[...]... could be packaged as an interactive presentation and downloaded in the background If this is cached on a local hard disk, it will always be available on demand, at an instant’s notice An updated copy can be delivered in the background as often as needed Similar services can be developed around airline flight details, traffic conditions, and sports results 15 16 A Practical Guide to Video and Audio Compression. .. challenging at first, but after a little experimentation and a look at the practical encoding chapter, it should all fall into place By the end of the book, you should have a good idea of how to build a small, medium, or large compression system from the available hardware components and software applications 14 A Practical Guide to Video and Audio Compression No doubt you will be tempted to start... To maintain a comfortable size and weight for portable use, the storage capacity in terms of hardware has very strict limits Video compression increases the capacity and thus the recording time available by condensing the data before recording takes place Current practice is to shoot on a small DV camera, edit the footage on a laptop, and then send it back to base via a videophone or satellite transceiver... from Gerry Anderson Productions; Guan at Etiumsoft; Jim Cooper at MOTU; David Carew-Jones, Anna Davidson, and Paul Dubery at Tektronix; Diogo Salari at DPI Productions; the folks at M -Audio; the Sales Web team at Apple Computer; Grant Petty and Simon Hollingworth at Black Magic Design; Julie Aguilar of ADC Telecommunications; Victoria Battison of AJA Video Systems; and Amanda Duffield of Pace Micro... The quality will clearly not be the same as that from a studio camera, but it is surprisingly good even though a high compression ratio is used Trials are underway to determine whether useful results can be obtained with a PDA device fitted with a video camera and integral mobile phone to send the material back to 20 A Practical Guide to Video and Audio Compression Figure 2-4 PDA video player prototype... sophisticated geometrical arrangements It is now feasible to fit video into the traditional banner advertising rectangles that have a very different aspect ratio from normal video Creating the content may need to be done using video editing tools that allow non-standard raster sizes to be used More information about these standard sizes is available at the Interactive Advertising Bureau Web site Interactive... bumps along the way as you try your hand at video compression These will manifest themselves in a particularly difficult -to- encode video 10 A Practical Guide to Video and Audio Compression sequence You will no doubt have a limited bit rate budget and the complexity of the content may require more data than you can afford to send So you will have to trade off some complexity to reduce the bandwidth requirements... frame That leads to loss of quality and a blocky appearance Judging the right setting is difficult, because certain content compresses more easily, while other material creates a spike in the bit rate required That spike can be allowed to momentarily absorb a higher bit rate, in which case the quality will stay the same Alternatively, you can cap the bit rate that is available If you cap the bit rate,... easier to use A film crew used to typically include a sound engineer, cameraperson, and producer, as well as the journalist being filmed These days, the camera is very likely carried by the journalist and is set up to operate automatically Broadcast news coverage is being originated on videophones, mini-cams, and videoenabled mobile-phone devices The quality of these cameras is rapidly improving To. .. open standards helps to reach a wider audience Beware of situations where a specific player is mandated This is either because you have chosen a proprietary codec or because the open standard is not supported correctly That may be accidental or purposeful Companies that manufacture encoders and players will sometimes advertise that they support an open standard but then deliver it inside a proprietary . Web team at Apple Computer; Grant Petty and Simon Hollingworth at Black Magic Design; Julie Aguilar of ADC Telecommunications; Victoria Battison of AJA Video Systems; and Amanda Duffield of Pace. capital items of equipment that only major broadcasters and production companies could afford. To think that now the same capability is available in a laptop that you can buy off the shelf and. 3/17/05 10:51 AM Page ii A Practical Guide to Video and Audio Compression From Sprockets and Rasters to Macroblocks Cliff Wootton Focal Press is an imprint of Elsevier AMSTERDAM • BOSTON • HEIDELBERG