Types Of Videos

Videoconferencing over the Internet.

Equipment necessary to perform their respective operations through a videoconference via the Internet look like a separate level of importance (Hardware and Software Requirements and Process via Internet videoconferencing).

Via videoconference through TV VideoPhone.

To make a video through the TV via VideoPhone need the following equipment:

A television whose resolution is optimal for viewing the video, we recommend a TV 21 "or more.

CAMCORDER * A camera which includes its own software, memory and the encoder / decoder.

A telephone line.

A phone that will bring the options of pulses and tones, we recommend the choice of tones.

A VCR and a computer VC5055.

Wiring: Telephone cable with RJ-11 connectors

Power cable

Coaxial cable.

Description of practice facility

It is necessary to connect the computer to dial the phone and VC5055 in their RJ-11 connectors.

Then you connect the camera to the computer CAMCORDER VC5055 in their respective video and audio inputs.

Tickets for video and audio equipment VC5055 should be connected to the output video and audio equipment VCR.

The output video and audio equipment VC5055 be connected to the input of video and audio from the TV.

The entrance to the TV antenna is connected to the output of the VCR's antenna equipment.

The entrance to the VCR antenna equipment goes directly to the external antenna or cable.

The team leaves for connecting the outlet of 110 volts.

Note: The same setting must be taken into account in the audiovisual remote.

General Operation.

Once installed and running the system in two audiovisual items is to make the video:

Suppose a user wishes to begin to communicate through the system it should take the phone and dial the code (phone number) assigned by the computer to the remote, once communication with the remote it will send video captured by the camera and audio captured by the phone's microphone to the source, which receptive audiovisual information via the TV, and vice versa.

We must note that sends the information to the camera at the TV is done by teams that are VC5055 VCR and equipment whose function is to convert digital signals into analog and vice versa, also controls the delay that exists to send signals video which aims to synchronize the audio with the video phone for the reception of audio-visual information is seen and heard by all participants in real time.

Description

ISO standards for storage and recovery audiovisual.

The MPEG Standard Group (Moving Picture Experts).

The standards of ISO have established a working group, known as MPEG (Expert Group on moving image) to develop three standards for coding audiovisual signals for storage in digital media. The speeds for the three standards (MPEG1, MPEG2, MPEG3) are 1.5, 10 and 40 mbps respectively. The MPEG1 standard has three parts or layers (system, video, audio), which are mentioned briefly below.

Layer systems:

A string of bit ISO is built in two layers, the outer layer is the layer system and the inner layer called compression. The system layer provides the functions necessary to use one or more strings of bits in a compressed system. The parts of video and audio of this specification define the compression coding layer for audio and video data. The coding of other data types not defined by the specification, but are supported by the layer system, allowing other types of data are attached to the compression system.

Extended system:

Extended Systems is the name given to a number of additional capabilities not provided by the system baseline. Each series is designed to work with, or be constructed from the internal components of the baseline, with the aim of expanding their operation modes. These optional capabilities, which include arithmetic coding, reconstruction and progressive "progressive lossless coding, and others, can be implemented individually or in appropriate combinations.

Arithmetic coding is an optional alternative, "modern" Because the arithmetic coding method is adapted to the chosen parameter values of the image, usually provides from 5 to 10 percent better compression than Huffman method chosen by JPEG. This benefit is offset by the increase in the complexity of the system.

Rebuilding progressive alternative to the reconstruction sequence is specifically useful when using databases of images with little channels of communication bandwidth. For coding progressive: first, a "coarse" is sent, then the refinements are sent by improving the quality of the image "coarse" until the desired quality is achieved. This process is carried out by applications such as databases of images with multiple resolutions and different quality requirements, in freeze frame video, photo videotext for low speeds.

Lossless coding refers to the progressive compression method, which operates in conjunction with the progressive reconstruction. In this mode of operation, the final stage of the reconstruction results in a progressive image, which is received bit by bit identical to the original.

The standard JBIG (United Group for bi-level images).

Some years back, a group of experts was formed to establish an international standard for coding of bi-level images. The JBIG (group united for bi-level images), JBIG has developed a document entitled "Progressive compression standard for bi-level images", which defines a method for compressing bi-level images (ie, an image black and white). Because the method is adapted to a wide range of features of images, encryption is a technique very robust.

The JBIG standard operates in the sequential mode and in the progressive mode. When decoding a progressively encoded image, an image of low resolution compared to the original is available first, the image resolution increases as more data are decoded. Progressive coding provides two benefits, the first is that a database of images can serve different output devices each with different resolutions. Only with such information in the file compressed images for the reconstruction to the resolution of the output device in particular needs to be sent and decoded.

other benefit is that the progressive coding provides subjectively superior images (on a monitor) on communication links of low or medium speeds. A low-resolution image is transmitted and displayed quickly, with improved resolution to be away. Each stage of improvement of the resolution is constructed in the image already available.

To send and receive video is needed:

Video capture card that supports Microsoft Video for Windows.

Video Camera to Connect to the video capture card.

A third option, which replaces the two previously mentioned, is to have a QuickCam, which connects to the parallel port or the keyboard and does not need a video card.

To send and receive audio is also needed:

Sound card that is in accordance with the specifications of Windows Multimedia (Sound Blaster or above) that handles audio, preferably in Full Duplex mode.

A microphone and speakers or headphones.

