‫ﺑﺎﺳﻤﻪ ﺗﻌﺎﻟﻲ‬
‫ﺳﻴﺴﺘﻢﻫﺎي ﭼﻨﺪرﺳﺎﻧﻪاي )‪(40-342‬‬
‫داﻧﺸﻜﺪه ﻣﻬﻨﺪﺳﻲ ﻛﺎﻣﭙﻴﻮﺗﺮ‬
‫ﺗﺮم ﺑﻬﺎر ‪1386‬‬
‫دﻛﺘﺮ ﺣﻤﻴﺪرﺿﺎ رﺑﻴﻌﻲ‬
‫ﺗﻜﻠﻴﻒ ﺷﻤﺎره ‪ :7‬ﻓﺸﺮده ﺳﺎزي وﻳﺪﺋﻮ‬
‫‪ -1‬ﻣﻘﺪﻣﻪ‬
‫ﺩﺭ ﺁﺯﻣﺎﻳﺶ ﻗﺒﻞ‪ ،‬ﺭﻭﺵ ﻫﺎﻱ ﻓﺸﺮﺩﻩ ﺳﺎﺯﻱ ﺗﺼﻮﻳﺮ ﺛﺎﺑﺖ ﺑﺮﺭﺳﻲ ﻭ ﺁﺯﻣﺎﻳﺶ ﺷﺪ‪ .‬ﺩﺭ ﺍﻳﻦ ﺁﺯﻣﺎﻳﺶ‪ ،‬ﻓﺸﺮﺩﻩ ﺳﺎﺯﻱ ﺗﺼﻮﻳﺮ ﻣﺘﺤﺮﻙ ﻳﺎ ﻭﻳـﺪﺋﻮ‪،‬‬
‫ﭘﻴﮕﻴﺮﻱ ﻣﻲ ﺷﻮﺩ‪ .‬ﺟﺪﻭﻝ ﻳﻚ‪ ،‬ﻧﺮﺥ ﺩﺍﺩﺓ ﻣﻮﺭﺩ ﻧﻴﺎﺯ ﺑﺮﺍﻱ ﻭﻳﺪﺋﻮ ﺩﻳﺠﻴﺘﺎﻝ ﺩﺭ ﺳﺎﺧﺘﺎﺭﻫﺎﻱ ﻣﺨﺘﻠﻒ ﺭﺍ ﻧﺸﺎﻥ ﻣﻲ ﺩﻫﺪ‪ .‬ﻣﺸﺨﺺ ﺍﺳﺖ ﻛﻪ ﻳﻚ‬
‫ﻭﻳﺪﺋﻮ ﺑﻪ ﺣﺎﻓﻈﻪ ﻭ ﻳﺎ ﭘﻬﻨﺎﻱ ﺑﺎﻧﺪ ﺑﻴﺸﺘﺮﻱ ﻧﺴﺒﺖ ﺑﻪ ﺗﺼﻮﻳﺮ‪ ،‬ﻧﻴﺎﺯ ﺩﺍﺭﺩ‪ .‬ﺑﺮﺍﻱ ﻣﺜـﺎﻝ ﻳـﻚ ﻭﻳـﺪﺋﻮ ﺑـﺎ ﺩﻗـﺖ ‪) CCIR 601‬ﻣﻌـﺎﺩﻝ ﺑـﺎ ﺩﻗـﺖ‬
‫ﺗﻠﻮﻳﺰﻳﻮﻥ ﺁﻧﺎﻟﻮﮒ( ﺑﺎ ﻧﺮﺥ ﻧﻤﻮﻧﻪ ﺑﺮﺩﺍﺭﻱ ﺭﻧﮓ ‪ ،4:2:0‬ﻧﺮﺧﯽ ﺑﺮﺍﺑـﺮ ‪ ١٢٨ Mbit/s‬ﻳـﺎ ‪ ١٦Mbyte/s‬ﺩﺍﺭﺩ‪ .‬ﺑﻌﺒـﺎﺭﺕ ﺩﻳﮕـﺮ‪ ،‬ﻳـﻚ ﻓـﻴﻠﻢ ‪٢‬‬
‫ﺳﺎﻋﺘﻪ‪ ١١٢ Gbyte ،‬ﺣﺎﻓﻈﻪ ﺍﺷﻐﺎﻝ ﻣﻲ ﻛﻨﺪ‪ .‬ﻳﻚ ﻓﻴﻠﻢ ‪ CIF‬ﺑﺎ ﻛﻴﻔﻴﺖ ﻛﻤﺘﺮ )ﻣﻌﺎﺩﻝ ﺑﺎ ﺩﻗﺖ ‪ VHS‬ﻳﺎ ﻓﻴﻠﻢ ﻫﺎﻱ ‪ (VCD‬ﻳﻚ ﭼﻬﺎﺭﻡ ﺍﻳﻦ‬
‫ﻣﻘﺪﺍﺭ ﺭﺍ ﺍﺷﻐﺎﻝ ﻣﻲ ﻛﻨﺪ‪ .‬ﻭﺍﺿﺢ ﺍﺳﺖ ﻛﻪ ﺩﺭ ﻣﻘﺎﻳﺴﻪ ﺑﺎ ﺗﺼﻮﻳﺮ‪ ،‬ﺭﻭﺵ ﻫﺎﻱ ﻣﺆﺛﺮﺗﺮﻱ ﺑﺮﺍﻱ ﻓﺸﺮﺩﻩ ﺳﺎﺯﻱ ﺩﺍﺩﻩ ﻫﺎ‪ ،‬ﺑـﺮﺍﻱ ﺫﺧﻴـﺮﻩ ﺳـﺎﺯﻱ ﻳـﺎ‬
‫ﺍﺭﺳﺎﻝ ﻭﻳﺪﺋﻮ ﻣﻮﺭﺩ ﻧﻴﺎﺯ ﺍﺳﺖ‪.‬‬
‫ﺍﺳﺘﺎﻧﺪﺍﺭﺩ ﻛﺮﺩﻥ ﺍﻟﮕﻮﺭﻳﺘﻢ ﻫﺎﻱ ﻓﺸﺮﺩﻩ ﺳﺎﺯﻱ ﺑﺮﺍﻱ ﻭﻳﺪﺋﻮ‪ ،‬ﺑﺮﺍﻱ ﺍﻭﻟﻴﻦ ﺑﺎﺭ ﺗﻮﺳﻂ ‪ CCTTT‬ﺑﺮﺍ ﻛﻨﻔﺮﺍﻧﺲ ﺗﻠﻔﻨﻲ ﻭ ﺗﻠﻔﻦ ﺗـﺼﻮﻳﺮﻱ‪ ،‬ﺍﻧﺠـﺎﻡ‬
‫ﺷﺪﻩ ﺍﺳﺖ‪ .‬ﻳﻚ ﮔﺮﻭﻩ ﺗﺨﺼـﺼﻲ ﺍﺯ ‪) ،CCTTT‬ﻛـﻪ ﺍﻛﻨـﻮﻥ ﺑﻨـﺎﻡ ‪The International Telecommunication Unit- ،ITU-T‬‬
‫‪ Telecommunication Sector‬ﻧﺎﻣﻴﺪﻩ ﻣﻲ ﺷﻮﺩ( ﺍﺳﺘﺎﻧﺪﺍﺭﺩﻱ ﺑﺮﺍﻱ ﺗﻜﻨﻴﻚ ﻫﺎﻱ ﻓﺸﺮﺩﻩ ﺳﺎﺯﻱ ﻭﻳﺪﺋﻮ ﺑﺮﺍﻱ ﻭﻳـﺪﺋﻮ ﻛﻨﻔـﺮﺍﻧﺲ ﻣﻄـﺮﺡ‬
‫ﻛﺮﺩﻩ ﺍﺳﺖ‪ .‬ﺍﻳﻦ ﺍﺳﺘﺎﻧﺪﺍﺭﺩ ﺩﺭ ﺳﺎﻝ ‪ ١٩٩٠‬ﺗﻬﻴﻪ ﺷﺪﻩ ﺍﺳﺖ‪ ،‬ﺑﻌﻨﻮﺍﻥ ‪ H.320‬ﺷﻨﺎﺧﺘﻪ ﻣﻲ ﺷﻮﺩ ﻛﻪ ﻗﺴﻤﺖ ﻣﺮﺑﻮﻁ ﺑـﻪ ﻛـﺪ ﻛـﺮﺩﻥ ﻭﻳـﺪﺋﻮ ﺁﻥ‪،‬‬
‫‪ H.261‬ﺍﺳﺖ‪ .‬ﺍﻳﻦ ﺍﺳﺘﺎﻧﺪﺍﺭﺩ ﺑﺮﺍﻱ ﻭﻳﺪﺋﻮ ﻛﻨﻔﺮﺍﻧﺲ ﺍﺯ ﺧﻄﻮﻁ ‪ ISDN‬ﺍﺳﺘﻔﺎﺩﻩ ﻣﻲ ﻛﻨﺪ ﻛـﻪ ﺩﺍﺭﺍﻱ ﭘﻬﻨـﺎﻱ ﺑﺎﻧـﺪ ‪ p*64 kpbs‬ﺍﺳـﺖ ﻛـﻪ‬
‫‪ p=1,2,…,30‬ﻣﻲ ﺗﻮﺍﻧﺪ ﺑﺎﺷﺪ‪ .‬ﻣﻨﺒﻊ ﻭﻳﺪﺋﻮ ﻳﺎ ‪ ٣٠ fps) CIF‬ﻭ ‪ (٣٥٢*٢٨٨‬ﻳﺎ ‪ ٣٠fpc) QCIF‬ﻭ ‪ (١٧٦*١٤٤‬ﺍﺳﺖ ﻭ ﻭﻳﺪﺋﻮ ﻫﻤﺮﺍﻩ ﺑـﺎ‬
‫ﺻﺪﺍ ﺑﺎﻳﺪ ﺑﻪ ﺍﻧﺪﺍﺯﺓ ﻣﻀﺮﺑﻲ ﺍﺯ ‪ ٦٤ kbps‬ﻓﺸﺮﺩﻩ ﺷﻮﺩ‪.‬‬
‫‪1‬‬
‫‪CE 342 – Multimedia HW# 7‬‬
‫‪H. Rabiee, Spring 2008‬‬
‫ﺟﺪﻭﻝ ‪ :۱‬ﻓﺮﺻﺖ ﻫﺎﻱ ﻭﻳﺪﺋﻮ ﺩﻳﺠﻴﺘﺎﻝ ﺑﺮﺍﻱ ﻛﺎﺭﺑﺮﺩﻫﺎﻱ ﻣﺨﺘﻠﻒ‬
‫ﻋﻤﻮﻣﹰﺎ ﺑﺮﺍﻱ ﺩﺍﺷﺘﻦ ﻛﻴﻔﻴﺖ ﻗﺎﺑﻞ ﻗﺒﻮﻝ‪ ،‬ﻳﻚ ﻭﻳﺪﺋﻮ ‪ ،CIF‬ﺑﻪ ‪ ٣٨٤ kbps‬ﻳﺎ ﺑﻴﺸﺘﺮ ﻭ ﻳﻚ ﻭﻳﺪﺋﻮ ‪ QCIF‬ﺑﻪ ‪ ٦٤kbps‬ﻳـﺎ ﺑﻴـﺸﺘﺮ ﻧﻴـﺎﺯ ﺩﺍﺭﺩ‪.‬‬
‫ﺑﺪﻧﺒﺎﻝ ﺍﻳﺠﺎﺩ ﺍﺳﺘﺎﻧﺪﺍﺭﺩ ‪ ،ITU-T ،H.320‬ﺗﻮﺳﻌﺔ ﻛﺎﺭ ﺭﺍ ﺑﺮﺍﻱ ﺳﺎﻳﺮ ﺭﺳﺎﻧﻪ ﻫﺎﻱ ﺍﻧﺘﻘﺎﻟﻲ ﺍﺩﺍﻣﻪ ﺩﺍﺩ‪ .‬ﺍﺯ ﻣﻬﻤﺘـﺮﻳﻦ ﺁﻧﻬـﺎ‪ ،‬ﺍﺳـﺘﺎﻧﺪﺍﺭﺩ ‪H.323‬‬
‫ﺍﺳﺖ ﻛﻪ ﺑﺮﺍﻱ ﺷﺒﻜﻪ ﻫﺎﻳﻲ ﻛﻪ ﻛﻴﻔﻴﺖ ﺳﺮﻭﻳﺲ ﺭﺍ ﺗﻀﻤﻴﻦ ﻧﻤﻲ ﻛﻨﻨﺪ‪ ،‬ﻣﺎﻧﻨﺪ ﺍﻳﻨﺘﺮﻧﺖ‪ ،‬ﺗﻬﻴﻪ ﺷﺪﻩ ﺍﺳﺖ ﻭ ﻧﻴـﺰ ﺍﺳـﺘﺎﻧﺪﺍﺭﺩ ‪ H.324‬ﻛـﻪ ﺑـﺮﺍﻱ‬
‫ﺧﻄﻮﻁ ﺑﺎ ﭘﻬﻨﺎﻱ ﺑﺎﻧﺪ ﺑﺴﻴﺎﺭ ﻛﻢ ﻣﺜﻞ ﺧﻄﻮﻁ ﺗﻠﻔﻦ ﺍﺯ ﻃﺮﻳﻖ ﻣﻮﺩﻡ ‪ ٢٨٠٨kbps‬ﻳﺎ ﻛﺎﻧﺎﻝ ﺑﻲ ﺳﻴﻢ‪ ،‬ﻣﻄﺮﺡ ﺷﺪﻩ ﺍﺳـﺖ‪ .‬ﺍﺳـﺘﺎﻧﺪﺍﺭﺩ ﻛـﺪ ﻛـﺮﺩﻥ‬
‫ﻭﻳﺪﺋﻮ ﺩﺭ ﻫﺮ ﺩﻭﻱ ﺍﻳﻦ ﺍﺳﺘﺎﻧﺪﺍﺭﺩﻫﺎﻱ ‪ H.323‬ﻭ ‪ H.263 ،H.324‬ﺍﺳﺖ ﻛﻪ ﭘﻴﺸﺮﻓﺖ ﻣﺤﺴﻮﺳﻲ ﻧـﺴﺒﺖ ﺑـﻪ ‪ H.261‬ﺑﺨـﺼﻮﺹ ﺑـﺮﺍﻱ‬
‫ﻧﺮﺥ ﺑﻴﺖ ﻫﺎﻱ ﭘﺎﻳﻴﻦ ﺩﺍﺭﺩ‪ .‬ﺑﺎ ‪ ،H.263‬ﻳﻚ ﻭﻳﺪﺋﻮ ‪ ،QCIF‬ﺑﺎ ﻛﻴﻔﻴﺖ ﻣﻌﺎﺩﻝ ﻳﺎ ﺑﻬﺘﺮ ﺍﺯ ‪ H.261‬ﺑـﺎ ﻧـﺮﺥ ‪ ،٦٤kbps‬ﺗـﺎ ﺣـﺪﻭﺩ ‪٢٤kbps‬‬
‫ﻓﺸﺮﺩﻩ ﻣﻲ ﺷﻮﺩ‪.‬‬
‫ﻫﻤﺰﻣﺎﻥ ﺑﺎ ﺗﻼﺵ ‪ ITU-T‬ﻳﻚ ﮔﺮﻭﻩ ﺗﺨﺼﺼﻲ ﺑﻪ ﻧـﺎﻡ ‪ ،Motion Picture Expert Group ،MPEG‬ﺍﺯ ‪ ISO‬ﻧﻴـﺰ ﺍﺳـﺘﺎﻧﺪﺍﺭﺩﻫﺎﻱ‬
‫ﻣﺨﺘﻠﻔﻲ ﺭﺍ ﺑﺮﺍﻱ ﺫﺧﻴﺮﻩ ﺳﺎﺯﻱ‪ ،‬ﺗﻮﺯﻳﻊ ﺍﺭﺳﺎﻝ ﻭ ﺍﻧﺘﺸﺎﺭ ﻭﻳﺪﺋﻮ‪ ،‬ﺗﻮﺳﻌﻪ ﺩﺍﺩﻧﺪ‪ .‬ﺍﻭﻟﻴﻦ ﺍﺳـﺘﺎﻧﺪﺍﺭﺩ ﺍﻳـﻦ ﮔـﺮﻭﻩ ‪ MPEG-1‬ﺍﺳـﺖ ﻛـﻪ ﻗﺎﺑﻠﻴـﺖ‬
‫ﻓﺸﺮﺩﻩ ﺳﺎﺯﻱ ﻭﻳﺪﺋﻮ ﻭ ﺻﻮﺕ ﺑﺎ ﺩﻗﺖ ‪ (٣٥٢*٢٤٠ pels/sec ٣٠ fps) ،SIF‬ﺭﺍ ﺗﺎ ‪ ١/٥Mbps‬ﺑـﺎ ﻛﻴﻔﻴـﺖ ﺧـﻮﺏ‪ ،‬ﺩﺍﺭﺩ‪ .‬ﺍﻳـﻦ ﺍﺳـﺘﺎﻧﺪﺍﺭﺩ‬
‫ﺍﻣﻜﺎﻥ ﺫﺧﻴﺮﻩﺳﺎﺯﻱ ﻭ ﭘﺨﺶ ﻓﻴﻠﻢ ﻫﺎ ﺭﻭﻱ ‪ CD-ROM‬ﺭﺍ ﻣﻲ ﺩﺍﺩ ﻛﻪ ﺩﺭ ﺁﻥ ﺯﻣﺎﻥ ﻧﺮﺥ ﺁﻧﻬﺎ ﺑﻪ ‪ ١/٥ Mbps‬ﻣﺤﺪﻭﺩ ﻣﻲ ﺷﺪ‪.‬‬
‫ﺍﺳﺘﻘﺒﺎﻝ ﺍﺯ ﻓﻴﻠﻢ ﻫﺎﻱ ‪ MPEG-1‬ﺭﻭﻱ ‪ VCD) CD‬ﻳﺎ ‪ (Video CD‬ﻋﺎﻣﻠﻲ ﺑﺮﺍﻱ ﺗﻮﺳﻌﺔ ﻭﻳﺪﺋﻮﻫﺎﻱ ﺩﻳﺠﻴﺘـﺎﻝ ﺷـﺪ‪ .‬ﻭﻗﺘـﻲ ﺍﺳـﺘﺎﻧﺪﺍﺭﺩ‬
