Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1997-08-01
2001-11-27
Garber, Wendy R. (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C386S349000
Reexamination Certificate
active
06324337
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus and technique for speeding up the playback of digitally recorded audio without changing pitch and optionally skipping over those sections of the audio which are below a given loudness threshold so as to be able to play the audio much faster, perhaps as much as 10 times faster, than the normal rate, and to use this feature in a video recorder.
BACKGROUND OF THE INVENTION
The vast majority of video tape recorders (VTRs) in use today are analog machines which record video (and accompanying audio) on tape, so that the playback of that video must be sequential. While digital VTRs may come into wide use shortly, it is more likely that random access media such as computer hard drives will replace current VTRs because of the advantages provided by random access.
U.S. Pat. No. 5,241,428 of the present inventor discloses a BVR (Buffered Video Recorder) which digitally records (buffers) video on a random access medium so that a previously stored portion of a program can be played from the buffer while the currently broadcasting portion of the program is simultaneously recorded. In one of the modes of operation of the BVR the viewer can speed the playback of portions of the material to be played-back from the buffer in order to “catch up” with the live broadcast. In another mode the viewer can playback portions of the buffered material in slow motion to do an instant replay. While conventional VTRs permit the video portion of recorded video with audio to be “speed-searched”, i.e. viewed at many times real time (typically 9 or more times real time), they do not play the audio portion while the video is being speed-searched, because the audio would change pitch and would therefore be impossible to understand. Similarly, when video with audio is played at a slower speed than it was recorded at, the pitch will change. It becomes impossible to understand speech when the playback rate is even one half the normal rate.
A new speech compression technology is now available from Voxware Inc. of Princeton, N.J., that permits digitized speech to be played at any speed from ⅕ to 5 times real time without a change of pitch. But at about 3 times real time the audio is likely to be too fast to understand if every word is played.
OBJECTS OF THE INVENTION
One object of the current invention is to use audio compression technology such as Voxware's to permit playback of understandable audio (that is primarily speech) as well as video, at low speed search rates of less than
5
times real time, and at slow motion rates that are less than real time.
Another object of the current invention is to permit the audio portion of recorded video to be played at higher speed-search rates by playing only certain portions of the audio that have high energy or other special distinguishing characteristics, and skipping portions that have low energy or lack the aforementioned characteristics. In this mode the listener would hear key words and phrases that will enable him/her to discern the subject matter.
Another object of the current invention is to allow a user of the BVR to watch and listen to the buffered video at a rate somewhat faster than real time without a change of pitch, so the user can catch up to the live broadcast while watching and listening to portions of the video that are of interest.
Another object of the current invention is to provide an inexpensive device similar to a BVR that can buffer only the audio portion of a video broadcast (that is primarily speech) and then play it back at a rate greater than real time without a change of pitch while simultaneously recording the audio portion of the currently broadcasting video. With this device a viewer who is interrupted while watching (and listening) to a video broadcast will be able to return from the interruption and listen to the buffered audio at a rate several times real time so as to catch up to the live broadcast. For example, if the viewer listens to the buffered audio at 2 times real time, the viewer will catch up to the live broadcast after a period of time equal to the duration of the interruption.
Another object of the current invention is to allow a user of the BVR to simultaneously record two programs and watch them at an accelerated rate so as to be able to watch both programs in the time interval of the actual broadcast.
SUMMARY OF THE INVENTION
These objects are achieved, according to the present invention, by recording the audio portion of the video with audio signal in a random access memory area that is separate from the area where the video is recorded. Then the audio is subjected to a compression step that extracts features of human speech. When the user directs the audio to be played back at a given rate, the speech-time-warper program uses the extracted features to play the audio at the rate specified by the user via the control panel and from the address in RAM (random access memory) that corresponds with the video portion that the user selects via the control panel.
If the user specifies a rate of playback which would make it difficult or impossible to understand every word, then the time warper program plays only selected sections of the audio which have been identified in the compression step as having greater energy or other characteristics that may indicate that they contain key words, and skips over other sections of the audio so as to play the key word sections at a rate that is understandable.
REFERENCES:
patent: 5161019 (1992-11-01), Emanuel
patent: 5241428 (1993-08-01), Goldwasser et al.
patent: 5386493 (1995-01-01), Degen et al.
patent: 5809454 (1998-09-01), Okada et al.
Garber Wendy R.
Onuaku Christopher
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