Video transcoding: an overview of various techniques and research issues

Abstract

Abstract-One of the fundamental challenges in deploying multimedia systems, such as telemedicine, education, space endeavors, marketing, crisis management, transportation, and military, is to deliver smooth and uninterruptible flow of audio-visual information, anytime and anywhere. A multimedia system may consist of various devices (PCs, laptops, PDAs, smart phones, etc.) interconnected via heterogeneous wireline and wireless networks. In such systems, multimedia content originally authored and compressed with a certain format may need bit rate adjustment and format conversion in order to allow access by receiving devices with diverse capabilities (display, memory, processing, decoder). Thus, a transcoding mechanism is required to make the content adaptive to the capabilities of diverse networks and client devices. A video transcoder can perform several additional functions. For example, if the bandwidth required for a particular video is fluctuating due to congestion or other causes, a transcoder can provide fine and dynamic adjustments in the bit rate of the video bitstream in the compressed domain without imposing additional functional requirements in the decoder. In addition, a video transcoder can change the coding parameters of the compressed video, adjust spatial and temporal resolution, and modify the video content and/or the coding standard used. This paper provides an overview of several video transcoding techniques and some of the related research issues. We introduce some of the basic concepts of video transcoding, and then review and contrast various approaches while highlighting critical research issues. We propose solutions to some of these research issues, and identify possible research directions.Index Terms-Frequency domain, heterogeneous video systems, H.26X, MPEG-X, motion vector refinement, spatial domain, video transcoding.

Efficient Transcoding of an MPEG-2 Bit Stream to an H.264 Bit Stream

“…When an initial delay is incorporated in the transcoding process, the statistics of the incoming bit stream can be used to improve the rate control [27].…”

Efficient Software HEVC to AVS2 Transcoding

“…There are quite a few research works on video transcoding between different coding standards, which is defined as heterogeneous transcoding in [10]. In [11], the authors discuss some key issues in generic video transcoding process.…”

A Cost-Shared Quantization Algorithm and Its Implementation for Multi-Standard Video Codecs

“…The architecture is later synthesized into both FPGA and ASIC level and the result is compared with existing designs. The proposed design serves as a key unit in a multi-codec system in transcoding applications [13] and [14]. …”

“…The MF for luminance and chrominance quantization matrix is calculated in the exact same way as the VC-1 and MPEG-2/4 described in the previous section. Equation (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) and (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) shows the MF matrices for luminance and chrominance quantization matrices respectively. shift is performed on the value coming from the first step which gives the desired quantized level.…”

“…The MF matrix with different amount of right shift can also be calculated for VC-1 and MPEG-2/4 based on equation (2)(3)(4)(5)(6). The MF matrix and the amount of right shift for VC-1/MPEG-2/4 are specified by (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18) and (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19) respectively. …”