‫‪ MPEG-1‬ﺑﺮﺍﻱ ﺍﻭﻟﻴﻦ ﺑﺎﺭ ﻣﻄﺮﺡ ﺷﺪ‪ ،‬ﺳﺨﺖ ﺍﻓﺰﺍﺭ ﭘﻴﭽﻴـﺪﻩ ﺑـﺮﺍﻱ ﻛـﺪ ﻭ ﻭﺍﻛـﺪ ﻛـﺮﺩﻥ ﺑـﻲ ﺩﺭﻧـﮓ ﺁﻥ ﻣـﻮﺭﺩ ﻧﻴـﺎﺯ ﺑـﻮﺩ‪ .‬ﻋﺮﺿـﻪ ﺷـﺪﻥ‬
‫ﻣﻴﻜﺮﻭﭘﺮﻭﺳﺴﻮﺭ ‪ ،Intel Pentium I‬ﻭﺍﻛﺪ ﻛﺮﺩﻥ ﻓﻴﻠﻢ ﻫﺎﻱ ‪ MPEG-1‬ﺑﻄﻮﺭ ﺑﻲ ﺩﺭﻧﮓ ﻭ ﮔﺮﻓﺘﻦ ﻓـﻴﻠﻢ ‪ MPEG-1‬ﺍﺯ ﻃﺮﻳـﻖ ‪WEB‬‬
‫ﺭﺍ ﻣﻴﺴﺮ ﻛﺮﺩ‪.‬‬
‫ﺑﻌﺪ ﺍﺯ ﻛﺎﻣﻞ ﺷﺪﻥ ‪ MPEG ،MPEG-1‬ﺭﻭﻱ ﺍﺳﺘﺎﻧﺪﺍﺭﺩ ﻛﺮﺩﻥ ﺷﻴﻮﺓ ﻓﺸﺮﺩﻩ ﺳﺎﺯﻱ ﻭﻳﺪﺋﻮ ﻭ ﺻﺪﺍ‪ ،‬ﺑـﺮﺍﻱ ﻛﺎﺭﺑﺮﺩﻫـﺎﻱ ﺍﻧﺘـﺸﺎﺭ ﻭﻳـﺪﺋﻮ ﺑـﺎ‬
‫ﻛﻴﻔﻴﺖ ﺑﺎﻻ‪ ،‬ﻣﺘﻤﺮﻛﺰ ﺷﺪ‪ ،‬ﺑﺎ ﺍﻳﻦ ﻫﺪﻑ ﻛﻪ ﻭﻳﺪﺋﻮ ﺑﺎ ﺩﻗﺖ ‪) CCIR601‬ﻛﻴﻔﻴﺖ ﺗﻠﻮﻳﺰﻳﻮﻥ( ﺑﻴﻦ ‪ ٣‬ﺗـﺎ ‪ ١٠Mbp‬ﻓـﺸﺮﺩﻩ ﺷـﻮﺩ‪ .‬ﺍﻳـﻦ ﺗـﻼﺵ‬
‫ﻣﻨﺠﺮ ﺑﻪ ﻣﻄﺮﺡ ﺷﺪﻥ ‪ MPEG–2‬ﺷﺪ‪ .‬ﺍﻳﺠﺎﺩ ﺍﺳﺘﺎﻧﺪﺍﺭﺩ ‪ MPEG-2‬ﻭﻗﺎﻳﻊ ﻣﻬﻤﻲ ﺑﺪﻧﺒﺎﻝ ﺩﺍﺷﺖ‪ :‬ﺍﻣﻜﺎﻥ ﺍﻧﺘﺸﺎﺭ ﻭﻳـﺪﺋﻮ ﺍﺯ ﻃﺮﻳـﻖ ﻣـﺎﻫﻮﺍﺭﻩ‬
‫)ﻣﺎﻧﻨﺪ ‪ ،(Direct-TV‬ﻓﻴﻠﻢ ﻫﺎﻱ ‪ DVD‬ﻭ ﺗﻠﻮﻳﺰﻳﻮﻥ ﺩﻳﺠﻴﺘﺎﻝ‪ .‬ﺍﺳـﺘﺎﻧﺪﺍﺭﺩ ‪ MPEG-2‬ﻫﻤﭽﻨـﻴﻦ ﺩﺍﺭﺍﻱ ﺍﻣﻜﺎﻧـﺎﺗﻲ ﺑـﺮﺍﻱ ﻓـﺸﺮﺩﻩ ﺳـﺎﺯﻱ‬
‫ﻭﻳﺪﺋﻮ ﺑﺎ ﺩﻗﺖ ‪ HDTV‬ﺍﺳﺖ‪ .‬ﻫﻤﭽﻨﻴﻦ ﻣﻲ ﺗﻮﺍﻧﺪ ﺑﺎ ﺩﻗﺖ ‪ (SIF) MPEG-1‬ﻧﻴﺰ ﻛﺎﺭ ﻛﻨﺪ ﻭ ﺑﺎ ‪ MPEG-1‬ﺳﺎﺯﮔﺎﺭ ﺍﺳﺖ‪.‬‬
‫ﺟﺪﻭﻝ ‪ ،٢‬ﺍﺳﺘﺎﻧﺪﺍﺭﺩﻫﺎﻱ ﻓﻮﻕ ﺑﺮﺍﻱ ﻓﺸﺮﺩﻩ ﺳﺎﺯﻱ ﺳﻴﮕﻨﺎﻝ ﻫﺎﻱ ﭼﻨﺪ ﺭﺳﺎﻧﻪ ﺍﻱ ﺭﺍ ﺟﻤﻊ ﺑﻨﺪﻱ ﻛﺮﺩﻩ ﺍﺳﺖ‪.‬‬
‫‪2‬‬
‫‪CE 342 – Multimedia HW# 7‬‬
‫‪H. Rabiee, Spring 2008‬‬
‫ﺟﺪول ‪ :2‬اﺳﺘﺎﻧﺪاردﻫﺎي ﻛﺪ ﻛﺮدن وﻳﺪﺋﻮ ﺑﺮاي ﻛﺎرﺑﺮدﻫﺎي ﻣﺨﺘﻠﻒ‬
‫ﺑﺪﻧﺒﺎﻝ ‪ ،MPEG-2‬ﺍﺳﺘﺎﻧﺪﺍﺭﺩ ﺩﻳﮕﺮﻱ ﺑﻪ ﻧﺎﻡ ‪ MPEG-4‬ﻃﺮﺍﺣﻲ ﺷﺪ ﻛﻪ ﻫﺪﻑ ﺁﻥ ﺍﻳﺠﺎﺩ ﻗﺎﺑﻠﻴﺘﻲ ﺑﺮﺍﻱ ﺩﺳﺘﺮﺳﻲ ﺑﻪ ﺍﺷﻴﺎﺀ ﻣﺨﺘﻠﻒ ﻭ ﻣﺠﺰﺍ‬
‫ﻼ ﻫﺮ ﺷﻲﺀ ﺑﻄﻮﺭ ﺟﺪﺍﮔﺎﻧﻪ ﻛﺪ ﻣـﻲ ﺷـﻮﺩ‪ .‬ﺗـﻼﺵ ﮔـﺮﻭﻩ ‪ MPEG‬ﺩﺭ‬
‫ﺩﺭ ﺗﺼﻮﻳﺮ ﻭﻳﺪﺋﻮ ﺑﻮﺩ‪ .‬ﻭﻳﺪﺋﻮ ﺑﺎ ﺭﻭﺵ ﻣﺒﺘﻨﻲ ﺑﺮ ﺷﻲﺀ ﻛﺪ ﻣﻲﺷﻮﺩ‪ .‬ﻣﺜ ﹰ‬
‫ﺍﺩﺍﻣﻪ ﺑﺮﺍﻱ ﺍﺳﺘﺎﻧﺪﺍﺭﺩ ‪ MPEG-7‬ﺍﺳﺖ‪ .‬ﻛﻪ ﻫﺪﻑ ﺁﻥ ﺍﻳﺠﺎﺩ ﺍﺳﺘﺎﻧﺪﺍﺭﺩﻱ ﺑﺮﺍﻱ ﺗﻮﺻﻴﻒ ﻭ ﻗﺎﺑﻠﻴﺖ ﻣﺮﺗﺐ ﺳﺎﺯﻱ ﺍﺳﺖ‪ ،‬ﺑﮕﻮﻧﻪﺍﻱ ﻛـﻪ ﺍﻣﻜـﺎﻥ‬
‫ﺗﻮﺻﻴﻒ ﻣﺤﺘﻮﺍﻱ ﺍﻃﻼﻋﺎﺕ ﺗﺼﻮﻳﺮﻱ ﻭ ﺻﻮﺗﻲ ﺭﺍ ﺩﺍﺷﺘﻪ ﺑﺎﺷﺪ ﺗﺎ ﺩﺳﺘﻴﺎﺑﻲ ﺑﻪ ﻭﻳﺪﺋﻮ ﺩﻳﺠﻴﺘﺎﻝ ﺭﺍ ﻣﻴﺴﺮ ﻛﻨﺪ‪.‬‬
‫ﺩﺭ ﺍﻳﻦ ﺁﺯﻣﺎﻳﺶ‪ ،‬ﺗﻜﻨﻴﻚ ﻫﺎﻱ ﺍﺑﺘﺪﺍﻳﻲ ﺑﺮﺍﻱ ﻓﺸﺮﺩﻩ ﺳﺎﺯﻱ ﻭﻳﺪﺋﻮ‪ ،‬ﺑﺨـﺼﻮﺹ ﺗﺨﻤـﻴﻦ ﺟﺒـﺮﺍﻥ ﺣﺮﻛـﺖ ﻭ ﻣـﺮﻭﺭ ﺍﺳـﺘﺎﻧﺪﺍﺭﺩﻫﺎﻱ ‪،H.261‬‬
‫‪ MPEG-1‬ﻭ ‪ ، MPEG-2‬ﺩﻧﺒﺎﻝ ﻣﻲ ﺷﻮﺩ‪ .‬ﺑﺮﺍﻱ ﺟﺰﺋﻴﺎﺕ ﺑﻴﺸﺘﺮ ﺩﺭ ﺍﻳﻦ ﺯﻣﻴﻨﻪ ﺑﻪ ]‪ [1‬ﻣﺮﺍﺟﻌﻪ ﻧﻤﺎﻳﻴﺪ‪.‬‬
‫‪ -2‬ﺗﺌﻮري ﻫﺎ و اﻟﮕﻮﻫﺎي ﻓﺸﺮده ﺳﺎزي وﻳﺪﺋﻮ‬
‫‪ -1-2‬ﺗﺨﻤﻴﻦ ﺣﺮﻛﺖ و ﺟﺒﺮان ﺣﺮﻛﺖ‬
‫ﺗﺨﻤﻴﻦ ﻭ ﺟﺒﺮﺍﻥ ﺣﺮﻛﺖ‪ ،‬ﭘﺎﻳﻪ ﻭ ﺍﺳﺎﺱ ﺍﻛﺜﺮ ﺍﻟﮕﻮﺭﻳﺘﻢ ﻫﺎﻱ ﻓﺸﺮﺩﻩ ﺳﺎﺯﻱ ﻭﻳﺪﺋﻮ ﻫﺴﺘﻨﺪ‪ .‬ﺑﺮﺍﻱ ﺟﺒﺮﺍﻥ ﺣﺮﻛﺖ‪ ،‬ﻓﺮﺽ ﻣﻲ ﻛﻨﻨﺪ ﻛـﻪ ﺗـﺼﻮﻳﺮ‬
‫ﺟﺎﺭﻱ‪ ،‬ﺗﺼﻮﻳﺮﻱ ﺑﺎ ﺗﻐﻴﻴﺮﺍﺕ ﺟﺰﻳﻲ ﻧﺴﺒﺖ ﺑﻪ ﺗﺼﻮﻳﺮ ﻗﺒﻠﻲ ﺍﺳﺖ‪ .‬ﺍﻳﻦ ﻓﺮﺽ‪ ،‬ﺍﻣﻜﺎﻥ ﺍﺳـﺘﻔﺎﺩﻩ ﺍﺯ ﺗﺨﻤـﻴﻦ ﻭ ﺩﺭﻭﻧﻴـﺎﺑﻲ ﺭﺍ ﺍﻳﺠـﺎﺩ ﻣـﻲ ﻛﻨـﺪ‪.‬‬
‫ﻫﻨﮕﺎﻣﻲ ﻛﻪ ﻳﻚ ﻓﺮﻳﻢ ﺑﻌﻨﻮﺍﻥ ﻣﺮﺟﻊ ﺍﺳﺘﻔﺎﺩﻩ ﻣﻲ ﺷﻮﺩ‪ ،‬ﻣﺠﻤﻮﻋﻪ ﻓﺮﻳﻢ ﻫﺎﻱ ﺩﻧﺒﺎﻟﺔ ﺁﻥ‪ ،‬ﺍﺧﺘﻼﻑ ﻫﺎﻱ ﺟﺰﻳـﻲ ﺑـﺎ ﻳﻜـﺪﻳﮕﺮ ﺩﺍﺭﻧـﺪ ﻛـﻪ ﻧﺘﻴﺠـﺔ‬
‫ﺣﺮﻛﺖ ﺍﺷﻴﺎﺀ ﻭ ﻳﺎ ﺣﺮﻛﺖ ﺩﻭﺭﺑﻴﻦ ﺍﺳﺖ‪ ،‬ﻛﻪ ﺩﺭ ﺷﻜﻞ ‪ ١‬ﻧﺸﺎﻥ ﺩﺍﺩﻩ ﺷﺪﻩ ﺍﺳﺖ‪ .‬ﺑﺮﺍﻱ ﺍﻳﻨﻜﻪ ﻣﻘﺎﻳﺴﺔ ﻓﺮﻳﻢ ﻫﺎ‪ ،‬ﺳﺎﺩﻩ ﺗﺮ ﺷﻮﺩ‪ .‬ﻳﻚ ﻓﺮﻳﻢ ﺑﻄﻮﺭ‬
‫ﻛﺎﻣﻞ ﻛﺪ ﻧﻤﻲ ﺷﻮﺩ‪ ،‬ﺑﻠﻜﻪ ﺑﻪ ﺑﻠﻮﻛﻬﺎﻳﻲ ﺗﻘﺴﻴﻢ ﻣﻲ ﺷﻮﺩ ﻭ ﺑﻠﻮﻛﻬﺎ ﺑﻄﻮﺭ ﻣﺴﺘﻘﻞ ﻛﺪ ﻣﻲ ﺷﻮﻧﺪ‪ .‬ﺑﺮﺍﻱ ﻫﺮ ﺑﻠﻮﻙ ﺩﺭ ﻓﺮﻳﻤﻲ ﻛـﻪ ﻛـﺪ ﻣـﻲ ﺷـﻮﺩ‬
‫)ﻓﺮﻳﻢ ﺟﺎﺭﻱ(‪ ،‬ﺑﻬﺘﺮﻳﻦ ﺑﻠﻮﻙ ﻣﻨﻄﺒﻖ‪ ،‬ﺩﺭ ﻓﺮﻳﻢ ﻣﺮﺟﻊ ﺩﺭ ﻣﻴﺎﻥ ﺗﻌﺪﺍﺩﻱ ﺍﺯ ﺑﻠﻮﻛﻬﺎﻱ ﺍﻧﺘﺨﺎﺏ ﺷﺪﻩ‪ ،‬ﺟﺴﺘﺠﻮ ﻣﻲ ﺷﻮﺩ‪ .‬ﺑﺮﺍﻱ ﻫـﺮ ﺑﻠـﻮﻙ‪ ،‬ﻳـﻚ‬
‫ﺑﺮﺩﺍﺭ ﺣﺮﻛﺖ ﺗﻮﻟﻴﺪ ﻣﻲ ﺷﻮﺩ ﻛﻪ ﺍﺧﺘﻼﻑ ﺑﻴﻦ ﻣﻜﺎﻥ ﺁﻥ ﺑﻠﻮﻙ ﻭ ﺑﻬﺘﺮﻳﻦ ﺑﻠﻮﻙ ﻣﻄﺎﺑﻖ ﺑﺎ ﺁﻥ‪ ،‬ﺩﺭ ﻓﺮﻳﻢ ﻣﺮﺟﻊ ﺭﺍ ﻧﺸﺎﻥ ﻣﻲ ﺩﻫﺪ‪ .‬ﺍﻳﻦ ﺍﻧﺘﺨـﺎﺏ‬
‫ﻣﻲ ﺗﻮﺍﻧﺪ ﺑﺎ ﻳﻚ ﺟﺴﺘﺠﻮﻱ ﻛﺎﻣﻞ ﻭ ﺟﺎﻣﻊ ﺍﻧﺠﺎﻡ ﺷﻮﺩ‪ ،‬ﺭﻭﺷﻲ ﻛﻪ ﺑﻄﻮﺭ ﻣﺨﺘﺼﺮ ﺷﺮﺡ ﺩﺍﺩﻩ ﺧﻮﺍﻫﺪ ﺷﺪ‪.‬‬
‫‪3‬‬
‫‪CE 342 – Multimedia HW# 7‬‬
‫‪H. Rabiee, Spring 2008‬‬
‫ﺷﻜﻞ‪ :1‬ﻣﻴﺰان ﺣﺮﻛﺖ ﻣﺒﺘﻨﻲ ﺑﺮ ﺑﻠﻮك‬
‫ﺩﺭ ﺭﻭﺵ ﺩﺭﻭﻧﻴﺎﺑﻲ‪ ،‬ﺑﺮﺩﺍﺭﻫﺎﻱ ﺣﺮﻛﺖ‪ ،‬ﺩﺭ ﺍﺭﺗﺒﺎﻁ ﺑﺎ ﺩﻭ ﻓﺮﻳﻢ ﻣﺮﺟﻊ ﺗﻮﻟﻴﺪ ﻣﻲ ﺷﻮﻧﺪ‪ ،‬ﻳﻜﻲ ﺍﺯ ﻓﺮﻳﻢ ﻣﺮﺟﻊ ﻗﺒﻠﻲ ﻭ ﺩﻳﮕﺮﻱ ﺍﺯ ﻓـﺮﻳﻢ ﻣﺮﺟـﻊ‬
‫ﺑﻌﺪﻱ‪ ،‬ﺑﻬﺘﺮﻳﻦ ﺑﻠﻮﻛﻬﺎﻱ ﺗﻄﺒﻴﻖ ﺩﺍﺩﻩ ﺷﺪﻩ ﺩﺭ ﻫﺮ ﺩﻭ ﻓﺮﻳﻢ ﺟﺴﺘﺠﻮ ﻣﻲ ﺷﻮﻧﺪ ﻭ ﺩﻭ ﺑﻠﻮﻙ ﺑﺪﺳﺖ ﺁﻣﺪﻩ ﻣﻴﺎﻧﮕﻴﻦ ﮔﺮﻓﺘﻪ ﻣﻲ ﺷﻮﻧﺪ‪.‬‬
‫‪ -1-1-2‬اﻟﮕﻮرﻳﺘﻢ ﺗﻄﺎﺑﻖ ﺑﻠﻮﻛﻬﺎ ﺑﺮاي ﺗﺨﻤﻴﻦ ﺣﺮﻛﺖ )‪(BMA‬‬
