Adaptive streaming transcoder synchronization

摘要

Techniques for synchronizing streams in an adaptive streaming environment include cross-chassis and intra-chassis synchronization of video and/or audio. In an adaptive streaming system that streams content in segments or chunks at varying levels of quality corresponding to different coding rates, implementations enable seamless switching between output streams. For example, synchronizing multiple output streams for switching between coded adaptive bit rate streams across multiple chassis involve calculating an NTP/UTC offset.

主权项

1. A method for synchronizing between multiple stream representations in an output group, the method comprising:
receiving, at a transcoder, an input stream and periodic external time clock stamps associated with the input stream; determining a master transcoding processor selected from a plurality of transcoding processors associated with said output group, computing external/internal clock offsets between the periodic external time clock stamp and an internal clock time stamped at a point in processing by the master transcoder processor; storing each computed external/internal clock offset and the respective internal clock time stamp as a pair in memory; deriving a segment boundary point time stamp associated with a segment in a stream representation generated by the master transcoding processor; identifying an internal clock time stamp in the stored pairs that is most recent relative to the derived segment boundary point time stamp; determining an adjusted segment boundary point time stamp based on the external/internal clock offset paired with the identified internal clock time stamp in memory and the derived segment boundary point time stamp; inserting the adjusted time stamp in to the stream representation for the segment corresponding to the derived segment boundary point time stamp; and outputting the same external/internal offset used to adjust the derived segment boundary point time stamp in the master transcoding processor to the one or more slave transcoding processors associated with the output group.