Abstract: A system and method for estimating a motion vector for transcoding digital video is presented. The method includes selecting a direction of an adjustment vector for estimation of a motion vector within a search region, and selecting the adjustment vector having a minimum SAD (sum absolute distance) within the search region.

Abstract: The present invention relates to a method for shortening the time to synchronize video/audio data in a mobile communication terminal. The method comprises receiving video/audio data in the mobile communication terminal through a set session, determining whether a current sampling rate of the received video/audio data is consistent with a previous sampling rate of the received video/audio data, calculating a standard time according to the determination, and synchronizing the video/audio data based on the calculated standard time. The standard time is calculated using a preset ratio if the current sampling rate is consistent with the previous sampling rate. However, the standard time is calculated using a variation value of a real time protocol (RTP) time stamp and a variation value of a network time protocol (NTP) time stamp if the current sampling rate is not consistent with the previous sampling rate.

Abstract: A method for recovering a lost block of an image processing system, which includes determining characteristics of a lost block by using a cost function with respect to the lost block, and recovering the lost block by applying an error concealment method that is best suitable for the characteristics of the lost block. Because an image is restored by applying the most suitable error concealment method according to characteristics of the lost block, error restoration performance of a receiving end is improved and the closest image of an original image can be reproduced.

Abstract: Provided are a method for determining the packet type for a Scalable Video Coded (SVC) video bitstream, and a Real-time Transport Protocol (RTP) packetizing apparatus and method using the same. The method for determining a packet type for a Scalable Video Coded (SVC) video bitstream, which includes the steps of: a) deriving temporal and spatial hierarchy information between Network Abstraction Layer (NAL) units from field information defined in the NAL unit headers of scalable layers; b) detecting the type of encoding information by applying combined scalability encoding to the hierarchical structure of the Scalable Video Coding (SVC); and c) determining a Real-time Transport Protocol (RTP) packet type for the corresponding SVC video bitstream by using the derived temporal and spatial hierarchy information between the NAL units and the detected type of encoding information.

Abstract: A streaming contents recording method of a mobile terminal including comparing a length of streaming contents with a remaining memory capacity of the mobile terminal, and recording the streaming contents by omitting a specific frame type if the length of the streaming contents is greater than the memory capacity. Further, the omitted specific frame types include a B-frame type or a B-frame type and a P-frame type.

Abstract: Provided are a<b> </b>time-stamping apparatus and method for RTP packetization of a SVC coded video, and a RTP packetization system using the same. The time stamping apparatus includes: a NAL unit classifier for checking a header of an input NAL unit and classifying the input NAL units based on a picture property; a first timestamp calculator for calculating a RTP timestamp value for a NAL unit classified as a key picture by the NAL unit classifier; a second timestamp calculator for calculating a RTP timestamp value for a NAL unit classified as a non-key picture by the NAL unit classifier; and a controller for setting a RTP timestamp value for an instantaneous decoding refresh (IDR) picture and controlling the first and second timestamp calculators for calculating a RTP timestamp value of a corresponding NAL unit.

Abstract: Provided is a real-time streaming protocol (RTSP) based progressive streaming method. The progressive streaming method based on a real-time streaming protocol, wherein a server transfers SDP information and performs streaming of a contents file to a client connected, the method including the steps of: a) if a “pause” request message is received from the client, transmitting a “pause” response message including the number of TCP packets already transferred to the client, and pausing streaming of the contents file; and b) if a “replay” request message including the number of the TCP packet to be transferred is received from the client, transmitting a “replay” response message and restarting transmission of the TCP packets from the next TCP packet to the TCP packet transferred to the client before the contents file is paused.

Abstract: An apparatus for converting a resolution of video including a decoding unit configured to convert a first resolution of a video signal to a second resolution according to a predetermined ratio, to scale a motion vector extracted from the video signal based on the predetermined ratio, and to compensate the scaled motion vector. Also included is a coding unit configured to code a signal output from the decoding unit.

Abstract: An apparatus for measuring a roundtrip delay time associated with communication of multimedia data is provided. In one embodiment, the apparatus comprises a video encoder for encoding multimedia data to produce encoded multimedia data; a transmission rate controller for controlling transmission rate of the encoded multimedia data according to an effective transmission rate; and a first sending/receiving unit for sending the multimedia data via a first channel.