‫ﻓﺮﺽ ﻛﻨﻴﺪ ﻛﻪ ﻫﺮ ﺑﻠﻮﻙ ‪ Bn‬ﺩﺭ ﻓﺮﻳﻢ ‪ ،fk‬ﻣﺘﻨﺎﻇﺮ ﺑﺎ ﻳﻚ ﺑﻠﻮﻙ ﺩﺭ ﻓﺮﻳﻢ ‪ fk-1‬ﺑﺎ ﻣﻮﻗﻌﻴﺖ ‪ Dn‬ﺑﺎﺷﺪ‪.‬‬
‫ﻛﻪ ‪ Dn‬ﺑﻨﺎﻡ ﺑﺮﺩﺍﺭ ﺣﺮﻛﺖ ‪ Bn‬ﻧﺎﻣﻴﺪﻩ ﻣﻲ ﺷﻮﺩ‪ .‬ﺗﺨﻤﻴﻦ ‪ Dn‬ﻣﻲ ﺗﻮﺍﻧﺪ ﺍﺯ ﻃﺮﻳﻖ ﺣﺪﺍﻗﻞ ﻛﺮﺩﻥ ﺧﻄﺎﻱ ﺗﺨﻤﻴﻦ‪ ،‬ﻣﺎﻧﻨﺪ ﺟﻤﻊ ﻣﺠﺬﻭﺭ ﺧﻄﺎﻫﺎ‬
‫ﻭ ﻳﺎ ﻗﺪﺭ ﻣﻄﻠﻖ ﺧﻄﺎﻫﺎ ﺑﺎﺷﺪ‪.‬‬
‫‪ BMA‬ﻳﻚ ﺭﻭﺵ ﺟﺴﺘﺠﻮﻱ ﻛﺎﻣﻞ ﺭﺍ ﺑﺮﺍﻱ ﭘﻴﺪﺍ ﻛﺮﺩﻥ ﺑﻠﻮﻛﻲ ﻛﻪ ﺩﺍﺭﺍﻱ ﺣﺪﺍﻗﻞ ﺧﻄﺎﺳﺖ‪ ،‬ﺍﺳﺘﻔﺎﺩﻩ ﻣﻲ ﻛﻨﺪ‪ .‬ﺑﻌﺒﺎﺭﺕ ﺩﻗﻴﻖ ﺗـﺮ‪ ،‬ﺍﻳـﻦ ﺭﻭﺵ‬
‫ﺑﻠﻮﻙ ﺟﺎﺭﻱ ﺭﺍ ﺑﺎ ﻛﻠﻴﺔ ﺑﻠﻮﻙ ﻫﺎﻱ ﻣﻤﻜﻦ ﺩﺭ ﻳﻚ ﻣﺤﺪﻭﺩﺓ ﺍﺯ ﻗﺒﻞ ﺗﻌﺮﻳﻒ ﺷﺪﻩ ﺩﺭ ﺍﻃﺮﺍﻑ ﻣﻜﺎﻥ ﻓﻌﻠﻲ‪ ،‬ﻣﻘﺎﻳﺴﻪ ﻣﻲ ﻛﻨﺪ‪ ،‬ﺑـﺮﺍﻱ ﻫـﺮ ﺑﻠـﻮﻙ‬
‫ﺗﻌﻴﻴﻦ ﺷﺪﻩ‪ ،‬ﺧﻄﺎﻱ ﺗﺨﻤﻴﻦ ﺭﺍ ﻣﺤﺎﺳﺒﻪ ﻣﻲ ﻛﻨﺪ ﺑﻌﺪ ﺍﺯ ﺑﺮﺭﺳﻲ ﺗﻤﺎﻡ ﺑﻠﻮﻛﻬﺎﻱ ﻣﻤﻜﻦ‪ ،‬ﺑﻠﻮﻛﻲ ﻛﻪ ﺣﺪﺍﻗﻞ ﺧﻄﺎ ﺭﺍ ﺩﺍﺷﺖ ﺑﻌﻨﻮﺍﻥ ﺑﻬﺘﺮﻳﻦ ﺑﻠﻮﻙ‬
‫ﻣﻄﺎﺑﻖ‪ ،‬ﺍﻧﺘﺨﺎﺏ ﻣﻲ ﺷﻮﺩ‪.‬‬
‫ﺣﺮﻛﺖ ﻭﺍﻗﻌﻲ ﺑﻴﻦ ﺩﻭ ﻓﺮﻳﻢ ﻭﻳﺪﺋﻮ‪ ،‬ﻋﻤﻮﻣﹰﺎ ﺑﺮ ﺍﺳﺎﺱ ﺑﻠﻮﻛﻬﺎﻱ ﺛﺎﺑﺖ ﻗﺎﺑﻞ ﺗﻌﻴﻴﻦ ﻧﻴﺴﺖ‪ .‬ﺑﻨﺎﺑﺮﺍﻳﻦ ﺍﺳﺘﻔﺎﺩﻩ ﺍﺯ ﺍﻟﮕـﻮﺭﻳﺘﻢ ﺗﻄـﺎﺑﻖ ﺑﻠﻮﻛﻬـﺎ ﺑـﺮﺍﻱ‬
‫ﺗﺨﻤﻴﻦ ﺣﺮﻛﺖ ﻭ ﺟﺒﺮﺍﻥ ﺣﺮﻛﺖ ﻧﻤﻲ ﺗﻮﺍﻧﺪ ﺗﺨﻤﻴﻦ ﻫﺎﻱ ﺩﻗﻴﻘﻲ ﺍﻳﺠﺎﺩ ﻛﻨﺪ‪ .‬ﻫﻨﮕﺎﻣﻲ ﻛﻪ ﺣﺮﻛﺖ ﺣﻘﻴﻘﻲ ﻳﻚ ﺑﻠﻮﻙ‪ ،‬ﻳﻚ ﺍﻧﺘﻘﺎﻝ ﺳﺎﺩﻩ ﻧﺒﺎﺷﺪ‪،‬‬
‫ﺍﻟﮕﻮﺭﻳﺘﻢ ﺑﺮﺍﻱ ﭘﻴﺪﺍ ﻛﺮﺩﻥ ﺑﻠﻮﻛﻲ ﺑﺎ ﺣﺪﺍﻗﻞ ﺧﻄﺎ‪ ،‬ﺗﻼﺵ ﻣﻲ ﻛﻨﺪ‪ .‬ﺷﮑﻞ ‪ ٢‬ﻣﺜﺎﻟﻲ ﺭﺍ ﺍﺯ ﺟﺒﺮﺍﻥ ﺣﺮﻛﺖ ﺑﺎ ﺍﺳﺘﻔﺎﺩﻩ ﺍﺯ ﺭﻭﺵ ﺗﻄﺎﺑﻖ ﺑﻠـﻮﻙ ﻫـﺎ‪،‬‬
‫ﻧﺸﺎﻥ ﻣﻲ ﺩﻫﺪ‪.‬‬
‫‪4‬‬
‫‪CE 342 – Multimedia HW# 7‬‬
‫‪H. Rabiee, Spring 2008‬‬
‫ﺷﻜﻞ‪ :2‬ﻣﺜﺎﻟﻲ از ﺟﺒﺮان ﺣﺮﻛﺖ ﺑﺎ اﺳﺘﻔﺎده از روش ﺗﻄﺎﺑﻖ ﺑﻠﻮك ﻫﺎ‬
‫ﺗﺼﻮﻳﺮ ﺑﺎﻻ ﺳﻤﺖ ﭼﭗ‪ ،‬ﺗﺼﻮﻳﺮ ﻓﺮﻳﻢ ﻗﺒﻠﻲ ﺍﺳﺖ‪ ،‬ﺗﺼﻮﻳﺮ ﺑﺎﻻ ﺳﻤﺖ ﺭﺍﺳﺖ‪ ،‬ﻓـﺮﻳﻢ ﺟـﺎﺭﻱ ﺍﺳـﺖ‪ ،‬ﺗـﺼﻮﻳﺮ ﭘـﺎﻳﻴﻦ ﺳـﻤﺖ ﺭﺍﺳـﺖ‪ ،‬ﻣﻴـﺪﺍﻥ‬
‫ﺣﺮﻛﺘﻬﺎﻱ ﺗﺨﻤﻴﻦ ﺯﺩﻩ ﺷﺪﻩ ﺍﺳﺖ )ﺑﺮﺩﺍﺭﻫﺎﻱ ﺣﺮﻛﺖ ﺗﻌﻴﻴﻦ ﺷﺪﻩ ﺍﺯ ﻣﺤﻞ ﻣﺮﻛﺰ ﻫﺮ ﺑﻠﻮﻙ ﺭﺳﻢ ﺷﺪﻩ ﺍﻧﺪ‪ (.‬ﻭ ﺗـﺼﻮﻳﺮ ﭘـﺎﻳﻴﻦ ﺳـﻤﺖ ﭼـﭗ‪،‬‬
‫ﺗﺼﻮﻳﺮ ﺗﺨﻤﻴﻦ ﺯﺩﻩ ﺷﺪﻩ ﺑﺎ ﺍﺳﺘﻔﺎﺩﻩ ﺍﺯ ﻣﻴﺪﺍﻥ ﺣﺮﻛﺖ ﺭﺍ ﻧﺸﺎﻥ ﻣﻲ ﺩﻫﺪ‪.‬‬
‫ﻣﻼﺣﻈﻪ ﻣﻲ ﺷﻮﺩ ﻛﻪ ﺍﻟﮕﻮﺭﻳﺘﻢ ﺑﻄﻮﺭ ﺩﻗﻴﻘﻲ ﻋﺪﻡ ﺣﺮﻛﺖ ﺩﺭ ﭘﺲ ﺯﻣﻴﻨﻪ ﺭﺍ ﺗﻌﻴﻴﻦ ﻛﺮﺩﻩ ﺍﺳﺖ ﺩﺭ ﺣﺎﻟﻴﻜﻪ ﺑـﺴﺘﻪ ﺑـﻮﺩﻥ ﭼـﺸﻢ ﺑـﺎ ﺍﻳـﻦ ﺭﻭﺵ‬
‫ﺳﺎﺩﻩ‪ ،‬ﺩﺭ ﺷﻜﻞ ﺗﺨﻤﻴﻦ ﺯﺩﻩ ﺷﺪﻩ ﺩﻳﺪﻩ ﻧﻤﻲ ﺷﻮﺩ‪.‬‬
‫‪5‬‬
‫‪CE 342 – Multimedia HW# 7‬‬
‫‪H. Rabiee, Spring 2008‬‬
‫ﺷﻜﻞ ‪ :3‬ﻣﺮاﺣﻞ ﻛﺪ و واﻛﺪ ﻛﺮدن ﺑﺮاي ﻳﻚ ﻣﺎﻛﺮوﺑﻼك در ﻳﻚ ﻛﺪ ﻛﻨﻨﺪة وﻳﺪﺋﻮ ﻣﻌﻤﻮﻟﻲ‬
‫‪ -2-1-2‬ﻛﺪ ﻛﺮدن وﻳﺪﺋﻮ ﺑﺎ اﺳﺘﻔﺎده از ﺟﺒﺮان ﺣﺮﻛﺖ و ﻛﺪ ﺗﺒﺪﻳﻞ‬
‫ﻣﺘﺪﺍﻭﻟﺘﺮﻳﻦ ﺭﻭﺵ ﻛﺪ ﻛﺮﺩﻥ ﻭﻳﺪﺋﻮ ﺑﻪ ﻧﺎﻡ ﻛﺪ ﻛﺮﺩﻥ ‪ block-based hybrid‬ﺷﻨﺎﺧﺘﻪ ﻣﻲ ﺷﻮﺩ‪ .‬ﺩﺭ ﺍﻳﻦ ﺭﻭﺵ ﻫﺮ ﻓﺮﻳﻢ ﺑﻪ ﻣﺎﻛﺮﻭ ﺑﻠﻮﻙ ﻫﺎ‬
‫)‪ (MBs‬ﺗﻘﺴﻴﻢ ﻣﻲ ﺷﻮﺩ‪ .‬ﻫﺮ ﻛﺪﺍﻡ ﺩﺍﺭﺍﻱ ﭼﻨﺪﻳﻦ ﺑﻠﻮﻙ ‪ 8*8‬ﺍﺳﺖ‪ .‬ﻫﺮ ﻣﺎﻛﺮﻭ ﺑﻠﻮﻙ ﺑﺎ ﺍﺳـﺘﻔﺎﺩﻩ ﺍﺯ ﺗﺮﻛﻴﺒـﻲ ﺍﺯ ﺟﺒـﺮﺍﻥ ﺣﺮﻛـﺖ ﻭ ﺗﺒـﺪﻳﻞ‬
‫‪ ،DCT‬ﻫﻤﺎﻧﻄﻮﺭ ﻛﻪ ﺩﺭ ﺷﻜﻞ ‪ ٣‬ﻧﺸﺎﻥ ﺩﺍﺩﻩ ﺷﺪﻩ ﺍﺳﺖ‪ ،‬ﻛﺪ ﻣﻲ ﺷﻮﺩ‪ .‬ﻫﺮ ﻣﺎﻛﺮﻭ ﺑﻠﻮﻙ ﻣﻲ ﺗﻮﺍﻧﺪ ﺩﺭ ﻳﻜـﻲ ﺍﺯ ﺩﻭ ﻣـﻮﺩ‪ ،‬ﻛـﺪ ﺷـﻮﺩ‪ .‬ﺩﺭ ﻣـﻮﺩ‬
‫‪ Intra‬ﻳﻚ ﺭﻭﺵ ﻣﺒﺘﻨﻲ ﺑﺮ ﻛﺪ ﻛﺮﺩﻥ ‪ DCT‬ﻭ ﺷﺒﻴﻪ ﺑﻪ ‪ JPEG‬ﺑﻄﻮﺭ ﻣـﺴﺘﻘﻴﻢ ﺭﻭﻱ ﻫـﺮ ﺑﻠـﻮﻙ ﺍﻋﻤـﺎﻝ ﻣـﻲﺷـﻮﺩ‪ .‬ﺍﻳـﻦ ﻣـﻮﺩ ﺑـﺮﺍﻱ ﻫـﺮ‬
‫ﻣﺎﻛﺮﻭﺑﻼﻙ ﺩﺭ ﺍﻭﻟﻴﻦ ﻓﺮﻳﻢ ﺑﻜﺎﺭ ﻣﻲ ﺭﻭﺩ ﻭ ﺑﻌﺪ ﺑﻄﻮﺭ ﻣﺘﻨﺎﻭﺏ ﺩﺭ ﻓﺮﻳﻢ ﻫﺎﻱ ﺯﻳﺮ ﺩﻧﺒﺎﻟﻪ ﻧﻴﺰ ﺍﺳﺘﻔﺎﺩﻩ ﻣﻲ ﺷـﻮﺩ‪ .‬ﺩﺭ ﻣـﻮﺩ ‪ ،Inter‬ﻳـﻚ ﺑـﺮﺩﺍﺭ‬
‫ﺣﺮﻛﺖ ﺩﺭ ﺍﺑﺘﺪﺍ ﺗﻌﻴﻴﻦ ﻣﻲ ﺷﻮﺩ ﻭ ﺭﻭﺵ ‪ DCT‬ﺑﺮﺍﻱ ﻛﺪ ﻛﺮﺩﻥ ﺧﻄﺎﻱ ﻣﻴﺰﺍﻥ ﺣﺮﻛﺖ ﺍﺳﺘﻔﺎﺩﻩ ﻣﻲ ﺷﻮﺩ‪ .‬ﺧﺼﻮﺻﺎﹰ‪ ،‬ﺍﻳﻦ ﺭﻭﺵ‪ ،‬ﻣـﺎﻛﺮﻭﺑﻼﻙ‬
‫ﺟﺎﺭﻱ ﺍﺯ ﻓﺮﻳﻢ ﺟﺎﺭﻱ ﺭﺍ ﺑﺎ ﺑﻬﺘﺮﻳﻦ ﻣﺎﻛﺮﻭﺑﻼﻙ ﻣﻄﺎﺑﻖ ﺑﺎ ﺁﻥ ﺩﺭ ﻓﺮﻳﻢ ﻗﺒﻠﻲ‪ ،‬ﺗﺨﻤﻴﻦ ﻣﻲ ﺯﻧﺪ )ﻓﻘﻂ ﻣﺆﻟﻔﻪ ﻫﺎﻱ ‪ (Luminance‬ﺍﮔﺮ ﺧﻄـﺎﻱ‬
‫ﺗﺨﻤﻴﻦ ﺯﺩﻥ ﻛﻤﺘﺮ ﺍﺯ ﺣﺪ ﺗﻌﻴﻴﻦ ﺷﺪﻩ ﺍﺯ ﻗﺒﻞ ﺑﺎﺷﺪ‪ .‬ﺍﺧﺘﻼﻑ ﺩﺍﺩﻩ ﻫﺎ ﺗﻌﻴﻴﻦ ﻧﻤﻲ ﺷـﻮﺩ‪ .‬ﺩﺭ ﻏﻴـﺮ ﺍﻳﻨـﺼﻮﺭﺕ ﺧﻄـﺎﻱ ﺗﺨﻤـﻴﻦ ﺑـﺎ ﺍﺳـﺘﻔﺎﺩﻩ ﺍﺯ‬
‫‪ DCT‬ﺗﺒﺪﻳﻞ ﻣﻲ ﺷﻮﺩ ﻭ ﻣﺆﻟﻔﻪ ﻫﺎﻱ ﺗﺒﺪﻳﻞ ﻳﺎﻓﺘﻪ‪ ،‬ﻛﻮﺍﻧﺘﻴﺰﻩ ﺷﺪﻩ ﻭ ﺑﺎ ﺍﺳﺘﻔﺎﺩﻩ ﺍﺯ ﺭﻭﺵ ‪ runlength‬ﻣﺸﺎﺑﻪ ﺑﺎ ‪ ،JPEG‬ﻛﺪ ﻣـﻲ ﺷـﻮﻧﺪ‪ .‬ﺩﺭ‬
‫ﻧﻬﺎﻳﺖ‪ ،‬ﺭﺷﺘﻪ ﺑﻴﺖ ﻛﺪ ﺷﺪﻩ ﻫﻤﺮﺍﻩ ﺑﺎ ﺍﻃﻼﻋﺎﺕ ﺑﺮﺩﺍﺭﻫﺎﻱ ﺣﺮﻛﺖ ﻛﺪ ﺷﺪﻩ ﺑـﻪ ‪ video multiplex‬ﺍﺭﺳـﺎﻝ ﻣـﻲﺷـﻮﻧﺪ‪ .‬ﻫﻤـﺎﻧﻄﻮﺭ ﻛـﻪ ﺩﺭ‬
‫ﺗﻮﺻﻴﻒ ‪ JPEG‬ﺷﺮﺡ ﺩﺍﺩﻩ ﺷﺪ‪ ،‬ﺍﻧﺪﺍﺯﺓ ‪ step‬ﻛﻮﺍﻧﺘﻴﺰ ﻛﻨﻨﺪﻩ‪ ،‬ﻣﻲ ﺗﻮﺍﻧﺪ ﺑﺮ ﺍﺳﺎﺱ ﻛﻴﻔﻴﺖ ﺗﺼﻮﻳﺮ ﺩﻟﺨﻮﺍﻩ ﻭ ﻛﺎﺭﺍﻳﻲ ﻛﺪ ﻛﺮﺩﻥ‪ ،‬ﺗﻐﻴﻴﺮ ﻛﻨﺪ‪.‬‬
