.
(see the examples in their content page).
For best results, AVI or Quicktime with no compression should be used, allowing the very effiicient DCT based H.263
to do all the compression.
Using Vivo's free demo producer software and one of the supplied parameter sets (in this case one designed for
28.8k Modem connection, but there are others),
we compressed a 10 sec video clip to 34 Kbytes, and embedded it into this
web page. To do this needed no special server software, just a bit of HTML code, of which Vivo provides an example.
If you have installed the player (see below),
then you can play the following clip by clicking on the image. (If you can't see the image
then you need to install the player first) Performance will depend on your network connection to the server where this web page is.
Typical Block-Based DCT artefacts can be seen in the compressed video, such as the mosquito effects at edges.
Downloadable producer and player for VivoActive.
Summary
RSVP