Server-side media stream manipulation for emulation of media playback functions

• US 20070271388A1
• Filed: 05/22/2006
• Published: 11/22/2007
• Est. Priority Date: 05/22/2006
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Speicher, Ashley C., Bowra, Todd, Fang, Nicholas J.
• Granted Patent: US 7,890,985 B2
• Time in Patent Office: Days
• US Class Current: 709/231
• CPC Class Codes: H04L 2012/2849 Audio/video appliances
• CPC Class Codes: H04L 65/762 at the source reformatting of additional data in video distribution servers H04N21/2355

Abstract

A media server in the home entertainment network allows a media rendering devices to act as a digital media receiver. The media server enables trick mode functions such as scan forward or reverse, slow motion, pause, and seek on rendering devices with capabilities limited to 1× playback. The media server receives commands from user input at the rendering device transmitted over the network to the media server. The media server manipulates the media stream before the transmission over the network by deleting or adding frames to the media stream as necessary to emulate the desired playback functions and replacing frame timestamps to create a media stream that appears to the media rendering device as a sequential 1× stream. The transmitted media stream may not contain all of the media content stored in the corresponding media file on the media server, thus avoiding limitations on the download bandwidth and local client storage.

Claims

1. A method for enabling, over a network, rate-altering media playback functions on a low capability and/or low capacity rendering device, the method comprising

adjusting frame timestamps of a stream of frames to generate a series of frames at a frame rate expected by the rendering device;

deleting frames from the stream of frames in excess of the frame rate expected by the rendering device before transmission of the series of frames over the network; and

inserting one or more intermediate frames into the stream of frames when insufficient frames originally exist in the stream of frames to fulfill the frame rate expected by the rendering device before transmission of the series of frames over the network.

2. The method of claim 1 further comprising transmitting the series of frames over the network to the rendering device.

3. The method of claim 1 wherein the inserting operation further comprises

calculating an inverse of a play rate corresponding to a selected, rate-altering media playback function;

subtracting 1 from the inverse to determine a difference; and

inserting a number of frames equal to the difference resulting from the subtracting operation between each pair of adjacent frames in the stream of frames.

4. The method of claim 1, wherein the one or more intermediate frames are duplicate frames of another frame in the stream of frames.

5. The method of claim 1, wherein the one or more intermediate frames are extrapolated and/or interpolated frames from at least one frame in the stream of frames.

6. The method of claim 1, wherein the adjusting operation further comprises

dividing the frame timestamps of frames remaining in the stream of frames by a play rate corresponding to a selected, rate-altering media playback function;

and

substituting a quotient of the dividing operation for the frame timestamps of the frames remaining in the stream of frames, respectively.

7. The method of claim 1, wherein the adjusting operation further comprises adjusting the frame timestamps of each of the frames remaining in the stream of frames after the deleting operation by subtracting a product of the total number of deleted frames to that point and the frame rate expected by the rendering device.

8. The method of claim 1, wherein the adjusting operation further comprises adjusting the frame timestamps of each of the frames in the stream of frames after the inserting operation by adding a product of the total number of inserted frames to that point and an inverse of the frame rate expected by the rendering device.

9. The method of claim 1, wherein the adjusting operation further comprises

subtracting the frame timestamps of adjacent frames originally in the stream of frames to determine a difference;

dividing the difference by a play rate corresponding to a selected, rate-altering media playback function to determine a quotient;

adding the quotient to an earlier frame of the adjacent frames to determine a first sum;

substituting the first sum for the frame timestamp of the earlier frame;

multiplying a respective insertion number of a respective of the one or more intermediate frames by an inverse of the frame rate to determine a product;

adding the product to the first sum to determine a second sum; and

assigning the second sum as a generated timestamp to the respective one of the one or more intermediate frames.

10. The method of claim 4, wherein the adjusting operation further comprises successively adding a product of an inverse frame rate amount and a respective insertion number of a respective of the one or more intermediate frames to an original frame timestamp of each of the one or more intermediate frames.

11. The method of claim 5, wherein the adjusting operation further comprises successively adding a product of an inverse frame rate amount and a respective insertion number of a respective of the one or more intermediate frames to an original frame timestamp of each of the one or more intermediate frames.

12. A computer-readable medium having computer-executable instructions for performing a computer process implementing the method of claim 1.

13. A method for emulating rate-altering media playback functions for playback of a media stream across a network on a constant rate rendering device, the method comprising

adjusting timestamps of frames in the media stream to generate a series of frames at a constant frame rate expected by the rendering device;

deleting frames from the media stream in excess of the constant frame rate before transmission of the media stream over the network; and

inserting one or more intermediate frames into the media stream when insufficient source frames exist to meet the constant frame rate before transmission of the media stream over the network.

14. The method of claim 13, wherein the one or more intermediate frames are duplicate frames of another frame in the media stream.

15. The method of claim 13, wherein the one or more intermediate frames are interpolated frames from at least one frame in the media stream.

16. A computer-readable medium having computer-executable instructions for performing a computer process implementing the method of claim 13.

17. A media server comprising

a processor;

a memory under control of the processor, wherein the memory stores media content;

an audio/video control module, under control of the processor, that receives instructions for a rate-altering, media playback function from a user;

an audio/video source module, under control of the audio/video control module and the processor, that accesses the media content stored on the memory and transmits the media content according to the instructions for the rate-altering, media playback function;

an audio/video sample manipulator module, under control of the audio/video control module and the processor, that

receives the media content from the audio/video source module,

manipulates the media content to emulate the rate-altering, media playback function, and

outputs a stream of the manipulated media content at a constant rate.

18. The media server of claim 17, wherein the audio/video sample manipulator module deletes frames from the media content in excess of the constant rate.

19. The media server of claim 17, wherein the audio/video sample manipulator module inserts one or more intermediate frames into the media content when insufficient frames originally exist in the media content to fulfill the constant rate.

20. The media server of claim 17, further comprising a network link for transmission of the stream over a network to a rendering device.