Abstract: The invention concerns a method for encoding at least a source image using a hierarchical mesh defining at least two nested spaces corresponding each to a decomposition level of said meshing, which consists, at least at a decomposition level n (except the first decomposition level), in delivering only image coefficients expressed in a base of functions defined in a space orthogonal to the space corresponding to the preceding decomposition level n?1, said functions being selected so that said image coefficients enable to optimize for said decomposition level n the data already transmitted for the preceding decomposition level n?1, so as to produce a reconstructed image, representing said source image, with optimized restoration quality for said decomposition level n.

Abstract: A method for designing an equalizer and tracking performance for upstream PCM in a digital communications network is described. The invention optimizes upstream data rate rates for data transmissions in a network between a client modem a server modem. During training, the upstream channel impulse response is identified compensating for any robbed bit signalling. The upstream transmit equalizer is computed in closed form based on the identified channel. An equalizer in the receiver is also used to track timing and channel variations. The invention approximates bit error rate performance by looking for code violations in the trellis code decoder and tracking their frequency. The bit error rate is used to determine if the current modem parameters need to be re-designed.

Abstract: A method for two-pass video encoding using sliding windows. The method receives a video sequence (VS), selects a portion of frames in the VS from the beginning as an analysis window, encodes each frame in the analysis window to acquire multiple statistical features, such as a bitrate to each frame in the analysis window, the quantization scale or complexity of the frame, redistributes the bitrate to each frame in the analysis window according to the statistical features, encodes the frames in the analysis window occurring between the beginning and an out point according to the redistributed bitrates, and selects a portion of frames in the VS from the next frame of the out point as a new analysis window if the VS is not completely encoded.

Abstract: A rate controller in run-level domain transcoder, which receives a stream of compressed frames carried in a bit stream, selectively determines whether to quantize and/or threshold portions of a frame carried in the stream of frames. The rate controller determines the input size of the frame and based at least in part upon at least a desired size, requantizes and/or thresholds the frame such that the output size of the frame is approximately the desired size.

Abstract: An image coding method and apparatus considering human visual characteristics are provided. The image coding method comprises (a) modeling image quality distribution of an input image in units of scenes such that the quality of an image input in units of scenes is gradually lowered from a region of interest to a background region, (b) determining a quantization parameter of each region constituting one scene according to the result of modeling of image quality distribution, (c) quantizing image data in accordance with the quantization parameter, and (d) coding entropy of the quantized image data.

Abstract: A quantizer and dequantizer for use in a video coding system that applies non linear, piece-wise linear scaling functions to video information signals based on a value of a variable quantization parameter. The quantizer and dequantizer apply different non linear, piece-wise linear scaling functions to a DC luminance signal, a DC chrominance signal and an AC chrominance signal. A code for reporting updates of the value of the quantization parameter is interpreted to require larger changes when the quantization parameter initially is large and smaller changes when the quantization parameter initially is small.

Abstract: A method and device for coding of digital video sequence, wherein an indication of quantization parameter (QP) is provided in the encoded bit-stream for decoding purposes. The QP related information is indicated by introducing a sequence level quantization parameter value SQP. More specifically, instead of coding the absolute values of picture/slice QPs, an indication of the difference ?QP between the sequence level quantization parameter SQP and the picture/slice QP is provided. This eliminates the need to transmit a full QP for every picture/slice, and enables a statistically smaller difference value to be transmitted, thus providing a reduction in transmission bit-rate. The difference value is subsequently used in a corresponding decoder to reconstruct the picture/slice QP.

Abstract: A system and method are provided for adaptive rate control in the transcoding of video streams. The method comprises: accepting frames of an input MPEG encoded video stream; decoding the video stream; determining video stream complexity; for each frame, calculating an output video stream quantization parameter (Qo) responsive to determined video stream complexity; and, encoding the output video stream into a protocol using Qo. Some aspects further comprise accepting a target bit rate ratio (r) for transcoding that is equal to the ratio of the target output video stream number of bits per frame (No), to the input video stream number of bits per frame (Ni). Then, Qo is also calculated in response to the value of r. More explicitly, Qo is calculated in response to a complexity ratio of: an accumulated complexity in the output video stream, to an accumulated complexity in the input video stream.

