Transportable digital video recorder system

A transportable digital video recorder system provides a transportable DVR containing a processor and persistent storage device storing a plurality of digital streams and is inserted into an authorized receiving device or a docking station. The system allows a receiving device to select a specific digital stream from the persistent storage device which is output to the receiving device and displayed to a user. User control commands are accepted via the receiving device and sent through the system and allow the user to view and listen to stored digital streams with at least the following functions: variable rate fast forward and rewind, frame step, index, pause, variable rate reverse play, variable rate play, and play.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention relates to the time shifting of television broadcast signals. More particularly, the invention relates to the real time capture, storage, and display of television broadcast signals.

2. Description of the Prior Art

The Video Cassette Recorder (VCR) has changed the lives of television (TV) viewers throughout the world. The VCR has offered viewers the flexibility to time shift TV programs to match their lifestyles.

The viewer stores TV programs onto magnetic tape using the VCR. The VCR gives the viewer the ability to play, rewind, fast forward and pause the stored program material. These functions enable the viewer to pause the program playback whenever he desires, fast forward through unwanted program material or commercials, and to replay favorite scenes. However, a VCR cannot both capture and play back information at the same time.

One approach to solving this problem is to use several VCRs. For example, if two video tape recorders are available, it might be possible to Ping-Pong between the two. In this case, the first recorder is started at the beginning of the program of interest. If the viewer wishes to rewind the broadcast, the second recorder begins recording, while the first recorder is halted, rewound to the appropriate place, and playback initiated. However, at least a third video tape recorder is required if the viewer wishes to fast forward to some point in time after the initial rewind was requested. In this case, the third recorder starts recording the broadcast stream while the second is halted and rewound to the appropriate position. Continuing this exercise, one can quickly see that the equipment becomes unwieldy, unreliable, expensive, and hard to operate, while never supporting all desired functions. In addition, tapes are of finite length, and may potentially end at inconvenient times, drastically lowering the value of the solution.

The use of digital computer systems to solve this problem has been suggested. U.S. Pat. No. 5,371,551 issued to Logan et al., on 6 Dec. 1994, teaches a method for concurrent video recording and playback. It presents a microprocessor controlled broadcast and playback device. Said device compresses and stores video data onto a hard disk. However, this approach is difficult to implement because the processor requirements for keeping up with the high video rates makes the device expensive and problematic. The microprocessor must be extremely fast to keep up with the incoming and outgoing video data.

More recently, digital videos recorders (DVR) have emerged in the marketplace that are based on structures beyond what was previously conceived. One example is U.S. Pat. No. 6,233,389 owned by the Applicant. There are a number of technology trends in force today that are continuing to expand the opportunities for DVR functionality. These trends, whose initial existence directly led to the invention of the DVR, are: the increasing density of gates on semiconductor media; and the increasing density of magnetic storage on hard drive platters.

Two recent announcements bring home these trends with full force.

Until recently, it was believed that the theoretical limit on hard drive platter storage density was 100 Gbits per square inch. This was due to the small number of atoms magnetized at that density versus the effects of parsistic magnetization, which would cause the magnetization to be randomized over short time periods. IBM Corporation recently announced that, by the addition of particlized ferromagnetic material to the platter surface (“pixie dust”), they could achieve 100 times the bit density, or 10 Tbits per square inch. This implies that on a one-inch microdrive (a size that allows placing the drive into a PCMCIA form factor), a density of over 500 GBytes is theoretically possible. This capacity results in over 500 hours of video storage for a typical DVR.

In the semiconductor industry, theoretical limits on chip density have come and gone many times, most of the most recent beliefs was that optical lithography could not etch fine enough lines on silicon. Intel Corporation recently announced that it has developed a transistor ten times smaller than any previously fabricated, from which chips 100 times denser than today's could be developed.

SUMMARY OF THE INVENTION

The invention provides a transportable digital video recorder system. The invention gives a user the ability to record and play back TV broadcast programs and digital video using a compact portable small form factor transportable digital video recorder package. In addition, the invention allows the user to store selected television broadcast programs while the user is simultaneously watching or reviewing another program.

A preferred embodiment of the invention provides a small form factor transportable digital video recorder containing a processor and persistent storage device storing a plurality of digital streams. The small form factor transportable digital video recorder is inserted into a receiving device or a docking station and will only operate with an authorized receiving device or docking station.

The invention allows a receiving device to select a specific digital stream from the persistent storage device. The specific digital stream is then output from the small form factor transportable digital video recorder to the receiving device where the receiving device displays the digital stream to a user. User control commands are accepted via the receiving device and sent through the small form factor transportable digital video recorder system. These commands affect the flow of digital streams output to the receiving device and allow the user to view and listen to stored digital streams with at least the following functions: variable rate fast forward and rewind, frame step, index, pause, variable rate reverse play, variable rate play, and play.

