Error concealment is a technique used in signal processing that aims to minimize the deterioration of the signals caused by missing data, called packet loss . [1] A signal is a message sent from a transmitter to a receiver in multiple small packets. Packet loss occurs when these packets are misdirected, delayed, resequenced, or corrupted. [2]
Receiver-Based Techniques
When it is recovered, it is receiver-based. These techniques focus on correcting corrupted or missing data.
Waveform substitution
Preliminary attempts at receiver-based error concealment involved packet repetition, replacing lost packets with copies of previously received packets. This function is computationally simple and is performed by a device on the receiver called a ” drop-out compensator “. [3] [4]
Zero Insertion
When this technique is used, its a packet is lost, its entries are replaced by 0s.
Interpolation
Interpolation involves making educated guesses about the nature of a missing packet. For example, by following speech patterns in audio or faces in video.
Buffer
Data buffers are used for storing data while waiting for delayed packets to arrive. They are common in internet browser loading bars and video applications, like YouTube.
Transmitter-Based Techniques
Rather than attempting to recover lost packets, other techniques involve anticipating data loss, manipulating the data prior to transmission. [4]
Retransmission
The simplest transmitter-based technique is retransmission, sending the message multiple times. Although this idea is simple, this technique is unable to support real-time applications. [2]
Packet Repetition
Packet repetition, also called forward error correction (FEC), adds redundant data, which the receiver can use to recover lost packets. This minimizes loss, but increases the size of the packet. [5] [6]
Interleaving
Interleaving involves scrambling the data before transmission. When a packet is lost, rather than losing a whole set of data, small portions of several sets will be gone. At the receiving end, the message is then deinterleaved to reveal the original message with minimal loss.
Transmission without interleaving :
This sentence was sent to the following address: ThisIsNotAnExampleOfInterleaving Received sentence with a burst error: ThisIsNot______pleOfInterleaving
The term “AnExample” ends up unintelligible and difficult to correct.
With interleaving :
Transmitted sentence: ThisIsAnExampleOfInterleaving ... Error-free transmission: TIEpfeaghsxlIrv.iAaenli.snmOten. Received sentence with a burst error: TIEpfe ______ Irv.iAaenli.snmOten. Received sentence after deinterleaving: T_isI_AnE_amp_eOfInterle_vin _...
No word is completely lost and the missing letters can be recovered with minimal guesswork. [7]
Applications
Depending on the method of transmission (analog or digital), there are a variety of ways to propagate errors in the message.
Analog Applications
Since its invention in the 1950s, the magnetic coating used in analog video tape has experienced radio frequency (RF) signal drop-outs. Some of the techniques that have been used for resolving these issues are analogous to those used for concealing errors in modern compressed video signals.
The process of click removal in audio restoration is another example of error concealment. A closely analogous example in the field of image processing is the use of digital dust and scratch removal processing in film restoration .
Digital Applications
Many people, including web browsing, video conferencing, Skype, and YouTube [2] [8]
See also
- Packet loss concealment
References
- Jump up^ “Video Signal Error Concealment” . National Institute of Standards and Technology (NIST). March 29, 2011 . Retrieved 2014-10-23 .
- ^ Jump up to:a b c Carle, Georg; Biersack, Ernst (August 6, 2002). “Survey of error recovery techniques for IP-based audio-visual multicast applications” . Network, IEEE . 11 (6): 24-36. doi : 10.1109 / 65.642357 . ISSN 0890-8044 . Retrieved 11 November 2014 .
- Jump up^ WKE Geddes (14 December 1964). “R & D Report 1964-77: Simple drop-out compensator for tape recorders” . Retrieved 2014-10-23 .
- ^ Jump up to:a b Kurose, James; Ross, Keith. Computer Networking: A Top-Down Approach (PDF) (6th ed.). Pearson Education Inc. p. 640. ISBN 978-0-13-285620-1 . Retrieved 30 October 2014 .
- Jump up^ Nimrod Peleg (January 2003). “Error Resilience and Concealment in Video Coding: With focus on H.261 / 3” (PDF) . Retrieved 2013-03-21 .
- Jump up^ Podolsky, M (29 Mar – 2 Apr 1998). “Simulation of FEC-based error control for audio packet on the Internet” . INFOCOM ’98. Seventeenth Annual Joint Conference of the IEEE Computer and Communications Societies. Proceedings. IEEE. 2 : 505-515. doi : 10.1109 / INFCOM.1998.665068 . ISBN 0-7803-4383-2 . ISSN 0743-166X .
- Jump up^ Forward error correction # Example
- Jump up^ Sat, Batu; Wah, Benjamin (9-12 July 2006). “Analysis and Evaluation of the Skype and Google Talk Voip Systems”. 2006 IEEE International Conference on Multimedia and Expo . pp. 2153-2156. doi : 10.1109 / ICME.2006.262681 . ISBN 1-4244-0366-9 .