Abstract: An apparatus for variable bit rate control in moving picture compression. First, a total activity measure for the current picture to be encoded in a set of consecutive pictures is calculated. Based on the total activity measure of the current picture and an activity-to-complexity ratio of a previously encoded picture of the same type in the set of consecutive pictures, a complexity measure of the current picture is estimated. A statistical complexity measure is then calculated from the complexity measure of the current picture. A target bit budget is allocated to the current picture depending on the instantaneous rate, the complexity measure and the instantaneous complexity measure. After encoding the current picture, the activity-to-complexity ratio for the current picture is computed based on the total activity measure, actual bits consumed by the current picture and an average of actual quantization step sizes used to encode the current picture.

Abstract: The invention is related to methods and apparatus that advantageously improve picture quality in a video encoder, such as an MPEG video encoder. Scene changes typically occur relatively frequently in picture sequences, such as movies. One embodiment of the invention detects a scene change within a group of pictures and allocates bits within the group of pictures in response to the detected scene change without changing a predetermined structure for the group of pictures.

Abstract: An apparatus and method for selecting a method from a set of methods for transcoding video data, where the data may be transmitted between at least two communication apparatuses via a communication network, the method comprising the steps of determining at least one weighting factor (W1, W2) to attribute to each of the transcoding methods of the set, the at least one weighting factor depending on the data to be transcoded, weighting a mean value of at least one characteristic representative of each of the transcoding methods of the set by applying adapted weighting factors (W1, W2), and selecting a transcoding method as a function of the weighted mean values.

Abstract: To provide a process for coding the moving picture with higher speed and enhanced efficiency. The present invention provides a moving picture coding method for coding a moving picture of processing object through a predetermined process including a motion estimating process, determining whether or not the predetermined process (e.g., DCT process and quantization process) for a block of processing object can be omitted on the basis of the information regarding a difference between the block and a reference block of a frame to be referenced in coding (i.e., a frame to be referenced in making the motion vector detection), and a quantization parameter for use in a quantization process of the moving picture, performing the predetermined process if it is determined that the predetermined process can not be omitted, and omitting the predetermined process if it is determined that the predetermined process can be omitted and making a set defined value the result of the predetermined process for the block.

Abstract: An apparatus and method for processing a multimedia digital bitstream is disclosed. The apparatus comprises a processing chain made up of a plurality of media processors. Each media processor processes a portion of the multimedia digital bitstream in real time. Each portion of the multimedia digital bitstream is split into a primary bitstream and a secondary bitstream. The primary bitstream is processed and merged with the unprocessed secondary bitstream. The parallel processing method of the present invention enables the processing chain to output a fully processed bitstream in real time. The processing chain may be used to transcode a high definition (HD) video bitstream in real time using a plurality of bitrate transcoder units.

Abstract: Apparatus and method for adaptively controlling a bit rate of a video transcoder are disclosed. Logarithmic R-Q characteristics obtaining the adaptive R-Q characteristics suitable to characteristics of an inputted image are proposed, and the parameter (?) compensating the difference between the coding efficiency of MPEG-1 and the coding efficiency of MPEG-4 is not fixed as a specific value but changed adaptively according to the characteristics of an image. Accordingly, an accurate quantization parameter of MPEG-4 is generated. Thus, on the basis of the proposed concepts, the bit rate is adaptively controlled when the bit stream of MPEG-1 is converted into a bit stream of MPEG-4, so that the picture quality (PSNR) can be heightened and more accurate output bit rate can be obtained.

Abstract: In the video data compression apparatus 1, the host computer 20 controls the operation of the constituent parts of the video data compression apparatus 1. Further, the host computer 20 receives the amount of data of the compressed video data generated by preliminarily compressing and coding the noncompressed video data VIN by the encoder 162 of the simplified two pass processing unit 16, the value of the direct current component (DC component) of the video data after the DCT processing, and the power value of the alternating current component (AC component) via a control signal C16 and calculates the difficulty of the pattern of the compressed video data based on these received values. Further, the host computer 20 allocates the target amount of data Tj of the compressed video data generated by the encoder 18 via the control signal C18 for every picture based on the calculated difficulty, sets the same in the quantization circuit 168 (FIG.

Abstract: A video encoding apparatus comprising a feature amount computation section which divides an input video signal into a plurality of scenes each comprising at least one temporally-continuous frame, and compute a statistical feature amount for each scene, an encoding parameter generator section which generates an encoding parameter for each scene based on the statistical feature amount, a number-of-generated-bits prediction section which predicts the number of bits to be generated when the input video signal is encoded using the encoding parameter, an encoding parameter correcting section which corrects the encoding parameter based on a result of the prediction of the number of generated bits, an encoder section which encodes the input video signal using the corrected encoding parameter.

