CN1404690A - Video playback equipment for replaying pre-recorded video at variable speeds without audio pitch distortion - Google Patents

Abstract

An apparatus for use in a video playback device capable of playing back a video program on a television coupled to the video playback device in a fast forward mode and a slow mode, the apparatus for playing back an audio track associated with the video program during the fast forward mode and the slow mode. The device includes: 1) a video playback controller capable of receiving a user input command during fast forward mode indicating a relative amount of acceleration of the video program; 2) an audio processor capable of receiving the audio track and compressing the 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 the audio processor to receive the compressed audio track and to enable receipt of 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 to the television set in synchronization.

Description

Video playback equipment for replaying pre-recorded video at variable speeds without audio pitch distortion

The present invention relates generally to video playback devices and, more particularly, to a system for replaying video without pitch distortion of the audio track in fast-forward mode and slow-motion mode.

A wide variety of video playback devices are available in the market. Many of us own or are familiar with a Video Cassette Recorder (VCR), also known as a Video Tape Recorder (VTR). More recently, video recorders that use computer hard disks instead of cassette tapes to store video programs have appeared on the market. Examples include ReplayTV VCRs or TiVO VCRs, which record television programs digitally to a hard drive using, for example, MPEG-2 compression. Additionally, some video playback devices record on readable/writable digital versatile discs (DVD) instead of magnetic disks.

Virtually all systems capable of playing video programs feature a fast-forward or rewind feature, and some of these systems have variable fast-forward and rewind speeds. During 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 fast forwarding, can cause audio distortion. This is due to the fact that audio cannot be easily subsampled. Several methods can be used to increase the speed of speech playback by 50% with minimal impact on quality. However, this is insufficient for high-speed playback modes and for non-speech segments of the audio track.

Therefore, there is a need in the art for a means of replaying audio tracks associated with a video program with minimal tonal distortion during fast forward and slow modes.

In order to overcome the above-mentioned defects in the prior art, the primary purpose of the present invention is to provide a video playback device (in fast forward mode and slow speed, the video playback device can be connected to the video playback device playback of a video program on a television set) for playback of the audio track associated with the video program during fast-forward mode and slow-motion mode. According to a preferred embodiment of the present invention, the apparatus includes: 1) a video playback controller capable of receiving user input commands indicating the relative amount of acceleration of the video program during fast-forward mode; 2) an audio processor capable of receiving an audio track and compressing the duration of the audio track with minimal tonal distortion, wherein the compression is proportional to the relative amount of acceleration of the video program; and 3) a video processor coupled to the audio processor capable of receiving the compressed audio track It is also capable of receiving accelerated video signals associated with video programs during fast-forward mode, wherein the video processor transmits the compressed audio track and the accelerated video signals to the television set synchronously.

According to one embodiment of the present invention, the video playback controller is capable of receiving user input commands during the slow mode indicating the relative amount by which the video program is slowed down, and the audio processor is capable of extending the duration of the audio track with minimal tonal distortion, wherein This expansion is proportional to the relative amount by which the video program is slowed down.

According to another embodiment of the present invention, a video processor is capable of receiving an extended audio track and a decelerated video signal associated with a video program during slow mode, wherein the video processor transmits the extended audio track and the decelerated video signal synchronously to the TV.

According to yet another embodiment of the present invention, the device further comprises a memory connected to the audio processor capable of storing executable instructions related to at least one compression algorithm.

According to another embodiment of the present invention, the memory is capable of storing executable instructions related to at least one extended algorithm.

The features and technical advantages of the present invention have been described in a very general manner above so that those skilled in the art can better understand the following detailed description of the present invention. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that they may readily use the conception and 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 scope and spirit of the invention in its broadest form.

Before carrying out the following detailed description, it is necessary to express the definition of certain words or phrases used throughout this patent document; the terms "comprising" and "comprising" and their derivatives mean including but not limiting; The term "or" is inclusive, means and/or; the phrases "in relation to" and "in relation to" and their derivatives may mean including, included in, interconnected with, comprising, included in in, connected to or connected with, coupled to or coupled with, communicable with, co-operating with, interleaved, juxtaposed, approximately, connected to or connected with, having, having the property of, etc. etc.; and the term "controller" means any device, system, or part thereof that controls at least one operation, such device may be implemented by hardware, firmware, or software, or some combination of at least two of them. 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 include one or more data processors and associated input/output devices and memory that execute one or more application programs and/or operating system programs. Throughout this patent document, where definitions for certain words or phrases are provided, those skilled in the art should understand that in many, if not most cases, these definitions also apply to the defined Past and future uses of words and phrases.