The small form factor transportable digital video recorder receives analog signals and digital video signals from the receiving device and converts them into digital streams which are stored on the persistent storage device.

Another embodiment of the invention provides a plurality of input signal tuners on the small form factor transportable digital video recorder. The input tuners accept analog and digital television broadcast signals and can be individually tuned to a specific broadcast signal. The analog and digital television broadcast signals are converted into digital streams and stored on the persistent storage device.

An electronic program guide is also stored on the persistent storage device which the small form factor transportable digital video recorder delivers portions of to the receiving device upon request from the receiving device.

A docking station comprises at least one small form factor transportable digital video recorder slot allowing a user to backup and transfer specific data between small form factor transportable digital video recorders. The small form factor transportable digital video recorders authenticate each other before transferring data. The docking station also allows a user to transfer data stored on the docking station to a small form factor transportable digital video recorder.

Other aspects and advantages of the invention will become apparent from the following detailed description in combination with the accompanying drawings, illustrating, by way of example, the principles of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention is embodied in a transportable digital video recorder system. A system according to the invention gives a user the ability to record and play back TV broadcast programs and digital video using a compact portable small form factor package. The invention additionally provides the user with the ability to store selected television broadcast programs while simultaneously watching or reviewing another program and to view stored programs with at least the following functions: variable rate fast forward and rewind, frame step, index, pause, variable rate reverse play, variable rate play, and play.

Referring toFIG. 1, a preferred embodiment of the invention has an Input Section101, Media Switch102, and an Output Section103. The Input Section101takes television (TV) input streams in a multitude of forms, for example, National Television Standards Committee (NTSC) or PAL broadcast, and digital forms such as Digital Satellite System (DSS), Digital Broadcast Services (DBS), or Advanced Television Standards Committee (ATSC). DBS, DSS and ATSC are based on standards called Moving Pictures Experts Group 2 (MPEG2) and MPEG2 Transport. MPEG2 Transport is a standard for formatting the digital data stream from the TV source transmitter so that a TV receiver can disassemble the input stream to find programs in the multiplexed signal. The Input Section101produces MPEG streams. An MPEG2 transport multiplex supports multiple programs in the same broadcast channel, with multiple video and audio feeds and private data. The Input Section101tunes the channel to a particular program, extracts a specific MPEG program out of it, and feeds it to the rest of the system. Analog TV signals are encoded into a similar MPEG format using separate video and audio encoders, such that the remainder of the system is unaware of how the signal was obtained. Information may be modulated into the Vertical Blanking Interval (VBI) of the analog TV signal in a number of standard ways; for example, the North American Broadcast Teletext Standard (NABTS) may be used to modulate information onto lines10through20of an NTSC signal, while the FCC mandates the use of line21for Closed Caption (CC) and Extended Data Services (EDS). Such signals are decoded by the input section and passed to the other sections as if they were delivered via an MPEG2 private data channel.

The Media Switch102mediates between a microprocessor CPU106, hard disk or storage device105, and memory104. Input streams are converted to an MPEG stream and sent to the Media Switch102. The Media Switch102buffers the MPEG stream into memory. It then performs two operations if the user is watching real time TV: the stream is sent to the Output Section103and it is written simultaneously to the hard disk or storage device105.

The Output Section103takes MPEG streams as input and produces an analog TV signal according to the NTSC, PAL, or other required TV standards. The Output Section103contains an MPEG decoder, On-Screen Display (OSD) generator, analog TV encoder and audio logic. The OSD generator allows the program logic to supply images which will be overlayed on top of the resulting analog TV signal. Additionally, the Output Section can modulate information supplied by the program logic onto the VBI of the output signal in a number of standard formats, including NABTS, CC and EDS.

With respect toFIG. 2, the invention easily expands to accommodate multiple Input Sections (tuners)201,202,203,204, each can be tuned to different types of input. Multiple Output Modules (decoders)206,207,208,209are added as well. Special effects such as picture in a picture can be implemented with multiple decoders. The Media Switch205records one program while the user is watching another. This means that a stream can be extracted off the disk while another stream is being stored onto the disk.

Referring toFIG. 3, the incoming MPEG stream301has interleaved video302,305,306and audio303,304,307segments. These elements must be separated and recombined to create separate video308and audio309streams or buffers. This is necessary because separate decoders are used to convert MPEG elements back into audio or video analog components. Such separate delivery requires that time sequence information be generated so that the decoders may be properly synchronized for accurate playback of the signal.

The Media Switch enables the program logic to associate proper time sequence information with each segment, possibly embedding it directly into the stream. The time sequence information for each segment is called a time stamp. These time stamps are monotonically increasing and start at zero each time the system boots up. This allows the invention to find any particular spot in any particular video segment. For example, if the system needs to read five seconds into an incoming contiguous video stream that is being cached, the system simply has to start reading forward into the stream and look for the appropriate time stamp.