‫‪ -2-2‬اﻟﮕﻮرﻳﺘﻢ ﻛﺪ ﻛﺮدن وﻳﺪﺋﻮ ‪H.261‬‬
‫ﺩﺭ ﺳﺎﻝ ‪ CCTTT ،١٩٩٠‬ﻣﺠﻤﻮﻋﻪ ﺍﻱ ﺍﺯ ﺍﺳﺘﺎﻧﺪﺍﺭﺩﻫﺎﻱ ﺑﻴﻦ ﺍﻟﻤﻠﻠﻲ ﻭﻳﺪﺋﻮ ﻛﻨﻔﺮﺍﻧﺲ‪ ،‬ﺷﺎﻣﻞ ﻛﺪ ﻛﻨﻨﺪﻩ ﻭﻳﺪﺋﻮﻳﻲ ‪ H.261‬ﺑﺮﺍﻱ ﺳـﺮﻭﻳﺲ‬
‫ﻫﺎﻱ ﺻﻮﺗﻲ ﺗﺼﻮﻳﺮﻱ ﺭﻭﯼ ‪) p*64 kbps ،ISDN‬ﻛﻪ ﺑﺎ ﺍﺳﺘﺎﻧﺪﺍﺭﺩ ‪ p*64‬ﻧﻴﺰ ﺷﻨﺎﺧﺘﻪ ﻣﻲ ﺷـﻮﻧﺪ( ﺗـﺼﻮﻳﺐ ﻛـﺮﺩ‪ .‬ﻛﺎﺭﺑﺮﺩﻫـﺎﻱ ﺩﺭ ﻧﻈـﺮ‬
‫ﮔﺮﻓﺘﻪ ﺷﺪﻩ ﺑﺮﺍﻱ ﺍﻳﻦ ﺍﺳﺘﺎﻧﺪﺍﺭﺩ‪ ،‬ﺗﻠﻔﻦ ﺗﺼﻮﻳﺮﻱ ﻭ ﺳﻴﺴﺘﻢ ﻭﻳﺪﺋﻮ ﻛﻨﻔﺮﺍﻧﺲ ﺍﺳﺖ‪ .‬ﺑﻨﺎﺑﺮﺍﻳﻦ ﺳﻴﺴﺘﻢ ﻫﺎﻳﻲ ﻛﻪ ﺑﺎ ﺍﻳﻦ ﺍﺳﺘﺎﻧﺪﺍﺭﺩ ﻣـﺮﺗﺒﻂ ﻫـﺴﺘﻨﺪ‬
‫‪6‬‬
‫‪CE 342 – Multimedia HW# 7‬‬
‫‪H. Rabiee, Spring 2008‬‬
‫ﺑﺎﻳﺪ ﻗﺎﺑﻠﻴﺖ ﻛﺪ ﻭ ﻭﺍﻛﺪ ﻛﺮﺩﻥ ﺑﻲ ﺩﺭﻧﮓ ﺍﻳﻦ ﺍﺳﺘﺎﻧﺪﺍﺭﺩ ﺭﺍ ﺩﺍﺷﺘﻪ ﺑﺎﺷﻨﺪ‪ .‬ﻣﺤﺪﻭﺩﺓ ‪ p‬ﺍﺯ ‪ ١‬ﺗﺎ ‪ ٣٠‬ﺍﺳﺖ‪ .‬ﺑـﺮﺍﻱ ﻳـﻚ ﺍﺭﺗﺒـﺎﻁ ‪ ISDN‬ﺑـﺎ ﻧـﺮﺥ‬
‫ﭘﺎﻳﻪ‪ p ،‬ﻳﻚ ﺗﺎ ‪ ٢‬ﺍﺳﺖ‪.‬‬
‫‪ ،CCTTT‬ﻓﺮﻣﺖ ﻫﺎﻱ ‪ CIF‬ﻭ ‪ QCIF‬ﺭﺍ ﺑﻌﻨﻮﺍﻥ ﻓﺮﻣﺖ ﻫﺎﻱ ﻭﻳﺪﺋﻮﻳﻲ ﺑﺮﺍﻱ ﺗﻠﻔﻦ ﺗـﺼﻮﻳﺮﻱ ﺩﺭ ﻧﻈـﺮ ﮔﺮﻓـﺖ‪ .‬ﻭﻳـﺪﺋﻮ ﺑـﺎ ﻓﺮﻣـﺖ ‪CIF‬‬
‫ﺩﺍﺭﺍﻱ ‪ ٣٥٢*٢٨٨‬ﭘﻴﻜﺴﻞ ﺑﺮﺍﻱ ‪ Y‬ﻭ ‪ ١٧٦*١٤٤‬ﭘﻴﮑﺴﻞ ﺑﺮﺍﻱ ‪ Cr&Cb‬ﺍﺳﺖ‪ .‬ﻧﺮﺥ ﻓﺮﻳﻢ ﻣﻲ ﺗﻮﺍﻧﺪ ﺑﻴﻦ ﻳﻚ ﺗـﺎ ‪ ٣٠‬ﻓـﺮﻳﻢ ﺩﺭ ﺛﺎﻧﻴـﻪ ﺑﺎﺷـﺪ‪.‬‬
‫ﻛﻠﻴﺔ ﻛﺪ ﻛﻨﻨﺪﻩ ﻫﺎ ﺑﺎﻳﺪ ﺩﺭ ﺳﻄﺢ ‪ QCIF‬ﻋﻤﻞ ﻛﻨﻨﺪ ﻭ ﻋﻤﻠﻜﺮﺩ ﺩﺭ ﺳﻄﺢ ‪ CIF‬ﺍﺧﺘﻴﺎﺭﻱ ﺍﺳﺖ‪ .‬ﺑﺎ ﺳﺮﻋﺖ ﺗﻘﺮﻳﺒﹰﺎ ‪ ٣٠‬ﻓﺮﻳﻢ ﺩﺭ ﺛﺎﻧﻴـﻪ )‪٢٩/٩٧‬‬
‫ﺣﺪﺍﻛﺜﺮ ﻣﻘﺪﺍﺭﻱ ﺍﺳﺖ ﻛﻪ ﭘﺸﺘﻴﺒﺎﻧﻲ ﻣﻲ ﺷﻮﺩ‪ CIF (.‬ﻓﺸﺮﺩﻩ ﻧﺸﺪﻩ ﻧﺮﺥ ‪ ٣٦/٤٥ Mb/s‬ﻭ ‪ QCIF‬ﻧﺮﺥ ‪ ٩/١١٥Mb/s‬ﺩﺍﺭﺩ‪ .‬ﺑﺮﺍﻱ ﻳﻚ ﻛﺎﻧﺎﻝ‬
‫‪ ،١/٥ Mb/s‬ﻛﺎﻫﺶ ﻗﺎﺑﻞ ﺗﻮﺟﻬﻲ ﻻﺯﻡ ﺍﺳﺖ ﻭﻟﻲ ﺑﺮﺍﻱ ﻳﻚ ﻛﺎﻧﺎﻝ ‪ (١٢٨ kb/s) p=2‬ﻛﺎﻫﺶ ‪ ،٢٤ :١‬ﺍﺣﺘﻴﺎﺝ ﺍﺳـﺖ‪ .‬ﻋﻤﻮﻣـﺎﹰ‪ CIF ،‬ﺑـﺮﺍﻱ‬
‫ﺍﺭﺳﺎﻝ ﻫﺎﻳﻲ ﺑﺎ ﻧﺮﺥ ﺑﻴﺸﺘﺮ ﺍﺯ ‪ (p=٦) ٣٨٤ kb/s‬ﺗﻮﺻﻴﻪ ﻣﻲ ﺷﻮﺩ‪.‬‬
‫ﻛﺪ ﻛﻨﻨﺪﺓ ‪ H.261‬ﺍﺯ ﻳﻚ ﺗﺮﻛﻴﺒﻲ ﺍﺯ ﺍﻟﮕﻮﻫﺎﻱ ‪ DCT‬ﻭ ‪ DPCM‬ﺑﺎ ﺗﺨﻤﻴﻦ ﺣﺮﻛﺖ‪ ،‬ﺍﺳﺘﻔﺎﺩﻩ ﻣﻲ ﻛﻨﺪ ﻫﻤﺎﻧﻄﻮﺭ ﻛﻪ ﺩﺭ ﺷﻜﻞ ‪ ٣‬ﻧـﺸﺎﻥ ﺩﺍﺩﻩ‬
‫ﺷﺪﻩ ﺍﺳﺖ‪ .‬ﻫﺮ ﻣﺎﻛﺮﻭ ﺑﻼﻙ ﻣﻲ ﺗﻮﺍﻧﺪ ﺑﻪ ﺻﻮﺭﺕ ﻳﻜﻲ ﺍﺯ ﺩﻭ ﻣﻮﺩ ‪ Intra‬ﻳﺎ ‪ Inter‬ﻛﺪ ﺷﻮﺩ‪ .‬ﻣﻮﺩ ‪ Intra‬ﺑـﺮﺍﻱ ﻫـﺮ ﻣـﺎﻛﺮﻭﺑﻼﻙ ﺩﺭ ﺍﻭﻟـﻴﻦ‬
‫ﻓﺮﻳﻢ ﺍﺳﺘﻔﺎﺩﻩ ﻣﻲ ﺷﻮﺩ ﻭ ﺑﻌﺪ ﻣﺘﻨﺎﻭﺑﹰﺎ ﺩﺭ ﺯﻳﺮ ﺩﻧﺒﺎﻟﺔ ﻓﺮﻳﻢ ﻫﺎ ﺍﺳﺘﻔﺎﺩﻩ ﻣﻲ ﺷﻮﺩ ﺗﺎ ﺍﺯ ﺍﻧﺘﺸﺎﺭ ﺧﻄﺎ ﻛﻪ ﺩﺭ ﺍﺛﺮ ﺧﻄﺎﻫﺎﻱ ﺍﺭﺳـﺎﻝ ﭘـﻴﺶ ﻣـﻲﺁﻳﻨـﺪ‪،‬‬
‫ﺟﻠﻮﮔﻴﺮﻱ ﻛﻨﺪ‪.‬‬
‫‪ H.261‬ﺍﺯ ﻳﻚ ﺳﺎﺧﺘﺎﺭ ﺩﺍﺩﻩ ﺍﻱ ﺳﻠﺴﻠﻪ ﻣﺮﺍﺗﺒﻲ ﺑﺮﺍﻱ ﻛﺪ ﻛﺮﺩﻥ ﺩﺍﺩﻩ ﻫﺎ ﺍﺳـﺘﻔﺎﺩﻩ ﻣـﻲ ﻛﻨـﺪ‪ .‬ﺍﻳـﻦ ﺳـﺎﺧﺘﺎﺭ ﺷـﺎﻣﻞ ﺗـﺼﻮﻳﺮ‪ ،‬ﮔـﺮﻭﻩ ﺑﻠﻮﻛﻬـﺎ‬
‫)‪ ،(GOB‬ﻣﺎﻛﺮﻭﺑﻼﻙ ﻭ ﺑﻠﻮﻙ ﻣﻲ ﺑﺎﺷﺪ‪ .‬ﻳﻚ ﺑﻠﻮﻙ ﻣﺠﻤﻮﻋﺔ ‪ ٨*٨‬ﺍﺯ ﭘﻴﻜﺴﻞ ﻫﺎﺳﺖ ﻛﻪ ﻣﻲ ﺗﻮﺍﻧﺪ ﺷﺎﻣﻞ ﻧﻤﻮﻧﻪ ﻫﺎﻱ ‪ Cb ،y‬ﻳﺎ ‪ Cr‬ﺑﺎﺷـﺪ‪.‬‬
‫ﻳﻚ ﻣﺎﻛﺮﻭ ﺑﻼﻙ ﺍﺯ ‪ ٤‬ﺗﺎ ﺑﻠﻮﻙ ‪ Luminance‬ﺑﺎ ﺍﺑﻌﺎﺩ ‪ (y) ٨*٨‬ﻭ ﺩﻭ ﺑﻠـﻮﻙ ‪ (Cr & Cb) Chrominance‬ﺗـﺸﻜﻴﻞ ﻣـﻲ ﺷـﻮﺩ‪ .‬ﻳـﻚ‬
‫‪ GOB‬ﺷﺎﻣﻞ ﻣﺎﻛﺮﻭﺑﻼﻙ ﻫﺎ ﺩﺭ ﭼﻨﺪﻳﻦ ﺳﻄﺮ ﻣﺘﻮﺍﻟﻲ ﻣﻲ ﺷﻮﺩ‪ .‬ﻳﻚ ﺗﺼﻮﻳﺮ ﺷﺎﻣﻞ ﭼﻨﺪﻳﻦ ‪ GOB‬ﻣﻲﺷـﻮﺩ‪ .‬ﺍﺳـﺘﺎﻧﺪﺍﺭﺩ ‪syntax ،H.261‬‬
‫ﺭﺷﺘﻪ ﺑﻴﺖ ﻛﺪ ﺷﺪﻩ ﺭﺍ ﺗﻌﺮﻳﻒ ﻣﻲ ﻛﻨﺪ‪ .‬ﻫﺮ ﺑﻠﻮﻙ ﺷﺎﻣﻞ ﻣﺆﻟﻔﻪﻫﺎﻱ ‪ (DCTCOEFF)DCT‬ﺍﺯ ﻳﻚ ﺑﻠﻮﻙ ﻭ ﻳﻚ ﻋﻼﻣﺖ ‪ EOB‬ﺑـﺪﻧﺒﺎﻝ‬
‫ﺁﻥ ﻣﻲ ﺑﺎﺷـﺪ‪ .‬ﻫـﺮ ﻣـﺎﻛﺮﻭﺑﻼﻙ ﺷـﺎﻣﻞ ﺩﺍﺩﻩﻫـﺎﻱ ‪ ٦‬ﺑﻠـﻮﻙ ﻭ ﻳـﻚ ﺳـﺮﺁﻳﻨﺪ ﻣـﺎﻛﺮﻭﺑﻼﻙ ﺍﺳـﺖ‪ .‬ﻳـﻚ ‪ GOB‬ﺍﺯ ﻛـﻲ ﺳـﺮﺁﻳﻨﺪ ‪ GOB‬ﻭ‬
‫ﻣﺎﻛﺮﻭﺑﻼﻙﻫﺎﻱ ﺁﻥ ‪ ،GOB‬ﺑﺪﻧﺒﺎﻝ ﺁﻥ ﺳﺎﺧﺘﻪ ﻣﻲ ﺷﻮﺩ‪ .‬ﺩﺭ ﻧﻬﺎﻳﺖ‪ ،‬ﺗﺼﻮﻳﺮ ﺷﺎﻣﻞ ﻳﻚ ﺳﺮﺁﻳﻨﺪ ﺗﺼﻮﻳﺮ ﺍﺳﺖ ﻛﻪ ﺁﺭﺍﻳﻪ ﺍﻱ ﻣﺘـﻮﺍﻟﻲ ﺍﺯ ‪GOB‬‬
‫ﻫﺎ ﺑﺪﻧﺒﺎﻝ ﺁﻥ ﻣﻲ ﺁﻳﻨﺪ‪.‬‬
‫‪ -3-2‬اﺳﺘﺎﻧﺪارد ‪MPEG-1‬‬
‫ﺍﺳﺘﺎﻧﺪﺍﺭﺩ ‪ MPEG-1‬ﺑﻪ ﻣﻨﻈﻮﺭ ﺫﺧﻴﺮﻩ ﻛﺮﺩﻥ ﻳﻚ ﻭﻳﺪﺋﻮ ﻣﺘﺤﺮﻙ ﺑﺎ ﺩﻗـﺖ ‪ ١٧٦*١٢٠ pels for Cr & Cb at 30 fps) SIF‬ﻭ ‪pels‬‬
‫‪ ( ٣٥٢*٢٤٠ for y‬ﺑﺎ ﻧﺮﺥ ‪ ،١/٥Mbps‬ﻃﺮﺍﺣﻲ ﺷﺪﻩ ﺍﺳﺖ‪.‬‬
‫ﺩﺭ ﺍﺩﺍﻣﻪ ﻧﺤﻮﺓ ﺍﻧﺠﺎﻡ ﺍﻳﻦ ﻣﻮﺍﺭﺩ ﺗﻮﺳﻂ ‪ ،MPEG-1‬ﺷﺮﺡ ﺩﺍﺩﻩ ﻣﻲ ﺷﻮﺩ‪.‬‬
‫‪ -1-3-2‬ﻣﻮدﻫﺎي ﻛﺪ ﻛﺮدن ﺗﺼﻮﻳﺮ و ﺟﺒﺮان ﺣﺮﻛﺖ دو ﺟﻬﺘﻪ‬
‫ﻳﻜﻲ ﺍﺯ ﺗﻔﺎﻭﺕ ﻫﺎﻱ ﺍﺳﺎﺳﻲ ﺑﻴﻦ ‪ MPEG–1‬ﻭ ‪ H.261‬ﺍﻳﻦ ﺍﺳﺖ ﻛﻪ ﻋﻼﻭﻩ ﺑﺮ ﺍﺳﺘﻔﺎﺩﻩ ﺍﺯ ﺟﺒﺮﺍﻥ ﺣﺮﻛﺖ ﺍﺯ ﻓﺮﻳﻢ ﻗﺒﻠﻲ‪ ،‬ﺍﺯ ﻓـﺮﻳﻢ ﺑﻌـﺪﻱ‬
‫ﻼ ﻛﺪ ﺷﺪﻩ ﺍﺳﺖ(‪ .‬ﺑﻄﻮﺭ ﻛﻠﻲ ﻓﺮﻳﻢ ﺟﺎﺭﻱ ﻣﻲ ﺗﻮﺍﻧﺪ ﺍﺯ ﺭﻭﻱ ﻫﺮ ﺩﻭ ﻓﺮﻳﻢ ﻗﺒﻠﻲ ﻭ ﺑﻌﺪﻱ‪ ،‬ﺗﺨﻤﻴﻦ ﺯﺩﻩ ﺷﻮﺩ‪ .‬ﺍﻳـﻦ‬
‫ﻧﻴﺰ ﺍﺳﺘﻔﺎﺩﻩ ﻣﻲ ﻛﻨﺪ )ﻛﻪ ﻗﺒ ﹰ‬