Abstract: An insertion-based error concealment method and apparatus are provided whereby, instead of directly inserting white noise, a filter is created to shape the white noise. The filtered white noise is then used to replace lost data. The method of the present invention is implemented by first estimating the power spectrum of the previous frame; then designing a filter with transfer function H(f), where |H(f)|2=the estimated power spectrum; and finally generating the replacement packet using noise which has been spectrally modified by the filter. The resulting filtered noise has the same power spectrum as the previous packet but is not highly correlated with it.

Abstract: A digital video encoder is presented adapted for dynamically switching between sets of quantizer matrix tables without pausing encoding of a stream of video data. Two or more sets of quantizer matrix tables are held at the encoder's quantization unit and compressed store interface for dynamically switching between sets of quant matrix tables at a picture boundary of the sequence of video data, i.e., without stopping encoding of the sequence of video data. Further, while one set of matrix tables is being employed to quantize the stream of video data, the encoder can be updating or modifying another set of quantization matrix tables, again without stopping encoding of the sequence of video data.

Abstract: A picture encoding system conversion device and a code rate conversion device for realizing the conversion taking into account both time delay and picture quality using the information on the code volume of the encoding parameters, input and output buffers and an input bitstream. There are provided a decoder 1 including an input buffer 21, a VLD unit 22, an inverse quantizer 23, an IDCT unit 24, an adder 35, a frame memory 26 and a motion compensation prediction unit 27; an encoder 2 including an adder 31, a DCT unit 32, a quantizer 33, an inverse quantizer 34, an IDCT unit 35, an adder 36, a frame memory unit 37, a motion compensation prediction unit 38, a VLD unit 39 and an output buffer 40; and a transcoder controller 3 including a decoder monitor unit 51, an input buffer monitor unit 52, a reception transmission channel monitor 53, a sending transmission channel monitor 63, an output buffer monitor unit 62 and a quantization step controller 74.

Abstract: An apparatus for partitioning moving picture data comprises a first quantizing unit for first-quantizing a received video signal and outputting a first-quantized signal; and a second quantizing unit for second-quantizing the first-quantized signal and partitioning the first-quantized signal into a preceding part and a succeeding part.

Abstract: The invention described herein improves and expedites compressed video data delivery by providing systems and methods for transcoding and pass through on a sub-picture level. For example, in MPEG embodiments described herein, transcoding and compressed video data pass through may occur on a macroblock or slice level. This permits portions of a picture that need no rate reduction to be passed through without transcoding. The invention may also implement pass through on a picture by picture basis. Accordingly, the invention may determine transcoding or pass through for each picture or picture subregion. Thus, systems and methods described herein provide flexible compressed video data transcoding and pass through, as determined by varying bit rate demands of compressed video data transmission.

Abstract: A method of compression is provided for transmission of digital video signals between an encoder buffer and a decoder buffer. A tunable delay is provided at the encoder, suitably in the form of a portion of encoder buffer memory, with data being read out to a communications channel at a rate determined by the input bit rate of signals received a predetermined number of frame periods later. Use of the tunable delay improves efficiency of decoder buffering by maintaining a relatively constant level of decoder buffer fullness irrespective of signal bit rates.

Abstract: A method of producing an output bitstream of coded digital video data with a bit-rate different from the bit-rate of an input bitstream includes dividing the input bitstream into a sequence of coded data and a sequence of control bits. The sequence of control bits is modified as a function of the desired bit-rate of the output bitstream that is different from the bit-rate of the input bitstream. An output sequence of control bits is produced. The method further includes decoding the sequence of coded data producing an intermediate sequence of data, and quantizing with a pre-established step and coding the intermediate sequence of data producing an output sequence of coded data. The output sequences producing the output bitstream are merged with the desired bit-rate.

Abstract: A rate and delivery time multiplexing for bandwidth optimization algorithm has an allocation portion and a transrating portion. The allocation portion determines how many bits are available for each group of pictures in each program stream that is to be inserted into an outgoing MPEG Transport Stream (MTS). Based upon the allocated bits the transrating portion, when necessary, further compresses the program streams either in the compressed domain when rate reduction is minimal or in the pixel domain when rate reduction is significant. The result is the ability to transmit more video program streams over a given fixed bandwidth pipe for a given level of acceptable picture degradation.