A binary search can be performed on a stored file to index into a stream. Each stream is stored as a sequence of fixed-size segments enabling fast binary searches because of the uniform timestamping. If the user wants to start in the middle of the program, the system performs a binary search of the stored segments until it finds the appropriate spot, obtaining the desired results with a minimal amount of information. If the signal were instead stored as an MPEG stream, it would be necessary to linearly parse the stream from the beginning to find the desired location.

With respect toFIG. 4, the Media Switch contains four input Direct Memory Access (DMA) engines402,403,404,405each DMA engine has an associated buffer410,411,412,413. Conceptually, each DMA engine has a pointer406, a limit for that pointer407, a next pointer408, and a limit for the next pointer409. Each DMA engine is dedicated to a particular type of information, for example, video402, audio403, and parsed events405. The buffers410,411,412,413are circular and collect the specific information. The DMA engine increments the pointer406into the associated buffer until it reaches the limit407and then loads the next pointer408and limit409. Setting the pointer406and next pointer408to the same value, along with the corresponding limit value creates a circular buffer. The next pointer408can be set to a different address to provide vector DMA.

The input stream flows through a parser401. The parser401parses the stream looking for MPEG distinguished events indicating the start of video, audio or private data segments. For example, when the parser401finds a video event, it directs the stream to the video DMA engine402. The parser401buffers up data and DMAs it into the video buffer410through the video DMA engine402. At the same time, the parser401directs an event to the event DMA engine405which generates an event into the event buffer413. When the parser401sees an audio event, it redirects the byte stream to the audio DMA engine403and generates an event into the event buffer413. Similarly, when the parser401sees a private data event, it directs the byte stream to the private data DMA engine404and directs an event to the event buffer413. The Media Switch notifies the program logic via an interrupt mechanism when events are placed in the event buffer.

Referring toFIGS. 4 and 5, the event buffer413is filled by the parser401with events. Each event501in the event buffer has an offset502, event type503, and time stamp field504. The parser401provides the type and offset of each event as it is placed into the buffer. For example, when an audio event occurs, the event type field is set to an audio event and the offset indicates the location in the audio buffer411. The program logic knows where the audio buffer411starts and adds the offset to find the event in the stream. The address offset502tells the program logic where the next event occurred, but not where it ended. The previous event is cached so the end of the current event can be found as well as the length of the segment.

With respect toFIGS. 5 and 6, the program logic reads accumulated events in the event buffer602when it is interrupted by the Media Switch601. From these events the program logic generates a sequence of logical segments603which correspond to the parsed MPEG segments615. The program logic converts the offset502into the actual address610of each segment, and records the event length609using the last cached event. If the stream was produced by encoding an analog signal, it will not contain Program Time Stamp (PTS) values, which are used by the decoders to properly present the resulting output. Thus, the program logic uses the generated time stamp504to calculate a simulated PTS for each segment and places that into the logical segment timestamp607. In the case of a digital TV stream, PTS values are already encoded in the stream. The program logic extracts this information and places it in the logical segment timestamp607.

The program logic continues collecting logical segments603until it reaches the fixed buffer size. When this occurs, the program logic generates a new buffer, called a Packetized Elementary Stream (PES)605buffer containing these logical segments603in order, plus ancillary control information. Each logical segment points604directly to the circular buffer, e.g., the video buffer613, filled by the Media Switch601. This new buffer is then passed to other logic components, which may further process the stream in the buffer in some way, such as presenting it for decoding or writing it to the storage media. Thus, the MPEG data is not copied from one location in memory to another by the processor. This results in a more cost effective design since lower memory bandwidth and processor bandwidth is required.

A unique feature of the MPEG stream transformation into PES buffers is that the data associated with logical segments need not be present in the buffer itself, as presented above. When a PES buffer is written to storage, these logical segments are written to the storage medium in the logical order in which they appear. This has the effect of gathering components of the stream, whether they be in the video, audio or private data circular buffers, into a single linear buffer of stream data on the storage medium. The buffer is read back from the storage medium with a single transfer from the storage media, and the logical segment information is updated to correspond with the actual locations in the buffer606. Higher level program logic is unaware of this transformation, since it handles only the logical segments, thus stream data is easily managed without requiring that the data ever be copied between locations in DRAM by the CPU.

A unique aspect of the Media Switch is the ability to handle high data rates effectively and inexpensively. It performs the functions of taking video and audio data in, sending video and audio data out, sending video and audio data to disk, and extracting video and audio data from the disk on a low cost platform. Generally, the Media Switch runs asynchronously and autonomously with the microprocessor CPU, using its DMA capabilities to move large quantities of information with minimal intervention by the CPU.

