On the Enhancement of Audio and Video in Mobile Equipment

Document type: Licentiates
Full text:
Author(s): Andreas Rossholm
Title: On the Enhancement of Audio and Video in Mobile Equipment
Series: Blekinge Institute of Technology Licentiate Dissertion Series
Year: 2006
Issue: 13
Pagination: 116
ISBN: 91-7295-101-X
ISSN: 1650-2140
Publisher: Blekinge Institute of Technology
City: Karlskrona
Organization: Blekinge Institute of Technology
Department: School of Engineering - Dept. of Signal Processing (Sektionen för teknik – avd. för signalbehandling)
School of Engineering S- 372 25 Ronneby
+46 455 38 50 00
Authors e-mail: andreas.rossholm@ericsson.com
Language: English
Abstract: Use of mobile equipment has increased exponentially over the last decade. As use becomes more widespread so too does the demand for new functionalities. The limited memory and computational power of many mobile devices has proven to be a challenge resulting in many innovative solutions and a number of new standards. Despite this, there is often a requirement for additional enhancement to improve quality.
The focus of this thesis work has been to perform enhancement within two different areas; audio or speech encoding and video encoding/decoding. The audio enhancement section of this thesis addresses the well known problem in the GSM system with an interfering signal generated by the switching nature of TDMA cellular telephony. Two different solutions are given to suppress such interference internally in the mobile handset. The first method involves the use of subtractive noise cancellation employing correlators, the second uses a structure of IIR noth filters. Both solutions use control algorithms based on the state of the communication between the mobile handset and the base station.
The video section of this thesis presents two post-filters and one pre-filter. The two post-filters are designed to improve visual quality of highly compressed video streams from standard, block-based video codecs by combating both blocking and ringing artifacts. The second post-filter also performs sharpening. The pre-filter is designed to increase the coding efficiency of a standard block based video codec. By introducing a pre-processing algorithm before the encoder, the amount of camera disturbance and the complexity of the sequence can be decreased, thereby increasing coding efficiency.
Subject: Signal Processing\General
Keywords: Audio enhancement, video enhancement, active noise cancellation, video coding, mobile equipment
URN: urn:nbn:se:bth-00344