Abstract: An improved loss recovery method for coding streaming media classifies each data unit in the media stream as an independent data unit (I unit), a remotely predicted unit (R unit) or a predicted data unit (P unit). Each of these units is organized into independent segments having an I unit, multiple P units and R units interspersed among the P units. The beginning of each segment is the start of a random access point, while each R unit provides a loss recovery point that can be placed independently of the I unit. This approach separates the random access point from the loss recovery points provided by the R units, and makes the stream more impervious to data losses without substantially impacting coding efficiency. The most important data units are transmitted with the most reliability to ensure that the majority of the data received by the client is usable. The I units are the least sensitive to transmission losses because they are coded using only their own data.

Abstract: A for method watermarking a compressed video bitstream selects for modification numerous sites within an MPEG compressed video bitstream, each of which sites includes a DCT coefficient which is apt for modification. Watermarking sites are preferably located in MPEG B frames, and the DCT coefficient to be modified preferably has a run-length of zero (0). The method then embeds the watermark by modifying the DCT coefficient for at least some of the selected sites. A list specifying the watermarking sites may be transmitted together with the compressed video bitstream to permit further watermarking by subsequent bitstream receivers. A system for detecting an unauthorized copy of a watermarked video forms a synchronized, frame-by-frame difference between a possibly unauthorized copy of the watermarked compressed video and an un-watermarked copy of the video. Data in the watermarking site list permits readily locating watermarks within the possibly unauthorized copy.

Abstract: A method is disclosed for transmitting video images over a data communication network, in which method the video image is encoded at the sending end, transmitted, and decoded at the receiving end. The first frame is compressed and transmitted to the receiving end where it is stored in image memory. A copy of the first frame is retained at the transmitting end and divided into blocks. The next frame is also divided into blocks. The blocks of the first frame and the blocks of the next frame are compared to determine a block difference for each block. For each block, the difference between successive blocks is compressed and transmitted if the block difference for the block exceeds a predetermined threshold.

Abstract: An adaptive blocking coding system selects an effective blocking of an input image signal to be encoded in accordance with the correlation between fields, even if motion is detected between the fields. The blocking patterns include an individual field blocking, a non-interlace blocking, a split blocking and an inverted split blocking. Further, the coding system searches for motion from both odd and even fields of a frame for producing a motion compensated prediction signal in order to provide high-efficient coding.