Referring toFIG. 7, the input side of the Media Switch701is connected to an MPEG encoder703. There are also circuits specific to MPEG audio704and vertical blanking interval (VBI) data702feeding into the Media Switch701. If a digital TV signal is being processed instead, the MPEG encoder703is replaced with an MPEG2 Transport Demultiplexor, and the MPEG audio encoder704and VBI decoder702are deleted. The demultiplexor multiplexes the extracted audio, video and private data channel streams through the video input Media Switch port.

The parser705parses the input data stream from the MPEG encoder703, audio encoder704and VBI decoder702, or from the transport demultiplexor in the case of a digital TV stream. The parser705detects the beginning of all of the important events in a video or audio stream, the start of all of the frames, the start of sequence headers—all of the pieces of information that the program logic needs to know about in order to both properly play back and perform special effects on the stream, e.g. fast forward, reverse, play, pause, fast/slow play, indexing, and fast/slow reverse play.

The parser705places tags707into the FIFO706when it identifies video or audio segments, or is given private data. The DMA709controls when these tags are taken out. The tags707and the DMA addresses of the segments are placed into the event queue708. The frame type information, whether it is a start of a video I-frame, video B-frame, video P-frame, video PES, audio PES, a sequence header, an audio frame, or private data packet, is placed into the event queue708along with the offset in the related circular buffer where the piece of information was placed. The program logic operating in the CPU713examines events in the circular buffer after it is transferred to the DRAM714.

The Media Switch701has a data bus711that connects to the CPU713and DRAM714. An address bus712is also shared between the Media Switch701, CPU713, and DRAM714. A hard disk or storage device710is connected to one of the ports of the Media Switch701. The Media Switch701outputs streams to an MPEG video decoder715and a separate audio decoder717. The audio decoder717signals contain audio cues generated by the system in response to the user's commands on a remote control or other internal events. The decoded audio output from the MPEG decoder is digitally mixed718with the separate audio signal. The resulting signals contain video, audio, and on-screen displays and are sent to the TV716.

The Media Switch701takes in 8-bit data and sends it to the disk, while at the same time extracts another stream of data off of the disk and sends it to the MPEG decoder715. All of the DMA engines described above can be working at the same time. The Media Switch701can be implemented in hardware using a Field Programmable Gate Array (FPGA), ASIC, or discrete logic.

Rather than having to parse through an immense data stream looking for the start of where each frame would be, the program logic only has to look at the circular event buffer in DRAM714and it can tell where the start of each frame is and the frame type. This approach saves a large amount of CPU power, keeping the real time requirements of the CPU713small. The CPU713does not have to be very fast at any point in time. The Media Switch701gives the CPU713as much time as possible to complete tasks. The parsing mechanism705and event queue708decouple the CPU713from parsing the audio, video, and buffers and the real time nature of the streams, which allows for lower costs. It also allows the use of a bus structure in a CPU environment that operates at a much lower clock rate with much cheaper memory than would be required otherwise.

The CPU713has the ability to queue up one DMA transfer and can set up the next DMA transfer at its leisure. This gives the CPU713large time intervals within which it can service the DMA controller709. The CPU713may respond to a DMA interrupt within a larger time window because of the large latency allowed. MPEG streams, whether extracted from an MPEG2 Transport or encoded from an analog TV signal, are typically encoded using a technique called Variable Bit Rate encoding (VBR). This technique varies the amount of data required to represent a sequence of images by the amount of movement between those images. This technique can greatly reduce the required bandwidth for a signal, however sequences with rapid movement (such as a basketball game) may be encoded with much greater bandwidth requirements. For example, the Hughes DirecTV satellite system encodes signals with anywhere from 1 to 10 Mb/s of required bandwidth, varying from frame to frame. It would be difficult for any computer system to keep up with such rapidly varying data rates without this structure.

With respect toFIG. 8, the program logic within the CPU has three conceptual components: sources801, transforms802, and sinks803. The sources801produce buffers of data. Transforms802process buffers of data and sinks803consume buffers of data. A transform is responsible for allocating and queuing the buffers of data on which it will operate. Buffers are allocated as if “empty” to sources of data, which give them back “full”. The buffers are then queued and given to sinks as “full”, and the sink will return the buffer “empty”.

A source801accepts data from encoders, e.g., a digital satellite receiver. It acquires buffers for this data from the downstream transform, packages the data into a buffer, then pushes the buffer down the pipeline as described above. The source object801does not know anything about the rest of the system. The sink803consumes buffers, taking a buffer from the upstream transform, sending the data to the decoder, and then releasing the buffer for reuse.

There are two types of transforms802used: spatial and temporal. Spatial transforms are transforms that perform, for example, an image convolution or compression/decompression on the buffered data that is passing through. Temporal transforms are used when there is no time relation that is expressible between buffers going in and buffers coming out of a system. Such a transform writes the buffer to a file804on the storage medium. The buffer is pulled out at a later time, sent down the pipeline, and properly sequenced within the stream.