Versions of Windows:

All versions of Windows

Windows 98

Windows 95

Windows 3.1

Windows for Workgroups 3.11

Not known for videoconferencing package that runs under OS / 2 or DOS.

5.4 Process of videoconferencing over the Internet

By having all the requirements outlined above, if a user runs a video packet, it may be carried out easily and quickly.

After installing any package if you need to configure some features. By this we mean that the user must specify certain parameters to the program, such as the type of camera and video and sound cards to be used in video conferencing, and management. Furthermore, some applications require the user's name, to show the other side of the videoconference.

Generally, you must set the agenda for the IP address of the computer that is on the other side of the connection, this connection is made via the Internet if the IP address is incorrect or could not be located, the program will present the video an explanatory message to the user connection, indicating that the connection could not be established.

As seen, the Internet is essential for video conferencing using these packages, because being a network, to which everyone has access, is the ideal means to establish communication between any points in the world, and make meetings.

With the advance of technology has made it possible to transport video and sound from one point to another, via the Internet. Packages that use this means of transport, used small video cameras that are connected to a capture card images on the computer, capture the image and voice of those who are opposed to it, makes them carry digital signals and use this information the network until it reaches the destination where they could be seen and heard by those who are there.

2. Operation of the Web Cams

Specifically, the video camera connected to the computer captures the image (s) of person (s) is (n) against it. Also, through a microphone and with a sound card, all audio is trapped. Thus, information to be captured by the devices connected to the computer, are encapsulated and sent to the network, where, through the Internet connection, the package uses the principles of TCP / IP to enable data to reach their final destination, or the person whose IP address was entered at the beginning of the videoconference.

And thanks to this also provides the means to ensure the safe arrival of information to its correct destination, because each program has special methods to detect loss of data packets sent either video or audio, and performs its own operations or apply algorithms that let you save video and ensure that data loss go unnoticed for the user.

In some of these packages for video conferencing over the Internet, any video capture is done via Microsoft Video for Windows Video Capture API. This allows them to capture video from any video card that supports Windows.

Each package has its own method of transmission of both video and audio, some such as Video Phone, using techniques that minimize the amount of information to convey, leading to a faster transmission and safer. Whatever the method used for each packet, all offer excellent quality sound and images, enabling videoconferences were performed successfully in most cases.

One advantage of using these packages and the current transmission medium of the Internet, which decreases discomfort and prevent other problems that caused the previous video. A few years earlier, required the installation of video conferencing rooms specially equipped and dedicated transmission links.

Historically, problems with the echo from the microphone and movements have adversely affected the quality of audio from a videoconference. For it is so spontaneous and natural as a face to face meeting, participants will require an audio "Full Duplex", which allows simultaneous conversations, however, to address economic and regeneration or feedback, audio systems of many took video, and even in some even take in a half-duplex mode, in which one person can talk at once, because even though the signals transmitted in both directions, only to pass in one direction once. Thus, people who are at one end of the video can not be heard while you are on the other side is talking, which differs from natural conversation, many of the current packages of video over the Internet offers ways Full Duplex.

5.6 Full Duplex Mode:

On both sides of the video you can speak and listen simultaneously, allowing for naturally occurring questions and interruptions by the speaker of the auditorium. A full duplex audio system requires either meeting room arrangements with specially designed acoustic technique AEC (Acoustic Echo Cancelation) or a combination of both.

Previously, to solve these problems require specialized microphones carefully located and complex calibration procedures for the room, ie fourth complex arrangements to produce a good sound effect. Most disposers echo, helps prevent signs of return to speech that occurs when someone speaks, with the signal from the microphone, however these systems require accurate calibration, a careful placement of microphones and speakers, and precise adjustment of the microphone sensitivity and volume of the speaker's voice. In many situations the quarter also requires special sound. These methods have the acoustic cover the walls with sound-absorbing elements such as heavy tapestries, tiles, tiles, carpets and special.

Currently, these problems have been eliminated because the video packets are techniques that minimize the AEC both the acoustic signal produced by the microphone when speaking as the echo of the videoconference in the fourth. Without AEC, the audience would hear an annoying echo the voice back to the other end of the video, however this technique has the disadvantage of requiring microphones routed to minimize the echo. As directed microphones lose the conversation in various areas of the room and do not allow much freedom in the speech of the participants of the videoconference.

However other packages incorporate a more modern technology and improved the IDEC (Integrated Dynamic Echo Cancellation), which dramatically improves audio quality. On the other hand, allows participants to hear and be heard easily from anywhere in the video conferencing room, without need for complex arrangements in the rooms and directed installation of microphones, CAPat farthest up conversations anywhere in the room.

Moreover, these packages have audio compression algorithms, which are responsible for providing an excellent sound fidelity, including any system previously installed.

Finally, the microphones for video conferencing available in the market, they can collect the voice of any spectator from anywhere in the room. Thus, people involved in the video are free to move around the room like they did if they were in a meeting face to face.

Analysis of contingencies

In any communications program, for more advanced and that is good, sometimes there are problems in its functioning and operation, especially the first few times you use it. Many of these flaws are out of control and even the user of the program, because they depend on the network, bandwidth, congestion exists, the number of stations that are using at any given time, etc. Others are human error that inexperienced users and even the experts sometimes committed for this reason some of the most common problems that can occur in a video and how to resolve to succeed.