| 摘要 |
Time stamps in an encoded digital motion video data stream (such as an MPEG Transport Stream) are re-stamped for seamless splicing. The re-stamping includes attainment of Presentation Time Stamp (PTS) agreement in the video stream, alignment of audio stream and video stream Presentation Time Stamps, and re-stamping of the Program Clock Reference (PCR) to eliminate jitter and to comply with MPEG standards. The MPEG compliance is achieved by padding, stuffing and insertion of freeze B and P frames and pre-encoded black I frames. Freeze frame insertion can be also achieved by replacing B and P frames by, smaller in size, freeze B and P frames respectively. No frames are discarded such that both spatial and temporal frame accuracy (no extra frame insertion assumed) is achieved. Moreover, padding is inserted into the data stream to compensate for irregularities in the decoder buffer level, and the audio and video buffer levels are managed dynamically to recover from data miss-delivery to minimize secondary effects, including prediction of errors, inducing freeze or skip, and insertion of padding. The start of the play of the second MPEG stream spliced to the first one is frame accurate and starts as scheduled based on the use of an external clock signal in a stream server computer. |