Referring toFIG. 9, a C++ class hierarchy derivation of the program logic is shown. The TiVo Media Kernel (Tmk)904,908,913mediates with the operating system kernel. The kernel provides operations such as: memory allocation, synchronization, and threading. The TmkCore904,908,913structures memory taken from the media kernel as an object. It provides operators, new and delete, for constructing and deconstructing the object. Each object (source901, transform902, and sink903) is multi-threaded by definition and can run in parallel.

The TmkPipeline class905,909,914is responsible for flow control through the system. The pipelines point to the next pipeline in the flow from source901to sink903. To pause the pipeline, for example, an event called “pause” is sent to the first object in the pipeline. The event is relayed on to the next object and so on down the pipeline. This all happens asynchronously to the data going through the pipeline. Thus, similar to applications such as telephony, control of the flow of MPEG streams is asynchronous and separate from the streams themselves. This allows for a simple logic design that is at the same time powerful enough to support the features described previously, including pause, rewind, fast forward and others. In addition, this structure allows fast and efficient switching between stream sources, since buffered data can be simply discarded and decoders reset using a single event, after which data from the new stream will pass down the pipeline. Such a capability is needed, for example, when switching the channel being captured by the input section, or when switching between a live signal from the input section and a stored stream.

The source object901is a TmkSource906and the transform object902is a TmkXform910. These are intermediate classes that define standard behaviors for the classes in the pipeline. Conceptually, they handshake buffers down the pipeline. The source object901takes data out of a physical data source, such as the Media Switch, and places it into a PES buffer. To obtain the buffer, the source object901asks the down stream object in his pipeline for a buffer (allocEmptyBuf). The source object901is blocked until there is sufficient memory. This means that the pipeline is self-regulating; it has automatic flow control. When the source object901has filled up the buffer, it hands it back to the transform902through the pushFullBuf function.

The sink903is flow controlled as well. It calls nextFullBuf which tells the transform902that it is ready for the next filled buffer. This operation can block the sink903until a buffer is ready. When the sink903is finished with a buffer (i.e., it has consumed the data in the buffer) it calls releaseEmptyBuf. ReleaseEmptyBuf gives the buffer back to the transform902. The transform902can then hand that buffer, for example, back to the source object901to fill up again. In addition to the automatic flow-control benefit of this method, it also provides for limiting the amount of memory dedicated to buffers by allowing enforcement of a fixed allocation of buffers by a transform. This is an important feature in achieving a cost-effective limited DRAM environment.

The MediaSwitch class909calls the allocEmptyBuf method of the TmkClipCache912object and receives a PES buffer from it. It then goes out to the circular buffers in the Media Switch hardware and generates PES buffers. The MediaSwitch class909fills the buffer up and pushes it back to the TmkClipCache912object.

The TmkClipCache912maintains a cache file918on a storage medium. It also maintains two pointers into this cache: a push pointer919that shows where the next buffer coming from the source901is inserted; and a current pointer920which points to the current buffer used.

The buffer that is pointed to by the current pointer is handed to the Vela decoder class916. The Vela decoder class916talks to the decoder921in the hardware. The decoder921produces a decoded TV signal that is subsequently encoded into an analog TV signal in NTSC, PAL or other analog format. When the Vela decoder class916is finished with the buffer it calls releaseEmptyBuf.

The structure of the classes makes the system easy to test and debug. Each level can be tested separately to make sure it performs in the appropriate manner, and the classes may be gradually aggregated to achieve the desired functionality while retaining the ability to effectively test each object.

The control object917accepts commands from the user and sends events into the pipeline to control what the pipeline is doing. For example, if the user has a remote control and is watching TV, the user presses pause and the control object917sends an event to the sink903, that tells it pause. The sink903stops asking for new buffers. The current pointer920stays where it is at. The sink903starts taking buffers out again when it receives another event that tells it to play. The system is in perfect synchronization; it starts from the frame that it stopped at.

The remote control may also have a fast forward key. When the fast forward key is pressed, the control object917sends an event to the transform902, that tells it to move forward two seconds. The transform902finds that the two second time span requires it to move forward three buffers. It then issues a reset event to the downstream pipeline, so that any queued data or state that may be present in the hardware decoders is flushed. This is a critical step, since the structure of MPEG streams requires maintenance of state across multiple frames of data, and that state will be rendered invalid by repositioning the pointer. It then moves the current pointer920forward three buffers. The next time the sink903calls nextFullBuf it gets the new current buffer. The same method works for fast reverse in that the transform902moves the current pointer920backwards.

A system clock reference resides in the decoder. The system clock reference is sped up for fast play or slowed down for slow play. The sink simply asks for full buffers faster or slower, depending on the clock speed.