‫ﻋﻤﻞ ﺑﻌﻨﻮﺍﻥ ﺗﺨﻤﻴﻦ ﺩﻭ ﺑﺴﺘﻪ ﺩﺭ ‪ MPEG‬ﻧﺎﻣﻴﺪﻩ ﻣﻲ ﺷﻮﺩ‪ MPEG-1 .‬ﻓﺮﻳﻢ ﻫﺎﻱ ﻳﻚ ﻭﻳﺪﺋﻮ ﺭﺍ ﺩﺭ ﺳﻪ ﻣﻮﺩ ﻣﺨﺘﻠﻒ ﻛﺪ ﻣﻲﻛﻨﺪ‪ ،‬ﺗـﺼﻮﻳﺮ‬
‫‪ ،I‬ﺗﺼﻮﻳﺮ ‪ p‬ﻭ ﺗﺼﻮﻳﺮ ‪ .B‬ﻓﺮﻳﻢ ﻫﺎ ﺑﻪ ‪ GOP‬ﻫﺎ ﺗﻘﺴﻴﻢ ﻣﻲ ﺷﻮﻧﺪ ﺑﻄﻮﺭﻳﻜﻪ ﻫﺮ ‪ GOP‬ﺷﺎﻣﻞ ﻳﻚ ﺗﺼﻮﻳﺮ ‪ I‬ﻭ ﭼﻨﺪﻳﻦ ﺗﺼﻮﻳﺮ ‪ P‬ﻭ ‪ B‬ﻣـﻲ‬
‫ﺑﺎﺷﺪ‪ .‬ﺍﻳﻦ ﺗﻘﺴﻴﻢ ﺑﻨﺪﻱ ﺩﺭ ﺷﻜﻞ ‪ ٤‬ﻧﺸﺎﻥ ﺩﺍﺩﻩ ﺷﺪﻩ ﺍﺳﺖ‪ .‬ﻋﻤﻠﻴﺎﺗﻲ ﻛﻪ ﺑﺮﺍﻱ ﺗﺼﺎﻭﻳﺮ ﻣﺨﺘﻠﻒ ﺍﻧﺠﺎﻡ ﻣﻲ ﺷﻮﺩ ﺑـﺎ ﺟﺰﺋﻴـﺎﺕ ﺑﻴـﺸﺘﺮ ﺩﺭ ﺍﺩﺍﻣـﻪ‬
‫ﺗﻮﺿﻴﺢ ﺩﺍﺩﻩ ﻣﻲﺷﻮﻧﺪ‪.‬‬
‫‪ : (I) Intra picture‬ﻳﻚ ﺗﺼﻮﻳﺮ ‪ I‬ﺑﺮ ﺍﺳﺎﺱ ﺧﻮﺩ ﺗﺼﻮﻳﺮ )ﺑﺎ ﺍﺳـﺘﻔﺎﺩﻩ ﺍﺯ ﻳـﻚ ﺭﻭﺵ ﻣـﺸﺎﺑﻪ ﺑـﺎ ‪ ،(JPEG‬ﻓـﺸﺮﺩﻩ ﻣـﻲ ﺷـﻮﺩ‪ .‬ﻫﻤﺎﻧﻨـﺪ‬
‫ﺍﻟﮕﻮﺭﻳﺘﻢ ‪ ،JPEG‬ﻫﺮ ﺑﻠﻮﻙ ‪ ٨*٨‬ﺩﺭ ﻳﻚ ﻣﺎﻛﺮﻭ ﺑﻠﻮﻙ ‪ ،١٦*١٦‬ﺗﺤﺖ ﺗﺒﺪﻳﻞ ‪ DCT‬ﻗﺮﺍﺭ ﻣﻲ ﮔﻴﺮﺩ ﻭ ﻣﺆﻟﻔﻪ ﻫﺎﻱ ‪ DCT‬ﺗﻮﻟﻴﺪ ﻣﻲ ﺷﻮﻧﺪ‪.‬‬
‫ﺍﻳﻦ ﻣﺆﻟﻔﻪ ﻫﺎ ﻛﻮﺍﻧﺘﻴﺰﻩ ﺷـﺪﻩ ﻭ ﺑـﻪ ﺻـﻮﺭﺕ ‪ zig-zag‬ﻣﺮﺗـﺐ ﻣـﻲ ﺷـﻮﻧﺪ ﺗـﺎ ﺑﻬﺘـﺮﻳﻦ ‪ runlength‬ﺍﺯ ﻣﺆﻟﻔـﻪ ﻫـﺎﻱ ﺻـﻔﺮ ﺑﺪﺳـﺖ ﺁﻳـﺪ‪.‬‬
‫‪7‬‬
‫‪CE 342 – Multimedia HW# 7‬‬
‫‪H. Rabiee, Spring 2008‬‬
‫‪ runlength‬ﻭ ﻣﻘﺎﺩﻳﺮ ﻏﻴﺮ ﺻﻔﺮ ﺑﺎ ﺍﺳﺘﻔﺎﺩﻩ ﺍﺯ ﺭﻭﺵ ﻛﺪ ﻛﺮﺩﻥ ﻫﻤﻴﻨﮓ‪ ،‬ﻛﺪ ﻣﻲ ﺷﻮﻧﺪ‪ .‬ﻣﻮﺩ ﺗﺼﻮﻳﺮ ‪ ،I‬ﺑـﺮﺍﻱ ﺍﻭﻟـﻴﻦ ﻓـﺮﻳﻢ ﺩﺭ ﻫـﺮ ‪،GOP‬‬
‫ﺑﺮﺍﻱ ﺍﻳﺠﺎﺩ ﺍﻣﻜﺎﻥ ﺩﺳﺘﻴﺎﺑﻲ ﺗﺼﺎﺩﻓﻲ‪ ،‬ﺍﺳﺘﻔﺎﺩﻩ ﻣﻲ ﺷﻮﺩ‪.‬‬
‫ﺷﻜﻞ‪ :4‬ﺳﺎﺧﺘﺎر ‪ GOP‬در‬
‫‪MPEG-1‬‬
‫‪ : (P) Unidirectional Predicted Pictures‬ﺍﻳﻦ ﻣﻮﺩ ﺍﺯ ﺗﻜﻨﻴﻚ ﺟﺒﺮﺍﻥ ﺣﺮﻛﺖ )ﺷﺒﻴﻪ ﺑﻪ ﺭﻭﺵ ﺍﺳﺘﺎﻧﺪﺍﺭﺩ ‪ (H.261‬ﺑـﺮﺍﻱ ﻓـﺸﺮﺩﻩ‬
‫ﺳﺎﺯﻱ‪ ،‬ﺍﺳﺘﻔﺎﺩﻩ ﻣﻲ ﻛﻨﺪ‪ .‬ﻫﺮ ﻣﺎﻛﺮﻭﺑﻼﻙ ﺍﺯ ﺗﺼﻮﻳﺮ ‪ P‬ﻳﺎ ‪ I‬ﻗﺒﻠﻲ ﺑﺮﺍﻱ ﺗﺨﻤﻴﻦ ﺯﺩﻥ ﻳﻚ ﺑﺮﺩﺍﺭ ﺣﺮﻛﺖ ﺍﺳﺘﻔﺎﺩﻩ ﻣﻲ ﻛﻨﺪ‪ .‬ﺧﻄﺎﻱ ﺗﺨﻤـﻴﻦ ﺯﺩﻥ‬
‫ﺑﺎ ﺍﺳﺘﻔﺎﺩﻩ ﺍﺯ ‪ ،DCT‬ﺗﺒﺪﻳﻞ ﺷﺪﻩ ﻭ ﻣﺆﻟﻔﻪ ﻫﺎﻱ ‪ ،DCT‬ﻛﻮﺍﻧﺘﻴﺰﻩ ﻭ ‪ runlength‬ﻣﻲ ﺷﻮﻧﺪ‪.‬‬
‫‪ : (B) Bidirectionally predicted picture‬ﺍﻳﻦ ﻣﻮﺩ ﻳﻜﻲ ﺍﺯ ﺳﻪ ﻧﻮﻉ ﺭﻭﺵ ﺟﺒﺮﺍﻥ ﺣﺮﻛﺖ ﺭﺍ ﺑﺮﺍﻱ ﻫﺮ ﻣـﺎﻛﺮﻭ ﺑـﻼﻙ ﺑﻜـﺎﺭ ﻣـﻲ‬
‫ﺑﺮﺩ‪.‬‬
‫ﺟﺒﺮﺍﻥ ﺣﺮﻛﺖ ﭘﻴﺶ ﺭﻭﻧﺪﻩ‪ ،‬ﺟﺒﺮﺍﻥ ﺣﺮﻛﺖ ﭘﺲ ﺭﻭﻧﺪﻩ ﻭ ﺟﺒﺮﺍﻥ ‪ ،Interpolative‬ﺟﺒﺮﺍﻥ ﺣﺮﻛﺖ ﭘـﻴﺶ ﺭﻭﻧـﺪﻩ ﺍﺯ ﺗـﺼﺎﻭﻳﺮ ‪ I‬ﻭ ‪ P‬ﻗﺒﻠـﻲ‬
‫)ﻣﺜﻞ ﺭﻭﺵ ﺗﺼﺎﻭﻳﺮ ‪ (P‬ﺍﺳﺘﻔﺎﺩﻩ ﻣﻲ ﻛﻨﺪ‪ .‬ﺟﺒﺮﺍﻥ ﺣﺮﻛﺖ ﭘﺲ ﺭﻭﻧﺪﻩ ﺍﺯ ﺍﻃﻼﻋﺎﺕ ﺗﺼﻮﻳﺮ ﺑﻌﺪﻱ ﺍﺳﺘﻔﺎﺩﻩ ﻣﻲ ﻛﻨﺪ ﻛﻪ ﻣﺎﻛﺮﻭ ﺑﻠﻮﻙ ﺟـﺎﺭﻱ ﺑـﺎ‬
‫ﺑﻬﺘﺮﻳﻦ ﺑﻠﻮﻙ ﻣﻨﻄﺒﻖ ﺷﺪﻩ ﺩﺭ ﺗﺼﺎﻭﻳﺮ ‪ I‬ﻳﺎ ‪ P‬ﺑﻌﺪﻱ‪ ،‬ﺗﺨﻤـﻴﻦ ﺯﺩﻩ ﻣـﻲ ﺷـﻮﺩ‪ .‬ﺟﺒـﺮﺍﻥ ‪ ،Interpolative‬ﺍﺯ ﻣﺘﻮﺳـﻂ ﮔﻴـﺮﻱ ﺑـﻴﻦ ﺑﻬﺘـﺮﻳﻦ‬
‫ﺑﻠﻮﻛﻬﺎﻱ ﻣﻨﻄﺒﻖ ﺷﺪﻩ ﺩﺭ ﺗﺼﺎﻭﻳﺮ ﻗﺒﻠﻲ ﻭ ﺑﻌﺪﻱ‪ ،‬ﺍﺳﺘﻔﺎﺩﻩ ﻣﻲ ﻛﻨﺪ‪ .‬ﺭﻭﺵ ﺟﺒﺮﺍﻥ ﺣﺮﻛﺖ ﺩﻭ ﺟﻬﺘﻪ ﺩﺭ ﺷﻜﻞ ‪ ٥‬ﻧﺸﺎﻥ ﺩﺍﺩﻩ ﺷﺪﻩ ﺍﺳﺖ‪.‬‬
‫‪8‬‬
‫‪CE 342 – Multimedia HW# 7‬‬
‫‪H. Rabiee, Spring 2008‬‬
‫ﺷﻜﻞ ‪ :5‬ﺗﺨﻤﻴﻦ و ﺟﺒﺮان ﺣﺮﻛﺖ دو ﺟﻬﺘﻪ‬
‫ﺍﺯ ﺁﻧﺠﺎ ﻛﻪ ﻛﻠﻴﺔ ﻓﺮﻳﻢ ﻫﺎ ﺩﺭ ﻳﻚ ‪ GOP‬ﻣﻲ ﺗﻮﺍﻧﻨﺪ ﺑﺪﻭﻥ ﺍﻃﻼﻉ ﺍﺯ ‪ GOP‬ﻗﺒﻠﻲ‪ ،‬ﻭﺍﻛـﺪ ﺷـﻮﻧﺪ‪ ،‬ﻳـﻚ ‪ GOP‬ﻭﺍﺣـﺪ ﭘﺎﻳـﻪ ﺍﻱ ﺍﺳـﺖ ﺑـﺮﺍﻱ‬
‫ﺩﺳﺘﻴﺎﺑﻲ ﺗﺼﺎﺩﻓﻲ‪ .‬ﻳﻚ ‪ fast forward‬ﻣﻲ ﺗﻮﺍﻧﺪ ﺑﺎ ﻭﺍﻛﺪ ﻛﺮﺩﻥ ﺗﻨﻬﺎ ﺗﺼﺎﻭﻳﺮ ‪ I‬ﻭ ﻳﺎ ﺗﺼﺎﻭﻳﺮ ‪ I‬ﻭ ‪ P‬ﺍﻧﺠﺎﻡ ﺷـﻮﺩ‪ .‬ﻳـﻚ ‪ fest rewind‬ﻧﻴـﺰ‬
‫ﻣﻲ ﺗﻮﺍﻧﺪ ﺑﺎ ﻭﺍﻛﺪ ﻛﺮﺩ ﺗﻨﻬﺎ ﺗﺼﺎﻭﻳﺮ ‪ I‬ﺍﻧﺠﺎﻡ ﺷﻮﺩ‪.‬‬
‫‪ -2-3-2‬ﺗﺨﻤﻴﻦ ﺣﺮﻛﺖ ﺑﺎ دﻗﺖ ‪Half-Pel‬‬
‫ﺍﺧﺘﻼﻑ ﺩﻳﮕﺮ ﺑﻴﻦ ‪ MPEG-1‬ﻭ ‪ H.261‬ﺍﻳﻦ ﺍﺳﺖ ﻛﻪ ﺑﺮﺩﺍﺭﻫﺎﻱ ﺣﺮﻛﺖ ﺩﺭ ‪ MPEG-1‬ﺑﺎ ﺩﻗـﺖ ‪ half-pel‬ﺗﺨﻤـﻴﻦ ﺯﺩﻩ ﻣـﻲ ﺷـﻮﺩ‪.‬‬
‫ﻳﻌﻨﻲ ﻳﻚ ﺟﺴﺘﺠﻮﻱ ﻛﺎﻣﻞ‪ ،‬ﺑﺎ ﺍﻓﺰﺍﻳﺶ ﻧﻴﻢ ‪ pel‬ﺍﻧﺠﺎﻡ ﻣﻲ ﺷﻮﺩ ﻧﻪ ﺑﺎ ﺍﻓﺰﺍﻳﺶ ﺑﻪ ﺍﻧﺪﺍﺯﺓ ﻋﺪﺩ ﺻﺤﻴﺢ‪ .‬ﺗﺨﻤﻴﻦ ﺣﺮﻛﺖ ﺑﻪ ﺍﻳﻦ ﺻﻮﺭﺕ ﺩﻗﻴﻖ ﺗﺮ‬
‫ﺍﺳﺖ ﻭ ﺍﻣﻜﺎﻥ ﻛﺎﻫﺶ ﺧﻄﺎﻱ ﺗﺨﻤﻴﻦ ﺭﺍ ﻣﻲ ﺩﻫﺪ‪ .‬ﻭﻟﻲ ﺑﺎﺯ ﻫﻢ ﺑﻪ ﺩﺭﻭﻧﻴﺎﺑﻲ ﻓﺮﻳﻢ ﻗﺒﻠﻲ ﺑﺮﺍﻱ ﺗﻮﻟﻴﺪ ﻧﻤﻮﻧﻪ ﻫـﺎ ﺩﺭ ﻣﻜـﺎﻥ ‪ half-pel‬ﺍﺣﺘﻴـﺎﺝ‬
‫ﺍﺳﺖ ﻛﻪ ﺍﻳﻦ ﺧﻮﺩ ﺑﻪ ﻣﺤﺎﺳﺒﺎﺕ ﺑﻴﺸﺘﺮ ﻧﺴﺒﺖ ﺑﻪ ﺣﺎﻟﺖ ﺗﺨﻤﻴﻦ ﺣﺮﻛﺖ ﺑﺎ ﺩﻗﺖ ‪ ،integer-pel‬ﻧﻴﺎﺯ ﺩﺍﺭﺩ‪.‬‬
‫‪ -4-2‬اﺳﺘﺎﻧﺪارد ﻛﺪ ﻛﺮدن وﻳﺪﺋﻮ ‪MPEG-2‬‬
‫ﻫﻤﺎﻧﻄﻮﺭ ﻛﻪ ﺩﺭ ﻣﻘﺪﻣﻪ ﺍﺷﺎﺭﻩ ﺷﺪ‪ ،‬ﺍﺳﺘﺎﻧﺪﺍﺭﺩ ‪ MPEG-2‬ﺑﺮﺍﻱ ﻛﺪ ﻛﺮﺩﻥ ﻭﻳﺪﺋﻮ ‪ CCTR601‬ﻣﻄﺮﺡ ﺷﺪﻩ ﺍﺳﺖ‪ .‬ﺭﻭﺵ ﺍﻭﻟﻴﺔ ﻛﺪ ﻛﺮﺩﻥ ﺩﺭ‬
‫‪ ،MPEG-2‬ﻣﺸﺎﺑﻪ ﺭﻭﺵ ‪ MPEG-1‬ﺍﺳﺖ‪ ،‬ﺑﺎ ﺳﺎﺧﺘﺎﺭ ‪ GOP‬ﻣﺸﺎﺑﻪ ﻛﻪ ﻫﺮ ﻣﺎﻛﺮﻭﺑﻼﻙ ﺑﺎ ﺍﺳﺘﻔﺎﺩﻩ ﺍﺯ ﺗﺒﺪﻳﻞ ﻣﺴﺘﻘﻴﻢ ‪) DCT‬ﻣﻮﺩ ‪ ،(I‬ﺑـﺎ‬
