Generating constant timecast information sub-streams using variable timecast information streams

• US 6,385,771 B1
• Filed: 04/13/1999
• Issued: 05/07/2002
• Est. Priority Date: 04/27/1998
• Status: Expired due to Term

• Current Assignee: Comcast IP Holdings I LLC (Comcast Corporation)
• Original Assignee: DIVA Systems Corporation
• Inventors: Gordon, Donald F.
• Primary Examiner(s): Faile, Andrew
• Assistant Examiner(s): BROWN, RUEBEN M
• Application Number:
  US09/290,618
• Time in Patent Office: 1,120 Days
• Field of Search: 386/688, 725/88-90, 725/20, 725/102, 725/131-134, 725/139-142, 725/151-153, 375/240.12, 375/240.13
• US Class Current: 725/90
• CPC Class Codes: H04L 12/5602 Bandwidth control in ATM Networks, e.g. leaky bucket
• CPC Class Codes: H04L 12/6418 Hybrid transport
• CPC Class Codes: H04L 2012/6483 Video, e.g. MPEG
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/70 Media network packetisation
• CPC Class Codes: H04L 65/762 at the source reformatting of additional data in video distribution servers H04N21/2355
• CPC Class Codes: H04L 65/765 intermediate
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04N 19/132 Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
• CPC Class Codes: H04N 19/587 involving temporal sub-sampling or interpolation, e.g. decimation or subsequent interpolation of pictures in a video sequence
• CPC Class Codes: H04N 21/234381 by altering the temporal resolution, e.g. decreasing the frame rate by frame skipping
• CPC Class Codes: H04N 21/23439 for generating different versions
• CPC Class Codes: H04N 21/2387 Stream processing in response to a playback request from an end-user, e.g. for trick-play
• CPC Class Codes: H04N 21/2389 Multiplex stream processing, e.g. multiplex stream encrypting
• CPC Class Codes: H04N 21/2662 Controlling the complexity of the video stream, e.g. by scaling the resolution or bitrate of the video stream based on the client capabilities
• CPC Class Codes: H04N 21/4385 Multiplex stream processing, e.g. multiplex stream decrypting
• CPC Class Codes: H04N 21/47202 for requesting content on demand, e.g. video on demand
• CPC Class Codes: H04N 21/6587 Control parameters, e.g. trick play commands, viewpoint selection
• CPC Class Codes: H04N 5/781 on disks or drums
• CPC Class Codes: H04N 5/783 Adaptations for reproducing at a rate different from the recording rate
• CPC Class Codes: H04N 7/17318 : Direct or substantially direct transmission and handling of requests
• CPC Class Codes: H04N 9/8042 : involving data reduction
• CPC Class Codes: H04N 9/8227 : the additional signal being at least another television signal

Abstract

A method and apparatus for processing an information stream comprising a plurality of compressed information frames having an associated original or source timecast parameter to produce an information sub-stream having a substantially constant timecast parameter. The invention generates an information substream having a timecast parameter that is held substantially constant, even though the timecast parameter of the input stream may vary.

Claims

1. Apparatus for processing an input video stream having a variable timecast to produce an output video stream having a predetermined timecast, comprising:

a selector, for selecting at least one of intra-coded, predictively-coded, and bi-directionally-coded video frames or video frame components from said input video stream in response to a timeslice indicative control signal;

an assembler, for assembling selected video frames or frame components to produce said output video stream; and

a controller, for producing said timeslice indicative control signal in response to a ratio between said input video stream timecast and said predetermined timecast;

said controller adapting said timeslice indicative control signal in response to changes in said input video stream timecast.

2. The apparatus of claim 1, wherein said selector further comprises a decoder, for decoding an encoded input video stream to produce a decoded input video stream.

3. The apparatus of claim 1, wherein each of said extracted timeslices comprise one of a video frame and a video sub-frame, said video sub-frame comprising a plurality of fields, slices, macroblocks, blocks and a raster line.

4. The apparatus of claim 1, wherein said output video stream comprises at least one of a fast forward (FF) video stream and a fast rewind (REW) video stream, said FF and REW video streams having respective predetermined timecasts.

5. The apparatus of claim 1, wherein said predetermined timecast comprises a substantially fixed timecast having a value of between approximately six frames per second and approximately twenty frames per second.