With respect toFIG. 10, two other objects derived from the TmkXform class are placed in the pipeline for disk access. One is called TmkClipReader1003and the other is called TmkClipWriter1001. Buffers come into the TmkClipWriter1001and are pushed to a file on a storage medium1004. TmkClipReader1003asks for buffers which are taken off of a file on a storage medium1005. A TmkClipReader1003provides only the allocEmptyBuf and pushFullBuf methods, while a TmkClipWriter1001provides only the nextFullBuf and releaseEmptyBuf methods. A TmkClipReader1003therefore performs the same function as the input, or “push” side of a TmkClipCache1002, while a TmkClipWriter1001therefore performs the same function as the output, or “pull” side of a TmkClipCache1002.

Referring toFIG. 11, a preferred embodiment that accomplishes multiple functions is shown. A source1101has a TV signal input. The source sends data to a PushSwitch1102which is a transform derived from TmkXform. The PushSwitch1102has multiple outputs that can be switched by the control object1114. This means that one part of the pipeline can be stopped and another can be started at the user's whim. The user can switch to different storage devices. The PushSwitch1102could output to a TmkClipWriter1106, which goes onto a storage device1107or write to the cache transform1103.

An important feature of this apparatus is the ease with which it can selectively capture portions of an incoming signal under the control of program logic. Based on information such as the current time, or perhaps a specific time span, or perhaps via a remote control button press by the viewer, a TmkClipWriter1106may be switched on to record a portion of the signal, and switched off at some later time. This switching is typically caused by sending a “switch” event to the PushSwitch1102object.

An additional method for triggering selective capture is through information modulated into the VBI or placed into an MPEG private data channel. Data decoded from the VBI or private data channel is passed to the program logic. The program logic examines this data to determine if the data indicates that capture of the TV signal into which it was modulated should begin. Similarly, this information may also indicate when recording should end, or another data item may be modulated into the signal indicating when the capture should end. The starting and ending indicators may be explicitly modulated into the signal or other information that is placed into the signal in a standard fashion may be used to encode this information.

With respect toFIG. 12, an example is shown which demonstrates how the program logic scans the words contained within the closed caption (CC) fields to determine starting and ending times, using particular words or phrases to trigger the capture. A stream of NTSC or PAL fields1201is presented. CC bytes are extracted from each odd field1202, and entered in a circular buffer1203for processing by the Word Parser1204. The Word Parser1204collects characters until it encounters a word boundary, usually a space, period or other delineating character. Recall from above, that the MPEG audio and video segments are collected into a series of fixed-size PES buffers. A special segment is added to each PES buffer to hold the words extracted from the CC field1205. Thus, the CC information is preserved in time synchronization with the audio and video, and can be correctly presented to the viewer when the stream is displayed. This also allows the stored stream to be processed for CC information at the leisure of the program logic, which spreads out load, reducing cost and improving efficiency. In such a case, the words stored in the special segment are simply passed to the state table logic1206.

During stream capture, each word is looked up in a table1206which indicates the action to take on recognizing that word. This action may simply change the state of the recognizer state machine1207, or may cause the state machine1207to issue an action request, such as “start capture”, “stop capture”, “phrase seen”, or other similar requests. Indeed, a recognized word or phrase may cause the pipeline to be switched; for example, to overlay a different audio track if undesirable language is used in the program.

Note that the parsing state table1206and recognizer state machine1207may be modified or changed at any time. For example, a different table and state machine may be provided for each input channel. Alternatively, these elements may be switched depending on the time of day, or because of other events.

Referring toFIG. 11, a PullSwitch is added1104which outputs to the sink1105. The sink1105calls nextFullBuf and releaseEmptyBuf to get or return buffers from the PullSwitch1104. The PullSwitch1104can have any number of inputs. One input could be an ActionClip1113. The remote control can switch between input sources. The control object1114sends an event to the PullSwitch1104, telling it to switch. It will switch from the current input source to whatever input source the control object selects.

An ActionClip class provides for sequencing a number of different stored signals in a predictable and controllable manner, possibly with the added control of viewer selection via a remote control. Thus, it appears as a derivative of a TmkXform object that accepts a “switch” event for switching to the next stored signal.

This allows the program logic or user to create custom sequences of video output. Any number of video segments can be lined up and combined as if the program logic or user were using a broadcast studio video mixer. TmkClipReaders1108,1109,1110are allocated and each is hooked into the PullSwitch1104. The PullSwitch1104switches between the TmkClipReaders1108,1109,1110to combine video and audio clips. Flow control is automatic because of the way the pipeline is constructed. The Push and Pull Switches are the same as video switches in a broadcast studio.

The derived class and resulting objects described here may be combined in an arbitrary way to create a number of different useful configurations for storing, retrieving, switching and viewing of TV streams. For example, if multiple input and output sections are available, one input is viewed while another is stored, and a picture-in-picture window generated by the second output is used to preview previously stored streams. Such configurations represent a unique and novel application of software transformations to achieve the functionality expected of expensive, sophisticated hardware solutions within a single cost-effective device.

