Method and apparatus for aligning IDR frames in transcoded multi-bitrate video streams

摘要

A video stream is transcoded to provide a plurality of primary profiles. Individual frames of the video stream have a Presentation Time Stamp (PTS). A PTS is used as a token to identify particular frames to be encoded as Instantaneous Decoder Refresh (IDR) frames in each profile. An IDR frame period is determined, indicative of a desired number of video frames between two IDR frames. An IDR frame is inserted into each profile every IDR frame period. The IDR frames of each profile are aligned with the same IDR frames of the other profiles. The PTS of each IDR frame in each profile is monitored. Upon determining that a PTS is out of alignment, the next PTS of the affected profile is aligned with the corresponding PTS of remaining profiles. Backup transcoders produce backup profiles that are maintained in alignment with each other and with the primary profiles.

主权项

1. A method for streaming video in a plurality of different profiles, comprising:
transcoding a video stream to provide said plurality of different profiles, said video stream comprising frames having a Presentation Time Stamp (PTS); using only said PTS as a token to identify a first frame of said video stream to be encoded as an Instantaneous Decoder Refresh (IDR) frame in each profile; determining an IDR frame period indicative of a desired number of video frames between two IDR frames for each of the profiles; encoding select subsequent frames in each profile of the video stream as IDR frames, said select subsequent frames occurring at a PTS period corresponding substantially to the IDR frame period for each corresponding profile for every IDR frame period, said encoding resulting in the IDR frames of each profile being aligned with the same IDR frames of each of the other profiles in said plurality of different profiles; monitoring the PTS of each IDR frame in each profile; and if said monitoring step determines that a PTS of one of the IDR frames is out of alignment, realigning the next IDR frame of the affected profile with the corresponding IDR frame of remaining profiles.