VIDEO PLAYBACK DEVICE FOR VARIABLE SPEED PLAY BACK OF PRE-RECORDED VIDEO WITHOUT PITCH DISTORTION OF AUDIO

Abstract: There is disclosed, for use in a video playback device for playing back a video program in fast forward mode and slow mode on a television set coupled to the video playback device, an apparatus for playing back an audio track associated with the video program during the fast forward mode and the slow mode. The apparatus comprises: 1) a video playback controller for receiving a user input command indicating a relative amount of acceleration of the video program during the fast forward mode; 2) an audio processor for receiving the audio track and compressing a duration of the audio track with minimal pitch distortion, wherein the compression is proportional to the relative amount of acceleration of the video program; and 3) a video processor coupled to audio processor for receiving the compressed audio track and capable of receiving an accelerated video signal associated with the video program during the fast forward mode, wherein the video processor transmits the compressed audio track and the accelerated video signal in synchronization to the television set.

Description: Video playback device for variable speed play back of pre-recorded video without pitch distortion of audio The present invention is directed, in general, to video playback devices and, more specifically, to a system for playing back video in fast forward mode and slow mode without pitch distortion of the audio track. A wide variety of video playback devices are available in the marketplace. Most people own, or are familiar with, a video cassette recorder (NCR), also referred to as a video tape recorder (VTR). More recently, video recorders that use computer magnetic hard disks rather than magnetic cassette tapes to store video programs have appeared in the market. For example, the ReplayTV recorder and the TiNO recorder digitally record television programs on hard disk drives using, for example, MPEG-2 compression. Additionally, some video playback devices may record on a readable/writable digital versatile disk (DND) rather than a magnetic disk. Virtually all the systems that are capable of playing video programs have fast forward and rewind features, with some systems having variable forward and rewind speeds. During the fast forwarding of a video program, the audio portion of the video program is usually muted. As is well known in the art, increasing or decreasing the speed of a video program, whether rewinding or forwarding, causes distortion in the audio. This is due to the fact that audio cannot be easily sub-sampled. There are methods for speeding up the playback of speech by 50% with minimal effect on quality. However, this is not sufficient for high speed play modes and non-speech segments of the audio track. There is therefore a need in the art for an apparatus for playing back an audio track, with minimal pitch distortion, associated with the video program during the fast forward mode and the slow mode. To address the above-discussed deficiencies of the prior art, it is a primary object of the present invention to provide, for use in a video playback device capable of playing back a video program, in fast forward mode and slow mode, on a television set coupled to the video playback device, an apparatus for playing back an audio track associated with the video program during the fast forward mode and the slow mode. According to an advantageous embodiment of the present invention, the apparatus comprises: 1) a video playback controller capable of receiving a user input command indicating a relative amount of acceleration of the video program during the fast forward mode; 2) an audio processor capable of receiving the audio track and compressing a duration of the audio track with minimal pitch distortion, wherein the compression is proportional to the relative amount of acceleration of the video program; and 3) a video processor coupled to audio processor capable of receiving the compressed audio track and capable of receiving an accelerated video signal associated with the video program during the fast forward mode, wherein the video processor transmits the compressed audio track and the accelerated video signal in synchronization to the television set. According to one embodiment of the present invention, the video playback controller is capable of receiving a user input command indicating a relative amount of deceleration of the video program during the slow mode and the audio processor is capable of expanding a duration of the audio track with minimal pitch distortion, wherein the expansion is proportional to the relative amount of deceleration of the video program. According to another embodiment of the present invention, the video processor is capable of receiving the expanded audio track and a decelerated video signal associated with the video program during the slow mode, wherein the video processor transmits the expanded audio track and the decelerated video signal in synchronization to the television set. According to still another embodiment of the present invention, the apparatus further comprises a memory coupled to the audio processor capable of storing executable instructions associated with at least one compression algorithm. According to yet another embodiment of the present invention, the memory is capable of storing executable instructions associated with at least one expansion algorithm. The foregoing has outlined rather broadly the features and technical advantages of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features and advantages of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they may readily use the conception and the specific embodiment disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form. Before undertaking the detailed description, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms "include" and "comprise," as well as derivatives thereof, mean inclusion without limitation; the term "or," is inclusive, meaning and/or; the phrases "associated with" and "associated therewith," as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term "controller" means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. In particular, a controller may comprise one or more data processors, and associated input/output devices and memory, that execute one or more application programs and/or an operating system program. