Granted Patent B2

US 8,797,457 · App. 12/067,080 · Granted Aug 5, 2014

Abstract

Claims (45)

1. An apparatus for matching timing of an input video stream with timing of an output video stream, the apparatus comprising:

at least one memory buffer for receiving and storing video data at an input frame rate of the input video stream,

an output frame generator coupled to the at least one memory buffer for receiving video data from the at least one memory buffer at an output frame rate, and

regulating means coupled to the at least one memory buffer and the output frame generator for implementing feedback control that permits a state of the at least one memory buffer, to be monitored, and for controlling a regulation, based on said state, between two or more different timing settings to selectively slow down or speed up the output frame rate.

2. The apparatus of claim 1 , wherein the regulating means sends at least one threshold signal from the at least one memory buffer to the output frame generator, and wherein the output frame generator samples each said threshold signal at at least one sampling point.

3. The apparatus of claim 2 , wherein, at each said sampling point, the output frame generator selectively switches the output frame rate by selectively switching between the two or more different timing settings.

4. The apparatus of claim 1 , wherein the output frame generator implements the two or more different timing settings as one of alternative output frame layouts, different output frame rates, and different output line lengths.

5. The apparatus of claim 4 , wherein the output frame generator uses respective ones of the alternative output frame layouts to respectively generate:

fast output frames that are slightly shorter in duration than a shortest possible input frame, and

slow output frames that are slightly longer in duration than the longest possible input frame.

6. The apparatus of claim 5 , wherein the output frame generator alternates between output frame sequences of the fast and slow output frames.

7. The apparatus of claim 2 , wherein one of the sampling points corresponds to a position, in an output frame layout implemented by the output frame generator, that guarantees no underflow of the at least one memory buffer.

8. The apparatus of claim 2 , wherein said monitored state is a fullness of the at least one buffer, and comprising setup means that allow the apparatus to be switched from a normal mode of operation into a setup mode which is used to set a threshold so that a corresponding said threshold signal is issued when the at least one memory buffer becomes filled to the threshold.

9. The apparatus of claim 1 , wherein the matching is done on a frame-by-frame or line-by-line basis.

10. The apparatus of claim 8 , wherein the setup mode is used to set a floor threshold and a ceiling threshold to compensate for phase shifts between the input video stream and the output video stream.

11. The apparatus of claim 10 , wherein said output frame generator selects one of

a normal said timing setting if the fullness of the at least one memory buffer is between the floor threshold and the ceiling threshold,

a slow said timing setting if the fullness of the at least one memory buffer falls below the floor threshold, and

a fast said timing setting if the fullness of the at least one memory buffer exceeds the ceiling threshold.

12. A method for processing an input video stream that includes video data transmitted at an input frame rate, comprising:

receiving the video data,

temporarily storing the video data in a memory buffer at the input frame rate,

monitoring the fullness of the memory buffer to determine whether the fullness reaches a pre-defined threshold, and

sampling the threshold signals received from the memory buffer at one or more positions in the output frame;

regulating, based on the fullness of the memory buffer, between two or more different timing settings of an output frame rate at which video data are output by the memory buffer and sent to an output frame generator, to selectively slow down or speed up the output frame rate.

13. The method of claim 12 being employed in order to maintain a frame synchronization between the input video stream and an output video stream produced by the output frame generator.

14. The method of claim 12 being employed in order to match the input frame rate with a frame rate of an output video stream produced by the output frame generator.

15. The method of claim 12 wherein an auto setup is performed in order to define at least one said pre-defined threshold for use in said monitoring.

16. An apparatus configured to match timing of an input video stream with timing of an output video stream, the apparatus comprising:

at least one memory buffer for receiving and storing video data at an input frame rate of the input video stream, the at least one memory buffer configured to generate a threshold signal indicative of a fullness of the at least one memory buffer; and

an output frame generator coupled to the at least one memory buffer for receiving video data from the at least one memory buffer and generating output frames of video data, said output frame generator configured to sample threshold signal;

a threshold measurement unit,

wherein the output frame generator selects among two or more different timing settings depending on the threshold signal, the two or more different timing settings including:

a fast timing setting where the output frame generator generates output frames that are slightly shorter in duration than the shortest possible input frame to ensure that video data is output from the at least one memory buffer faster than video data is input to the at least one memory buffer, and

a slow timing setting where the output frame generator generates output frames that are slightly longer in duration than the longest possible input frame to ensure that video data is output from the at least one memory buffer slower than video data is input to the at least one memory buffer.

17. The apparatus of claim 16 , wherein the at least one memory buffer is configured to send a plurality of threshold signals to the output frame generator, and the output frame generator is configured to sample each of the threshold signals at at least one sampling point.

18. The apparatus of claim 16 , wherein the output frame generator implements the two or more different timing settings as alternative output frame layouts

a fast setting generating output frames that are shorter in duration than a shortest possible input frame, and

a slow setting generating output frames that are longer in duration than the longest possible input frame.

19. The apparatus of claim 16 , wherein the output frame generator implements the two or more different timing settings as one of: alternative output frame layouts, different output frame rates, and different output line lengths.

20. The apparatus of claim 16 , wherein the at least one memory buffer is further configured to support a floor threshold and a ceiling threshold to facilitate monitoring the fullness of the at least one memory buffer in order to compensate for phase shifts between the input video stream and the output video stream;

the output frame generator being further configured to, based on the fullness of the memory buffer, selectively implement one of:

a normal timing setting if the fullness of the memory buffer is between the floor threshold and the ceiling threshold,

the slow timing setting if the fullness of the memory buffer falls below the floor threshold, and

the fast timing setting if the fullness of the memory buffer exceeds the ceiling threshold.

Assignments (19)