Sigma Designs, Inc.

Michael Ignaszewski

Vincent Trinh

Jacques Mahe

The present invention provides a method for matching the rate of presentation of digital video data at a receiver/client with the rate the server is serving the data without the need of a voltage control oscillator or other hardware. An embodiment of the invention compares the presentation time at the receiver with the server elapsed time estimated from timestamp values on the served data. When the presentation time and the server elapsed time differ by an unacceptably large amount, an adjustment is made to the audio data stream to re-synchronize the presentation time with the elapsed time, which effectively also synchronizes the overall presentation rate with the overall server rate. The video data stream is then synchronized to the adjusted audio stream. The video data stream and audio data stream are converted to analog signals for presentation.

Method, apparatus and computer program product for synchronizing presentation of digital video data with serving of digital video data

The present invention increases the difficulty of reverse engineering sensitive information protected by an encryption algorithm by increasing the difficulty associated with tracing the code that generates the key or the encryption algorithm. This is accomplished by generating the key, used to encrypt and decrypt the sensitive information, as a function of the program instruction values of the procedures used to generate the key and perform the decryption of the sensitive information. Thus, if the key generation code or the decryption code is modified (such as (but without limitation) by placement of a breakpoint, a trace function, or a halt instruction in the code) the resulting key will be different from the key used to encrypt the sensitive information and the decryption attempt will fail.

Method and apparatus for generating and using a tamper-resistant encryption key

Apparatus and methods, and computer program products are disclosed that accepts time-stamped information and feeds that information to a buffered system that consumes the information. The invention accepts an initial interval of the time-stamped information and when a pre-fill limit is reached, starts consumption of the data. The pre-fill limit is determined by monitoring the time stamp on the data that is ready to be consumed and the time stamp of data that has just been accepted. The difference between these time stamps provides an interval that represents the amount of time related to the data associated with the time-stamped information. Once the interval exceeds a pre-fill limit, the invention allows the buffered time-stamped information to be consumed. As the time-stamped information is consumed, the invention monitors the interval (other embodiments use the time stamp of data that is in the process of being consumed, or data that has just been consumed). If the interval falls below a lower limit, the invention stops consumption of the time-stamped information and waits for the interval to exceed a resume consumption trigger. Once the interval reaches the resume consumption limit the invention resumes consumption of the time-stamped information. This process continues until all the time-stamped information is consumed.

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Fremont, CA, United States of America

Michael Ignaszewski