Browsing by Author "Shih-Hao Wang"

Now showing 1 - 2 of 2

An efficient FGS to MPEG-1/2/4 single layer transcoder with R-D optimized multi-layer streaming technique for video quality improvement
(2007-09-01)
Shih-Hao Wang
;
Wei-Lin Chen
;
Tihao Chiang
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The need for interoperability poses a challenge with the widespread use of multiple video formats. A Multi Layer Streaming-Simplified DCT Domain Transcoder (MLS-SDDT) is proposed to achieve efficient transcoding and video quality improvement. However, an efficient architecture is needed to handle drifting errors. The MLS-SDDT algorithm addresses these issues by proposing: (1) an FGS compatible Simplified DCT Domain Transcoder (FGS-SDDT) architecture for MPEG-1/2/4 single layer transcoding, and (2) an R-D optimized multi-layer streaming technique for video quality improvement. To support efficient transcoding from FGS to MPEG-1/2/4, the FGS-SDDT adopts low complexity Simplified DCT Domain Transcoder (SDDT) architecture as an FGS compatible SDDT. To resolve the serious error-drifting problem from SDDT, especially for heterogeneous transcoding, a mathematical analysis of the error-drifting problem is provided and a solution by multi-layer streaming is adopted. The multi-layer streaming approach pre-computes the errors according to the mathematical analysis and encodes the errors as the second enhancement layer for error compensation. For different network conditions, an R-D optimized model is used to improve the bit allocation in the two enhancement layers for better R-D performance. Our experiments show that the MLS-SDDT can deliver 1.4 similar to 7.0 dB PSNR improvement for MPEG-1 and 1.9 similar to 8.6 dB improvement for MPEG-2 as compared to the SDDT. For FGS to MPEG-4 single layer transcoding, the MLS-SDDT can achieve minor PSNR loss (0.0 similar to 0.4 dB) with lower computational complexity as compared to the SDDT approach.
我國H海運公司貨櫃定期航線技術效率分析
(2010-10-01)
張寶光
;
黃台心
;
王士豪
;
Bao-Guang Chang
;
Tai-Hsin Huang
本文使用translog隨機邊界生產函數，探討我國H海運公司各定期貨櫃航線的技術效率及其影響因素。針對個案公司所屬歐洲、美洲、亞洲及大西洋等四個航區21條定期航線，2003至2006年的季資料進行分析後發現，2004年之效率最差，2006年最佳；若以航程別區分，去程航線較回程航線有效率；另以航區別區分時，亞洲區航線最有效率，歐洲區航線次之，大西洋區航線再次之，美洲區航線效率最低。航程與航區之交叉分析顯示，亞洲航線之去、回航程技術效率最高。另外，在季節因素方面，第一季之平均技術效率最佳，第四季最低。最後，個案公司各航線處在規模報酬遞增階段，擴大服務規模可降低平均成本，其中尤以海勤人員的產出彈性相對最高，凸顯出人力資源在提供航運服務過程的重要性。異於過去相關文獻大多以廠商或產業爲探討對象，本研究以較難取得的公司內部航線資料進行分析，一方面希望提供更貼近管理階層經營決策之資訊；另一方面，或可促使此領域文獻更爲豐富。