Wide-band multi-format audio/video production system with frame-rate conversion
A multi-format digital video production system enables a user to process an input video program to produce an output version of the program in a final format which may have a different frame rate, pixel dimensions, or both. An internal production format of 24 fps is preferably chosen to provide the greatest compatibility with existing and planned formats associated with HDTV standard 4:3 or widescreen 16:9 high-definition television, and film. Images are re-sized horizontally and vertically by pixel interpolation, thereby producing larger or smaller image dimensions so as to fill the particular needs of individual applications. Frame rates are adapted by inter-frame interpolation or by traditional schemes, including “3:2 pull-down” for 24-to-30 fps conversions. Simple speed-up (for 24-to-25 conversions) or slow-down (for 25-to-24 conversions) for playback, or by manipulating the frame rate itself using a program storage facility with asynchronous reading and writing capabilities. The step of converting the signal to a HDTV format is preferably performed using a modified upconversion process for wideband signals (utilizing a higher sampling clock frequency) and a resizing to HDTV format frame dimensions in pixels.
1. A method of processing an audio/video program to output a modified version of the program, comprising the steps of:
receiving an input video program in a first interlaced format having no added redundant frames or fields;
de-interlacing the input video program to generate a video program in a first progressive format comprising a sequence of progressive frames, each progressive frame being derived from a respective one, and only one, of the fields in the first interlaced format;
removing or repeating some of the frames of the video program in the first progressive format to generate a program in an intermediate progressive format; and
re-interlacing the program in the intermediate progressive format to output the program in a second interlaced format.
2. The method of claim 1 , wherein the first interlaced format is NTSC or HDTV at 30 fps interlaced.
3. The method of claim 2 , wherein the second interlaced format is PAL or HDTV at 25 fps interlaced.
4. The method of claim 1 , wherein the first interlaced format is PAL or HDTV at 25 fps interlaced.
5. The method of claim 2 , wherein the second interlaced format is NTSC or HDTV at 30 fps interlaced.
6. The method of claim 1 , further including a buffer for buffering the video program after it has been converted into the first progressive format.
7. The method of claim 6 , wherein the first interlaced format is NTSC or HDTV at 30 fps.
8. The method of claim 7 , wherein the second interlaced format is PAL or HDTV at 25 fps.
9. The method of claim 6 , wherein the first interlaced format is PAL or HDTV at 25 fps.
10. The method of claim 9 , wherein the second interlaced format is NTSC or HDTV at 30 fps.
11. The method of claim 6 , further including circuitry for varying the rate at which the video program in the first progressive format is output in the second interlaced format, in conjunction with the removal or repetition of frames in the first progressive format.
12. The method of claim 11 , wherein the first interlaced format is NTSC or HDTV at 30 fps.
13. The method of claim 12 , wherein the second interlaced format is PAL or HDTV at 25 fps.
14. The method of claim 11 , wherein the first interlaced format is PAL or HDTV at 25 fps.
15. The method of claim 14 , wherein the second interlaced format is NTSC or HDTV at 30 fps.
16. The method of claim 1 , wherein the first interlaced format is 24 fps.
17. The method of claim 6 , wherein the second interlaced format is 24 fps.
18. The method of claim 11 , wherein the second interlaced format is 24 fps.