Technical Merits To Reduced Resolution
In 1998 ABC Television made available the "Frequently Asked Questions" document in regards to HDTV standard, chosen by the company, which was 720p. One of the questions, titled "Which scanning standard is best suited for future?" contained the following information:
The 1080 x 1920 (1080I) interlace format specified in the ATSC standard CANNOT be compressed to fit in a 6MHz channel without creating objectionable artifacts and it has been recommended that the 1920 pixels be sub-sampled to 1440 to reduce compression artifacts. Therefore, encoder manufacturers have elected to discard approximately 25% of the picture for over-the-air transmission.
—
Besides subsampling that occurs during broadcast, many professional video recording formats do not deliver full horizontal resolution as well. For example, frame size of 1080-line HDCAM format is 1440x1080, frame size of 1080-line DVCPRO HD format is either 1440x1080 or 1280x1080 depending on scanning rate, frame size of 720-line DVCPRO HD format is 960x720. Horizontal downsampling is used in preference to vertical downsampling because vertical downsampling would break any interlacing, and also because Cathode Ray Tube (CRT) displays (which were still common when the HD formats were standardised) scan horizontal rows continuously, but vertical lines discretely, making changes to vertical resolution more visible on such displays. The situation has begun to change with launch of newer video recording formats that use full 1920x1080 raster, like XDCAM HD422 or AVC-Intra.
New encoding schemes allow reducing data rate even further. For example, MPEG-4/AVC is considered to be twice as efficient as MPEG-2, originally used for HD broadcast.
Read more about this topic: HD Lite
Famous quotes containing the words technical, merits, reduced and/or resolution:
“I rather think the cinema will die. Look at the energy being exerted to revive it—yesterday it was color, today three dimensions. I don’t give it forty years more. Witness the decline of conversation. Only the Irish have remained incomparable conversationalists, maybe because technical progress has passed them by.”
—Orson Welles (1915–1984)
“This letter will be delivered to you by my child,—the child of my adoption,—my affection! Unblest with one natural friend, she merits a thousand. I send her to you innocent as an angel, and artless as purity itself; and I send you with her the heart of your friend, the only hope he has on earth, the subject of his tenderest thoughts, and the object of his latest cares.”
—Frances Burney (1752–1840)
“I’ve tried to reduce profanity but I reduced so much profanity when writing the book that I’m afraid not much could come out. Perhaps we will have to consider it simply as a profane book and hope that the next book will be less profane or perhaps more sacred.”
—Ernest Hemingway (1899–1961)
“The changes in our life must come from the impossibility to live otherwise than according to the demands of our conscience ... not from our mental resolution to try a new form of life.”
—Leo Tolstoy (1828–1910)