MPEG System Research Articles

MPEG Column: 145th MPEG Meeting (Virtual/Online)

The 145th MPEG meeting was held online from 22-26 January 2024, and the official press release can be found here. It comprises the following highlights: •Latest Edition of the High Efficiency Image Format Standard Unveils Cutting-Edge Features for Enhanced Image Decoding and Annotation •MPEG Systems finalizes Standards supporting Interoperability Testing •MPEG finalizes the Third Edition of MPEG-D Dynamic Range Control •MPEG finalizes the Second Edition of MPEG-4 Audio Conformance •MPEG Genomic Coding extended to support Transport and File Format for Genomic Annotations •MPEG White Paper: Neural Network Coding (NNC) - Efficient Storage and Inference of Neural Networks for Multimedia Applications This column will focus on the High Efficiency Image Format (HEIF) and interoperability testing. As usual, a brief update on MPEG-DASH et al. will be provided.

Layered Motion Compensation for Moving Image Compression

Block-based motion compensation began with MPEG-1 and H.261 and has continued into MPEG-2, MPEG-4_part 2, MPEG-4_AVC_part 10, H.264, and SMPTE VC1. The general principle used by these conventional motion compensation systems is that there is one motion vector for a square or rectangular group of pixels. The group of pixels associated with the motion vector is generally referred as a “macroblock.” It is common in MPEG and other compression systems to use reduced resolution for Red-Y (U) and Blue-Y (V) compared to Y (luminance), where Y usually equals approximately .59Green + .29Red + .12Blue. Intra-coded frames and the motion-compensated-difference frames use a common quantized discrete cosine transform (DCT). The macroblock structure provides a common boundary for the Y, U, and V DCT-coded regions. The DCT size is usually 8 × 8 pixels, but may be anywhere from 4 × 4 up to 16 × 16 (e.g., in MPEG-4 AVC_part 10 and H.264). The nature of the DCT is that it is a self-contained regional transform that does not extend to any pixel outside its block (usually 8 × 8). In a sense, quantization errors in the DCT wrap from one edge to the other (i.e., left to right, and top to bottom) of the DCT block. Differing quantization errors in adjacent DCT blocks yield block edge discontinuities. Thus, because macroblock boundaries coincide with DCT block boundaries, they share a common edge. When a motion vector differs between adjacent macroblocks, the inherent edge discontinuity does not appear within the DCT block, but rather at its edge. The DCT block edge “wraps around” to see its opposite edges, so the DCT is quite tolerant of the edges inherent in macroblock-based motion compensation.

Algorithm and architecture design of adaptive brightness correction for video application

Some factors of the environment and user behavior always dominate the captured image quality when we use a digital camera. According to the overviews and analysis of adaptive brightness correction, we understand that techniques can provide an available method to reduce the interference of environmental light in digital cameras, but current methods are still not suitable for VLSI design. In this paper, we propose an efficient method, called local bi-histogram equalization (LBHE), to remedy the local visibility and control the degree of enhancement. In architecture design, we utilize the hybrid architecture to implement adaptive brightness correction with the MPEG system. The hybrid architecture design can decrease the implementation area and successfully applies our LBHE in MPEG application. Through comparison of content, we can find that our design can exactly satisfy the chip specification of realtime processing. Our chip implementation is efficient to achieve motion and brightness estimation in the MPEG system. This design makes adaptive brightness correction compatible to current video applications.

Adaptive ADPLL architecture for MPEG system clock related measurements in variable rate environment

Measurements such as jitter, frequency offset and drift are very important in the quality of service evaluation in digital video broadcast, especially under varying rate environment. This paper presents an all digital phase locked loop (ADPLL) architecture for either VLSI or low cost FPGA implementation. The operation of proposed ADPLL is based on a frequency synthesizer for a very narrow band frequency ( ± 800 Hz), small frequency step and high central frequency (27 MHz). The proposed solution is designed for the real time measurements, feature a very low intrinsic jitter, and adaptive rate variation. The system description and adaptation method are presented with corresponding hardware implementation. Experimental results in term of jitter analysis and adaptation behavior are detailed and discussed.

Adaptive filtering of MPEG system streams in IP networks

Congestion and large differences in available link bandwidth create challenges for the design of applications that want to deliver high quality video over the Internet. We present an efficient adaptive filter for MPEG System streams that can be placed in the network (e.g., as an active service). This filter adjusts the bandwidth demands of an MPEG System stream to the available bandwidth without transcoding while maintaining synchronization between the streams embedded in the MPEG System. The filter is network-friendly: it is fair with respect to other (TCP) competing streams and it avoids generating bursty traffic. This paper presents the system architecture and an evaluation of our implementation in three different operating environments: a networking testbed in a laboratory environment, a home-user scenario (DSL line with 640 Kbit/s), and a wide area network covering the Atlantic (server in Europe, client in the US). Moreover we examine the network-friendliness of the adaptation protocol and the relationship between the quality of the received continuous media and the protocol's aggressiveness. Our architecture is based on efficient MPEG System filtering to achieve high-quality video over best-effort networks.

