System and method for decreasing end-to-end-delay during video conferencing session

Abstract

A method for decreasing end-to-end delay in a video conferencing context is disclosed. At video conferencing system startup, a processor is initialized to receive either a top field or a bottom field of video frame data. If the first line of a new field arriving after initialization does not match a field state that the processor is initialized to, the present invention senses the state mismatch and adjusts a display buffer by one display line, and the field is stored in the display buffer. The display buffer is adjusted in order to preserve a vertical spatial relationship between the top and bottom fields.

We claim:  
     
         1 . A method of buffering video frame data in a video display system, comprising: 
 initializing a processor to receive an initial field of video frame data having a first state;    receiving an initial field of video frame data having a second state;    adjusting a display buffer by one display line; and    storing the initial field of video frame data having the second state into the display buffer.    
     
     
         2 . The method of  claim 1 , wherein the first state is a top field and the second state is a bottom field.  
     
     
         3 . The method of  claim 2 , wherein the display buffer is adjusted down by one display line.  
     
     
         4 . The method of  claim 1 , wherein the first state is a bottom field and the second state is a top field.  
     
     
         5 . The method of  claim 4 , wherein the display buffer is adjusted up by one display line.  
     
     
         6 . The method of  claim 1 , further comprising sequentially storing subsequent received fields according to the state of each of the subsequent received fields in the display buffer.  
     
     
         7 . The method of  claim 1 , further comprising displaying the video frame data by reading the received fields from the buffer.  
     
     
         8 . A method of buffering video frame data in a video display system, comprising: 
 initializing at least one buffer pointer to either a first state or a    second state to form a first initialized buffer pointer;    receiving an initial field of video frame data having either the first state or the second state;    if a state of the initial field of video frame data is not the same as a state of the first initialized buffer pointer, toggling the state of the first initialized buffer pointer; and    storing the received initial field of video frame data into a buffer using the first initialized buffer pointer.    
     
     
         9 . The method of  claim 8 , wherein the first state is associated with a top field of the video frame data and the second state is associated with a bottom field of the video frame data.  
     
     
         10 . The method of  claim 8 , wherein the toggling further comprises changing the state of the first initialized buffer pointer.  
     
     
         11 . The method of  claim 8 , wherein the toggling further comprises replacing the first initialized buffer pointer with a second initialized buffer pointer having a state different from the state of the first initialized buffer pointer.  
     
     
         12 . The method of  claim 8 , further comprising sequentially storing subsequent received fields according to the state of each of the subsequent received field in the display buffer.  
     
     
         13 . The method of  claim 8 , further comprising displaying the video frame data by reading the received fields from the display buffer.  
     
     
         14 . An electronically readable medium having embodied thereon a program, the program being executable by a machine to perform method steps for use in buffering video frame data in a video display system, comprising: 
 initializing a processor to receive an initial field of video frame data having a first state;    receiving an initial field of video frame data having a second state;    adjusting a display buffer by one display line; and    storing the initial field of video frame data having the second state into the display buffer.    
     
     
         15 . An electronically readable medium having embodied thereon a program, the program being executable by a machine to perform method steps for use in buffering video frame data in a video display system, comprising: 
 initializing at least one buffer pointer to either a first state or a second state to form a first initialized buffer pointer;    receiving an initial field of video frame data having either the first state or the second state;    if a state of the initial field of video frame data is not the same as a state of the first initialized buffer pointer, toggling the state of the first initialized buffer pointer; and    storing the received initial field of video frame data into a buffer using the first initialized buffer pointer.    
     
     
         16 . The program executable by machine of  claim 15 , wherein the toggling further comprises changing the state of the first initialized buffer pointer.  
     
     
         17 . The program executable by machine of  claim 15 , wherein the toggling further comprises replacing the first initialized buffer pointer with a second initialized buffer pointer having the state different from the state of the first initialized buffer pointer.  
     
     
         18 . A video frame data buffering system in a video display system, comprising: 
 means for initializing a processor to receive an initial field of video frame data having a first state;    means for receiving an initial field of video frame data having a second state;    means for adjusting a display buffer by one display line; and    means for storing the initial field of video frame data having the second state into the display buffer.    
     
     
         19 . A video frame data buffering system in a video display system, comprising: 
 means for initializing at least one buffer pointer to either a first state or a second state to form a first initialized buffer pointer;    means for receiving an initial field of video frame data having either the first state or the second state;    means for toggling the state of the first initialized buffer pointer if a state of the initial field of video frame data is not the same as a state of the first initialized buffer pointer;    means for storing the received initial field of video frame data into a buffer using the first initialized buffer pointer.    
     
     
         20 . A method of coding a video signal comprising: 
 Initializing a codec to receive a video signal of a first type into a buffer;    Receiving a video signal of a second type; and    Adjusting parameters of the codec relating to storage of the video signal in the buffer to receive the video signal of the second type.    
     
     
         21 . The method of  claim 20  wherein, the video signal of a first type is a top field and the video signal of the second type is a bottom field.  
     
     
         22 . The method of  claim 20  wherein, the video signal of a first type is a bottom field and the video signal of the second type is a top field.  
     
     
         23 . The method of  claim 20  wherein the step of adjusting parameters of the codec comprises redirecting a pointer to a location in the buffer to a location one line down in the buffer.  
     
     
         24 . The method of  claim 20  wherein the step of adjusting parameters of the codec comprises remapping the buffer to map a new line before the line where a pointer to a location in the buffer is set after the step of initializing the codec, and storing the video signal of the second type in the new line.  
     
     
         25 . The method of  claim 20  wherein the step of receiving a video signal of a second type comprises receiving a video signal from a camera.  
     
     
         26 . The method of  claim 20  wherein the step of receiving a video signal of a second type comprises receiving a video signal from a remote video conferencing device.  
     
     
         27 . A method of storing received video signals containing top fields and bottom fields, wherein the vertical spatial relationship between top fields and bottom fields is preserved even though the first field received was not the expected field, comprising, initializing a codec, wherein the codec is set to store first field data in the first line of a frame buffer memory; 
 Receiving second field data at the codec;    Adjusting the codec to receive the second field data, rather than the expected first field data; and    Storing the second field data in the frame buffer.    
     
     
         28 . The method of  claim 27  wherein, the first field data is top field data and the second field data is bottom field data.  
     
     
         29 . The method of  claim 27  wherein, the first field data is bottom field data and the second field data is top field data.  
     
     
         30 . The method of  claim 27  wherein the step of adjusting the codec comprises redirecting a pointer to the first line of the frame buffer memory, to point one line down in the frame buffer memory.  
     
     
         31 . The method of  claim 27  wherein the step of adjusting the codec comprises remapping the frame buffer memory to add a new line before the first line set to store first field data, and storing the second field data in the new line.  
     
     
         32 . The method of  claim 27  wherein the step of receiving second field data at the codec comprises receiving second field data from a camera.  
     
     
         33 . The method of  claim 27  wherein the step of receiving second field data at the codec comprises receiving second field data from a remote video conferencing device.  
     
     
         34 . A video conferencing device comprising a codec that once initialized to store first field data upon receipt, is adjustable to store second field data instead of first field data.  
     
     
         35 . The device of  claim 34  wherein the first field data is top field data and the second field data is bottom field data.  
     
     
         36 . The device of  claim 34  wherein the first field data is bottom field data and the second field data is top field data.