Joel R. Jackson

Optimal packet scheduling for wireless video streaming with error-prone feedback

In wireless video transmission, burst packet errors generally produce more catastrophic results than equal number of isolated errors. To miniimize the playback distortion it is crucial for the sender to know the packet errors at the receiver and then optimally schedule next transmissions. Unfortunately, in practice, feedback errors result in inaccurate observations of the receiving status. In this paper, we develop an optimal scheduling framework to minimize the expected distortion by first estimating the receiving status. Then, we jointly consider the source and channel characteristics and optimally choose the packets to transmit. The optimal transmission strategy is computed through a partially observable Markov decision process. The experimental results show that the proposed framework improves the average peak signal-to-noise ratio (PSNR) by 0.6-1.3 dB upon using a traditional system without packet scheduling. Moreover, we show that the proposed method smoothes out the bursty distortion periods and results in less fluctuating PSNR values.

DSP for practicing engineers: a case study in Internet course delivery

With the explosion of the Internet and the desire of many institutions to disseminate courses across the world, many students look to online education with promise. However, institutions planning to provide distance learning opportunities may wish to have a model to analyze before venturing forth. There are many factors that ultimately influence the methods of delivery, content, length, and technical support for an online course. This paper presents the design, implementation, and evaluation of an online course titled DSP for Practicing Engineers at the Georgia Institute of Technology, Atlanta, and analyzes feedback from students who have taken the course and the staff who administered it. Different aspects of course development are discussed at length, including curriculum and media type.

Low-bit rate motion JPEG using differential encoding

Motion JPEG (MJPEG) can be simply defined as a compression scheme in which each frame in a video sequence is JPEG compressed. This method though simple and intuitive has the disadvantages of high bandwidth requirements for transmission and low resilience to errors due to missing frames. In this paper, we present a modification to the MJPEG compression called MJPEG with differential pulse code modulation (MJPEG-DPCM) where differential encoding between coefficients of adjacent frames is carried out The modification provides higher compression, maintains perceptual visual quality and reduces video degradation due to missing frames or missing packets.

Multiple global affine motion model for H.264 video coding with low bit rate

A multiple global affine motion model is proposed for low bit rate video compression. Block-wise motion segmentation is first performed with the number of motion objects L predefined. The affine motion models for multiple MOs are estimated and coded in the frame header. The scaling parameters a1, a2, a4 and a5 are coded with a 4-dimensional vector-quantizer (VQ), whose 16 most recently used code words are maintained on line and searched for VQ match, and the 300-word long main code book stored offline. The translational parameters a3 and a6 are coded predicatively as a classical motion vector. L new macro-block modes are added to the standard’s list of 7 intra and inter modes. No segmentation information is transmitted, for the mode already indicates that if one of the affine modes is selected by Lagrange rate-distortion optimization. A metric S is defined to measure locality of the motion and will disable use of affine models when a threshold is surpassed. Simulation shows that abut 20-40% of the MB’s choose one of the affine modes. When 100kbps or lower bandwidths are available, the proposed codec not only saves 1~18% bit rate, but also enhances error-resilience in multiple slice frames and reduces blocking artifacts notably.

High Definition video support for natural interaction through distance learning

Using high definition video distance learning allows large areas of the classroom to be captured at a resolution approaching human visual acuity. This allows instructors and students to interact with significantly less constraints then the classic television based distance learning design. Hi Definition Television (HDTV) is becoming commonplace. This drives cost down, but more significantly it creates an increase in student expectation as HDTV replaces standard television in the home. Implementing a useful distance learning classroom based on HDTV requires significant attention to layout in order to achieve a pedagogically functional classroom, especially when applications beyond a simple lecture are considered. The classrooms considered here use two channel video in each direction, as well as stereo audio. This paper will discuss the issues in capturing an entire instructional area (whiteboard and podium) using multiple HD cameras. Careful attention to audio design is also critical to natural interaction.

DSP for practicing engineers: an online course for continuing DSP education

The recent rapid increase in applications of DSP has generated a need for technical personnel with a DSP background. Until recently, most DSP education has been at the graduate level, so many practicing engineers are developing a need for additional DSP education. At Georgia Institute of Technology, we are delivering an online continuing education course that is targeted at these engineers. The 12-week course is comprised of three interconnected tracks in DSP system theory, real-time implementation principles, and laboratory assignments with MATLAB and the latest fixed-point TI DSP chips. The course was designed after a needs analysis performed by Texas Instruments training specialists. It is intended specifically to provide a full semesters course in a way that is adapted to the schedules and circumstances of practicing engineers. We describe both the content of the course and the technology for delivering it online.

An adaptive coding scheme using affine motion model for MPEG P-VOP

Block matching has been used for motion estimation and motion compensation in MPEG standards for years. While it has an acceptable performance in describing motion between frames, it requires quite a few bits to represent the motion vectors. In certain circumstances, the use of whole frame affine motion models would perform equally well or even better than block matching in terms of motion accuracy, while it results in the coding of only 6 parameters. In this paper, we modify an MPEG-4 codec by adding: (1) 6 affine model parameters to the frame header; and (2) mode selection among INTRA, SKIP, INTER-16/spl times/16, INTER-8/spl times/8, and GLOBAL-AFFINE modes by Lagrange optimal rate-distortion criteria. Simulation results demonstrate 10-20% decrease in bit-rate, compared to the MMS codec for an average coded P-frame with the same reconstruction PSNR.

Synchronous and asynchronous distributed DSP education

The Georgia Tech Regional Engineering Program (GTREP) was originally created to provide the opportunity for students in southeastern Georgia to earn a Georgia Tech undergraduate engineering degree without leaving the region. Students complete two years of general education and engineering prerequisites at their home institutions before beginning the Georgia Tech curriculum as juniors. Georgia Tech courses are taught both by local faculty in southeast Georgia and remotely by faculty on the main campus. This system is further complicated by the fact that courses are delivered to three partner institutions as well as the GTREP facilities. The GTREP program is an ideal testbed for novel distributed education methods. We present some results for the combined approach we have developed, and outline plans for future scaling as the GTREP program expands.

Georgia Tech's online continuing education DSP program

Georgia Tech has been offering online continuing education courses in DSP for almost three years. During this period, there has been an evolution both in how these courses are developed and taught and in the variety of courses that are offered. Here, we will describe these changes and look ahead to where this program is going in the near future.