Abstract: The present invention enables to effectively coding a predetermined time length of a video signal with a variable bit rate at real time (one-path) into a total coding bit amount of a constant data capacity. A coding difficulty calculator 13 determines a coding difficulty of an input signal for each unit time. An allocation bit amount calculator 14 interrelates an allocation sign amount with a coding difficulty for each unit time standardized in advance using an ordinary input signal of the type to which the input signal belongs, so as to obtain a reference value of the allocation sign amount for each unit time interrelated with the coding difficulty supplied from the coding difficulty calculator 13. This reference value of the allocation sign amount is modified by a controller 15 into an actual allocation sign amount, according to which the input signal is coded by a moving picture image coding apparatus 18, so as to create a coded data.

Abstract: A decoder and method for using a new picture or frame type is provided. This type is referred to a an SP-picture. The temporal redundancies are not exploited in I-frames, compression efficiency of I-frame coding is significantly lower than the predictive coding. A method in accordance with an embodiment of the invention allows use of motion compensated predictive coding to exploit temporal redundancy in the sequence while still allowing identical reconstruction of the frame using different reference frames. Methods in accordance with embodiments of the invention using this new picture type provide for error resilience/recovery, bandwidth scalability, bitstream switching, processing scalability, random access and other functions. The SP-type picture provides for, among other functions, switching between different bitstreams, random access, fast forward and fast error-recovery by replacing I-pictures to increase the coding efficiency.

Abstract: A method and apparatus for temporally allocating bits between frames in a coding system such that temporal fluctuations are smoothed out. Namely, a picture quality is monitored on a frame by frame basis. An average distortion measure is derived from previous picture frames and that average is compared to the distortion measure of a current frame, where the result is used to effect bit budget allocation for each frame in an input image sequence.

Abstract: A method of determining a quantization parameter for video compression. A block characteristic for blocks in a video frame is quantized and then used to obtain a candidate quantization parameter. With the candidate quantization parameter, a number of bits for the blocks in the video frame is summed, producing a candidate bit rate. If the candidate bit rate is greater than a predetermined bit rate threshold, the candidate quantization parameter is set as the quantization parameter.

Abstract: A digital recording and playback apparatus adopting an MPEG encoder and decoder, and a method thereof. The digital recording and playback apparatus includes: a first encoder for coding input video data in picture units, and outputting coded video data; a second encoder for coding input audio data and outputting coded audio data; a packetized elementary stream (PES) packetizer for packetizing the coded video data and audio data and user data into each PES, and outputting a video PES, audio PES and user PES; and a transport stream (TS) packetizer for multiplexing the video PES, audio PES and user PES into a TS. The digital recording and playback apparatus can be compatible with a digital television or multimedia applications adopting the MPEG standard, and can perform editing in picture units as well as high-speed search.

Abstract: At second or later generation coding of video signal in tandem video coding, at least one coding parameter of previous coding is estimated in accordance with picture properties of the input video signal, and the estimated coding parameter in the previous coding is used in the second or later coding.

Abstract: In a multimedia compression system such as is used in compressing data in a video stream, “zero blocks” from an MPEG block array are identified prior to encoding and subjecting blocks to the process of quantized discrete cosine transform (DCT). A zero block as understood herein is an MPEG video data block that results when an unencoded block of video data is identical to an adjacent un-encoded block of video data, i.e., when there is little or no change between consecutive frames of video. The efficiency of the compression system is increased in this invention by not having to perform the functions of DCT, quantization, dequantization or inverse DCT on the identified zero blocks, but simply directly encoding zero blocks.

Abstract: This method and apparatus described herein imposes masking factors to the determined quantization step sizes of macroblocks of a video sequence such that encoding efficiency is increased. A conditional masking method can be used to take advantage of the fact that P-pictures are more important than B-pictures in terms of motion and scene updates as coding noise in such updates are likely propagated by P-pictures. The masking can be applied conditionally to motion/scene update regions of a picture such that coding noise is reduced and therefore bits are saved from less propagation of this noise. Before encoding each macroblock of a picture from an input video sequence, a video encoder with conditional masking determines if the macroblock type belongs to a significant motion or scene update region. A conditional masking factor is then determined for the macroblock based on the determined macroblock type and the picture coding type.

