Method and apparatus for adaptively compressing streaming video

• US 9,992,252 B2
• Filed: 09/29/2015
• Issued: 06/05/2018
• Est. Priority Date: 09/29/2015
• Status: Active Grant

• Current Assignee: RGB Systems Incorporated
• Original Assignee: RGB Systems Incorporated
• Inventors: Smith, Peter Lionel
• Primary Examiner(s): SOSANYA, OBAFEMI OLUDAYO
• Application Number:
  US14/868,941
• Publication Number:
  US 20170093947A1
• Time in Patent Office: 980 Days
• CPC Class Codes: H04L 65/70 Media network packetisation
• CPC Class Codes: H04N 19/115 Selection of the code volume for a coding unit prior to coding
• CPC Class Codes: H04N 19/152 by measuring the fullness of the transmission buffer
• CPC Class Codes: H04N 19/162 User input
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/188 the unit being a video data packet, e.g. a network abstraction layer [NAL] unit
• CPC Class Codes: H04N 19/60 using transform coding
• CPC Class Codes: H04N 21/23805 Controlling the feeding rate to the network, e.g. by controlling the video pump

Abstract

The present invention is a method and apparatus for adaptively compressing and transmitting streaming video, preferably implemented in hardware as part of a codec, that adaptively applies a variable rate of compression to images in a video stream to optimize the quality attainable for a given transport bandwidth. In one or more embodiments, image frames from the video stream are divided into blocks, and a variable compression ratio compression engine compresses the blocks for transmission over a network. Depending on their compressed sizes, one or more of the compressed blocks are packaged into fixed size data packets for transmission over a network. The data packets are fed into a packet buffer. A packet servo releases packets from the buffer to achieve a desired transport data rate. The amount of compression applied by the compression engine is controlled based on the number of packets in the buffer. In one or more embodiments, a plurality of indexed compression vectors are predefined for the compression engine that provide increasing amounts of compression. In one or more embodiments, the index of the compression vector used by the compression engine is incremented when the buffer level of the packet buffer increases, and decremented when the buffer level decreases. In this manner the compression applied by the compression engine automatically adapts to changing entropy within the images of the video stream to optimize the video quality for a given transport data rate.

Claims

1. An apparatus for adaptively compressing a video stream comprising:

a variable compression rate compression engine configured to compress incoming uncompressed image data blocks of a video stream, where said video stream includes images having different entropy, using a compression vector selected from a set of predetermined compression vectors to produce compressed image data blocks;

a data packager configured to receive said compressed image data blocks from said compression engine and to package said compressed image data blocks into data packets;

a packet buffer configured to receive said data packets from said data packager, store said data packets, release said data packets in response to data packet release signals received from a packet servo configured to release packets from said packet buffer at a constant rate to achieve a desired transport data rate;

said packet delay controller being configured to receive a desired transport data rate from a user interface, to determine a delay time between said data packets corresponding to said transport data rate, and to provide said delay time to said packet servo;

said packet servo being configured to receive said delay time from said packet delay controller, and to send said packet release signals to said packet buffer according to said delay time;

a compression controller configured to maintain a buffer level count indicating a level of said data packets in said packet buffer, to determine a current compression vector from said buffer level count, to receive a maximum compression vector, determine if said current compression vector is greater than said maximum compression vector, and;

if said current compression vector is greater than said maximum compression vector, provide said maximum compression vector to said compression engine and cause an additional packet that may accrue to be sent in an unused frame interval, and

if said current compression vector is less than or equal to said maximum compression vector, provide said current compression vector to said compression engine that automatically adapts to changing entropy within said images of said video stream based at least in part on said desired transport data rate.

2. The apparatus of claim 1 wherein said packet servo is further configured to send decrement signals to said compression controller.

3. The apparatus of claim 2 wherein said data packager is further configured to send increment signals to said compression controller.

4. The apparatus of claim 3 wherein said compression controller is further configured to maintain said buffer level count based upon said decrement and increment signals.

5. The apparatus of claim 3 wherein said data packager is configured to package said compressed data blocks in data packets having a fixed size.

6. The apparatus of claim 1 comprising a logical auto rate control module comprising logical modules that implement functions of said data packager, packet buffer, compression controller, and packet servo.

7. The apparatus of claim 1 further comprising a non-volatile memory comprising a plurality of predetermined maximum compression vectors for a plurality of video stream formats.

8. The apparatus of claim 1 further comprising a non-volatile memory comprising a plurality of predetermined minimum transport data rates for a plurality of video stream formats.

9. The apparatus of claim 7 wherein said packet delay controller is configured to receive a current video stream format from said user interface.

10. The apparatus of claim 9 wherein said packet delay controller is configured to select a current maximum compression vector for said current video stream format from said non-volatile memory and provide said current maximum compression vector to said compression controller.

11. A method for adaptively compressing a video stream comprising a series of image data blocks by a video encoding apparatus, where said video stream includes images having different entropy, the method comprising:

compressing each of said data blocks using a current compression vector selected from a set of predetermined compression vectors to produce compressed data blocks;

packaging said compressed data blocks into a plurality of data packets;

storing said data packets in a packet buffer;

determining a packet delay time from a transport data rate;

releasing, at a desired transport rate, said data packets from said packet buffer at intervals based on said packet delay time;

maintaining a buffer level count indicating a current level of data packets in said packet buffer;

determining said current compression vector from said current buffer level count;

accessing a maximum compression vector;

determining if said current compression vector is greater than said maximum compression vector;

if said current compression vector is greater than said maximum compression vector, performing data packet compression using said maximum compression vector and causing an additional packet that may accrue to be sent in an unused frame interval, and

if said current compression vector is less than or equal to said maximum compression vector, performing data packet compression using said using said current compression.

12. The method of claim 11 further comprising receiving said transport data rate from a user interface.

13. The method of claim 11 further comprising receiving a format type of said video stream from a user interface.

14. The method of claim 13 wherein determining said current compression vector comprises determining a maximum compression vector from said format type.

15. The method of claim 13 wherein determining said packet delay time comprises determining a minimum transport data rate from said format type.

16. The method of claim 11 wherein maintaining said buffer level count comprises incrementing said buffer level count for each data packet packaged in said packaging step.

17. The method of claim 16 wherein maintaining said buffer level count comprises decrementing said buffer level count for each data packet released from said packet buffer.

18. The method of claim 11 wherein said packaging comprises packaging said compressed data blocks into a plurality of fixed size data packets.

19. The method of claim 11 wherein said releasing said data blocks from said packet buffer comprises monitoring a timer.

20. The method of claim 19 wherein said monitoring of said timer comprises starting said timer after one of said data blocks is released from said packet buffer.