摘要:
A device for regulating bit rate in a system for statistically multiplexing several streams of MPEG 2 coded images is disclosed. The statistical multiplexing system includes a device (1) for allocating bit rate using the complexity calculated by a bit rate regulating device (10). Each coder E(i) of an image stream includes a first coding device (20) for performing spatial coding, a second coding device and a memory for storing the complexity X1st| of the last image coded spatially by the first coding device. The complexity (X−GOP) of the last group of pictures is coded by the second coding device (30). Device (10) regulates the bit rate of coder E(i) for determining the complexity value for the next image coded by the second coding device (30), using stored complexity values. This complexity value is transmitted to the bit rate allocator (1) to determine the next bit rate sent to the coder E(i).
摘要:
Image sequences are advantageously recoded based on an evaluation of complexities before and after trans-coding of the images. Initially, information is extracted representing at least the complexity of recoding each image. A complexity ratio is calculated in accordance with the complexities of images recoded previously using the aforementioned mode to the complexities of the initial coding of said images. After smoothing the complexity ratio undergoes updating. Each image is recoded according to the mode by estimating the complexity of each image to be recoded as the product of the complexity of the initial coding of the image by the smoothed complexity ratio for the mode.
摘要:
The invention relates to a process, to a device for smoothing dark regions of images and to a coding system. a noise level is associated with each image and a luminance value is associated with each pixel, a threshold value is calculated, at least two values delimiting a smoothing range are defined, for each current pixel, the luminance of the pixel is compared with the said values, if the luminance of the current pixel lies in a smoothing range, the luminance of several pixels in an analysis window is compared with the said values, if the luminance of certain pixels lies in the same range as the value of the luminance of the current pixel, the value of the luminance of the current pixel is modified as a function of the said threshold values.
摘要:
A device and a method for coding video images by motion compensation. The device incorporates a coding unit and a filtering unit. A calculation unit for calculating a recursivity coefficient as a function of an estimated noise level and a prediction error, a measurement unit for measuring the intra-image correlation and the inter-image correlation, a selection unit for selecting a type of coding applied to the current input image as a function at least of the measurements of the inter-image correlation and of the measurements of the intra-image correlation and as a function of the estimated noise level, a coding unit for coding the current input image as a function of the type of coding selected.
摘要:
The invention lies within the area of image compression coding, in particular of MPEG type, which uses recoding help data. The invention affords a solution for reusing the help data selectively. To this end, the invention adjoins an electronic signature representative of the constraints of the coder. Thus, it becomes possible to determine whether the help data are reusable or not for a subsequent coding using other constraints.
摘要:
The invention relates to a device for coding video frame sequences, comprising means (1) for measuring the spatial activity of the video frames to be coded, means (1) for measuring the temporal activity of the video frames to be coded, means (2) for coding the frames as a frame structure or as a field structure. According to the invention, the means (2) for coding the frames as a frame structure or as a field structure are able to choose the field or frame structure dynamically as a function of the measurements of spatial and temporal activity of the said frame.
摘要:
The invention relates to a device for pre-processing video images intended to be coded in the MPEG 2 format. The MPEG 2 standard provides that, mode which exploits the spatial redundancy of the images. The images thus coded then define a succession of groups of images, a group of images being referred to as a GOP. The pre-processing device according to the invention comprises an image memory and an analysis circuit. The image memory makes it possible to store the various images contained in the forecast GOP of rank ok and ax of the first few images contained in the GOP of rank ok+l, ax being an integer greater than or equal to 1. The analysis circuit is linked to the image memory and makes it possible to perform measurements on the images contained therein. The knowledge about the images of the GOP of rank and about the first images of the forecast GOP of rank k+1 which is ascertained following the above mentioned measurements is then used for coding the GOP of rank k. The invention applies to systems for coding images according to the MPEG 2 standard.
摘要:
A multiplexing device is coupled to various coding devices. The multiplexing device does not attempt to mutually synchronize the various coding devices but, instead, circumvents such synchronization while making it possible to work with the various coding devices and to obtain synchronous actions at the input of the multiplexer. In particular, the multiplexing device transmits control commands and an instant of action to each of the coding devices.
摘要:
The present invention relates to a method and a device for monitoring the quality of video data having to undergo coding and decoding, making it possible to maintain predetermined constant quality of the video data after decoding. The method is such that information representing the complexity of video data to be coded is received from at least one coder. For each video-data item to be coded, a reference quantization value is calculated as a function of the complexity. For each video-data item to be coded, a reference throughput calculated as a function of the reference quantization value and of the value of the predetermined constant quality is calculated and transmitted to the coder, allowing the coder to code each video data item so as to obtain video data at the predetermined quality, after decoding.
摘要:
The invention relates to a method and a device for multiplexing. The device is able to receive data packets from at least one coding device, some of the data packets comprising a time label, said device comprising a time reference and being able to transmit commands to the said coding device. According to the invention, the device is characterized in that it comprises: means for calculating an instant of action for the coding device at which it desires that the coding device perform the said command as a function of the instant at which it transmits the said command to the said coding device, of the time label of the data packets, of its time reference and of the maximum transfer time between the coding device and the multiplexing device, means for transmitting said instant of action and the said command to the coding device.