Synthesis of vertical blanking signal

• US 20040252231A1
• Filed: 12/23/2003
• Published: 12/16/2004
• Est. Priority Date: 06/13/2003
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Computer Incorporated (Apple Inc.)
• Inventors: Agnoli, Giovanni M., Dillon, Jeffrey C., Delwiche, James A., Abt, John O., Yanowitz, Andrew, Bowman, Samuel R.
• Granted Patent: US 7,668,099 B2
• Time in Patent Office: Days
• US Class Current: 348/435.1
• CPC Class Codes: H04N 21/4135 external recorder interface circuits between an apparatus for recording television signals and a television receiver H04N5/775
• CPC Class Codes: H04N 21/4143 embedded in a Personal Computer [PC]
• CPC Class Codes: H04N 21/4223 Cameras H04N23/00 takes precedence
• CPC Class Codes: H04N 21/4305 Synchronising client clock from received content stream, e.g. locking decoder clock with encoder clock, extraction of the PCR packets arrangements for synchronising receiver with transmitter by comparing receiver clock with transmitter clock H04L7/0012; arrangements for synchronising receiver with transmitter wherein the receiver takes measures against momentary loss of synchronisation H04L7/0083
• CPC Class Codes: H04N 21/43632 involving a wired protocol, e.g. IEEE 1394 high-speed IEEE 1394 serial bus H04L12/40052
• CPC Class Codes: H04N 5/765 Interface circuits between an apparatus for recording and another apparatus
• CPC Class Codes: H04N 7/088 the inserted signal being digital
• CPC Class Codes: H04N 7/56 Synchronising systems therefor

Abstract

A method of controlling transmission of data from a computer to a video client via an interface device, comprising: reading a register on the interface device to obtain a value indicating temporal proximity to an occurrence of a vertical blanking interval occurs, the value increased incrementally until a vertical blanking interval occurs, and then being reset; deriving a time value, the time value indicating the occurrence of a vertical blanking interval; sending an interrupt to a processor on the computer at the occurrence of the vertical blanking interval; and invoking code in response to an occurrence of the video blanking interval.

Claims

1. A method of controlling transmission of data from a computer to a video client via an interface device that buffers data frames sent between the computer and the video client and communicates to the computer and the video client using different protocols, the method comprising:

reading a register on the interface device to obtain a value indicating temporal proximity to an occurrence of a vertical blanking interval occurs;

deriving a time value, the time value indicating the occurrence of a vertical blanking interval;

sending an interrupt to a processor on the computer at the occurrence of the vertical blanking interval; and

invoking code in response to an occurrence of the video blanking interval.

2. The method of claim 1, wherein the time value is derived through extrapolation.

3. The method of claim 1, wherein invoking code comprises sending a command over serial bus to obtain a time code value, the time code value describing video data.

4. The method of claim 1, wherein invoking code comprises sampling a time code value through the serial port.

5. The method of claim 1, wherein invoking code comprises recapturing video data using the time code value.

6. The method of claim 5, wherein recapturing is performed on video data in batch mode based on time code value.

7. The method of claim 1, wherein time code value is used in a seek operation on a storage device to select stored video data.

8. The method of claim 1, wherein use time code value to uniquely identify a frame.

9. The method of claim 1, wherein store time code with associated frame.

10. The method of claim 1, wherein invoking code comprises transmitting a data frame from the computer to the interface in response to the sending of the interrupt.

11. The method of claim 1, wherein reading the register comprises reading a register that rolls over at a multiple of an occurrence of the vertical blanking register.

12. The method of claim 1, wherein invoking code comprises sampling a time code value multiple times per frame.

13. A computer program product containing instructions which, when executed by a computer, control transmission of data from a computer to a video client via an interface device that buffers data frames sent between the computer and the video client and communicates to the computer and the video client using different protocols, by performing the acts of:

reading a register on the interface device to obtain a value indicating temporal proximity to an occurrence of a vertical blanking interval occurs;

deriving a time value, the time value indicating the occurrence of a vertical blanking interval;

sending an interrupt to a processor on the computer at the occurrence of the vertical blanking interval; and

invoking code in response to an occurrence of the video blanking interval.

14. An apparatus that controls transmission of data from a computer to a video client via an interface device that buffers data frames sent between the computer and the video client and communicates to the computer and the video client using different protocols, the apparatus comprising:

means for reading a register on the interface device to obtain a value indicating temporal proximity to an occurrence of a vertical blanking interval occurs;

means for deriving a time value, the time value indicating the occurrence of a vertical blanking interval;

means for sending an interrupt to a processor on the computer at the occurrence of the vertical blanking interval; and

means for invoking code in response to an occurrence of the video blanking interval.