One-pass adaptive bit rate control
AssigneesSony Corporation, Sony Electronics Inc.
InventorMichael A. Kutner
Life of this patent
Estimating the term…
Abstract
A one pass adaptive bit rate control method. Data from a previous video field is used to calculate a quantizer scale factor for use in compressing a current video field. Large changes in compressed data size is used to detect scene changes. When a scene change is detected, a marker is inserted into the compressed data stream in place of the compressed field. An interpolated field is substituted during decompression for the scene change marker.
Claims33
A method for compressing a sequence of fields of video data F.sub.n in a video compressor, where n is a field counting number, comprising the steps of:
- (a) establishing a desired data size S.sub.desired for fields of compressed data;
- (b) calculating a quantization factor Q.sub.n in a bit rate controller for a field of data
- F.sub.n to achieve said desired data size, said quantization factor Q.sub.n being calculated from an actual data size S.sub.n-1 obtained when a preceding field F.sub.n-1 was compressed by said video compressor;
- (c) compressing field F.sub.n in said video compressor using the quantization factor Q.sub.n ;
- and
- (d) repeating steps (b) and (c) for each value of n for said sequence of fields of video.
A method for compressing a sequence of fields of video data F.sub.n-1 in a video compressor, where n is a field counting number, comprising the steps of:
- establishing a desired data size S.sub.desired for fields of compressed data;
- calculating an initial quantization factor Q.sub.1 for compressing field F.sub.1 as:
- ##EQU18## where k is a constant;
- compressing said field F.sub.1 in said video compressor using said quantization factor Q.sub.1 ;
- for n>1, calculating a quantization factor Q.sub.n in a bit rate controller for compressing each field of data F.sub.n using ##EQU19## and;
- for n>1, compressing each field of data F.sub.n using the quantization factor Q.sub.n in said video compressor.
A method for compressing a sequence of fields of video data F.sub.n in a video compressor, where n is a field counting number, comprising the steps of:
- establishing a desired data size S.sub.desired for fields of compressed data;
- calculating an initial quantization factor Q.sub.1 for compressing field F.sub.1 as:
- ##EQU21## where k is a constant;
- compressing said field F.sub.1 in said video compressor, using said quantization factor Q.sub.1 ;
- ##EQU22## for n>1, calculating a quantization factor Q.sub.n in a bit rate controller for each field of data F.sub.n using where C is a constant;
- and
- for n>1, compressing each field of data F.sub.n using the quantization factor Q.sub.n in said video compressor.
A method for compressing a sequence of fields of video data F.sub.1 in a video compressor, where n is a field counting number, comprising the steps of:
- establishing a desired data size S.sub.desired for fields of compressed data;
- establishing an initial quantization factor Q.sub.1 for compressing field F.sub.1 ;
- in said video compressor, compressing said field F.sub.1 using said quantization factor Q.sub.1 ;
- for n>1, establishing a quantization factor Q.sub.n in a bit rate controller for each field of data F.sub.n, where Q.sub.n is calculated from an actual data size S.sub.n-1 obtained when field F.sub.n-1 was compressed;
- and
- for n>1, compressing each field of data F.sub.n in said video compressor, using the quantization factor Q.sub.n.
A method for compressing a sequence of fields of video data F.sub.n where n is a field counting number, comprising the steps of:
- establishing a desired data size S.sub.desired for fields of compressed data;
- establishing an initial quantization factor Q.sub.1 for compressing field F.sub.1 ;
- compressing said field F.sub.1 using said quantization factor Q.sub.1 ;
- for n>1, establishing a quantization factor Q.sub.n for each field of data F.sub.n, Q.sub.n being calculated from an actual data size S.sub.n-1 obtained when field F.sub.n-1 was compressed;
- for n>1, compressing each field of data F.sub.n using the quantization factor Q.sub.n ;
- and
- for n>1, comparing each field's compressed data size S.sub.n with the previous field's compressed data size S.sub.n-1 and if the difference between S.sub.n and S.sub.n-1 is greater than a predetermined threshold, then generating scene change marker and substituting said field change marker for field F.sub.n.
A video compression device, comprising:
- a video compressor receiving a first video frame as an input and producing a first compressed video frame as an output by compressing said first video frame;
- means for determining a size of said first compressed video frame;
- means for generating a first quantization scale factor as a function of said size of said first compressed video frame;
- and
- wherein, said video compressor further receives a second video frame immediately subsequent to receipt of said first video frame, and wherein said second video frame is compressed according to said first quantization scale factor to produce a second compressed video frame.
A video compression device, comprising:
- a video compressor receiving a first video frame as an input and producing a first compressed video frame as an output by compressing said first video frame;
- a counter for determining a size of said first compressed video frame;
- a bit rate controller generating a first quantized scale factor being generated as a function of said size of said first compressed video frame;
- and
- wherein, said video compressor further receives a second video frame immediately subsequent to receipt of said first video frame, and wherein said second video frame is compressed according to said first quantization scale factor to produce a second compressed video frame.
Dependencies are inferred from the claim text.