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases. For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, wherein like numbers designate like objects, and in which: Fig. 1 illustrates an exemplary video playback device and a television set according to one embodiment of the present invention; Fig. 2 illustrates in greater detail the exemplary video playback device according to one embodiment of the present invention; and Fig. 3 is a flow diagram illustrating the operation of the exemplary video playback device according to one embodiment of the present invention. Figs. 1 through 3, discussed below, and the various embodiments used to describe the principles of the present invention in this patent document are by way of illustration only and should not be construed in any way so as to limit the scope of the invention. Those skilled in the art will understand that the principles of the present invention may be implemented in any suitably arranged video playback device. Fig. 1 illustrates exemplary video playback device 150 and television set 105 according to one embodiment of the present invention. Video playback device 150 receives incoming television signals from an external source, such as a set-top box of a cable television service provider (Cable Co.) or the phone company, a local antenna, the Internet, or an attached DVD or VHS tape player, and transmits a viewer-selected channel to television set 105. In record mode, video playback device 150 may demodulate an incoming radio frequency (RF) television signal to produce a baseband video signal that is recorded and stored on a storage medium within or connected to video playback device 150. In PLAY mode, video playback device 150 reads a stored baseband video signal (i.e., program) selected by the user from the storage medium and transmits it to television set 105. For example, if video playback device 150 is a video cassette recorder (VCR), also referred to as a video tape recorder (VTR), video playback device 150 stores and retrieves the incoming television signals to and from a magnetic cassette tape. If video playback device 150 is a disk drive-based device, such as a ReplayTV recorder or a TiVO recorder, video playback device 150 stores and retrieves the incoming television signals to and from a computer magnetic hard disk rather than a magnetic cassette tape. In still other embodiments, video playback device 150 may store and retrieve from a local read/write (R/W) digital versatile disk (DVD) or R/W CD-ROM. Thus, the local storage medium may be fixed (i.e., hard disk drive) or removable (i.e., DVD, CD-ROM, VCR tape). Video playback device 150 comprises infrared (IR) sensor 160 that receives commands (such as Channel Up, Channel Down, Volume Up, Volume Down, Record, Play, Fast Forward (FF), Reverse, and the like) from a remote control device operated by the viewer. Television set 105 is a conventional television comprising screen 110, infrared (IR) sensor 115, and one or more manual controls 120 (indicated by a dotted line). IR sensor 115 also receives commands (such as volume up, volume down, power ON/OFF) from a remote control device operated by the viewer. It should be noted that video playback device 150 is not limited to receiving a particular type of incoming television signal from a particular type of source. As noted above, the external source may be a cable service provider, a conventional RF broadcast antenna, a satellite dish, an Internet connection, or another local storage device, such as a DVD player or a VHS tape player. In some embodiments, video playback device 150 may not even be able to record, but may be limited to playing back television signals that are retrieved from a removable DVD or CD-ROM. Thus, the incoming signal may be a digital signal, an analog signal, or Internet protocol (IP) packets of any other communication protocol. However, for the purposes of simplicity and clarity in explaining the principles of the present invention, the descriptions that follow shall generally be directed to an embodiment in which video playback device 150 receives incoming television signals (analog and/or digital) from a cable service provider. Nonetheless, those skilled in the art will understand that the principles of the present invention may readily be adapted for use with wireless broadcast television signals, local storage systems, an incoming stream of IP packets containing MPEG data, and the like. Fig. 2 illustrates exemplary video playback device 150 in greater detail according to one embodiment of the present invention. Video playback device 150 comprises IR sensor 160, video processor 210, MPEG2 encoder 220, hard disk drive 230, MPEG2 decoder/NTSC encoder 240, and video recorder (VR) controller 250. Video playback device 150 further comprises video buffer 260, audio compression/expansion processor 270, and compression/ expansion algorithms 280, which may be embodied as a memory that stores one or more of a number of well-known audio compression and audio expansion algorithms as a sequence of program instructions executed by audio compression/expansion processor 270. Audio compression and expansion techniques may be used to play back an audio signal with low pitch distortion or minimal pitch distortion. Apparatuses and methods for compressing or expanding audio signals during faster or slower playback are disclosed in United States Patent No. 5,386,493 to Degen et al., entitled "Apparatus and Method for Playing Back Audio at Faster or Slower Rates Without Pitch Distortion"; United States Patent No. 5,479,564 to Vogten et al., entitled "Method and Apparatus for Manipulating Pitch and/or Duration of a Signal"; and United States Patent No. 5,694,521 to Shlomot et al., entitled "Variable Speed Playback System." United States Patent Nos. 5,386,493, 5,479,564 and 5,694,521 are hereby incorporated by reference into the present disclosure as if fully set forth herein. In an advantageous embodiment of the present invention, one or more of the compression/expansion algorithms disclosed