‫ﺗﺨﻤﻴﻦ ﻳﻚ ﻃﺮﻓﻪ )ﻣﻮﺩ ‪ (P‬ﻭ ﻳﺎ ﺑﺎ ﺗﺨﻤﻴﻦ ﺩﻭ ﻃﺮﻓﻪ )ﻣﻮﺩ ‪ (B‬ﻛﺪ ﻣﻲ ﺷﻮﺩ‪ .‬ﮔﺬﺷﺘﻪ ﺍﺯ ﺩﻗﺖ ‪ spatial‬ﺑﻴﺸﺘﺮ‪ ،‬ﺍﺧﺘﻼﻑ ﺍﺳﺎﺳﻲ ﺑـﻴﻦ ﻭﻳـﺪﺋﻮ‬
‫‪ CCTR601‬ﻭ ‪ ،CIF/SIF‬ﺍﺳﺘﻔﺎﺩﻩ ﺍﺯ ‪ interlacing‬ﺩﺭ ﻭﻳﺪﺋﻮ ‪ CCTR601‬ﺍﺳﺖ‪ .‬ﺍﻳﻦ ﺳﺒﺐ ﻣﻲﺷﻮﺩ ﻛـﻪ ﭘـﺮﺩﺍﺯﺵ ﻓـﺸﺮﺩﻩ ﺳـﺎﺯﻱ‪،‬‬
‫ﺑﻄﻮﺭ ﻗﺎﺑﻞ ﺗﻮﺟﻬﻲ ﭘﻴﭽﻴﺪﻩ ﺷﻮﺩ‪ .‬ﺑﻨﺎﺑﺮﺍﻳﻦ ﺭﻭﺵ ﻫﺎﻱ ﺧﺎﺻﻲ ﺑﺮﺍﻱ ﻛﻨﺘﺮﻝ ﻛﺮﺩﻥ ﺗﺼﺎﻭﻳﺮ ‪ ،interlaced‬ﻣﻄـﺮﺡ ﺷـﺪﻩ ﺍﺳـﺖ ﻛـﻪ ﻋﻤﻠﻜـﺮﺩ‬
‫ﺟﺒﺮﺍﻥ ﻭ ﺗﺨﻤﻴﻦ ﺣﺮﻛﺖ ﻭ ‪ DCT‬ﺭﺍ ﺗﻐﻴﻴﺮ ﻣﻲ ﺩﻫﺪ‪ .‬ﺟﺰﺋﻴﺎﺕ ﺑﻴﺸﺘﺮ ﺩﺭ ]‪ [١‬ﻳﺎﻓﺖ ﻣﻲ ﺷﻮﺩ‪.‬‬
‫‪ MPEG-2‬ﻣﻲ ﺗﻮﺍﻧﺪ ﻓﺮﻣﺖ ﻫﺎﻱ ﻭﻳﺪﺋﻮ ﺑﺎ ﺳﻄﻮﺡ ﺭﺯﻭﻟﻮﺷﻦ ﻣﺨﺘﻠﻒ ﺭﺍ ﻫﻨﺪﻝ ﻛﻨﺪ‪ .‬ﺍﻳﻦ ﺍﺳﺘﺎﻧﺪﺍﺭﺩ ﺩﺍﺭﺍﻱ ‪ profile‬ﻫﺎﻱ ﻣﺨﺘﻠﻔـﻲ ﺍﺳـﺖ‬
‫ﻛﻪ ﻗﺎﺑﻠﻴﺖ ﻫﺎﻱ ﺑﻴﺸﺘﺮﻱ ﺭﺍ ﺩﺭ ﺍﺧﺘﻴﺎﺭ ﻣﻲ ﮔﺬﺍﺭﺩ‪ .‬ﺑﺤﺚ ﻓﻮﻕ ﺗﻨﻬـﺎ ﺑـﻪ ‪ profile‬ﺍﺻـﻠﻲ ﺩﺭ ﺳـﻄﺢ ﺍﺻـﻠﻲ )‪ (mp@ml‬ﺍﺷـﺎﺭﻩ ﺩﺍﺭﺩ‪ .‬ﻳـﻚ‬
‫ﺳﻴﮕﻨﺎﻝ ‪ HDTV‬ﺑﺎ ﺍﺳﺘﻔﺎﺩﻩ ﺍﺯ ‪ profile‬ﺍﺻﻠﻲ ﺩﺭ ﺳﻄﺢ ﺑﺎﻻ ﻛﺪ ﻣﻲ ﺷﻮﺩ‪ .‬ﻳﻚ ﺗﻮﺳﻌﺔ ﻣﻬﻢ ﺩﻳﮕﺮ ‪ MPEG-2‬ﺩﺭ ﻣﻘﺎﻳﺴﻪ ﺑﺎ ‪،MPEG-1‬‬
‫‪ scalability profile‬ﺍﺳﺖ ﻛﻪ ﻳﻚ ﻭﻳﺪﺋﻮ ﺭﺍ ﻗﺎﺩﺭ ﻣﻲ ﺳﺎﺯﺩ ﻛﻪ ﺑﺼﻮﺭﺕ ﻳﻚ ﻻﻳﺔ ﺍﺻﻠﻲ ﻭ ﻳﻚ ﻻﻳﺔ ﺗﻜﻤﻴﻠـﻲ‪ ،‬ﻛـﺪ ﺷـﻮﺩ‪ .‬ﻻﻳـﺔ ﺍﺻـﻠﻲ‪،‬‬
‫ﻛﻴﻔﻴﺖ ﭘﺎﻳﻪ ﺭﺍ ﺍﻳﺠﺎﺩ ﻣﻲ ﻛﻨﺪ ﻭ ﻻﻳﺔ ﺗﻜﻤﻴﻠﻲ‪ ،‬ﻫﻨﮕﺎﻣﻴﻜﻪ ﺑﻪ ﻻﻳﺔ ﺍﺻﻠﻲ ﺍﻓﺰﻭﺩﻩ ﻣﻲ ﺷﻮﺩ‪ ،‬ﻣﻲ ﺗﻮﺍﻧﺪ ﻛﻴﻔﻴﺖ ﺭﺍ ﺑﻬﺒﻮﺩ ﺩﻫﺪ‪ .‬ﻳﻚ ﻭﻳﺪﺋﻮ ﻛﺪ ﺷﺪﻩ‬
‫ﺑﺎ ‪ ،MPEG-2‬ﺑﺎ ﺍﺳﺘﻔﺎﺩﻩ ﺍﺯ ﻣﻮﺩ ‪ scalability‬ﻣﻲ ﺗﻮﺍﻧﺪ ﺭﻭﻱ ﺷﺒﻜﻪ ﻫﺎﻳﻲ ﺑﺎ ﭘﻬﻨﺎﻱ ﺑﺎﻧﺪﻫﺎﻱ ﻣﺨﺘﻠـﻒ ﺑـﺮﺍﻱ ﮔﻴﺮﻧـﺪﻩ ﻫـﺎﻳﻲ ﺑـﺎ ﻗﺎﺑﻠﻴـﺖ‬
‫ﺩﺭﻳﺎﻓﺖ ﺑﺎ ﺩﻗﺖ ﻫﺎﻱ ‪ spatial‬ﻣﺨﺘﻠﻒ‪ ،‬ﻣﻨﺘﻘﻞ ﺷﻮﺩ‪ .‬ﺷﻜﻞ ‪ profile ،٦‬ﻫﺎﻱ ﻣﺨﺘﻠﻒ ﻭ ﺳﻄﺢ ﻣﺨﺘﻠﻔﻲ ﻛـﻪ ﺗﻮﺳـﻂ ‪ MPEG2‬ﭘـﺸﺘﻴﺒﺎﻧﻲ‬
‫ﻣﻲ ﺷﻮﻧﺪ ﺭﺍ ﺧﻼﺻﻪ ﻣﻲ ﻛﻨﺪ‪.‬‬
‫‪9‬‬
‫‪CE 342 – Multimedia HW# 7‬‬
‫‪H. Rabiee, Spring 2008‬‬
‫ﺷﻜﻞ ‪ :6‬ﺳﻄﻮح و ‪ profile‬ﻫﺎي ﻣﻮرد ﺣﻤﺎﻳﺖ‬
‫‪MPEG-2‬‬
‫‪ -5-2‬ﺳﺎﻳﺮ اﺳﺘﺎﻧﺪاردﻫﺎي ﺗﺠﺎري ﻓﺸﺮده ﺳﺎزي وﻳﺪﺋﻮ‬
‫‪ -1-5-2‬ﺗﻜﻨﻮﻟﻮژي ‪Intel’s Indeo‬‬
‫ﻭﻳﺪﺋﻮ ‪ Indeo‬ﻳﻚ ﺗﻜﻨﻮﻟﻮﮊﻱ ﻧﺮﻡ ﺍﻓﺰﺍﺭﻱ ﺍﺳﺖ ﻛﻪ ﺗﻮﺳﻂ ‪ Intel Architecture Labs‬ﺗﻮﻟﻴﺪ ﺷﺪﻩ ﻭ ﺍﻧﺪﺍﺯﺓ ﻓﺎﻳﻞ ﻫﺎﻱ ﻭﻳﺪﺋﻮ ﺩﻳﺠﻴﺘـﺎﻝ‬
‫ﻓﺸﺮﺩﻩ ﻧﺸﺪﻩ ﺭﺍ ﺍﺯ ‪ ٥‬ﺗﺎ ‪ ١٠‬ﺑﺮﺍﺑﺮ ﻛﺎﻫﺶ ﻣـﻲ ﺩﻫـﺪ‪ .‬ﺍﻳـﻦ ﺗﻜﻨﻮﻟـﻮﮊﻱ ﺩﺭ ﻣﺤـﺼﻮﻻﺗﻲ ﻣﺎﻧﻨـﺪ ‪ Microsoft’s video for windows‬ﻭ‬
‫‪ Apple’s Quicktime‬ﮔﻨﺠﺎﻧﺪﻩ ﺷﺪﻩ ﺍﺳﺖ‪.‬‬
‫ﺗﻜﻨﻮﻟﻮﮊﻱ ‪ ،Indeo‬ﺍﺯ ﭼﻨﺪﻳﻦ ﻧﻮﻉ ﺗﻜﻨﻴﻚ ﻓﺸﺮﺩﻩ ﺳﺎﺯﻱ ”‪ “Lossy‬ﻭ ”‪ “Loos less‬ﺍﺳﺘﻔﺎﺩﻩ ﻣـﻲﻛﻨـﺪ‪ .‬ﺗﻜﻨﻮﻟـﻮﮊﻱ ‪ ،Indeo‬ﻭﻳـﺪﺋﻮ ﺭﺍ‬
‫ﺑﻄﻮﺭ ﻫﻤﺰﻣﺎﻥ ﺑﺎ ﺩﺭﻳﺎﻓﺖ ﺁﻥ ﺍﺯ ﻃﺮﻳﻖ ‪ ،video capture board‬ﻓﺸﺮﺩﻩ ﻣﻲ ﻛﻨﺪ ﺑﻨﺎﺑﺮﺍﻳﻦ ﺩﺍﺩﺓ ﻓﺸﺮﺩﻩ ﻧﺸﺪﻩ ﻧﻴﺎﺯﻱ ﺑﻪ ﺫﺧﻴـﺮﻩ ﺷـﺪﻥ ﺭﻭﻱ‬
‫ﺩﻳﺴﻚ ﺭﺍ ﻧﺪﺍﺭﺩ‪ .‬ﻭﻳﺪﺋﻮ ﺁﻧﺎﻟﻮﮒ ﺩﺭﻳﺎﻓﺘﻲ ﺍﺯ ﻳﻚ ﺩﻭﺭﺑﻴﻦ ﻭﻳﺪﺋﻮ‪ ،VCR ،‬ﻳﺎ ﺩﻳﻚ ﻟﻴﺰﺭﯼ‪ ،‬ﺑﺎ ﻫﺮ ﻧﻮﻉ ﻓﺮﻣﺖ ﺍﺳـﺘﺎﻧﺪﺍﺭﺩﻱ ﻣﺎﻧﻨـﺪ ‪ ،NTSC‬ﺍﺯ‬
‫ﻃﺮﻳﻖ ‪ video capture board‬ﻣﺎﻧﻨﺪ ﻳﻚ ‪ ،Intel smart video Recorder board‬ﺑﻪ ﻓﺮﻣﺖ ﺩﻳﺠﻴﺘﺎﻝ ﺗﺒﺪﻳﻞ ﻣﻲ ﺷﻮﺩ‪.‬‬
‫ﺭﻭﺵ ‪ Indeo‬ﺷﺎﻣﻞ ﻣﺮﺍﺣﻞ ﺯﻳﺮ ﺍﺳﺖ )ﺗﻤﺎﻣﻲ ﺁﻧﻬﺎ ﺍﻟﺰﺍﻣﻲ ﻧﻴﺴﺘﻨﺪ(‪:‬‬
‫‪ -١‬ﻧﻤﻮﻧﻪ ﺑﺮﺩﺍﺭﻱ ‪ ،yuv‬ﺑﺮﺍﻱ ﻛﺎﻫﺶ ﻣﺴﺎﺣﺖ ﭘﻴﻜﺴﻞ ﺑﻪ ﻳﻚ ﻣﻘﺪﺍﺭ ﺭﻧﮓ ﻣﺘﻮﺳﻂ‪.‬‬
‫‪ -٢‬ﺍﺧﺘﻼﻑ ﭘﻴﻜﺴﻞ ﻭ ﻓﺸﺮﺩﻩ ﺳﺎﺯﻱ ﺯﻣﺎﻧﻲ‪ ،‬ﺑﺮﺍﻱ ﻛﻢ ﻛﺮﺩﻥ ﺩﺍﺩﻩ ﺍﺯ ﻃﺮﻳﻖ ﺫﺧﻴﺮﻩ ﻛﺮﺩﻥ ﺗﻨﻬﺎ ﺍﻃﻼﻋﺎﺗﻲ ﻛﻪ ﺑﻴﻦ ﭘﻴﻜﺴﻞ ﻫﺎ ﻳﺎ ﻓﺮﻳﻢ ﻫﺎ ﺗﻐﻴﻴـﺮ‬
‫ﻛﺮﺩﻩ ﺍﺳﺖ‪) .‬ﺍﻳﻦ ﺑﺎ ﻛﻮﺍﻧﺘﻴﺰﻩ ﻛﺮﺩﻥ ﺍﺧﺘﻼﻑ ﻓﺮﻳﻢ ﺍﺯ ﺭﻭﺵ ﻛﻮﺍﻧﺘﻴﺰﺍﺳﻴﻮﻥ ﺑﺮﺩﺍﺭﻱ ﺍﻧﺠﺎﻡ ﻣﻲ ﺷﻮﺩ‪(.‬‬
‫‪ -٣‬ﻛﺪ ﻛﺮﺩﻥ ‪ run-length‬ﺑﺮﺍﻱ ﻓﺸﺮﺩﻩ ﻛﺮﺩﻥ ﺷﺎﺧﺺ ﻫﺎﻱ ﻛﻠﻤﺔ ﻛﺪ‪.‬‬
‫‪ -٤‬ﻛﺪ ﻛﺮﺩﻥ ‪ ،variable – content‬ﺑﺮﺍﻱ ﻛﺎﻫﺶ ﻳﻚ ﻣﺠﻤﻮﻋﺔ ﻣﺘﻔﺎﻭﺕ ﺍﺯ ﺍﻃﻼﻋﺎﺕ ﺑﻪ ﺗﻌﺪﺍﺩ ﺛﺎﺑﺘﻲ ﺑﻴﺖ‪.‬‬
‫ﻓﺎﻳﻞ ﻭﻳﺪﺋﻮ ﺩﻳﺠﻴﺘﺎﻝ ﺷﺪﻩ ﺑﺎ ﺍﻃﻼﻋﺎﺕ ﺻﺪﺍ‪ ،‬ﻃﺒﻖ ﻳﻚ ﻓﺮﻣﺖ ﺍﺳﺘﺎﻧﺪﺍﺭﺩ‪ ،‬ﻣﺜﻞ ‪ Microsoft’s AVI‬ﻳﺎ ‪ Apple’s Quicktime‬ﺗﺮﻛﻴـﺐ‬
‫ﻣﻲ ﺷﻮﺩ ﻭ ﺭﻭﻱ ﺩﻳﺴﻚ ﺳﺨﺖ ﺫﺧﻴﺮﻩ ﻣﻲ ﺷﻮﺩ‪ .‬ﻓﺎﻳﻞ ﺗﺮﻛﻴﺐ ﺷﺪﻩ ﻣﻲ ﺗﻮﺍﻧﺪ ﺑﺮﺍﻱ ﭘﺨﺶ ﺷﺪﻥ ﻳﺎ ﺗﺼﺤﻴﺢ ﺷﺪﻥ‪ ،‬ﺗﻮﺯﻳﻊ ﺷﻮﺩ‪ .‬ﺑﺮﺍﻱ ﭘﺨﺶ‬
‫‪10‬‬
‫‪CE 342 – Multimedia HW# 7‬‬
‫‪H. Rabiee, Spring 2008‬‬
‫ﻛﺮﺩﻥ‪ ،‬ﻓﺎﻳﻞ ﺑﺎﻳﺪ ﺑﻪ ﻗﺴﻤﺖﻫﺎﻱ ﻭﻳﺪﺋﻮ ﻭ ﺻﺪﺍ ﺗﺠﺰﻳﻪ ﺷﻮﺩ ﻭ ﻭﻳﺪﺋﻮ ﺍﺯ ﻃﺮﻳﻖ ﻳﻚ ﺗﻌﺪﺍﺩ ﺭﻭﺵ )ﻋﻜﺲ ﻋﻤﻠﻴﺎﺕ ﻓﺸﺮﺩﻩﺳﺎﺯﻱ(‪ ،‬ﻭﺍﻛﺪ ﺷـﻮﺩ‬
