TITRE Adaptive Packet Video Streaming Over IP Networks - LaBRI

encoders within the motion compensation loop in order to reduce visual artifacts and improve
prediction [27].
One of the main properties of the H.264 codec is the complete decoupling of the transmission
time, the decoding time, and the sampling or presentation time of slices and pictures. The codec
itself is unaware of time, and does not carry information such as the number of skipped frames (as
common in the form of the Temporal Reference in earlier video compression standards). Also,
there are NAL units that are affecting many pictures and are, hence, inherently time-less. IETF is
working now on defining RTP payload format for H.264 codec, which defines essentially timing
information of NAL units [28].
3.2.1.1.6 Proprietary Format
There exists a number a proprietary solution for video compression such as Windows Media
Format by Microsoft [29] and Real Video by Real Network [30].
Windows Media 9 Series product was developed and published in November 2002. It includes
many technologies and tools for media creation, delivery, security and playback. However Windows
Media is proprietary, OS-based system and details information of this format is not available for
public domain. A little work considers streaming using Windows Media Format.
The last release of Real Network has developed recently Real Video 9 and published in July
2002. A compression format designed for broadband and high definition television. It promises a
good quality with a reasonable bandwidth. Furthermore, real video is a multiplatform solution.
Recently there were many efforts among the Real Network to move to an open source solution.
Helix project was the result of these efforts. Helix initiative consists of three major elements: (1)
Helix Platform, (2) Helix Community, and (3) Helix Universal Server. Helix platform is an open
source platform for media production and applications for any format and operating system.
3.2.1.1.7 Other Related Standards: MPEG-7 and MPEG-21
The Moving Expert Group (MPEG) has not stop after getting the MPEG-4 ready for use.
Currently it is defining standards related to multimedia such MPEG-7 [20], and MPEG-21 [21].
(a) MPEG-7
Before one can use any information (audio, video, data, etc), it have to be identified and
located first. More and more audio-visual information is available in digital form, in various content
delivery systems and networks. At the same time, the increasing availability of potentially interesting
material makes this search harder. The question of finding content is not restricted to database
retrieval applications; also in other areas similar questions exist. For instance, there is an increasing
amount of (digital) broadcast channels available, and this makes it harder to select the broadcast
channel (radio or TV) that is potentially interesting.
In October 1996, MPEG started a new work item to provide a solution for the urging
problem of generally recognized descriptions for audio-visual content, which extend the limited
capabilities of proprietary solutions in identifying content that exist today. The new member of the
MPEG family is called "Multimedia Content Description Interface", or in short MPEG-7 [20].
43