in United States Patent Nos. 5,386,493, 5,479,564 and 5,694,521 may be stored in compression/expansion algorithms 280 and executed by audio compression/expansion processor 270. VR controller 250 directs the overall operation of video playback device 150, including View mode, Record mode, Play mode, Fast Forward (FF) mode, Reverse mode, among others. In View mode, VR controller 250 causes the incoming television signal from the cable service provider to be demodulated and processed by video processor 210 and transmitted to television set 105, without storing or retrieving from hard disk drive 230. Video processor 210, which may be, for example, a TriMedia (TM) 1100 media processor, contains radio frequency (RF) front-end circuitry for receiving incoming television signals from the cable service provider, tuning to a user-selected channel, and converting the selected RF signal to a baseband television signal (e.g., super video signal) suitable for display on television set 105. Video processor 210 also is capable of receiving a conventional NTSC, PAL or SECAM signal from MPEG2 decoder/NTSC encoder 240 (after buffering in video buffer 260) during Play mode and transmitting baseband television signal (e.g., super video signal) to television set 105. In Record mode, VR controller 250 causes the incoming television signal to be stored on hard disk drive 230. Under the control of VR controller 250, MPEG2 encoder 220 receives the incoming television signal from the cable service provider and converts the received RF signal to MPEG format for storage on hard disk drive 230. In Play mode, VR controller 250 directs hard disk drive 230 to stream the stored television signal (i.e., program) to MPEG2 decoder/NTSC encoder 240, which converts the MPEG2 data from hard disk drive 230 to, for example, a super video (S-Video) signal that is buffered in video buffer 260 before video processor 210 transmits it to television set 105. It should be noted that the choice of the MPEG2 standard for MPEG2 encoder 220 and MPEG2 decoder/NTSC encoder 240 is by way of illustration only. In alternate embodiments of the present invention, the MPEG encoder and decoder may comply with one or more of the MPEG-1, MPEG-2, MPEG-4, and MPEG-7 standards. For the purposes of this application and the claims that follow, hard disk drive 230 is defined to include any mass storage device that is both readable and writable, including conventional magnetic disk drives, magnetic tapes for a video cassette recorder (VCR) or video tape recorder (NTR), and optical disk drives for read/write digital versatile disks (DVD-RW), re-writable CD-ROMs, and the like. In fact, hard disk drive 230 need not be fixed in the conventional sense that is permanently embedded in video playback device 150. Rather, hard disk drive 230 includes any mass storage device that is dedicated to video playback device 150 for the purpose of storing recorded video and audio programs. Thus, hard disk drive 230 may include an attached peripheral drive or removable disk drives (whether embedded or attached), such as a juke box device that holds read/write DVDs or rewritable CD-ROMs. Furthermore, in an advantageous embodiment of the present invention, hard disk drive 230 may include external mass storage devices that video playback device 150 may access and control via a network connection (e.g., Internet protocol (IP) connection), including, for example, a disk drive in the user's home personal computer (PC) or a disk drive on a server at the user's Internet service provider (ISP). During Play mode, VR controller 250 may receive a Fast Forward (FF) command from a user via IR sensor 160. In FF mode, video playback device 150 is capable of playing selected portions of the audio signal with minimum pitch distortion using video buffer 260, audio compression/expansion processor 270, and compression expansion algorithm 280. When a FF command is received, VR controller 250 causes hard disk drive 230 and MPEG2 decoder/NTSC encoder 240 to play video at a faster forward speed. However, VR controller 250 also directs video processor 210 to stop receiving the audio output of MPEG2 decoder/NTSC encoder 240 as a source of the audio signal. Instead, video processor 210 is switched to receive the audio signal from the output of audio compression/expansion processor 270 as the source of the audio signal. Fig. 3 depicts flow diagram 300, which illustrates the operation of exemplary video playback device 150 according to one embodiment of the present invention. A fast forward or slow mode input command is received during play mode by VR controller 250. VR controller 250 determines the rate of acceleration or deceleration from the user input (process step 305). As the playback rate speeds up or slows down, a duration of the audio track is compressed with minimal pitch distortion. The corresponding video is buffered in video buffer 260. The compression is directly proportional to the relative amount of acceleration or deceleration of the video program (process step 310). The process continues wherein the audio track from the played back video is received by audio compression/expansion processor 270. Audio is expanded for slow play and compressed for fast forward mode. Expansion or compression is proportional to the rate of deceleration or acceleration selected by the user (process step 315). Compressed or expanded audio is transferred to a television set, in synchronization with a corresponding portion of fast forward or slow play video from video buffer 260 (process step 320). Audio compression/expansion algorithms are utilized to adjust the audio signal according to the playback rates. As the playback rate increases, audio compression increases. As the playback rate decreases, the algorithms cause the compression rate to decrease. As the playback rate slows below normal, the audio expansion rate increases. The rates of audio compression and expansion are directly proportional to the playback speeds. Although the present invention has been described in detail, those skilled in the art should understand that they can make various changes, substitutions and alterations herein without departing from the spirit and scope of the invention in its broadest form.