For a more complete understanding of the present invention and its advantages, reference should now be made to the following description taken in conjunction with the accompanying drawings, wherein like numerals represent like objects; and wherein:

Figure 1 shows a typical video playback device and television set according to one embodiment of the present invention;

Figure 2 shows in detail a typical video playback device according to one embodiment of the present invention; and

FIG. 3 shows a flowchart of the operation of a typical video playback device according to one embodiment of the present invention.

1-3, discussed below, and the various embodiments used to describe the principles of the invention in this patent document are by way of illustration only and should not be construed as limiting the scope of the invention in any way. Those skilled in the art will understand that the principles of the present invention may be implemented in any suitably configured video playback device.

Figure 1 illustrates an exemplary video playback device 150 and television 105 according to one embodiment of the present invention. Video playback device 150 receives an incoming television signal from an external source, which may be a cable service provider (cable company) or telephone company set-top box, a local antenna, the Internet, or an attached DVD or VHS tape player. Playback device 150 also transmits the channel selected by the viewer to television 105. In recording 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 in a storage device within or connected to video playback device 150. medium. In play mode, video playback device 150 reads a stored baseband video signal (ie, a program) selected by a user from the storage medium and transmits it to television 105 .

For example, if video playback device 150 is a video cassette recorder (VCR), also known as a video tape recorder (VTR), then video playback device 150 will store the incoming television signal on a cassette tape and Retrieves the incoming TV signal. If video playback device 150 is a disk drive based device, such as a ReplayTV recorder or TiVO recorder, then video playback device 150 will utilize a computer hard disk instead of a cassette tape to store and retrieve the incoming television signal. In other embodiments, video playback device 150 may utilize a local read/write (R/W) digital versatile disc (DVD) or R/W CD-ROM for storage and retrieval. Thus, the local storage medium may be fixed (ie, hard drive), or removable (ie, DVD, CD-ROM, VCR tape).

Video playback device 150 includes an infrared (IR) sensor 160 that receives viewer-operated remote control commands (such as channel up, channel down, volume up, volume down, record, play, fast forward (FF), reverse wait). Television 105 is a conventional television that includes a screen 110, an infrared (IR) sensor 115, and one or more manual control keys 120 (indicated by dashed lines). The IR sensor 115 also receives commands (eg, volume up, volume down, power on/off) from a viewer-operated remote control.

It should be noted that video playback device 150 is not limited to receiving a particular type of input television signal from a particular type of signal source. As noted above, the external signal source can be a cable service provider, a traditional RF broadcast antenna, a satellite dish, an Internet connection, or another local storage device such as a DVD player or VHS tape player. In some embodiments, the video playback device 150 is not even capable of recording, but may be limited to playback of television signals retrieved from a removable DVD or CD-ROM. Thus, the input signal may be a digital signal, an analog signal, or an Internet Protocol (IP) packet of any other communication protocol. However, for the sake of simplicity and clarity in explaining the principles of the present invention, the following description will generally be directed to an embodiment in which video playback device 150 receives an incoming television signal (analog and/or digital) from a cable service provider . However, those skilled in the art will appreciate that the principles of the present invention are readily applicable to over-the-air broadcast television signals, local storage systems, incoming data streams containing IP packets of MPEG data, and the like.

Figure 2 illustrates in detail an exemplary video playback device 150 according to one embodiment of the present invention. Video playback device 150 includes IR sensor 160 , video processor 210 , MPEG2 encoder 220 , hard drive 230 , MPEG2 decoder/NTSC encoder 240 and video recorder (VR) controller 250 . Video playback device 150 also includes video buffer 260, audio compression/expansion processor 270, and compression/expansion algorithm 280, which may be embodied as one or more of some well-known audio compression and audio expansion algorithms as A memory for storing a series of program instructions executed by the audio compression/expansion processor 270 .

