摘要:
A conditional access subsystem is proved which is to reside with an end-user for receiving, decrypting and decoding all programs distributed by a content provider that the end user is entitled to access so that the decrypted and decoded programs are available for display on one or more display devices without use of a set-top terminal dedicated to each of the display devices. The subsystem includes a receiver for receiving and demodulating a multi-program transport (MPTS) stream distributed by the content provider. The MPTS includes a plurality of packets constituting a plurality of programs using one of N different encryption schemes each associated with one of N service tiers, wherein N is an integer greater than one. Each of the N different encryption schemes has a different encryption/decryption key associated therewith. The packet identifiers for the packets associated with programs in any given one of the service tiers are in a consecutive sequence. A decryptor is provided for decrypting each of the programs associated with each of the N service tiers that the end user is entitled to access. A decoder is also provided for decoding each of the decrypted programs.
摘要:
Data overflow in a buffer of a set-top decoder for receiving asynchronous data, such as digital television signals, is prevented while also maintaining compliance with an interface timing standard such as the RS404-A standard. A fullness level of the buffer is monitored to determine whether the fullness falls within a first, nominal range, or into second or third higher ranges. A clocking signal is derived from a ratio of a fixed reference clock signal and a divisor for outputting asynchronous data from the buffer at a desired rate. A direct digital synthesis (DDS) circuit may be used to provide a fractional divisor. The divisor is selected to provide the clocking signal at a rate so that a difference between a target output rate and the actual output rate falls within a data performance standard such as the RS404-A standard.
摘要:
Audio data is processed from a packetized data stream carrying digital television information in a succession of fixed length transport packets. Some of the packets contain a presentation time stamp (PTS) indicative of a time for commencing the output of associated audio data. After the audio data stream has been acquired, the detected audio packets are monitored to locate subsequent PTS's for adjusting the timing at which audio data is output, thereby providing proper lip synchronization with associated video. Errors in the audio data are processed in a manner which attempts to maintain synchronization of the audio data stream while masking the errors. In the event that the synchronization condition cannot be maintained, for example in the presence of errors over more than one audio frame, the audio data stream is reacquired while the audio output is concealed. An error condition is signaled to the audio decoder by altering the audio synchronization word associated with the audio frame in which the error has occurred.
摘要:
Variable rate data is reformatted for communication to an external device at a fixed rate. Fixed length packets of the variable rate data are recovered from a multiplex of data packets. A packet start byte is added to the beginning of each of the recovered packets. Fill bits are added to the recovered packets as necessary to maintain the desired fixed output rate if the output rate is greater than an information rate of the variable rate data. The recovered packets with the added packet start byte and fill bits are provided as output to the external device at the fixed rate. The recovered packets with the added packet start byte and fill bits are advantageously encoded using alternate mark inversion (AMI) and binary eight zero substitution (B8ZS). The packet start byte and B8ZS substitution can comprise unique AMI violation sequences.
摘要:
Apparatus is provided for decoding variable length code words to recover transform coefficients, such as DCT transform coefficients provided by a high definition television encoder. A first category of the code words has a length of no more than n bits. A second category has a length of greater than n bits. A feedback ROM is used to decode the code words. Code words from the first category are processed by directly addressing a lookup table in the ROM. Code words from the second category are processed using multiple passes through the ROM, wherein a portion of the data output during a prior pass is fed back to address the memory during a subsequent pass.
摘要:
A system is provided for selectively transmitting horizontal television lines including video and digital audio components or equivalent digital data lines containing a plurality of audio program signals. A conventional television signal transmission places a digital audio signal in the horizontal blanking interval, followed by analog video information. In accordance with the present invention, the "window" containing the analog video information is replaced with a plurality of digital audio signals that are time division multiplexed within the window. An additional audio channel is placed in the horizontal blanking interval, at the same location the audio is placed when video information is transmitted. Selector switches are provided in the encoder and decoder for processing a composite waveform as either a video signal with an associated audio channel, or as a multiple channel digital audio signal. Independent encryption and decryption of each of the multiple audio channels is provided.
摘要:
A system for companding digital audio signal samples processes the digital audio signal samples to correct errors induced by the compression and expansion processes. These errors are calculated prior to compressing the samples. Such errors are calculated in accordance with a predetermined compression process and a predetermined expansion process; and the digital audio signal samples are corrected in accordance with such calculations prior to compression. The compression process includes providing a 3-bit gain word for a block of 70 samples. The gain word is computed in accordance with the position of the most significant "1" bit in the sample(s) having the peak magnitude. Each individual sample is processed in accordance with the block gain word to compress the sample by reducing the number of magnitude bits. The error calculation process includes calculating an error signal by subtracting a calculated reproduced digital audio signal sample from the digital audio signal sample to be compressed, filtering the error signal by noise-spectral filtering and adding the filtered error signal to the next-providing digital audio signal sample to provide a corrected digital audio signal sample for compression. The error calculation process also includes calculating an error value based upon the effect of using a single gain word for compressing a block of samples. The error value is subtracted from the corrected digital audio signal sample prior to compression. The gain word is forward error corrected by (5,1) encoding to enable detection and correction of both single-bit and double-bit errors in transfer by majority voting. The sign bit and the most significant magnitude bits of the compressed samples are forward error corrected to enable detection and correction of single-bit errors in transfer and to enable detection and concealment of double-bit errors in transfer.
摘要:
A method for enforcing a software upgrade for software operable on a device includes receiving, at the device, a message including software-version information for the software from a domain controller. The software-version information indicates a list of approved versions of the software. The method includes determining, by the device, the software-version information from the message, and determining a current version of the software included on the device by performing a comparison of versions in the list of approved versions to the current version of the software on the device. If the current version of the software is not included in the list of approved versions, the method includes causing the device to not have or use a set of up-to-date security credentials for a set of content servers, for accessing any pieces of media on the set of content servers until the device has an approved version of the software.
摘要:
Apparatus forming part of a home entertainment system includes an electronic device having an input accepting a signal corresponding to an externally-generated first user interface, a control module for internally-generating a signal corresponding to a second user interface, and an output for transmitting a combination of the above referenced signals for display. The control module controls an arrangement of display of the first user interface and the second user interface. The apparatus also includes a remote controller for communicating via a two-way communication link with the control module of the electronic device concerning a selection of one of the first user interface and the second user interface. The remote controller having an emitter for emitting control code signals, and the operation of the emitter is controlled by communications received by the remote controller from the control module of the electronic device. A method is also provided.
摘要:
In a method of registering a plurality of client devices with a device registration server for secure data communications, a unique symmetric key is generated for each of the client devices using a cryptographic function on a private key of the device registration server and a respective public key of each of the client devices, and a broadcast message containing the public key of the device registration server is sent to the client devices, in which the client devices are configured to generate a respective unique symmetric key from the public key of the device registration server and its own private key using a cryptographic function, and in which the unique symmetric key generated by each client device matches the respective unique symmetric key generated by the device registration server for the respective client device.