Claims: CLAIMS: 1. For use in a video playback device (150) capable of playing back a video program in fast forward mode and slow mode on a television set (105) coupled to said video playback device (150), an apparatus for playing back an audio track associated with said video program during said fast forward mode and said slow mode, said apparatus comprising: - a video playback controller (250) capable of receiving a user input command indicating a relative amount of acceleration of said video program during said fast forward mode; - an audio processor (270) capable of receiving said audio track and compressing a duration of said audio track with minimal pitch distortion, wherein said compression is proportional to said relative amount of acceleration of said video program; and - a video processor (210) coupled to audio processor (270) capable of receiving said compressed audio track and capable of receiving an accelerated video signal associated with said video program during said fast forward mode, wherein said video processor (210) transmits said compressed audio track and said accelerated video signal in synchronization to said television set (105). 2. The apparatus as set forth in Claim 1 wherein said video playback controller (250) is capable of receiving a user input command indicating a relative amount of deceleration of said video program during said slow mode and said audio processor (270) is capable of expanding a duration of said audio track with minimal pitch distortion, wherein said expansion is proportional to said relative amount of deceleration of said video program. 3. The apparatus as set forth in Claim 2 wherein said video processor (210) is capable of receiving said expanded audio track and a decelerated video signal associated with said video program during said slow mode, wherein said video processor (210) transmits said expanded audio track and said decelerated video signal in synchronization to said television set (105). 4. The apparatus as set forth in Claim 3 wherein said apparatus further comprises a memory coupled to said audio processor (270) capable of storing executable instructions associated with at least one compression algorithm. 5. The apparatus as set forth in Claim 4 wherein said memory is capable of storing executable instructions associated with at least one expansion algorithm. 6. A video playback device (150) capable of playing back video programs in fast forward mode and slow mode on a television set (105) coupled to said video playback device (150), said video playback device (150) comprising: - a magnetic disk drive (230) capable of storing thereon a plurality of video programs; - a video playback controller (250) capable of receiving a user input command indicating a relative amount of acceleration of a first selected video program to be played back during said fast forward mode; -an audio processor (270) capable of receiving an audio track associated with said first selected video program and compressing a duration of said audio track with minimal pitch distortion, wherein said compression is proportional to said relative amount of acceleration of said first selected video program; and - a video processor (210) coupled to audio processor (270) capable of receiving said compressed audio track and capable of receiving an accelerated video signal associated with said first selected video program during said fast forward mode, wherein said video processor (210) transmits said compressed audio track and said accelerated video signal in synchronization to said television set (105). 7. The video playback device (150) as set forth in Claim 6 wherein said video playback controller (250) is capable of receiving a user input command indicating a relative amount of deceleration of said video program during said slow mode and said audio processor (270) is capable of expanding a duration of said audio track with minimal pitch distortion, wherein said expansion is proportional to said relative amount of deceleration of said video program. 8. The video playback device (150) as set forth in Claim 7 wherein said video processor (210) is capable of receiving said expanded audio track and a decelerated video signal associated with said video program during said slow mode, wherein said video processor (210) transmits said expanded audio track and said decelerated video signal in synchronization to said television set (105). 9. The video playback device (150) as set forth in Claim 8 wherein said apparatus further comprises a memory coupled to said audio processor (270) capable of storing executable instructions associated with at least one compression algorithm. 10. The video playback device (150) as set forth in Claim 9 wherein said memory is capable of storing executable instructions associated with at least one expansion algorithm. 11. A video playback device (150) capable of playing back video programs in fast forward mode and slow mode on a television set (105) coupled to said video playback device (150), said video playback device (150) comprising: - a video cassette drive capable of receiving a video cassette tape and retrieving a first selected video program stored on said video cassette tape; - a video playback controller (250) capable of receiving a user input command indicating a relative amount of acceleration of said first selected video program to be played back during said fast forward mode; - an audio processor (270) capable of receiving an audio track associated with said first selected video program and compressing a duration of said audio track with minimal pitch distortion, wherein said compression is proportional to said relative amount of acceleration of said first selected video program; and - a video processor (210) coupled to audio processor (270) capable of receiving said compressed audio track and capable of receiving an accelerated video signal associated with said first selected video program during said fast forward mode, wherein said video processor (210) transmits said compressed audio track and said accelerated video signal in synchronization to said television set (105). 