Abstract: The invention concerns a method for assessing the degradation of a video image coded by blocks of picture elements or pixels, comprising the following steps: a) selecting an input image and determining its spatial activity (SA) in an analysis window according to the following sub-steps: i) determining for each block (n, m) the transformed coefficients Fn m (i, y) by a block transform; ii) determining from the transformed coefficients Fn, m (i, y) each block spatial activity bsa; iii) determining the analysis window global spatial activity SA1; b) selecting the output image corresponding to the input image and determining said global spatial activity SA2 of the output image; c) comparing the spatial activities (SA2) and (SA1)

Abstract: An improved motion image encoding method is based on a discrete cosine transform (DCT)-based motion image encoding method that uses a plurality of modified quantization weight matrices, the method including selecting one of the plurality of modified quantization weight matrices based on noise information from input image data, performing DCT on the input image data, and performing quantization on the DCT input image data using the selected modified quanitzation weight matrix.

Abstract: An apparatus for partitioning moving picture data comprises a first quantizing unit for first-quantizing a received video signal and outputting a first-quantized signal; and a second quantizing unit for second-quantizing the first-quantized signal and partitioning the first-quantized signal into a preceding part and a succeeding part.

Abstract: A method and system for determining and recording a minimal ending video buffer verifier fullness at each of a plurality of entry points in a compressed variable bit rate video bit stream.

Abstract: The invention relates to a transcoding method and device for converting input coded signals previously quantized with a first quantization scale Q1 into output coded signals quantized with a second quantization scale Q2. The transcoding device comprises a variable length decoder, a quantization step modifying stage, and a variable length encoder, said modifying stage itself comprising: (i) means of selection of one out of two parallel requantizing devices; (ii) a first requantizing device provided to be selected when the coding type corresponds to pictures used as references; (iii) a second requantizing device provided to be selected when said coding type does not correspond to reference pictures.

Abstract: A method and device for coding of digital video sequence, wherein an indication of quantization parameter (QP) is provided in the encoded bit-stream for decoding purposes. The QP related information is indicated by introducing a sequence level quantization parameter value SQP. More specifically, instead of coding the absolute values of picture/slice QPs, an indication of the difference &Dgr;QP between the sequence level quantization parameter SQP and the picture/slice QP is provided. This eliminates the need to transmit a full QP for every picture/slice, and enables a statistically smaller difference value to be transmitted, thus providing a reduction in transmission bit-rate. The difference value is subsequently used in a corresponding decoder to reconstruct the picture/slice QP.

Abstract: An image information encoding system that includes detecting an image portion for which higher image quality is desired based on the motion vector value and the image error value, calculating a bit rate control value based on the detection result as well as the buffer usage rate, and changing the roughness of the quantization step based on the bit rate control value. The objective is to minimize the degradation of an image due to compression of a still image portion.

Abstract: A method and corresponding apparatus for selecting a sequence of quantization parameter values in a video encoder, the video encoder being arranged to encode a video frame as a sequence of n macroblocks and to assign a quantization parameter value for each macroblock of the video frame. The method includes steps (23 24 25) in which quantization parameter values assigned to at least a subset of said sequence of n macroblocks are optimized in such a way as to minimize a cost associated with their encoding.

Abstract: Methods and systems for providing a video stream from a server to a client over a network include a memory for storing a forward-encoded bit-stream and a reverse-encoded bit-stream for a video data, The forward-encoded bit-stream includes I-frames encoded without inter-frame dependencies and P-frames encoded depending on forward-direction preceding frames, and the reverse-encoded bit-stream includes I-frames and P-frames encoded depending on reverse-direction preceding frames. When the server receives a request with a video cassette recoding (VCR) function from the client, the server reads out and transmits frames selectively from among the first, second, third, and fourth frames in accordance with the request. The server can select the closest I-frame to a requested frame in an either bit-stream for a fast-mode play or a random-access play, and switch the bit-streams to use subsequent P-frames in a different direction than that of the closest I-frame.

Abstract: A process for encoding digital video signals organized in frames comprises the operations of dividing said frames into blocks starting from macroblocks subjected to motion-compensation and applying to said blocks a discrete cosine transform in such a way as to generate respective sets of coefficients. The said sets of coefficients are then assembled by being organized into sets of vectors by means of masking. Once the variance of the vectors has been detected, the vectors themselves are quantized on a number of available bits by means of a pyramid vector quantizer, associating to the vectors respective quantization pyramids having given sizes according to the variance detected and to the number of available bits. Finally, the vectors are encoded with respective codewords.