Audio compression and expansion techniques may be used to reproduce audio signals with low or minimal pitch distortion. Apparatus and methods for compressing or expanding audio signals during faster or slower playback are disclosed in U.S. Patent No. 5,386,493 to Degen et al. Apparatus and method for reproducing audio at frequencies without pitch distortion"; U.S. Patent No. 5,479,564 to Vogten et al., entitled "Method and Apparatus for Manipulating the Pitch and/or Duration of a Signal"; and to Shlomot et al. United States Patent No. 5,694,521, entitled "Variable Speed Playback System." US Patent Nos. 5,386,493, 5,479,564, 5,694,521 are incorporated by reference into this disclosure as if expressed herein. In a preferred embodiment of the present invention, one or more compression/expansion algorithms disclosed in U.S. Patent Nos. 5,386,493, 5,479,564, 5,694,521 may be stored in the compression/expansion algorithm 280 and processed by the audio compression/expansion processor 270 executions.

The VR controller 250 guides the entire operation of the video playback device 150, including viewing mode, recording mode, playback mode, fast forward (FF) mode, and reverse mode. In viewing mode, VR controller 250 causes the incoming television signal from the cable service provider to be demodulated and processed by video processor 210 and sent to television 105 without storing or retrieving from hard drive 230 . Video processor 210 may be, for example, a TriMedia(TM) 1100 media processor, which includes radio frequency (RF) front-end circuitry for receiving incoming television signals from a cable service provider; Converted to a baseband television signal suitable for display on television 105 (eg super video signal). Video processor 210 can also receive conventional NTSC, PAL or SECAM signals (after buffering in video buffer 260) from MPEG2 decoder/NTSC encoder 240 during play mode, and send baseband television signals (such as super video signals) to television set 105.

In recording mode, the VR controller 250 causes the input television signal to be stored on the hard disk drive 230 . Under the control of VR controller 250 , MPEG2 encoder 220 receives an incoming television signal from a cable service provider and converts the received RF signal into MPEG format for storage in hard disk drive 230 . In play mode, the VR controller 250 instructs the hard drive 230 to stream stored television signals (i.e., programs) to the MPEG2 decoder/NTSC encoder 240 to convert the MPEG2 data from the hard drive 230 into, for example, super video ( S-Video) signal, which is buffered in video buffer 260 before video processor 210 sends it to television 105.

It should be noted that the selection of the MPEG2 standard for the MPEG2 encoder 220 and the MPEG2 decoder/NTSC encoder 240 is for illustration purposes only. In other embodiments of the present invention, the MPEG encoder and decoder may conform to one or more of the MPEG-1, MPEG-2, MPEG-4, and MPEG-7 standards.

For purposes of this application and the following claims, hard disk drive 230 is defined to include any mass storage device that is both readable and writable, including conventional magnetic disk drives, video cassette recorders (VCRs) or video tape recorders (VTRs). tapes, and optical drives for reading/writing Digital Versatile Discs (DVD-RW), rewritable CD-ROMs, and more. In fact, hard drive 230 need not be fixed in the conventional sense, ie, permanently embedded in video playback device 150 . Rather, hard drive 230 includes any mass storage device used by video playback device 150 to store recorded video and audio programming. Thus, hard drive 230 may include additional peripherals or removable disk drives (whether embedded or attached), such as jukeboxes that hold read/write DVDs or rewritable CD-ROMs. Also, in a preferred embodiment of the present invention, hard drive 230 may include an external mass storage device that video playback device 150 may access and control over a network connection, such as an Internet Protocol (IP) connection, for example, which Included are disk drives in the user's home personal computer (PC) or on the server of the user's Internet Service Provider (ISP).

In the play mode, the VR controller 250 may receive a user's fast forward (FF) command through the IR sensor 160 . In FF mode, by using video buffer 260, audio compression/expansion processor 270, and companding algorithm 280, video playback device 150 is able to play selected portions of the audio signal with minimal tonal distortion. When the FF command is received, the VR controller 250 causes the hard disk drive 230 and the MPEG2 decoder/NTSC encoder 240 to play the video at a faster forward speed. However, the VR controller 250 also instructs the video processor 210 to stop receiving the audio output of the MPEG2 decoder/NTSC encoder 240 as the source of the audio signal. Instead, the video processor 210 is switched to receive the audio signal as the output of the audio compression/expansion processor 270 as the source of the audio signal.