‫ﺗﺎ ﻧﻤﺎﻳﺶ ﭘﻴﻜﺴﻞ ﻫﺎﻱ ﺩﻳﺠﻴﺘﺎﻝ ﻭﺍﻗﻌﻲ ﻣﺮﺑﻮﻁ ﺑﻪ ﻭﻳﺪﺋﻮ ﺩﻳﺠﻴﺘﺎﻝ ﻓﺸﺮﺩﻩ ﺷﺪﻩ‪ ،‬ﻣﻴﺴﺮ ﺷﻮﺩ‪.‬‬
‫ﺳﻪ ﻋﺎﻣﻞ ﻣﺆﺛﺮ ﺩﺭ ﻛﺎﺭﺍﻳﻲ ﻋﺒﺎﺭﺗﻨﺪ ﺍﺯ‪:‬‬
‫‪ (۱‬ﺳﺮﻋﺖ ﻣﻴﻜﺮﻭﭘﺮﻭﺳﺴﻮﺭ‪،‬‬
‫‪ (۲‬ﺍﻧﺪﺍﺯﺓ ﭘﻨﺠﺮﺓ ‪ playback‬ﺑﺮ ﺣﺴﺐ ﭘﻴﻜﺴﻞ ﻭ ‪ (۳‬ﻧﺮﺥ ﻓﺮﻳﻢ‬
‫ﻛﻮﭼﻜﺘﺮ ﺑﻮﺩﻥ ﭘﻨﺠﺮﺓ ‪ playback‬ﺑﺎﻋﺚ ﻣﻲ ﺷﻮﺩ ﻛﻪ ﺗﺼﺎﻭﻳﺮ ﻭﻳﺪﺋﻮ‪ ،‬ﻃﺒﻴﻌﻲ ﺗﺮ ﺑﺎﺷﻨﺪ‪ .‬ﻣﻴﻜﺮﻭﭘﺮﻭﺳﺴﻮﺭ ﭘﻨﺠﺮﻩ ﻫـﺎﻱ ‪ playback‬ﺑﺰﺭﮔﺘـﺮ‬
‫ﻭ ﻧﺮﺥ ﻫﺎﻱ ﻓﺮﻳﻢ ﺑﻴﺸﺘﺮ ﺭﺍ ﺣﻤﺎﻳﺖ ﻛﻨﺪ‪.‬‬
‫ﺗﻜﻨﻮﻟﻮﮊﻱ ‪ scalable ،Indeo‬ﺍﺳﺖ‪ ،‬ﻳﻌﻨﻲ ﻧﺮﺥ ﻫﺎﻱ ﺳﺮﻳﻌﺘﺮ ﻓﺮﻳﻢ ﺑﺮﺍﻱ ﻣﺸﺘﺮﻳﺎﻥ ﺑﺎ ﻗﺪﺭﺕ ﭘﺮﺩﺍﺯﺵ ﺑﻴﺸﺘﺮ ﺭﺍ ﻓﺮﺍﻫﻢ ﻣﻲ ﻛﻨﺪ‪.‬‬
‫‪Apple’s Quicktime -2-5-2‬‬
‫ﻣﺤﺼﻮﻝ ‪ Quicktime‬ﺑﺎ ﻫﺰﻳﻨﺔ ﻛﻢ‪ ،‬ﺑﺮﺍﻱ ﺳﻴﺴﺘﻢ ﻫﺎﻱ ‪ ،end-user desktop‬ﻭﻳﺪﺋﻮ ﺗﻤﺎﻡ ﻣﺘﺤﺮﻙ ﺭﺍ ﺑﻪ ﺍﺭﻣﻐـﺎﻥ ﺁﻭﺭﺩ‪ ، Apple.‬ﻋﻤـﻞ‬
‫ﻓﺸﺮﺩﻩ ﺳﺎﺯﻱ ﻭ ﻋﻜﺲ ﺁﻥ ﺭﺍ ﺑﻪ ﻃﻮﺭ ﻧﺮﻡ ﺍﻓﺰﺍﺭﻱ ﭘﻴﺎﺩﻩ ﻛﺮﺩ‪ .‬ﻛﻮﺍﻧﺘﻴﺰﻩ ﻛﺮﺩﻥ ﺑﺮﺩﺍﺭﻱ ﻳﻜﻲ ﺍﺯ ﺭﻭﺵ ﻫﺎﻱ ﻓﺸﺮﺩﻩ ﺳﺎﺯﻱ ﻧﺮﻡ ﺍﻓﺰﺍﺭﻱ ﺍﺳﺖ ﻛـﻪ‬
‫ﺩﺭ ‪ Quicktime‬ﻣﻮﺟﻮﺩ ﺍﺳﺖ‪ .‬ﺍﻳﻦ ﺭﻭﺵ ﺍﻣﻜﺎﻥ ﺩﺍﺷﺘﻦ ﻭﻳﺪﺋﻮ ﺑﺎ ﺩﻗﺖ‪ ٣٢٠*٢٤٠ ،‬ﺗـﺎ ‪ ٣٠ frame/sec‬ﺑـﺪﻭﻥ ﻛﻤـﻚ ﺳـﺨﺖ ﺍﻓـﺰﺍﺭ ﺭﺍ‬
‫ﻓﺮﺍﻫﻢ ﻣﻲﻛﻨﺪ‪ .‬ﻧﺴﺒﺖ ﻫﺎﻱ ﻓﺸﺮﺩﻩ ﺳﺎﺯﻱ ﻛﻪ ﺑﺎ ﺍﻳﻦ ﺭﻭﺵ ﺑﺪﺳﺖ ﻣﻲ ﺁﻳﻨﺪ ﺑﻴﻦ ‪ ٢٥‬ﺗﺎ ‪ ٢٠٠‬ﺍﺳﺖ‪.‬‬
‫‪Microsoft AVI -3-5-2‬‬
‫ﻫﻤﺎﻧﻨﺪ ‪ ،Quicktime‬ﻫـﺪﻑ ﺍﺯ ‪ ،Microsoft AVI‬ﺍﻳﺠـﺎﺩ ﻭﻳـﺪﺋﻮ ﺑـﺎ ﺩﻗـﺖ ﻛـﻢ ﻭ ﻫﺰﻳﻨـﺔ ﻛـﻢ ﺭﻭﻱ ‪ desktop‬ﺍﺳـﺖ‪ .‬ﺑـﺮ ﺧـﻼﻑ‬
‫‪ ،Quicktime‬ﻛﻪ ﻗﺴﻤﺘﻲ ﺍﺯ ﺳﻴﺴﺘﻢ ﻋﺎﻣﻞ ﺍﺳﺖ‪ AVI ،‬ﺑﻌﻨﻮﺍﻥ ﻳﻚ ﻣﺎﮊﻭﻥ ﺳﻄﺢ ﻣﺠﺰﺍ‪ ،‬ﺗﻌﺮﻳﻒ ﺷﺪﻩ ﺍﺳﺖ‪ AVI .‬ﺑﻌﻨـﻮﺍﻥ ﻳـﻚ ﺭﺍﻩ ﺣـﻞ‬
‫ﺗﻨﻬﺎ ﻧﺮﻡ ﺍﻓﺰﺍﺭﻱ‪ ،‬ﻃﺮﺍﺣﻲ ﺷﺪﻩ ﺍﺳﺖ ﺗﺎ ﺭﻭﻱ ﻣﺎﻧﻴﺘﻮﺭﻫﺎﻱ ‪ VGA‬ﻭ ‪ ،Super VGA‬ﻭﻳﺪﺋﻮ ﺭﺍ ﻧﻤﺎﻳﺶ ﺩﻫـﺪ‪ .‬ﺩﻗـﺖ ‪ ،AVI‬ﻫﻨﮕﺎﻣﻴﻜـﻪ ﺑـﺎ‬
‫ﺩﻗﺖ ‪ VCR‬ﺩﺭ ﻣﺤﺪﻭﺩﺓ ‪ ٣٢٠‬ﺧﻂ ﻳﺎ ﺑﻴﺸﺘﺮ ﻣﻘﺎﻳﺴﻪ ﻣﻲ ﺷﻮﺩ‪ ،‬ﻋﻤﻮﻣﹰﺎ ﻛﻤﺘﺮ ﺍﺯ ﻳﻚ ﺳﻴﮕﻨﺎﻝ ﺗﻠﻮﻳﺰﻳﻮﻥ ﻋﺎﺩﻱ ﺍﺳﺖ‪ .‬ﻳـﻚ ﺧـﺼﻮﺻﻴﺖ ﻣﻬـﻢ‬
‫‪ Scalability, AVI‬ﺁﻥ ﺍﺳﺖ‪.‬‬
‫ﻛﺎﺭﺍﻳﻲ ﺗﺤﺖ ‪ ،AVI‬ﺑﺴﺘﮕﻲ ﺑﻪ ﺳﺨﺖ ﺍﻓﺰﺍﺭ ﻣﻮﺭﺩ ﺍﺳﺘﻔﺎﺩﻩ ﺩﺭ ﻻﻳﺔ ﺯﻳﺮﻳﻦ ﺁﻥ ﺩﺍﺭﺩ‪ AVI .‬ﺷﺎﻣﻞ ﭼﻨـﺪﻳﻦ ﺍﻟﮕـﻮﺭﻳﺘﻢ ﻧـﺮﻡ ﺍﻓـﺰﺍﺭﻱ ﻓـﺸﺮﺩﻩ‬
‫ﺳﺎﺯﻱ ﻭ ﻋﻜﺲ ﺁﻥ ﺍﺳﺖ‪ .‬ﺑﺮﺧﻲ ﺍﺯ ﺍﻳﻦ ﺍﻟﮕﻮﺭﻳﺘﻢ ﻫﺎ ﺑﺮﺍﻱ ﺣﺮﻛﺖ ﺑﻬﻴﻨﻪ ﺷﺪﻩ ﺍﻧﺪ ﺩﺭ ﺣﺎﻟﻴﻜﻪ ﺑﺮﺧﻲ ﺩﻳﮕﺮ ﺑﺮﺍﻱ ﻭﻳﺪﺋﻮﻫﺎﻱ ﺛﺎﺑﺖ ﺑﻬﻴﻨﻪ ﺷـﺪﻩ‬
‫ﺍﻧﺪ‪.‬‬
‫‪ AVI‬ﭼﻨﺪﻳﻦ ‪ dialog box‬ﺑﺮﺍﻱ ﺍﻧﺘﺨﺎﺏ ﺍﻧﺪﺍﺯﺓ ﭘﻨﺠﺮﻩ ﻫﺎ‪ ،‬ﻧﺮﺥ ﻓﺮﻳﻢ‪ ،‬ﻛﻴﻔﻴﺖ ﻭ ﺍﻟﮕﻮﺭﻳﺘﻢ ﻓﺸﺮﺩﻩ ﺳﺎﺯﻱ ﺩﺭ ﺍﺧﺘﻴﺎﺭ ﻗﺮﺍﺭ ﻣﻲ ﺩﻫﺪ‪ .‬ﻛﻴﻔﻴﺘـﻲ‬
‫ﻛﻪ ﺑﺎ ‪ AVI‬ﺑﻪ ﺩﺳﺖ ﻣﻲ ﺁﻳﺪ‪ ،‬ﺑﺎ ﻛﻴﻔﻴﺖ ‪ Quick Time‬ﻗﺎﺑﻞ ﻣﻘﺎﻳﺴﻪ ﺍﺳﺖ‪ .‬ﺑﺎ ﻭﺟﻮﺩﻱ ﻛﻪ ﺑﺮ ﺍﺳﺎﺱ ﺗﻜﻨﻮﻟﻮﮊﻱ ﻫﺎﻱ ﻣﺘﻔﺎﻭﺗﻲ ﻋﻤـﻞ ﻣـﻲ‬
‫ﻛﻨﻨﺪ‪ ،‬ﺩﺭ ﻇﺎﻫﺮ ﺧﻴﻠﻲ ﺷﺒﻴﻪ ﻳﻜﺪﻳﮕﺮ ﻫﺴﺘﻨﺪ‪.‬‬
‫‪Intel’s DVI -4-5-2‬‬
‫‪ Intel’s Digital Video Interface‬ﻳﻚ ﺍﺳﺘﺎﻧﺪﺍﺭﺩ ﺳﺨﺖ ﺍﻓﺰﺍﺭﻱ ﺍﺳﺖ‪ .‬ﺍﺯ ﺁﻧﺠﺎ ﻛﻪ ﺍﺳﺘﺎﻧﺪﺍﺭﺩﻫﺎﻱ ﺟﺪﻳﺪﺗﺮﻱ ﺑﻄﻮﺭ ﻧﺮﻡ ﺍﻓﺰﺍﺭﻱ ﭘﻴﺎﺩﻩ‬
‫ﺳﺎﺯﻱ ﺷﺪﻩ ﺍﻧﺪ )ﻭ ‪ DVI‬ﺍﻫﻤﻴﺖ ﺧﻮﺩ ﺭﺍ ﺑﻪ ﻋﻨﻮﺍﻥ ﺍﺳﺘﺎﻧﺪﺍﺭﺩ ﺗﺎ ﺣﺪﻭﺩﻱ ﺍﺯ ﺩﺳﺖ ﺩﺍﺩﻩ ﺍﺳﺖ(‪ ،‬ﺟﺰﺋﻴﺎﺕ ﺍﻳﻦ ﺭﻭﺵ ﺩﺭ ﺍﻳﻨﺠﺎ ﻣﻄـﺮﺡ ﻧـﺸﺪﻩ‬
‫ﺍﺳﺖ‪.‬‬
‫ﺍﻓﺮﺍﺩﻱ ﻛﻪ ﺑﻪ ﺍﻳﻦ ﺍﺳﺘﺎﻧﺪﺍﺭﺩ ﻋﻼﻗﻤﻨﺪ ﻫﺴﺘﻨﺪ ﻣﻲ ﺗﻮﺍﻧﻨﺪ ﻳﻚ ﻧﺴﺨﻪ ﺍﺯ ﺍﺳﺘﺎﻧﺪﺍﺭﺩ ﺭﺍ ﺗﻬﻴﻪ ﻭ ﺟﺰﺋﻴﺎﺕ ﺁﻥ ﺭﺍ ﻣﻄﺎﻟﻌﻪ ﻧﻤﺎﻳﻨﺪ‪.‬‬
‫‪ -3‬آزﻣﺎﻳﺶ‬
‫‪ -١‬ﺑﺎ ﻓﺮﺽ ﺩﺍﺷﺘﻦ ﺩﻭ ﻓﺮﻳﻢ ﺍﺯ ﻳﻚ ﺩﻧﺒﺎﻟﺔ ﻭﻳﺪﺋﻮ‪ ،‬ﺑﺮﻧﺎﻣﻪ ﺍﻱ ﺑﻨﻮﻳﺴﻴﺪ ﻛﻪ ﺑﺮﺩﺍﺭ ﺣﺮﻛﺖ ﺭﺍ ﺑﺮﺍﻱ ﺍﻭﻟـﻴﻦ ﺑﻠـﻮﻙ ‪) ١٦*١٦‬ﺑـﺮﺍﻱ ﻣﺜـﺎﻝ ﺑﻠـﻮﻙ‬
‫)‪٠‬ﻭ‪ (٠‬ﻭ )‪١٥‬ﻭ‪ (٠‬ﻭ )‪٠‬ﻭ‪ (١٥‬ﻭ )‪١٥‬ﻭ‪ (١٥‬ﺩﺭ ﺩﻭﻣﻴﻦ ﻓﺮﻳﻢ ﭘﻴﺪﺍ ﻛﻨﺪ‪ .‬ﺩﻭ ﻓـﺮﻳﻢ ﺭﺍ ﺑﺨﻮﺍﻧﻴـﺪ ﺍﺯ ﺗﻮﺍﺑـﻊ )(‪ fopen‬ﻭ )(‪ fread‬ﺍﺳـﺘﻔﺎﺩﻩ ﻛﻨﻴـﺪ‪،‬‬
‫ﭘﺎﺭﺍﻣﺘﺮﻫﺎﻱ ‪ S-end ،S-start ،BK-location ،BK-size ،B,A‬ﺭﺍ ﺑﻌﻨﻮﺍﻥ ﻭﺭﻭﺩﻱ ﺗﺎﺑﻊ )(‪ EBLK‬ﻛﻪ ﺩﺭ ﭘﻴﻮﺳﺖ ‪ A‬ﺁﻣﺪﻩ ﺍﺳﺖ‪ .‬ﺩﺭ‬
‫‪11‬‬
‫‪CE 342 – Multimedia HW# 7‬‬
‫‪H. Rabiee, Spring 2008‬‬
‫ﻧﻈﺮ ﺑﮕﻴﺮﻳﺪ‪ EBLK .‬ﺗﺎﺑﻌﻲ ﺍﺳﺖ ﻛﻪ ﻣﻲ ﺗﻮﺍﻧﺪ ﺑﺮﺩﺍﺭ ﺣﺮﻛﺖ ﺭﺍ ﺑﺮﺍﻱ ﺑﻠﻮﻙ ﻣﺸﺨﺼﻲ ﭘﻴﺪﺍ ﻛﻨﺪ‪ .‬ﻣﻲﺗﻮﺍﻧﻴﺪ ﻣﺤﺪﻭﺩﺓ ﺟﺴﺘﺠﻮ ﺭﺍ ﺑﻄﻮﺭ ﺛﺎﺑﺖ‬
‫‪ -١٦‬ﻭ ‪ ١٦‬ﺩﺭ ﻧﻈﺮ ﺑﮕﻴﺮﻳﺪ‪.‬‬
‫‪ -٢‬ﺑﺮﻧﺎﻣﻪ ﺍﻱ ﺭﺍ ﻛﻪ ﺩﺭ ﻗﺴﻤﺖ ‪ ١‬ﻧﻮﺷﺘﻪ ﺍﻳﺪ ﺗﻜﻤﻴﻞ ﻛﻨﻴﺪ ﻃﻮﺭﻳﻜﻪ ﺑﺮﺩﺍﺭﻫﺎﻱ ﺣﺮﻛﺖ ﺭﺍ ﺑﺮﺍﻱ ﺗﻤﺎﻡ ﺑﻠﻮﻙ ﻫﺎ ﺩﺭ ﻓﺮﻳﻢ ﻳﻚ ‪ ١‬ﺑﻪ ‪) ٢‬ﺑـﺮﺩﺍﺭ ‪٢‬‬