With respect toFIG. 13, a high-level system view is shown which implements a VCR backup. The Output Module1303sends TV signals to the VCR1307. This allows the user to record TV programs directly on to video tape. The invention allows the user to queue up programs from disk to be recorded on to video tape and to schedule the time that the programs are sent to the VCR1307. Title pages (EPG data) can be sent to the VCR1307before a program is sent. Longer programs can be scaled to fit onto smaller video tapes by speeding up the play speed or dropping frames.

The VCR1307output can also be routed back into the Input Module1301. In this configuration the VCR acts as a backup system for the Media Switch1302. Any overflow storage or lower priority programming is sent to the VCR1307for later retrieval.

The Input Module1301can decode and pass to the remainder of the system information encoded on the Vertical Blanking Interval (VBI). The Output Module1303can encode into the output VBI data provided by the remainder of the system. The program logic may arrange to encode identifying information of various kinds into the output signal, which will be recorded onto tape using the VCR1307. Playing this tape back into the input allows the program logic to read back this identifying information, such that the TV signal recorded on the tape is properly handled. For example, a particular program may be recorded to tape along with information about when it was recorded, the source network, etc. When this program is played back into the Input Module, this information can be used to control storage of the signal, presentation to the viewer, etc.

One skilled in the art will readily appreciate that such a mechanism may be used to introduce various data items to the program logic which are not properly conceived of as television signals. For instance, software updates or other data may be passed to the system. The program logic receiving this data from the television stream may impose controls on how the data is handled, such as requiring certain authentication sequences and/or decrypting the embedded information according to some previously acquired key. Such a method works for normal broadcast signals as well, leading to an efficient means of providing non-TV control information and data to the program logic.

Additionally, one skilled in the art will readily appreciate that although a VCR is specifically mentioned above, any multimedia recording device (e.g., a Digital Video Disk-Random Access Memory (DVD-RAM) recorder) is easily substituted in its place.

Although the invention is described herein with reference to the preferred embodiment, one skilled in the art will readily appreciate that other applications may be substituted for those set forth herein without departing from the spirit and scope of the present invention. For example, the invention can be used in the detection of gambling casino crime. The input section of the invention is connected to the casino's video surveillance system. Recorded video is cached and simultaneously output to external VCRs. The user can switch to any video feed and examine (i.e., rewind, play, slow play, fast forward, etc.) a specific segment of the recorded video while the external VCRs are being loaded with the real-time input video.

Multimedia Time Warping on a Small Form Factor Transportable Digital Video Recorder

The PCMCIA form factor provides a very effective vehicle for provisioning electronic capabilities. It is small, easily handled, and has a very effective docking mechanism. Similar small form-factor standardized plug-in architectures are constantly being developed, such as the Sony Memory Stick and the SD memory card. Both of these examples are now being extended to non-memory applications.

Until recently, it was believed that the theoretical limit on hard drive platter storage density was 100 Gbits per square inch. This was due to the small number of atoms magnetized at that density versus the effects of parsistic magnetization, which would cause the magnetization to be randomized over short time periods. IBM Corporation recently announced that, by the addition of particlized ferromagnetic material to the platter surface (“pixie dust”), they could achieve 100 times the bit density, or 10 Tbits per square inch. This implies that on a one-inch microdrive (a size that allows placing the drive into a PCMCIA form factor), a density of over 500 GBytes is theoretically possible. This capacity results in over 500 hours of video storage for a typical DVR.

In the semiconductor industry, theoretical limits on chip density have come and gone many times, most of the most recent beliefs was that optical lithography could not etch fine enough lines on silicon. Intel Corporation recently announced that it has developed a transistor ten times smaller than any previously fabricated, from which chips 100 times denser than today's could be developed.

Referring toFIG. 14, given all of the foregoing, the invention can be incorporated into many popular plug-in formats having these basic features:A high-density microdrive (persistent storage device)1402contained within the plug-in module1401, supplemented by a large amount of DRAM for software and buffering1402,A single chip, or small number of chips1403, implementing the machinery needed for basic capabilities of the invention described above:a processor of adequate capability,data handling i.e., the MediaSwitch,disk management hardwareDepending on the application, an integrated security subsystem1403providing secure data access and transfer.

There are several forms the small form factor transportable digital video recorder1401would take. In one form, the card is designed to accept digital signals1405for storage and retrieval. Thus, it would accept compressed digital streams and reproduce compressed digital streams. A separate control channel would be used to read information from the small form factor transportable digital video recorder1401, such as program guide or state data, and write information to the small form factor transportable digital video recorder1401, such as implementing trick-play modes (e.g., variable rate fast forward and rewind, frame step, index, pause, variable rate reverse play, variable rate play, and play) or updating EPG data.