Abstract: A motion vector and macroblock type determining method is provided. The method comprises receiving a high frame-rate video stream having N frames; skipping a frame N-1; allocating a motion vector to a macroblock of frame N according to a macroblock type of the skipped frame N-1; allocating a macroblock type to a macroblock type of frame N according to a macroblock type of the skipped frame N-1; and outputting a low frame-rate video stream.

Abstract: A digital video signal processing apparatus for providing video conferencing services in a mobile communication system includes a plurality of mobile terminals each having a video camera and a MCU (multipoint control unit) for mixing video signals received from the video conference terminals to generate a composite signal and for transmitting the composite signal to each of the terminals.

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: A transcoding method and apparatus for converting a digital bitstream complying with a certain compression method into a digital bitstream complying with a different (or the same) compression method is provided. The transcoding apparatus performs conversion between compressed bitstreams having at least syntax elements and video elements corresponding to video data.

Abstract: An apparatus for measuring a roundtrip delay time associated with communication of multimedia data is provided. In one embodiment, the apparatus comprises a video encoder for encoding multimedia data to produce encoded multimedia data; a transmission rate controller for controlling transmission rate of the encoded multimedia data according to an effective transmission rate; and a first sending/receiving unit for sending the multimedia data via a first channel.

Abstract: A method for adaptively estimating a transmission rate of multimedia data by monitoring an RTCP network state is provided. The method comprises receiving a real-time transport protocol (RTCP) receiver report packet from a multimedia data reception unit; detecting packet loss rate from the RTCP receiver report packet; and adaptively estimating an available transmission rate according to a range within which the packet loss rate belongs.

Abstract: The present invention relates to a method for encoding a signal of a wireless communication system, the method comprising dividing a current frame of the signal into a plurality of GOBs (Groups of Blocks) each having a certain size, determining whether a current GOB to be encoded of the plurality of GOBs is a first GOB of the current frame, calculating a control parameter value of the current GOB according to whether the current GOB is the first GOB of the current frame, controlling an encoding bit rate of the current GOB according to the control parameter value, and encoding the current GOB. Preferably, a hybrid method wherein an inter-frame GOB update method and an intra-frame GOB update method is used, so that a bit rate change between frames is reduced and data transmission of a channel is efficiently made to therefore provide a user with optimum image quality.

Abstract: The present invention relates to a method for shortening the time to synchronize video/audio data in a mobile communication terminal. The method comprises receiving video/audio data in the mobile communication terminal through a set session, determining whether a current sampling rate of the received video/audio data is consistent with a previous sampling rate of the received video/audio data, calculating a standard time according to the determination, and synchronizing the video/audio data based on the calculated standard time. The standard time is calculated using a preset ratio if the current sampling rate is consistent with the previous sampling rate. However, the standard time is calculated using a variation value of a real time protocol (RTP) time stamp and a variation value of a network time protocol (NTP) time stamp if the current sampling rate is not consistent with the previous sampling rate.

Abstract: A method for recovering a lost block of an image processing system, which includes determining characteristics of a lost block by using a cost function with respect to the lost block, and recovering the lost block by applying an error concealment method that is best suitable for the characteristics of the lost block. Because an image is restored by applying the most suitable error concealment method according to characteristics of the lost block, error restoration performance of a receiving end is improved and the closest image of an original image can be reproduced.

Abstract: A system and method is disclosed for converting a codec of image data. The system comprises a syntax converter for selectively converting first image data having a first syntax into second image data having a second syntax in response to a comparison of the first image data and the second image data, and a decoder for decoding a bit stream outputted from the syntax converter.

Abstract: A system and method is disclosed for estimating a motion vector for transcoding digital video. The method comprises choosing a direction of an adjustment vector for estimation of a motion vector within a search region, and choosing an adjustment vector having a minimum sum absolute difference (SAD) within the search region. The method further comprises estimating the motion vector by summing an adjustment vector and a base motion vector. In one embodiment, the direction of the adjustment vector is along an arbitrary axial direction of the search region. In another embodiment, the direction of the adjustment vector is along an arbitrary quadrant direction of the search region. In yet another embodiment, the direction of the adjustment vector is a direction of an optimum adjustment vector.