Figure 3 shows a flowchart 300 illustrating the operation of an exemplary video playback device 150 in accordance with one embodiment of the present invention. A fast forward or slow mode input command is received by VR controller 250 during play mode. VR controller 250 determines the rate of increase or decrease based on user input (process step 305). As playback speed increases or decreases, the duration of the audio track is compressed with minimal tonal distortion. The corresponding video is buffered in video buffer 260 . This compression is proportional to the relative amount of acceleration or deceleration of the video program (process step 310).

The process continues with the audio track from the playback video being received by the audio compression/expansion processor 270 . In slow playback, the audio is expanded, and in fast forward mode, the audio is compressed. The expansion or compression is proportional to the rate of reduction or increase selected by the user (process step 315). The compressed or expanded audio is sent to the television in synchronization with the corresponding portion of the fast-forwarded or slow-moved video from the video buffer 260 (process step 320).

Audio compression/expansion algorithms are used to adjust the audio signal according to the playback rate. As the playback rate increases, so does the audio compression. This algorithm reduces the compression rate as the playback rate decreases. The audio expansion rate will increase when the playback rate drops below the normal value. The rate at which audio is compressed and expanded is directly proportional to the playback rate.

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 (23)

1. An apparatus for use in a video playback device (150), wherein the video playback device (150) is capable of viewing a television set coupled to the video playback device (150) in a fast-forward mode and a slow mode (105) replaying a video program, said means for replaying an audio track associated with said video program during said fast forward mode and said slow mode, said means comprising: - a video playback controller (250) capable of receiving user input commands during said fast-forward mode indicating a relative amount of acceleration of said video program; - an audio processor (270) capable of receiving said audio track and compressing the duration of said audio track with minimal tonal distortion, wherein said compression is proportional to said relative amount of acceleration of said video program; and - a video processor (210) coupled to the 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 A video processor (210) synchronously transmits the compressed audio track and the accelerated video signal to the television (105). 2. The apparatus of claim 1, wherein said video playback controller (250) is capable of receiving a user input command during said slow mode indicating a relative amount by which said video program is slowed down, and said audio processing The controller (270) is capable of extending the duration of the audio track with minimal pitch distortion, wherein the extension is proportional to the relative amount by which the video program is slowed down. 3. The apparatus of claim 2, wherein said video processor (210) is capable of receiving said extended audio track and a decelerated video signal associated with said video program during said slow mode, wherein said A video processor (210) synchronously transmits the expanded audio track and the decelerated video signal to the television (105). 4. The apparatus of claim 3, wherein said apparatus further comprises a memory coupled to said audio processor (270) capable of storing executable instructions related to at least one compression algorithm. 5. The apparatus of claim 4, wherein the memory is capable of storing executable instructions related to at least one extended algorithm. 6. A video playback device (150) capable of playing back a video program on a television (105) coupled to said video playback device (150) during fast forward mode and slow mode, said video Playback devices (150) include: - a disk drive (230) capable of storing a plurality of video programs therein; - a video playback controller (250) capable of receiving user input commands indicating the relative amount of acceleration of the first selected video program being 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 the duration of said audio track with minimal tonal distortion, wherein said compression is consistent with said first selected video program proportional to said relative amount of acceleration; and - a video processor (210) coupled to the 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 synchronously to said television (105). 7. The video playback device (150) of claim 6, wherein said video playback controller (250) is capable of receiving a user input command during said slow mode indicating a relative amount by which said video program is slowed down , and the audio processor (270) is capable of extending the duration of the audio track with minimal pitch distortion, wherein the extension is proportional to the relative amount by which the video program is slowed down. 8. The video playback device (150) of claim 7, wherein said video processor (210) is capable of receiving said extended audio track and a deceleration associated with said video program during said slow mode A video signal, wherein said video processor (210) transmits said extended audio track and said decelerated video signal synchronously to said television (105). 9. The video playback device (150) as claimed in claim 8, wherein said device further comprises a memory connected to said audio processor (270) capable of storing executable instructions related to at least one compression algorithm . 