Emiliano Piccinelli

An innovative, high quality and search window independent motion estimation algorithm and architecture for MPEG-2 encoding

This paper describes an innovative, pipelined, cache-based architecture for a motion estimation coprocessor. The coprocessor is based on a predictive/recursive algorithm whose computational complexity is low and not dependent on the search window. The synergies between the architecture and algorithms features allow a high picture quality, low-area, low-bandwidth, unlimited search window implementation.

Adding SVC Spatial Scalability to Existing H.264/AVC Video

This paper describes an innovative algorithm for adding SVC Spatial Scalability to all existing non-scalable H.264/AVC video streams. The algorithmic system builds on a full-decode-full-encode method of conversion and employs reuse of available data by an efficient downscaling of video information for different layers, thus reducing the complexity of the algorithm by manifold whilst maintaining a high coding efficiency. The complexity is further reduced by bypassing of various time consuming processes of the encoding process by the use of sharing and reuse of video information coming from original bitstream. Extensive analysis has been done to evaluate the gains in the coding efficiency and complexity of the algorithm using the full-decode-full-encode approach as a benchmark. The ultimate reduction in complexity is at least 60% from full-decode-full-encode while maintaining the output video quality. The modular nature of the algorithm is designed to be easily adaptable to other scalable video standards as well.

Code compression for VLIW embedded processors

The implementation of processors for embedded systems implies various issues: main constraints are cost, power dissipation and die area. On the other side, new terminals perform functions that require more computational flexibility and effort. Long code streams must be loaded into memories, which are expensive and power consuming, to run on DSPs or CPUs. To overcome this issue, the “SlimCode” proprietary algorithm presented in this paper (patent pending technology) can reduce the dimensions of the program memory. It can run offline and work directly on the binary code the compiler generates, by compressing it and creating a new binary file, about 40% smaller than the original one, to be loaded into the program memory of the processor. The decompression unit will be a small ASIC, placed between the Memory Controller and the System bus of the processor, keeping unchanged the internal CPU architecture: this implies that the methodology is completely transparent to the core. We present comparisons versus the state-of-the-art IBM Codepack algorithm, along with its architectural implementation into the ST200 VLIW family core.

Smart 3D video coding

In this paper we explore a method to encode/decode multiview textures and associated supplementary data (depth map as an example) together in a single bitstream. Least significant bit (LSB) of last two levels in each transform block has been modified according to the depth encoded bits, thus resulting in very minimal loss in PSNR of textures (0.1 - 0.5dB) with overall bitrate gain of about 13% for natural scenes. The remaining encoded information have been inserted after the slice NAL of corresponding texture ensuring backward compatibility and correct extraction and decoding by a modified decoder. Benchmarking results in terms of compression efficiency and quality on HD sequences have been reported to explore further the viability of using this technique for Free Viewpoint Video (FVV) or 3DV use cases. Experiments are also carried out to evaluate subjective quality of the synthesized views.

Image-based three-dimensional free viewpoint video synthesis

In this paper we describe an image-based rendering chain that realizes the free viewpoint video functionality throughout the whole scene. We summarize the most common problems that may be encountered in such an application and provide different solutions to each core stage of the rendering process. Moreover, we propose a novel way to specify the virtual cameras path that moves throughout the scene and implement a procedure to render the 3D effect by exploiting the stereoscopy principle. Finally, we give some results about the objective quality of the synthesized views w.r.t. their original counterparts acquired from real viewpoints.

A scene change independent high quality constant bit rate control algorithm for MPEG4 simple profile transcoding

Video transcoding is becoming nowadays more and more popular, due to the necessity to cope with several different encoding standards, available bandwidth and decoder capabilities. In this paper we are going to discuss the strategy for implementation of a buffer-based rate control algorithm (constant bit rate) in a MPEG2 to MPEG4 Simple profile transcoder which is over performing during scene changes, always preserving the so called VBV compliancy. This technique is extendable to the transcoding to any video standard having onlypredicted (P) frames.

Pre-Coded Video Transcoding into H.264 with Arbitrary Resolution Change

This paper describes a new transcoding algorithm, able to transcode any coded (e.g. MPEG-2) bit-stream into an H.264 sequence with arbitrary spatial resolution change. The visual quality at a given input and output bit-rate is close or equal to full decoding followed by a full encoding (0.5 dB-to-2 dB less in PSNR than that of re-encoding the stream at the target resolution) while, from the complexity point of view, the proposed transcoding approach is at least ten times faster than re-encoding. The experimental results show that this H.264 transcoder always gives about 20 to 60% better compression than that of the size of the original MPEG2 sequence scaled by the target resolution ratio at equal subjective quality. Using constant quantization parameters both in the transcoding and re-encoding, transcoding gives 20 to 40% lesser compression than re-encoding.

Multiview video and depth coding

In this paper we propose a method to encode/decode multiview textures and associated depth maps together in a single bitstream. Encoded bits of depth maps have been merged into that of associated textures in an innovative way with very minimal loss in PSNR of textures, 0.1-0.2 dB for high delay and 0.2-1 dB for low delay applications. Benchmarking results in terms of compression efficiency and quality on HD sequences have been reported to explore the viability of using this technique for Free-view point Video (FVV) or 3DV use cases.

Transcoding Compressed Video Signals to WMV9

This paper describes a transcoding algorithm able to transcode a compressed video bitstream into a WMV9 (VC1) compliant bitstream. A Closed-Loop Spatial Domain Transcoding approach, modeled on the Cascaded Pixel Domain Transcoder (CPDT) is presented here. It incorporates reusing of information obtained from the input bitstream. To enhance the performance of the transcoder, an approach for pipelining the encoder/decoder processes in the transcoder is proposed here. These modifications can be easily adapted to all the transcoders producing WMV9 as output, the input for whom may include video streams of type MPEG-2, MPEG-4 or H.264. As a proof of concept, the suggested approach has been applied to the case of MPEG-2 to VC1 transcoding. Extensive analysis has been performed and the ultimate gain in transcoding speed achieved for the presented approach compared with MPEG-2 to VC1 CPDT, is in the range of 3 to 7 times faster than CPDT.

Real-time Free Viewpoint Television for embedded systems

In this paper we describe an image-based rendering pipeline for interactive real-time Free Viewpoint Television (FTV) on embedded systems. Description of the processing steps and optimizations implemented targeting the hardware acceleration of a commercial programmable Graphics Processing Unit (GPU) is given. As a result, real-time view synthesis at 70 fps in XGA resolution has bee achieved. Restrictions and modifications introduced to support the application on OpenGL ES 2.0 based GPUs for embedded systems have also been discussed.