Motion analysis method and code stream conversion method based on video compression code stream and apparatus thereof

Patent metadata

Field	Value
Publication number	US-9380309-B2
Application number	US-201114358897-A
Country	US
Kind code	B2
Filing date	Dec 19, 2011
Priority date	Nov 18, 2011
Publication date	Jun 28, 2016
Grant date	Jun 28, 2016

Abstract

The present invention relates to security video monitoring for and discloses a motion analysis method and a code stream conversion method based on video compression code stream and apparatus thereof. In the invention, a total number of bits or a residual bit number of a macro block in a video I frame is extracted from the video compression code stream; weighted average is performed to the total number of bits or a residual bit number of the macro block whose position corresponds with the current macro block in the latest M frames and a background value is obtained through calculating; a difference value between the total number of bits or the residual bit number of the current macro block and the background value is calculated, and if the difference value is greater than a predetermined first threshold, then a moving object is determined to be detected. Weighted average background modeling is performed to macro block information, such as the total numbers of bits or the residual bit number of the macro block corresponds with the current macro block in latest M frames. Threshold determination is performed to a background difference value matching result and motion analysis is performed. Coding picture of the macro block between the frames does not need to be calculated. Calculated quantity is small and the adaptability to the code stream and a scene is strong.

First claim

What claimed is:

1. A motion analysis method based on video compression code stream, wherein includes following steps:
a total number of bits or a residual bit number of a macro block in a video frame is extracted from video compression code stream;
after the extraction, the total number of bits or the residual bit number of a macro block is remapped to the total number of bits or the residual number being independent with quantization parameter according to quantization algorithm defined by compression standard of the video compression code stream;
weighted average is performed to the total number of bits or the residual bit number of macro blocks whose positions correspond with the current macro block in the latest M frames and a background value is obtained through calculating, in which M is a natural number;
difference value between the total number of bits or the residual bit number of the current macro block and the background value is calculated, and then a moving object is determined that has been detected if the difference is greater than predetermined first threshold.

2. A motion analysis method based on video compression code stream according to claim 1 , wherein before the step of the remapping, the method includes following steps:
classification of the macro block is merged into inter macro block and intra macro block according to the compression standard of the video compression code stream;
in the step of the remapping, the total number of bits or the residual bit number of the macro block is remapped to the total number of bits or the residual bit number being independent with the quantization parameter according to the quantization algorithm defined by the compression standard of the video compression code stream and the classification of the macro block.

3. A motion analysis method based on video compression code stream according to claim 1 , wherein the weighted average to residual bit number of the macro blocks whose positions correspond with the current macro block in latest M frames can be performed by following mode:
bg_avg_rsd( k )=Σ i=0 m−1 ω( k−i )×block_rsd( k−i )

wherein, bg_avg_rsd(k) indicates that the residual bit number of the macro blocks whose positions correspond with the current macro block in latest M frames is the residual bit number having been weighted average, k indicates current moment in time domain, block_rsd(k−i) indicates residual bit number of macro blocks having the same position in former moment i of time-domain, m is a positive integer and indicates to perform weighted average to the residual bit number of the macro blocks whose positions correspond with M frames, ω(k−i) is the weight of the residual bit number of the macro blocks whose positions correspond with M frames and needs to meet the condition of Σ i=0 m−1 ω(k−i)=1 and ω(k−i)≧0 is satisfied.

4. A motion analysis method based on video compression code stream according to claim 1 , wherein before the step that difference value between the total number of bits or the residual bit number of the current macro block and the background value is calculated, the method further includes following step:
a motion vector of a macro block in a video frame is extracted from video compression code stream;
after the step that difference value between the total number of bits or the residual bit number of the current macro block and the background value is calculated, the method further includes following step:
a moving object is determined that has been detected if the difference is greater than predetermined third threshold and the motion vector of the current macro block is greater than predetermined second threshold, in which the predetermined first threshold is greater than or equal to the predetermined third threshold.

5. A motion analysis method based on video compression code stream according to claim 4 , wherein before the step that a motion vector of a macro block in a video frame is extracted from video compression code stream, the method further includes following step:
classification of the macro block is merged into inter macro block and intra macro block according to the compression standard of the video compression code stream;
the step that a motion vector of a macro block in a video frame is extracted from video compression code stream further includes following sub-steps:
weighted average is performed to motion vectors of all sub-macro blocks to obtain the motion vector of the current macro block when the current macro block is an inter macro block and has been divided to multiple sub-macro blocks;
weighted average is performed to motion vectors of inter macro blocks around the intra macro block to obtain the motion vector of the current macro block when the current macro block is an intra macro block.

6. A motion analysis method based on video compression code stream according to claim 1 , wherein before the step that a background value is obtained through calculating, the method further includes following steps:
whether the current macro block is the macro block in designated area is determined and then if the current macro block is the macro block in designated area, the step that a background value is obtained through calculating is executed, otherwise detection for the current macro block ends.

7. A motion analysis method based on video compression code stream according to claim 5 , wherein before the step that a background value is obtained through calculating, the method further includes following steps:
whether the angle between direction of the motion vector of current macro block and the designated direction is smaller than a predetermined threshold is determined and then the step that a background value is obtained through calculating is executed if the angle is smaller than the predetermined threshold, otherwise detection for the current macro block ends.

8. A motion analysis method based on video compression code stream according to claim 1 , wherein before the step that a total number of bits or a residual bit number of a macro block in a video frame is extracted from video compression code stream, the method further includes following steps:
classification of the current frame is determined;
if the current frame is a B frame or a P frame, then the step that a total number of bits or a residual bit number of a macro block of a video frame is extracted from video compression code stream is executed;
if the current frame is an I frame, the picture of I frame is reconstructed and then the motion analysis is implemented according to the reconstructed picture of I frame.

9. A code stream conversion method based on video compression code stream, wherein includes following steps:
the motion analysis is implemented on video compression code stream according to the motion analysis method of claim 1 ;
if the motion analysis has determined that a moving object has been detected, code stream in group of picture of the detected moving object is outputted, otherwise only code stream of pictures represented I frame in group of picture of undetected moving object is outputted.

10. A motion analysis apparatus based on video compression code stream, wherein includes following units:
a first extraction unit is configured to extract a total number of bits or a residual bit number of a macro block in a video frame from video compression code stream;
a remapping unit is configured to remap the total number of bits or the residual bit number of the macro block extracted in the first extraction unit to the total number of bits or the residual bit number being independent with quantization parameter according to quantization algorithm defined by compression standard of the video compr

Assignees

• Huang Chongji
• Yu Hai
• Su Hui
• Jia Yonghua
• Hangzhou Hikvision Digital Tec

Inventors

• Huang Chongji
• Yu Hai
• Su Hui
• Jia Yonghua

Classifications

• H04N19/132

  Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking · CPC title

• H04N19/40

  using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream · CPC title

• H04N19/174

  the region being a slice, e.g. a line of blocks or a group of blocks · CPC title

• G06T2207/20021

  Dividing image into blocks, subimages or windows · CPC title

• H04N19/48 Primary

  using compressed domain processing techniques other than decoding, e.g. modification of transform coefficients, variable length coding [VLC] data or run-length data (motion estimation in a transform domain H04N19/547; processing of decoded motion vectors H04N19/513) · CPC title