Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1995-06-07
2001-03-13
Tran, Thai (Department: 2715)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C386S349000
Reexamination Certificate
active
06201924
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Microfiche Appendix
This patent disclosure includes a computer program in a microfiche appendix which has 173 total frames and 2 fiche.
2. Field of the Invention
This invention relates to editing video tape by a computer-based system which includes a random access memory device such as a disk drive. More specifically, the invention relates a method and apparatus for storing portions of video taped material on disk and using the information on the disk to edit the taped material. In one embodiment, the computer platform is a Macintosh computer.
3. Description of the Prior Art
Various methods of video tape editing are well known in the art. Traditional editing is tape-based; the editor cycles tapes back and forth on a source VCR (video cassette recorder) or VTR (video tape recorder) to find the scene that he means to edit. He positions the record (destination) tape on the record (destination) VCR to receive the scene from the source tape. Then the scene from the source tape is recorded on the record tape; this process is repeated for each successive scene. This linear process requires constant cycling of tapes.
Also known is disk-based editing wherein a computer system including a random storage rotating memory device such as a hard disk drive, optical, or magneto-optical disk drive. All the video material is stored on a disk drive controllable by a computer used as an editor. Then random access of the disk via the computer finds any frame in the stored video material virtually instantaneously. The computer keeps track of all the edit and record frames for the entire production. When the edit decisions of the program are completed, the editor inserts source tapes in one or more VTR's and a new record tape into the record VCR and the computer executing the edit decision list created when using the disk video records the entire edited program onto the tape. Disk-based editing is fast, easy, and vastly reduces tape handling and is currently used by professional editing companies and movie studios.
However, even with such professional systems, the problem remains that a disk drive can only store a very short amount of video material. Typically, 300 megabytes or more of disk storage are needed to edit even a relatively short 10 minute program or film. Also, fast access disks (such as 16 milliseconds or less) are needed. This prohibits use of typical magneto-optical disks. Thus the disk-based systems are expensive and need large amounts of disk storage.
Additionally, disk-based editing typically requires logging the video material from the tape onto the disk which is a separate and time consuming step. This step is especially problematic when many hours of video material are available, such as when editing a film in which typically 10 to 20 times as much material is recorded as is needed for the final production. In this case, disk-based editing is virtually impossible except for short segments of the project. For instance, it requires 22 megabytes of disk capacity to store one minute of highly compressed source video. One hour of source video therefore requires approximately 1.3 gigabytes of storage. Thus even a very expensive disk-based system is not capable of storing a large amount of video recorded material. Without compression of the video, the cost of disk storage would rise dramatically. One commercial system costing $60,000 stores only 25 seconds of uncompressed video. The effects of compression result in significantly degrading the quality of the video signal to the point of making it impossible to make critical edit decisions.
Therefore, the prior art systems suffer from the deficiency in the on-line system using physical tapes of having very slow access times, and in the case of the off-line disk-based systems, of being quite expensive and also only allowing the editor to work with a limited amount of video material at any one time and with reduced video quality. Additionally, the disk-based systems have the deficiency of requiring a separate step of logging the video material onto the disk and then after editing of generating an edit list and using that to edit the actual video tape.
SUMMARY OF THE INVENTION
In accordance with the present invention, a disk-assisted editing system and method is provided. The computer system including a mass storage device such as a disk drive used for interactive editing of video material caches that portion of the information which is in use from video tape to the disk. Actual editing of the tape is done by an edit decision list generated by the computer. “Video” optionally includes audio, and can include just audio, excluding the video.
In one embodiment, the material from the tape as it is viewed by the editor is automatically logged on to the disk by an algorithm which determines that only a portion of each scene i.e., typically a few seconds at the beginning and end of each scene, are stored on disk. Optionally, all of certain scenes is stored on the disk. Also provided is a “least-used” algorithm for conserving disk space by removing from the disk those scenes or portions of scenes not in current use. The original taped material is always available by means of tape recorders connected to and controlled by the computer system. The video material is reclaimed from the tape as needed.
The video information recorded on a disk is in one embodiment stored by means of conventional video compression techniques, so as to conserve disk space. This is not a problem because the original video information is accessible at all times from the tapes which as discussed above are kept on video tape recorders connected to the computer. Thus the disk is a “virtual VTR”, because to the editor it appears that he is using a physical VTR in terms of the editing and VTR controls. Also provided in addition to standard full-motion video are graphics, still frame video, and audio. All of these may be edited. One embodiment of the invention uses a conventional Macintosh computer as a platform with additional hardware for interfacing and controlling the VTRs and viewing the video material.
In one embodiment of the invention, in addition to use of a conventional magnetic disk drive for interactive editing, a magneto-optical disk drive (capable of being removed from the computer for storage and transportability unlike larger magnetic disk drives but with slower access speeds) or local area networks, such as Ethernet and Apple Talk are intermediary storage devices between the magnetic disk drive and the physical video tapes. The slower drives and networks automatically display more time compressed video (i.e. 10 frame per second vs. 30 frame per second video). Alternatively one can use the slower drives or networks to feed faster disk drives (as a back-ground or batch process) that can keep up with the 30 frames per second display rate.
In accordance with the invention, the computer effectively stores pointers to particular video frames denoted by conventional SMPTE time codes on the video tapes. The pointers act as a computer data base and are manipulated as is a conventional computer data base to perform editing tasks.
Thus advantageously the system allows caching of information back and forth between the relative high access speed, low capacity magnetic disk and the low access speed, high capacity video tapes to allow interactive editing at high speed while maintaining the highest possible video quality, with the actual high quality video material at all times remaining available on the video tapes. The system compiles an edit list so it is possible to go back to the actual tapes to assemble the file material. The video tape recorders are physically connected to the computer so that information from them may be drawn upon as desired during the actual editing process. Thus the system simultaneously has both (1) an on-line capability for executing an edit list recording information from source tape to record tape; and (2) an off-line capability for only creating the edit list but not recording high quality video from source tape
Crane Stephen E.
Heringer LeeAnn
Mayer Steven T.
Ogrinc Michael A.
Raitzer Gerald A.
Adobe Systems Incorporated
Fish & Richardson P.C.
Tran Thai
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