Conversion Between Video Compression Protocols Performed by: Dmitry Sezganov, Vitaly Spector Instructor: Stas Lapchev, Artyom Borzin Cooperated with:

Abstract Through past years a lot of video compression algorithms have been developed. There is a great need for converting between different video protocols. Many partial solutions (encoders/decoders) are proposed by leading companies in the field of Video Compression Technologies, living on user the annoying integration issues. Our goal is to develop a general approach to integration of such conversion systems.

Project Requirements A prototype system will be implemented demonstrating conversion between MPEG-2 and MPEG-4/JPEG2000 compression formats. A system should define a clear interface between too conversion modules and a logic unit in order to ensure easy integration of other encoders/decoders for new similar systems.

Project Requirements A compressed data streams may be sent to different devices: Appropriate API for system control should be implemented. Some GUI application will be supplied.

MPEG2:  MPEG2 compresses analog video up to 10 times almost without quality loss.  Thus it is widely used to store high quality video. MPEG4 / JPEG2000:  MPEG4/JPEG2000 capable of compressing video at very high ratio with minimal quality loss.  Thus are essential for broadcast in limited Band Width systems such as Internet and cable TV. Why MPEG2=>MPEG4/JPEG2000?

Facts and Conclusions An average movie in MPEG2 format is ~5Gb – big bandwidth is needed. Various source and destination locations are possible. The system is implemented as a PCI board, accommodating decoder and encoder modules (ASIC, DSP) with memory buffer between them. According to specified source path, data stream is transferred to decoder inputs. Then raw video data is processed by video encoder. Finally, ready encoded video stream is copied to specified destination location.

Facts and Conclusions Large stream size causes some performance limitations upon 33MHz 32bit PCI Bus. Lets take DMA data transfer rate of 11Mb/sec. Bi-directional transfers on PCI can take ~10 minutes. Decompressed video bit-stream is 6-10 times bigger then original MPEG2.

Facts and Conclusions The Local Bus have to be fast enough. After simple calculations we get the following: With frequency of PCI (33MHz) - minimal data path width is 24 bits. With data path width of 8 bits – we need bus at least with 100Mhz frequency.

Block Diagram Decoder D/A Vaddis4PC PCI Bus Encoder PCI Bridge

Vaddis4PC Block Diagram

System Description The MPEG-2 data is transferred through PCI bus to the PCI Bridge on the board. Then, it is directed to decoder module. The decoder’s output stream is sent to Video Encoder. Its output can be connected to some monitor for debugging purposes. A MPEG-4 encoder will receive digital output, extracted by decoder chip. One of the possible options is integrating an MPEG-4 encoder that will sample a raw video signal.

System Description

Current Status & Goals There are several problems implementing system from the scratch – can take undefined time. The Vaddis4PC by Zoran can give us a part of the system – something that is already implemented and works (?). The Vaddis4PC board is a real-time system => the system we build for now won’t be faster than real-time processing.

Current Status & Goals What we are going to do for now: Learning the Vaddis4PC board. Check for drivers compatibility. Writing User Interface for interacting the board. At the same time, searching for appropriate MPEG-4 available HW. Later, it will be integrated to already debugged MPEG2 decoding system.