An Adaptive Video Coding Control Scheme for Real-Time MPEG Applications

This paper proposes a new rate control scheme to increase the coding efficiency for MPEG systems. Instead of using a static group of picture (GOP) structure, we present an adaptive GOP structure that uses more P-and B-frame coding, while the temporal correlation among the video frames maintains high. When there is a scene change, we immediately insert intramode coding to reduce the prediction error. Moreover, an enhanced prediction frame is used to improve the coding quality in the adaptive GOP. This rate control algorithm can both achieve better coding efficiency and solve the scene change problem. Even if the coding bit rate is over the predefined level, this coding scheme does not require re-encoding for real-time systems. Simulations demonstrate that our proposed algorithm can achieve better quality than TM5, and satisfactory reliability for detecting scene changes.

Dynamic Frame Dropping for Bandwidth Control in MPEG Streaming System

In a network environment where the available bandwidth changes dynamically, it is desirable for a streaming system to control the media quality in an adaptive way according to the dynamics of underlying network resource. This paper presents the implementation of a real-time MPEG filtering system which uses the concept of dynamic frame-drop. The filtering system drops video frames in a controlled way and reconstructs a valid MPEG system stream in real-time. The system consists of a sequence of filtering modules and each module is carefully designed to maintain the synchronization characteristics of real-time streaming. A special effort is given to the correct implementation of video and audio synchronization after frame-drop. The experiments show that the implemented system produces a valid MPEG system stream after filtering as well as the media bandwidth of a filtered stream is dynamically controlled by a given frame-drop policy.

Design of an MPEG-2 codec

We review the design of a single-chip MPEG-2 a/v codec, covering the design process from the MPEG specifications and system requirements to the final design. After a brief overview of MPEG-1 and MPEG-2 standards, we examine the system requirements using as an example a universal serial bus (USB)-based MPEG-2 real-time digital video recorder. Finally, we present in more detail the hardware and software architecture of a specific MPEG a/v codec.

A method to improve the robustness of MPEG video applications over wireless networks

It is important that applications deployed in wireless networks be robust enough to accommodate different kinds of data losses due to link errors, connection re-routing, and network congestion. A scheme to improve the robustness of MPEG based video applications is proposed. Under this scheme, the packet size at the sender is optimized to the MPEG system layer unit size to enable fast recovery of the time stamps. The receiver buffers the data packets for re-playing during packet losses, preserves useful time stamps for synchronisation, and re-synchronises the decoder when packet loss occurs. This involves no feedback and results in faster recovery of critical timing information for video decoding. The proposed method has been implemented on a video application based on MPEG-I over an Asynchronous Transfer Mode (ATM) network. The experiments show that the proposed technique is very effective when there is deterministic/random packet losses with burst size less than 21. The method is equally applicable to video applications based on MPEG-II program stream and, to wireless Internet.

A high quality VBR MPEG system for Internet and broadcasting applications

A high quality variable bit rate (VBR) MPEG-2 encoding scheme that offers optimum video quality and bandwidth allocation is presented. This scheme utilizes a real-time bit redistribution method, insertion of I frames at scene changes and large GOP (group of pictures) size to produce high picture quality. An encoders-bank with predetermined sets of nominal-long-term, minimum and maximum bit rates in combination with a sophisticated picture quality control process allows a bit rate selector to choose the optimum bit stream from a set of encoders, thus resulting in a high quality VBR video stream. The proposed scheme is very easy to implement and offers an efficient real-time VBR solution for broadcasting applications that involve multiplexed distribution of multiple video sources.

The MPEG systems coding specification

The MPEG Systems Committee has produced a specification for the syntax and semantics of system layer coding of combined MPEG compressed digital video and audio. The systems layer provides a framework and information required for these functions: a multiplex of various numbers of audio, video and private streams; synchronization of audio and video; management of buffers for coded information; random access and start-up conditions; and absolute time identification. In addition the specification allows for the later inclusion by ISO of other data streams.

Single chip MPEG audio decoder

An IC has been designed and fabricated which can take an MPEG system or MPEG audio stream and decode Layer I and Layer II (MUSICAM) encoded into 16-b pulse code modulation (PCM) data. Presentation can be delayed and audio frames skipped by means of the channel buffer, an external 256 K bit*4 DRAM controlled by this IC. This allows coarse synchronization of audio and video for skews of up to 1 s for Layer I and 2.5 s for Layer II. Control over which frames are played or provides cue/review features. The MPEG audio IC takes into account system-level, interface, and rate control issues, rather than just the computations involved in MPEG audio compression. >