Adobe 65021048 User Guide - Page 389

ADOBE PREMIERE PRO CS3 383 User Guide About MPEG MPEG is the name of a family of file formats specified by the ISO/IEC Moving Picture Experts Group. MPEG formats include several compression methods. It requires significant processing power and time to generate these keyframe-based file formats from other video formats. MPEG-1 Generally used for the Internet and CD-ROM, providing picture quality comparable with VHS quality at quarter-screen frame size. MPEG-2 Delivers higher quality video than MPEG-1. A specific form of MPEG-2 was chosen as the standard for compressing video for DVD video. This is called DVD-compliant MPEG-2. MPEG-2 compression is also used in HDV, and supported in the HD-DVD, and Blu-ray formats. MPEG-4 Includes many of the features of MPEG-1 and MPEG-2, and adds support for interactivity. It offers better compression and reduces file size while maintaining the same perceptual quality level as MPEG-2. MPEG-4 part 10 (H.264, AVC) is the supported by the Blu-ray and HD-DVD formats. After Effects and Adobe Premiere Pro offer a number of MPEG presets to optimize the output quality for various project types. If you're experienced with MPEG encoding, you can further fine-tune projects for specific playback situations by customizing the presets in the Export Settings dialog box. In After Effects, you can create MPEG-2 and MPEG-2 DVD video. In Adobe Premiere Pro, you can create various types of MPEG video by using the File > Export > Adobe Media Encoder command or export directly to DVD-compliant video by using the Export To Encore command (any video you export to DVD is automatically transcoded to MPEG-2 if it isn't already in that format). After Effects and Adobe Premiere Pro add metadata to MPEG-2 files that Encore can read for aid in authoring and building DVDs. This metadata contains information that enables Encore to multiplex audio and video, automatically generate DVD chapter points, and open clips in the applications from which they were rendered. For more information, see Encore Help. Add XMP metadata to an exported file Metadata is descriptive file information that can be searched and processed by a computer. Adobe's eXtensible Metadata Platform (XMP) lets you include metadata with a file to provide information about the contents of the file. Applications that support XMP can read, edit, and share this information across databases, file formats, and platforms. Some Adobe software, such as Adobe Bridge, can use or write XMP information. You can specify XMP metadata to be included with files you export using the Adobe Media Encoder. ❖ In the Export Settings dialog box, select XMP Info on the settings tab menu, and then enter information in the appropriate fields. Understanding video compression, file size, and data rate Recording video and audio to a digital format involves balancing quality with file size and data rate. Most formats use compression to reduce file size and data rate by selectively reducing quality. Without compression, a single frame of standard-definition video takes up nearly 1 MB (megabyte) of storage. At the NTSC frame rate of approximately 30 frames per second, uncompressed video plays at nearly 30 MB per second, and 45 seconds of footage takes up about 1 GB of storage. By comparison, an NTSC file compressed in DV format fits 5 minutes of footage into 1 GB of storage at a data rate of about 3.6 MB per second. When compressing video for distribution at the highest possible quality, select the smallest compression ratio that delivers video within the file size and data rate constraints of your target delivery media and playback devices. April 1, 2008