With respect toFIG. 15, this form1501can work as an adjunct to a “docking station”, for example, a home theatre receiver1503, in-dash car stereo1502, or back-seat video player1502. It allows the storage of all interesting media on the small form factor transportable digital video recorder and the easy transport of it between various devices. The security subsystem is used to authenticate the docking station to the small form factor transportable digital video recorder and vice-versa, so that content protection could be assured, as well as the rights of personal use.

The docking of the small form factor transportable digital video recorder1501and a dock can be accomplished via directly inserting the small form factor transportable digital video recorder into a small form factor transportable digital video recorder slot built into the dock (or connected to the dock) or connected to the dock via a wired interface using USB (original and 2.0) or Firewire (IEEE 1394).

Referring toFIG. 16, for example, the way in which an authentication might happen is as follows: a central registration1603is maintained in which the embedded, unique serial number of every registered device is maintained. A user registers a device1601under his ownership by having it contact the registry1603(assuming it has a security subsystem similar to the invention's), authenticate itself, and register the users ownership. The device1601also gets a copy of the small form factor transportable digital video recorder1602public key and its serial number. The user then has the small form factor transportable digital video recorder1602contact the registry1603(docked, of course), and the registry1603downloads the public keys and serial numbers of devices registered to that user. Then the dock1601and the small form factor transportable digital video recorder1602can authenticate each other whenever the small form factor transportable digital video recorder1602is plugged in.

Another form incorporates more of the invention's functionality described above into the card chipset1403, for instance the encoders and decoders (and optionally tuners), and relies only on the dock to provide digitized video and audio signals, and network connections.

Still another completes the spectrum, where the dock provides analog media signals, accepts analog signals, and provides a phone connection. The small form factor transportable digital video recorder1401then includes the analog-to-digital conversion and the modem, as described above, in the chipset1403.

Thus, a range of useful versions of the small form factor transportable digital video recorder and dock can be built that address different price/performance tradeoffs and evolving technology.

The Small Form Factor Transportable Digital Video Recorder and the Handheld

With respect toFIG. 17, a small form factor transportable digital video recorder1702containing either form described above can be inserted into a dock1701. The dock1701and small form factor transportable digital video recorder1702authenticate each other using each other's public key and serial number. The dock downloads audio/video onto the small form factor transportable digital video recorder's microdrive. The user can then insert the small form factor transportable digital video recorder into a handheld device1703. Since the small form factor transportable digital video recorder1702has the invention's MediaSwitch onboard, the handheld device1703accepts the digital streams for display from the small form factor transportable digital video recorder1702. The user sends selection and control commands through the handheld1703to the small form factor transportable digital video recorder1702. The user can use the trick-play features of the MediaSwitch on the audio/video material from the small form factor transportable digital video recorder's microdrive to listen to and view the material.

The Small Form Factor Transportable Digital Video Recorder and the PC

Referring toFIG. 18, the invention's small form factor transportable digital video recorder1801is easily interfaced to a typical PC, such as a laptop computer1802or desktop computer1803with PCMCIA ports. Typical PCs of this era have the capability in software to perform encoding and decoding functions. An outboard analog video input1804can be added to the small form factor transportable digital video recorder1801(for example, with a dongle of some kind, similar to those found on PCMCIA ethernet cards or with a doublewide card; or a TV antenna similar to the RF antennas on Richochet or other wide-area-wireless cards).

The small form factor transportable digital video recorder1801can digitize the analog signal and encode it, or pass it to the PC software for encoding, whence it is passed back to the small form factor transportable digital video recorder1801for storage. On output, the digital signal is passed from the small form factor transportable digital video recorder1801to the PC1802,1803for decoding and display.

Another preferred embodiment of the invention modifies the analog video input to accept digital video and broadcast signals. At least one tuner, as described above, can also be onboard the small form factor transportable digital video recorder1801. The tuner can tune to specific channels within the analog signal if the analog signal is a broadcast signal or the digital broadcast signal. Digital video signals are translated as described above and stored through the MediaSwitch.

Another preferred embodiment of the invention is an all-analog small form factor transportable digital video recorder1801, in which the dongle1804provides analog out as well. The analog output from the dongle1804is connected to the PC's video input for display on its monitor. This provides complete content security, at least for the purely digital parts.

Otherwise, if the PC contains an embedded security system of some kind, an authentication phase can be entered that ensures that the software handling the video and audio media is untampered with (ala the Windows XP mechanisms) before permitting operation.

Backing up the Small Form Factor Transportable Digital Video Recorder

With respect toFIG. 19, a dock1901with two (or more) slots1904can be used to transfer information between or backup the invention's small form factor transportable digital video recorders. The dock1901basically provides a backplane between the slots1904. Stick two small form factor transportable digital video recorders1902,1903in and they authenticate to each other. The user presses a button (real or virtual) and the content is copied from one small form factor transportable digital video recorder to the other. Even further, the user can selectively choose content to be copied from one card to the other.