10. The video playback device (150) of claim 9, wherein said memory is capable of storing executable instructions related to at least one expanding algorithm. 11. A video playback device (150) capable of playing back a video program on a television (105) coupled to said video playback device (150) during fast forward mode and slow mode, said video Playback devices (150) include: - a videocassette drive capable of accepting a videocassette and retrieving a first selection video program stored on said videocassette; - a video playback controller (250) capable of receiving user input commands indicating a relative amount of acceleration of said first selected video program being 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 the duration of said audio track with minimal tonal distortion, wherein said compression is consistent with said first selected video program proportional to said relative amount of acceleration; and - a video processor (210) coupled to the 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 synchronously to said television (105). 12. The video playback device (150) of claim 11, wherein said video playback controller (250) is capable of receiving a user input command during said slow mode indicating a relative amount by which said video program is slowed down , and the audio processor (270) is capable of extending the duration of the audio track with minimal pitch distortion, wherein the extension is proportional to the relative amount by which the video program is slowed down. 13. The video playback device (150) of claim 12, wherein said video processor (210) is capable of receiving said extended audio track and a deceleration associated with said video program during said slow mode A video signal, wherein said video processor (210) transmits said extended audio track and said decelerated video signal synchronously to said television (105). 14. The video playback device (150) as claimed in claim 13, wherein said means further comprises a memory connected to said audio processor (270) capable of storing executable instructions related to at least one compression algorithm . 15. The video playback device (150) of claim 14, wherein said memory is capable of storing executable instructions related to at least one expanding algorithm. 16. A video playback device (150) capable of playing back a video program on a television (105) coupled to said video playback device (150) during fast forward mode and slow mode, said video Playback devices (150) include: - a digital versatile disk (DVD) drive capable of accepting a digital versatile disk and retrieving a first selection of video programs stored on said digital versatile disk; - a video playback controller (250) capable of receiving user input commands indicating a relative amount of acceleration of said first selected video program being 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 the duration of said audio track with minimal tonal distortion, wherein said compression is consistent with said first selected video program proportional to said relative amount of acceleration; and - a video processor (210) coupled to the 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 synchronously to said television (105). 17. The video playback device (150) of claim 16, wherein said video playback controller (250) is capable of receiving a user input command during said slow mode indicating a relative amount by which said video program is slowed down , and the audio processor (270) is capable of extending the duration of the audio track with minimal pitch distortion, wherein the extension is proportional to the relative amount by which the video program is slowed down. 18. The video playback device (150) of claim 17, wherein said video processor (210) is capable of receiving said extended audio track and a deceleration associated with said video program during said slow mode A video signal, wherein said video processor (210) transmits said extended audio track and said decelerated video signal synchronously to said television (105). 19. The video playback device (150) as claimed in claim 18, wherein said means further comprises a memory connected to said audio processor (270) capable of storing executable instructions related to at least one compression algorithm . 20. The video playback device (150) of claim 19, wherein said memory is capable of storing executable instructions related to at least one expanding algorithm. 21. A method for use in a video playback device (150), wherein the video playback device (150) is capable of viewing a television set coupled to the video playback device (150) during a fast forward mode and a slow mode (105) replaying the video program, the method is used to replay the audio track associated with the video program during the fast forward mode and the slow mode, the method comprises the following steps: - receiving a user input command during fast forward mode indicating a relative amount of acceleration of the video program; - receiving an audio track and compressing the duration of the audio track with minimal tonal distortion, wherein the compression is proportional to the relative amount of acceleration of the video program; and - Simultaneous transmission of the compressed audio track and the accelerated video signal to the television set (105). 22. The method of claim 21, further comprising the step of: - receiving a user input command during slow mode indicating a relative amount to slow down the video program; and - Extending the duration of the audio track with minimal pitch distortion, where the expansion is proportional to the relative amount the video program is slowed down. 23. The method of claim 22, further comprising the step of synchronously transmitting the extended audio track and said decelerated video signal to a television (105).

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