‫ﺑﻌﺪﻱ ﺑﺮﺍﻱ ﺫﺧﻴﺮﻩ ﺳﺎﺯﻱ ﻛﻠﻴﺔ ﺑﺮﺩﺍﺭﻫﺎﻱ ﺣﺮﻛﺖ ﻧﻴﺎﺯ ﺍﺳﺖ ﻳﻜﻲ ﺑﺮﺍﻱ ‪ mv-x‬ﻭ ﺩﻳﮕﻴﺮﻱ ﺑﺮﺍﻱ )‪ (،(mv-y‬ﺑﺪﺳﺖ ﺁﻭﺭﺩ‪ .‬ﻣﻴﺪﺍﻥ ﺣﺮﻛﺖ ﺭﺍ‬
‫ﺑﺎ ﺍﺳﺘﻔﺎﺩﻩ ﺍﺯ ﺗﺎﺑﻊ )(‪ quiver‬ﺭﺳﻢ ﻛﻨﻴﺪ‪.‬‬
‫‪ -٣‬ﺑﺮﻧﺎﻣﻪ ﺍﻳﻲ ﻛﻪ ﺩﺭ ﻗﺴﻤﺖ ‪ ٢‬ﻧﻮﺷﺘﻪﺍﻳﺪ ﺭﺍ ﺗﻜﻤﻴﻞ ﻛﻨﻴﺪ ﻃﻮﺭﻳﻜﻪ ﺗﺼﻮﻳﺮ ﺗﺨﻤﻴﻦ ﺯﺩﻩ ﺷﺪﻩ ﺍﺯ ﻓﺮﻳﻢ ﺩﻭﻡ ﺭﺍ ﺑﺎ ﻛﭙﻲ ﻛﺮﺩﻥ ﺑﻠـﻮﻙ ﻣﺮﺑـﻮﻁ ﺍﺯ‬
‫ﻓﺮﻳﻢ ﺍﻭﻝ )ﺗﻌﻴﻴﻦ ﺷﺪﻩ ﺗﻮﺳﻂ ﺑﺮﺩﺍﺭ ﺣﺮﻛﺖ( ﺩﺭ ﻓﺮﻳﻢ ﺩﻭﻡ‪ ،‬ﺑﺪﺳﺖ ﺁﻭﺭﻳﺪ‪ .‬ﺩﻭ ﻓﺮﻳﻢ ﺍﺻﻠﻲ‪ ،‬ﻓﺮﻳﻢ ﺩﻭﻡ ﺗﺨﻤﻴﻦ ﺯﺩﻩ ﺷﺪﻩ‪ ،‬ﺗﺼﻮﻳﺮ ﺧﻄﺎ )ﻗـﺪﺭ‬
‫ﻣﻄﻠﻖ ﺧﻄﺎﻱ ﭘﻴﻜﺴﻞ( ﺑﻴﻦ ﺩﻭ ﻓﺮﻳﻢ ﺍﺻﻠﻲ‪ ،‬ﺗﺼﻮﻳﺮ ﺧﻄﺎ ﺑﻴﻦ ﻓﺮﻳﻢ ﺩﻭﻡ ﺗﺨﻤﻴﻦ ﺯﺩﻩ ﺷﺪﻩ ﻭ ﻓﺮﻳﻢ ﺩﻭﻡ ﺍﺻﻠﻲ ﺭﺍ ﻧﻤﺎﻳﺶ ﺩﻫﻴﺪ‪ .‬ﻣﻴﺪﺍﻥ ﺣﺮﻛﺖ‬
‫ﺭﺍ ﺑﺎ ﻛﻤﻚ ﺩﺳﺘﻮﺭ ‪ quiver‬ﺩﺭ ﻣﻄﻠﺐ ﻧﻤﺎﻳﺶ ﺩﻫﻴﺪ‪ .‬ﻫﻤﭽﻨﻴﻦ ﻣﻘﺪﺍﺭ ‪ PSNR‬ﺍﺯ ﺗﺼﺎﻭﻳﺮ ﺧﻄﺎﻱ ﺍﺻﻠﻲ ﻭ ﺟﺪﻳﺪ ﺭﺍ ﻣﺤﺎﺳﺒﻪ ﻛﻨﻴﺪ‪.‬‬
‫‪ PSNR‬ﺑﺼﻮﺭﺕ ﺯﻳﺮ ﺗﻌﺮﻳﻒ ﻣﻲ ﺷﻮﺩ‪:‬‬
‫ﻛﻪ ﺩﺭ ﺁﻥ )‪ e(m,n‬ﻣﻘﺪﺍﺭ ﺧﻄﺎ ﺩﺭ ﭘﻴﻜﺴﻞ )‪ (m,n‬ﺍﺳﺖ‪.‬‬
‫ﻛﻠﻴﺔ ﻣﺸﺎﻫﺪﺍﺕ ﺧﻮﺩ ﺭﺍ ﺩﺭ ﻣﻮﺭﺩ ﺗﺼﻮﻳﺮ ﺗﺨﻤﻴﻦ ﺯﺩﻩ ﺷﺪﻩ‪ ،‬ﻣﻴﺪﺍﻥ ﺣﺮﻛﺖ‪ ،‬ﺍﺧﺘﻼﻑ ﺑﻴﻦ ﺗﺼﺎﻭﻳﺮ ﺧﻄﺎ ﻭ ﻣﻘﺎﺩﻳﺮ ‪ PSNR‬ﺑﻨﻮﻳﺴﻴﺪ‪ .‬ﭼﻪ ﻧـﻮﻉ‬
‫‪ artifact‬ﺩﺭ ﺗﺼﻮﻳﺮ ﺗﺨﻤﻴﻦ ﺯﺩﻩ ﺷﺪﻩ ﻣﺸﺎﻫﺪﻩ ﻣﻲ ﻛﻨﻴﺪ؟ ﻋﻠﺖ ﺁﻥ ﭼﻴﺴﺖ؟‬
‫‪ -٤‬ﺑﺮﻧﺎﻣﺔ ‪ encode.m‬ﺩﺭ ﭘﻴﻮﺳﺖ ‪ B‬ﺭﺍ ﺑﺨﻮﺍﻧﻴﺪ‪ .‬ﺍﻳﻦ ﺑﺮﻧﺎﻣﻪ ﺗﻮﺍﺑﻊ ﺷﻤﺎ ﺩﺭ ﻗـﺴﻤﺖ ‪ ٣‬ﺭﺍ ﻓـﺮﺍ ﻣـﻲﺧﻮﺍﻧـﺪ ﻛـﻪ ﺑﻨـﺎﻡ )(‪getprediction‬‬
‫ﻧﺎﻣﻴﺪﻩ ﺷﺪﻩ ﺍﺳﺖ‪ .‬ﺍﻳﻦ ﺑﺮﻧﺎﻣﻪ ﺗﺒﺪﻳﻞ ‪ DCT‬ﺭﺍ ﺭﻭﻱ ﺗﺼﻮﻳﺮ ﺧﻄﺎ ﺍﻧﺠﺎﻡ ﻣﻲ ﺩﻫﺪ‪ .‬ﺗﺒﺪﻳﻞ ‪ ٨*٨ DCT‬ﺭﺍ ﺭﻭﻱ ﻫﺮ ﺑﻠﻮﻙ ﺩﺭ ﺗﺼﻮﻳﺮ ﺧﻄـﺎﻱ‬
‫ﺗﺨﻤﻴﻦ ﺯﺩﻩ ﺷﺪﻩ‪ ،‬ﺍﻋﻤﺎﻝ ﻛﻨﻴﺪ‪ .‬ﭼﻨﺪ ﻣﺆﻟﻔﺔ ﺍﻭﻝ ‪ DCT‬ﺩﺭ ﻫﺮ ﺑﻠﻮﻙ ﺭﺍ ﻧﮕﻪ ﺩﺍﺭﻳﺪ ﻭ ﺑﻌﺪ ﺗﺼﻮﻳﺮ ﺧﻄﺎﻱ ﺗﺨﻤﻴﻦ ﺭﺍ ﻛﻪ ﺑﺪﺳﺖ ﻣـﻲ ﺁﻳـﺪ ﺑـﻪ‬
‫ﻓﺮﻡ ﺗﺨﻤﻴﻦ ﺯﺩﻩ ﺷﺪﻩ ﺍﺿﺎﻓﻪ ﻛﻨﻴﺪ ﺗﺎ ﺗﺼﻮﻳﺮ ﺑﺎﺯﺳﺎﺯﻱ ﺷﺪﻩ ﺭﺍ ﺑﺪﺳﺖ ﺁﻭﺭﻳﺪ‪ PNR .‬ﺑﻴﻦ ﺗﺼﻮﻳﺮ ﺑﺎﺯﺳﺎﺯﻱ ﺷﺪﻩ ﻭ ﺗـﺼﻮﻳﺮ ﺍﺻـﻠﻲ ﻣﺤﺎﺳـﺒﻪ‬
‫ﻣﻲ ﺷﻮﺩ ﺗﺎ ﻛﻴﻔﻴﺖ ﺗﺼﻮﻳﺮ ﻛﺪ ﺷﺪﻩ ﺑﺮﺭﺳﻲ ﺷﻮﺩ‪ .‬ﻟﻄﻔﹰﺎ ﺩﺭ ﻣﻮﺭﺩ ﻫﺮ ﺧﻂ ﺩﺳﺘﻮﺭﻱ‪ ،‬ﺗﻮﺿﻴﺤﻲ ﺩﻫﻴﺪ ﻛﻪ ﻧﺸﺎﻥ ﺩﻫﺪ ﻭﻇﻴﻔـﺔ ﺁﻥ ﺧـﻂ ﺩﺳـﺘﻮﺭ‬
‫ﭼﻴﺴﺖ؟‬
‫‪ -٥‬ﺣﺪﺍﻗﻞ ﺗﻌﺪﺍﺩ ﻣﺆﻟﻔﻪ ﻫﺎ ﻳﺎ ﺗﻌﺪﺍﺩ ﺿﺮﺍﻳﺒﻲ ﺭﺍ ﭘﻴﺪﺍ ﻛﻨﻴﺪ ﻛﻪ ﻻﺯﻡ ﺍﺳﺖ‪ ،‬ﻧﮕﻬﺪﺍﺭﻱ ﺷﻮﻧﺪ ﺗﺎ ﻧﺘﻴﺠﺔ ﺭﺿﺎﻳﺖ ﺑﺨﺸﻲ ﺍﺯ ﻧﻈﺮ ﺗﺸﺨﻴﺺ ﭼـﺸﻢ‬
‫ﺑﺪﺳﺖ ﺁﻳﺪ )ﻣﻲ ﺗﻮﺍﻥ ﺍﺯ ﻣﺤﺎﺳﺒﺔ ‪ PSNR‬ﻧﻴﺰ ﺍﺳﺘﻔﺎﺩﻩ ﻛﺮﺩ ﻛﻪ ‪ PSNR‬ﺑﻴـﺸﺘﺮ ﺍﺯ ‪ dB ٣٠‬ﻻﺯﻡ ﺍﺳـﺖ(‪ .‬ﻫﻤﭽﻨـﻴﻦ ﺍﻳـﻦ ﺭﻭﺵ ﻛـﺪ ﻛـﺮﺩﻥ‬
‫‪ DCT‬ﺭﺍ ﺑﻄﻮﺭ ﻣﺴﺘﻘﻴﻢ ﺑﺮﺍﻱ ﻓﺮﻳﻢ ﺍﺻﻠﻲ ﺩﻭﻡ ﺑﻜﺎﺭ ﺑﺮﻳﺪ‪ ٨*٨ DCT ،‬ﺭﺍ ﺭﻭﻱ ﻫﺮ ﻳﻚ ﺍﺯ ﺑﻠﻮﻛﻬﺎﻱ ﻓﺮﻳﻢ ﺍﺻﻠﻲ ﺩﻭﻡ ﺍﻋﻤﺎﻝ ﻛﻨﻴـﺪ ﻭ ﭼﻨـﺪ‬
‫ﻣﺆﻟﻔﺔ ﺍﻭﻝ ‪ DCT‬ﺭﺍ ﻧﮕﻪ ﺩﺍﺭﻳﺪ‪ .‬ﺗﻌﺪﺍﺩ ﺣﺪﺍﻗﻞ ﻣﺆﻟﻔﻪ ﻫﺎﻱ ﻣﻮﺭﺩ ﻧﻴﺎﺯ ﺭﺍ ﻛﻪ ﻧﺘﻴﺠﺔ ﺭﺿﺎﻳﺖ ﺑﺨﺶ ﻣﻲ ﺩﻫﻨﺪ‪ ،‬ﭘﻴﺪﺍ ﻛﻨﻴﺪ ﻭ ﺣﺪﺍﻗﻞ ﻣﺆﻟﻔﻪ ﻫـﺎﻱ‬
‫ﻻﺯﻡ ﺩﺭ ﺍﻳﻦ ﺩﻭ ﺣﺎﻟﺖ ﺭﺍ ﻣﻘﺎﻳﺴﻪ ﻛﻨﻴﺪ‪ .‬ﻓﺮﺽ ﻛﻨﻴﺪ ﻛﻪ ﻛﺪ ﻛﺮﺩﻥ ﺗﻌﺪﺍﺩ ﻳﻜﺴﺎﻧﻲ ﺍﺯ ﻣﺆﻟﻔﻪ ﻫـﺎﻱ ‪ DCT‬ﺩﺭ ﻫـﺮ ﺑﻠـﻮﻙ‪ ،‬ﺗﻌـﺪﺍﺩ ﺑﻴـﺖ ﻫـﺎﻱ‬
‫ﻳﻜﺴﺎﻧﻲ ﺭﺍ ﻣﺼﺮﻑ ﺧﻮﺍﻫﺪ ﻛﺮﺩ‪ ،‬ﻛﺪﺍﻡ ﺭﻭﺵ ﻛﻴﻔﻴﺖ ﺑﻬﺘﺮﻱ ﺭﺍ ﺑﺎ ﻧﺮﺥ ﺑﻴﺖ ﻳﻜﺴﺎﻥ ﺧﻮﺍﻫﺪ ﺩﺍﺷﺖ؟‬
‫‪-4‬ﮔﺰارش‬
‫‪ -١‬ﻛﺪﻫﺎﻱ ‪ matlab‬ﻭ ﻛﻠﻴﺔ ﻧﺘﺎﻳﺞ ﺗﺼﺎﻭﻳﺮ ﻣﻴﺎﻧﻲ ﻭ ﻧﻬﺎﻳﻲ ﺧﻮﺩ ﺭﺍ ﺗﺤﻮﻳﻞ ﺩﻫﻴﺪ‪ .‬ﺍﺭﺍﺋﻪ ﻣﺸﺎﻫﺪﺍﺕ ﻭ ﺗﻮﺿﻴﺢ ﺁﻥ ﺿﺮﻭﺭﻱ ﺍﺳﺖ‪.‬‬
‫‪ -٢‬ﺩﺭ ﻳﻚ ﺳﻴﺴﺘﻢ ﻛﺪ ﻛﺮﺩﻥ ﻭﻳﺪﺋﻮ ﻣﻌﻤﻮﻟﻲ‪ ،‬ﺍﺑﺘﺪﺍ ﺗﺨﻤﻴﻦ ﺟﺒﺮﺍﻥ ﺣﺮﻛﺖ ﺍﻧﺠﺎﻡ ﻣﻲ ﺷﻮﺩ ﻭ ﺑﻌﺪ ﺗﺼﻮﻳﺮ ﺧﻄﺎﻱ ﺗﺨﻤﻴﻦ ﺯﺩﻥ‪ ،‬ﺑﺎ ﺍﺳـﺘﻔﺎﺩﻩ ﺍﺯ‬
‫‪ ،DCT‬ﻛﺪ ﻣﻲ ﺷﻮﺩ‪ .‬ﺍﻳﻦ ﺑﺮ ﺍﺳﺎﺱ ﺍﻳﻦ ﻓﺮﺽ ﺍﺳﺖ ﻛﻪ ﺍﺳﺘﻔﺎﺩﻩ ﺍﺯ ﻛﺪ‪ DCT‬ﺭﻭﻱ ﺗﺼﻮﻳﺮ ﺧﻄﺎ‪ ،‬ﻧﺴﺒﺖ ﺑﻪ ﺍﻋﻤـﺎﻝ ‪ DCT‬ﺭﻭﻱ ﺗـﺼﻮﻳﺮ‬
‫ﺍﺻﻠﻲ ﺑﻄﻮﺭ ﻣﺴﺘﻘﻴﻢ‪ ،‬ﺍﺣﺘﻴﺎﺝ ﺑﻪ ﻧﺮﺥ ﺑﻴﺖ ﻛﻤﺘﺮﻱ ﺩﺍﺭﺩ‪.‬‬
‫ﺁﻳﺎ ﺍﻳﻦ ﻓﺮﺽ ﺻﺤﻴﺢ ﺍﺳﺖ؟ ﺁﻳﺎ ﻣﻲ ﺗﻮﺍﻧﻴﺪ ﺑﺎ ﺍﺳﺘﻔﺎﺩﻩ ﺍﺯ ﻳﻚ ﺑﺮﻧﺎﻣﺔ ‪ ،matlab‬ﻣﺤﺎﺳﺒﺎﺗﻲ ﺍﻧﺠﺎﻡ ﺩﻫﻴﺪ ﻛـﻪ ﺻـﺤﺖ ﭘﺎﺳـﺨﺘﺎﻥ ﺭﺍ ﻣـﺸﺨﺺ‬
‫ﻛﻨﺪ‪.‬‬
‫‪12‬‬
‫‪CE 342 – Multimedia HW# 7‬‬
‫‪H. Rabiee, Spring 2008‬‬
‫)ﻧﺘﺎﻳﺞ ﺑﺪﺳﺖ ﺁﻣﺪﻩ ﺩﺭ ﻗﺴﻤﺖ ﻫﺎﻱ ‪ ٤‬ﻭ ‪ ٥‬ﺩﺭ ﻗﺴﻤﺖ ﺁﺯﻣﺎﻳﺶ ﺭﺍ ﻣﻘﺎﻳﺴﻪ ﻛﻨﻴﺪ‪(.‬‬
‫‪ -5‬ﻣﺮاﺟﻊ‬
‫‪ -6‬ﺿﻤﺎﺋﻢ‪:‬‬
‫ﺿﻤﻴﻤﻪ اﻟﻒ‪:‬‬
‫ﺑﻠﻮك دﻳﺎﮔﺮام ﺗﺎﺑﻊ ‪encode.m‬‬
‫‪13‬‬
‫‪CE 342 – Multimedia HW# 7‬‬
‫‪H. Rabiee, Spring 2008‬‬
CE 342 – Multimedia HW# 7
H. Rabiee, Spring 2008
14
:‫ﺿﻤﻴﻤﻪ ب‬
CE 342 – Multimedia HW# 7
H. Rabiee, Spring 2008
15