ALGORITHMS FOR DETERMINING BITRATE FOR A STATISTICAL MULTIPLEXING SYSTEM USING SCENE CHANGE
An improved statistical multiplexer (statmux) system for coding and multiplexing multiple channels of standard definition (SD) digital television data, or multiple panels of high definition (HD) digital television data is provided, the system considering when a scene change occurs. A need parameter (NP) is determined for each of the multiple encoders considering scene change that occur, and the NP is provided to a statmux controller to enable a bit rate to be determined for the encoder. The system considers the new scene data after a scene change as well as current scene data being evaluated to determine data complexity for the NP value. This ensures significantly different complexity data after the scene change does not cause an inadequate bit rate determination.
1 . A method for allocating bits to individual encoders in a statistical multiplexer (statmux) system comprising:
detecting a scene change present in video data to be encoded in a given one of the individual encoders;
determining a first complexity of a current scene prior to the detected scene change;
determining a second complexity of a new scene after the detected scene change;
determining an overall complexity rate for encoding the video data in the given encoder by combining the first complexity and the second complexity; and
providing the overall complexity rate as a need parameter for determination of a bit rate for encoding the video data.
2 . The method of claim 1 , wherein a look ahead buffer (LAB) provides data in the given encoder, and wherein the determining of the first complexity and the second complexity are performed on the video data within the LAB.
3 . The method of claim 1 , wherein a third complexity data from a previous scene occurring prior to the current scene is not used in determining the bit rate for encoding the video data.
4 . The method of claim 1 wherein the first complexity and the second complexity include a determination of the number of I, P and B type pictures within the current scene and the new scene.
5 . The method of claim 4 , wherein difficult frames are identified in the video data and wherein the overall complexity determination is made with consideration of the difficult frames.
6 . The method of claim 2 , wherein a target frame within the LAB is determined to begin the complexity determination process to enable time for the encoder to send the overall complexity data and receive a bit rate in response for encoding the video data.
7 . The method of claim 6 , further comprising determining the size of the LAB following the target frame to provide as part of the complexity data for the current scene and the new scene.
8 . A statistical multiplexer for coding a plurality of channels of video data sources, the statistical multiplexer comprising:
a look ahead buffer (LAB) for storing the video data prior to encoding;
an encoder for compressing the video data and providing the video data to a multiplexer in the statistical multiplexer; and
a processor for evaluating data within the LAB to determine complexity of the data, providing a need parameter to a statmux controller based on the determined complexity of the data and for receiving a bit rate from the statmux controller to control the compressing of the video data in the encoder, wherein the processor operates based on code stored in a memory that causes the processor to perform the following during the process of evaluating data within the LAB:
detect a scene change present in the video data to be encoded;
determine a first complexity of a current scene prior to the detected scene change;
determine a second complexity of a new scene after the detected scene change; and
determine an overall complexity rate for encoding the video data in the given encoder by combining the first complexity and the second complexity.
9 . The statistical multiplexer of claim 8 , wherein the processor comprises a state machine.
10 . The statistical multiplexer of claim 8 , wherein a third complexity data from a previous scene occurring prior to the current scene is not used in determining the bit rate for encoding the video data.
11 . The statistical multiplexer of claim 8 , wherein the first complexity and the second complexity include a determination of the number of I, P and B type pictures within the current scene and the new scene.
12 . The statistical multiplexer of claim 8 , wherein difficult frames are identified in the video data and wherein the complexity determination is made with consideration of the difficult frames.
13 . The statistical multiplexer of claim 8 , wherein the LAB is integrated with the encoder as a single component.
14 . A non-transitory computer readable medium containing an executable program to enable allocating bits to a state machine in an individual encoder in a statistical multiplexer (statmux) system, the program causing the state machine to:
detect a scene change present in video data to be encoded in the individual encoder;
determine a first complexity of a current scene prior to the detected scene change;
determine a second complexity of a new scene after the detected scene change;
determine an overall complexity rate for encoding the video data in the individual encoder by combining the first complexity and the second complexity; and
provide the overall complexity rate as need parameter for determination of a bit rate for encoding the video data.
15 . The computer readable medium of claim 14 , wherein a look ahead buffer (LAB) provides data to a data compressor within the individual encoder, and wherein the determining of the first complexity and the second complexity are performed on the video data within the LAB.
16 . The computer readable medium of claim 14 , wherein a third complexity data from a previous scene occurring prior to the current scene is not used in determining the bit rate for encoding the video data.
17 . The computer readable medium of claim 14 , wherein the state machine forms part of a processor.