摘要:
A real-time MPEG video coding system with information look-ahead for constant bit rate (CBR) applications, such as, for example, Video-on-Demand (VoD) over ADSL. This scheme employs two MPEG encoders. The second encoder has a buffer to delay the input by an amount of time relative to the first encoder to create a look-ahead window. In encoding, the first encoder collects the information of statistics and rate-quality characteristics. An on-line information processor then uses the collected information to derive the best coding strategy for the second encoder to encode the incoming frames in the look-ahead window. The second encoder uses the encoding parameters from the processor as the coding guide to execute the coding strategy and generate the final bitstream.
摘要:
A video transcoding method is provided for transcoding a first signal stream compressed by a first coding scheme to a second signal stream compressed by a second coding scheme. The method employs an adaptive frame rate and a joint temporal-spatial rate control technique, such that the overall quality of compressed MPEG video can be significantly enhanced when the transcoding is controlled in the joint temporal (picture or frame rate) and spatial (quantization) domains. One embodiment considers transcoding from high bit rate video with larger image size (e.g. 4CIF/4SIF, CIF) coded by one coding technique, e.g., MPEG-2 to a lower bit rate video with smaller image size (e.g. CIF, QCIF) coded by the same or another coding technique, e.g., MPEG-4.
摘要:
A system and method for generating an MPEG compliant video stream with satisfactory visual quality. The method employs re-encoding at a higher (or lower) bit rate, only the segments with unsatisfactory visual picture quality while retaining other parts of the original video stream and then merging the re-encoded segments with the remaining original portions. If the original video stream is coded at a reasonable bit rate, the number and length of those segments with unsatisfactory visual picture quality will be few and short. Re-encoding only those segments can save very significant amount of cost and only requires minimal additional storage space. Furthermore, the portions with satisfactory picture quality will be retained. The system and method is applicable to MPEG and non-MPEG compliant data streams.