Abstract: A conversion server and a plurality of clients are connected via a transmission line. The conversion server that receives image coded data from the clients converts the image coding system in accordance with the coding system available to each client, the coding setting, and the status of the transmission line, and transmits the converted image coded data. For a client where the number of images that can be displayed is limited, the conversion server decodes a selected plurality items of image coded data, re-encodes the selected pieces into one composite image, and transmits the re-encoded image. The conversion server also comprises decoding processing units, one for each connected client, for decoding image coded data from each client. In response to a display image switching request from a client, the conversion server intraframe-codes the decoded image data of an image that will be used after the switching and transmits the intraframe-coded data.

Abstract: A code conversion/transmission apparatus for being supplied with compressed encoded data and converting and outputting the data to a transmission path has code converter/transmitters for outputting the encoded data input thereto and encoded data produced by re-encoding the encoded data input thereto, or outputting a plurality of encoded data comprising encoded data produced by separately re-encoding the encoded data input thereto, respectively, and transmitting the plurality of encoded data to at least one transmission path. At least a portion of the encoded data input thereto and at least a portion of the re-encoded encoded data are transmitted to the transmission path.

Abstract: A transmission side has first through Nth moving picture encoder/senders (101-1 through 101-N) for compressing moving picture frames into N encoded data and sending the encoded data. Second through Nth moving picture encoder/senders (101-2 through 101-N) compress frames encoded by the first moving picture encoder/sender (101-1) at compression ratios, which are higher than that of the first encoder/sender, using interframe prediction parameters and residual image data which are obtained in compression performed by the first moving picture encoder/sender (101-1) or a reference frame used in compression by the first moving picture encoder/sender (101-1). Each one of reception sides selects the encoded data having the lowest compression ratio and high image quality with frame-by-frame-selection or packet-by-packet-selection from the encoded data received without error and decodes the selected encoded data.

Abstract: A transmission side has first through Nth moving picture encoder/senders (101-1 through 101-N) for compressing moving picture frames into N encoded data and sending the encoded data. Second through Nth moving picture encoder/senders (101-2 through 101-N) compress frames encoded by the first moving picture encoder/sender 101-1 at compression ratios which are higher than that of the first encoder/sender based on interframe prediction by referring to frames at the same time as the interframe prediction performed by the first moving picture encoder/sender. Each one of reception sides selects the encoded data having the lowest compression ratio and high image quality with frame-by-frame or packet-by-packet selection from the received encoded data without error and decodes the selected encoded data.