6. The apparatus of claim 1, wherein:

said selector comprises a memory for storing at least one information;

frame and said assembler comprises a memory for storing a plurality of information frames;

said selector, in response to said timeslice indicative control signal, communicating to said assembler a stored information frame; and

said assembler appending said communicated information frame to a previously communicated information frame.

7. The apparatus of claim 1, further comprising:

an encoder, for encoding said output video stream to produce an encoded video stream, said encoded video stream comprising at least one of an encoded fast forward video stream and an encoded fast rewind video stream.

8. A method for processing an information stream to produce an information sub-stream, said method comprising the steps of:

extracting, from said information stream, a plurality of timeslices at intervals determined by a relationship between a timecast of said information stream and a desired timecast of said information sub-stream; and

assembling said extracted timeslices to form said information sub-stream;

said timeslice intervals being modified in response to changes in said timecast of said information stream.

9. The method of claim 8, wherein each said extracted timeslices comprise one of a video frame and a video sub-frame, said video sub-frame comprising at least one of a plurality of field, slice, macroblock, block and raster line components.

10. In a system for processing an information stream having a timecast parameter susceptible to variations, a method for producing an information sub-stream having a substantially constant timecast comprising the steps of:

deriving, in response to said information stream timecast and a desired information sub-stream timecast, a timeslice parameter;

extracting, from said information stream according to said derived timeslice parameter, a plurality of information frames or information frame components, said extracted information frames or information frame components forming said information substream; and

adapting, in response to changes in said information stream timecast, said timeslice parameter such that said information sub-stream maintains a substantially constant timecast.

11. The method of claim 10, wherein each information frame is said information stream is passed through a frame store memory, and said step of extracting comprises the step of retrieving, from said frame store memory, information frames at a rate determined by said timeslice parameter.

12. The method of claim 10, further comprising the steps of:

deriving, in response to said information stream timecast and a second desired information sub-stream timecast, a second timeslice parameter;

extracting, from said information stream according to said derived second timeslice parameter, a plurality of information frames or information frame components, said extracted information frames or information frame components forming a second information substream; and

adapting, in response to changes in said information stream timecast, said second timeslice parameter such that said second information sub-stream maintains a substantially constant timecast.

13. The method of claim 10, wherein said information stream comprises a video information stream, and said information substream comprises at least one of a fast forward (FF) or fast rewind (REW) substream.

14. The method of claim 12, wherein said information stream comprises a video information stream, and said information substream comprises at least one of a fast forward (FF) or fast rewind (REW) substream.

15. The method of claim 10, wherein said information stream comprises an encoded information stream, and said step of extracting includes the step of decoding said encoded information stream to produce at least one of an information frame and an information frame component.

16. The method of claim 10, further comprising the step of encoding said information substream to produce an encoded information substream.

17. The method of claim 10, wherein said information stream comprises a sequence of compressed information frames, and said step of extracting comprises the steps of:

identifying an Nth compressed information frame in said sequence of compressed information frames, where N is an integer;

decoding said identified Nth compressed information frame to produce an uncompressed information frame; and

repeating said steps of identifying and decoding until each of said Nth compressed information frames in said compressed information stream has been processed.

18. The method of claim 17, wherein said step of identifying further comprises the step of

determining if said identified information frame is a non-predicted information frame or a predicted information frame;

and

in the case of said identified information frame being a predicted information frame of a first type;

examining each of up to M compressed information frames subsequent or prior to said identified information frame to identify a one compressed information frame that is not a predicted information frame of said first type, where M is an integer; and

substituting, for decoding purposes, said identified one information frame for said identified information frame.

19. The method of claim 18, wherein said information stream comprises an MPEG-like information stream, and said first type of information frame comprises a bi-directionally predicted frame.

20. The method of claim 17, wherein said step of identifying further comprises the step of:

determining if said identified information frame is a bi-directionally predicted information frame or a predicted information frame; and

in the case of said identified information frame being a bi-directionally predicted information frame of a first type;

examining each of up to M compressed information frames subsequent or prior to said identified information frame to identify a one compressed information frame that is not a bi-directionally predicted information frame of said first type, where M is an integer; and

substituting, for decoding purposes, said identified one information frame for said identified information frame.