Abstract: A normalized activity calculating unit calculates a normalized activity that is calculated from luminescence component pixel values of an original image on the basis of information from an information buffer such as bit rate, an amount of bits generated in each frame, and an amount of bits generated and quantization step size in each macroblock. The normalized activity calculating unit then outputs the normalized activity to a code amount control unit. The code amount control unit calculates a quantization scale code corresponding to a target bit rate which quantization scale code matches visual characteristics, using the normalized activity inputted from the normalized activity calculating unit, and then outputs the quantization scale code to a quantizing unit. The quantizing unit quantizes discrete cosine transform coefficients inputted from a band limiting unit on the basis of the quantization scale code inputted to the quantizing unit.

Abstract: In video compression processing, such as MPEG-2 compression processing, the quantization (Q) matrix used to quantize discrete cosine transform (DCT) coefficients is updated from frame to frame based on a parameterized Q matrix adaptation algorithm. According to the algorithm, the Q matrix for the current frame is generated based on DCT coefficient data from the previously encoded frame of the same type (e.g., I, P, or B) as the current frame. In particular, the Q matrix is generated using a function based on shape parameters (e.g., the slope of the diagonal of the Q matrix and/or the convexity of the diagonal of the Q matrix), where the diagonal slope for the Q matrix of the current frame is generated based on the diagonal slope of a DCT map for the previously encoded frame. Before using the generated Q matrix to quantize the DCT coefficients for the current frame, the Q matrix is preferably adjusted for changes in the target mean from the previously encoded frame to the current frame.

Abstract: The invention concerns a method comprising a step which consists in a quantizing step relative to a pixel or group of pixels in accordance with a desired rate. The invention is characterized in that it comprises an additional step which consists in modifying the quantizing step on the basis of an information of a subjective nature concerning said pixel or group of pixels. The invention is applicable to compression of video images.

Abstract: This invention is designed to encode the image area information of a multilevel image within a target size without re-inputting the information. For this purpose, from the multilevel image data input from the input unit (101), an image area information generating unit (1701) generates, for each pixel, image area information constituted by an image area component indicating whether the pixel exists in a character•line drawing area or halftone area and an image area component indicating whether the pixel is chromatic or achromatic. A lossless encoding unit (1705) encodes this information on a block basis, and stores the resultant information in a third memory (1709). An encoding control unit (1713) monitors an amount of code. Upon determining that the amount of code exceeds a target amount, the encoding control unit causes the lossless encoding unit (1705) to perform encoding upon changing image area components, of subsequently input image area components, which coincide with a condition.

Abstract: A video signal processing apparatus and a video signal processing method can switch resolution effectively and efficiently. The video signals coming from an imaging apparatus is converted into digital signals by an A/D converter 2 an compressed by a compressor 3. The compressed video signals are written into a recording medium 5 by means of a write device 4. The compressor 3 encodes the video signals for each group of pictures comprising a plurality of pictures and the camera compression control unit 6 controls the compressor 3 so as encode the pictures of a first group of pictures and those of a second group of pictures arranged temporally adjacent to the first group of pictures, while maintaining the number of pictures of two temporally adjacent groups of pictures that contain a resolution change point of video signals to a constant value, and change the resolution of the pictures of the two groups of pictures.

Abstract: A moving picture encoding system includes an encoding control unit for setting a target quantiser step size used to encode each of different types of pictures included in a unit group to be encoded, and for performing a control operation to generate and furnish a quantiser step size to an encoding unit so that a ratio among the target quantiser step sizes set for the different types of pictures is a predetermined one.

Abstract: A video data compression apparatus with which compressed video data of suitable amounts of data can be produced and in addition the time required for processing is short.

Abstract: A controller allocates a bit size for a current frame in a group of pictures of a first compression-encoded digital video signal that is to be spliced following transmission of the group of pictures with a second compression-encoded digital video signal. The signals are spliced after a predetermined switching time. The spliced signals are buffered by a decoder buffer and then decoded by a decoder. When the second signal has a variable bit-encoding rate and the current frame is not decoded until after the predetermined switching time, the maximum bit size is determined in accordance with an estimate of the decoder buffer fullness at the predetermined switching time. When the second signal has a predetermined maximum variable bit-encoding rate and the current frame is not decoded until after the predetermined switching time, the minimum bit size is determined in accordance with the predetermined maximum bit-encoding rate of the second signal.