Truyền thông đa phương tiện (HUST)

• A video signal is a sequence of two dimensional (2D) images projected from a dynamic three dimensional (3D) scene onto the image plane of a video camera.

• Unformatted text (i.e., plain text) enables pages to be
created, which consist of strings of fixed-sized characters
from a limited character set

• Content Relations
▫ It defines a dependency of media objects on some data. An
example of a content relation is two graphics that are based
on the same data but show different interpretations of the
data.

• The preferred range of audio transfer delay is 0-150 ms
(below 30 ms the user does not notice any delay at all).

• Source generates the data to be transmitted
• Transmitter transforms and encodes the information to
produce electromagnetic signals that can be transmitted
across some sort of transmission system

1) What is band-limited signal?
2) What is the Nyquist sampling theorem? Provide a definition for the Nyquist frequency.
3) What is an anti-aliasing filter?
4) Define the meaning of the term “quantization interval” and
how this influences the accuracy of the sampling process of
an analogue signal.
5) Why does the quantization error gets worse with fewer bits
to present an analogue signal?

• The use of timestamps may overcome the jitter problem. Each packet has a time of the packet with respect to the first packet.
• The playback is delayed 7s after receiving the first packet.
• Playback buffer is needed to separate playback time from the arrival time.

• An IVOD system is capable of serving a large number of
end users to concurrently access large number of repositories of stored data.
• IVOD is an extension of VOD. In addition to the freedom
of choosing movies, users can interact with videos and decide the viewing schedule (tricky play, i.e., fast forward, rewind, pause)

• All types of images are displayed in the form of a two-dimensional matrix of individual picture elements
(pixels).

• As mentioned earlier the amplitude of the signal varies
continuously with time
• The Fourier transform decomposes a signal into the
frequencies that make it up