12. The video playback device (150) as set forth in Claim 11 wherein said video playback controller (250) is capable of receiving a user input command indicating a relative amount of deceleration of said video program during said slow mode and said audio processor (270) is capable of expanding a duration of said audio track with minimal pitch distortion, wherein said expansion is proportional to said relative amount of deceleration of said video program. 13. The video playback device (150) as set forth in Claim 12 wherein said video processor (210) is capable of receiving said expanded audio track and a decelerated video signal associated with said video program during said slow mode, wherein said video processor (210) transmits said expanded audio track and said decelerated video signal in synchronization to said television set (105). 14. The video playback device (150) as set forth in Claim 13 wherein said apparatus further comprises a memory coupled to said audio processor (270) capable of storing executable instructions associated with at least one compression algorithm. 15. The video playback device (150) as set forth in Claim 14 wherein said memory is capable of storing executable instructions associated with at least one expansion algorithm. 16. A video playback device (150) capable of playing back video programs in fast forward mode and slow mode on a television set (105) coupled to said video playback device (150), said video playback device (150) comprising: - a digital versatile disk (DVD) drive capable of receiving a digital versatile disk and retrieving a first selected video program stored on said digital versatile disk; - a video playback controller (250) capable of receiving a user input command indicating a relative amount of acceleration of said first selected video program to be played back during said fast forward mode; - an audio processor (270) capable of receiving an audio track associated with said first selected video program and compressing a duration of said audio track with minimal pitch distortion, wherein said compression is proportional to said relative amount of acceleration of said first selected video program; and - a video processor (210) coupled to audio processor (270) capable of receiving said compressed audio track and capable of receiving an accelerated video signal associated with said first selected video program during said fast forward mode, wherein said video processor (210) transmits said compressed audio track and said accelerated video signal in synchronization to said television set (105). 17. The video playback device (150) as set forth in Claim 16 wherein said video playback controller (250) is capable of receiving a user input command indicating a relative amount of deceleration of said video program during said slow mode and said audio processor (270) is capable of expanding a duration of said audio track with minimal pitch distortion, wherein said expansion is proportional to said relative amount of deceleration of said video program. 18. The video playback device (150) as set forth in Claim 17 wherein said video processor (210) is capable of receiving said expanded audio track and a decelerated video signal associated with said video program during said slow mode, wherein said video processor (210) transmits said expanded audio track and said decelerated video signal in synchronization to said television set (105). 19. The video playback device (150) as set forth in Claim 18 wherein said apparatus further comprises a memory coupled to said audio processor (270) capable of storing executable instructions associated with at least one compression algorithm. 20. The video playback device (150) as set forth in Claim 19 wherein said memory is capable of storing executable instructions associated with at least one expansion algorithm. 21. For use in a video playback device (150) capable of playing back a video program in fast forward mode and slow mode on a television set (105) coupled to the video playback device (150), a method of playing back an audio track associated with the video program during the fast forward mode and the slow mode, the method comprising the steps of: - receiving a user input command indicating a relative amount of acceleration of the video program during the fast forward mode; - receiving the audio track and compressing a duration of the audio track with minimal pitch distortion, wherein the compression is proportional to the relative amount of acceleration of the video program; and - transmitting the compressed audio track and an accelerated video signal in synchronization to the television set (105). 22. The method as set forth in Claim 21 further comprising the steps of: - receiving a user input command indicating a relative amount of deceleration of the video program during the slow mode; and - expanding a duration of the audio track with minimal pitch distortion, wherein the expansion is proportional to the relative amount of deceleration of the video program. 23. The method as set forth in Claim 22 further comprising the step of transmitting the expanded audio track and said decelerated video signal in synchronization to the television set (105).

Inventors: SITNIK ERAN, SITNIK, ERAN
Applicants: KONINKL PHILIPS ELECTRONICS NV, KONINKLIJKE PHILIPS ELECTRONICS N.V.
Application year: 2001
Main classification: H04N5
IPC codes: G11B20, H04N5, H04N9