Adaptive bitrate streaming latency reduction
A method of transmitting media content is provided that provides for a significantly reduced chunk size. The method includes receiving one or more adaptive transport streams into a memory buffer at a HTTP streamer from a media preparation unit. The received transport streams include a plurality of switchable segments each comprising one or more delivery chunks, the switchable segments being marked with segment boundary points and the delivery chunks being marked with chunk boundary points. One or more of the delivery chunks are then transmitted from a requested switchable segment to a requesting client device until a terminating segment boundary point is reached, wherein each delivery chunk is independently decodable, and a client device can begin decoding and rendering received delivery chunks even when the HTTP streamer has not yet completely received the entire requested switchable segment from the media preparation unit.
1. A method of transmitting media content, comprising:
receiving an adaptive transport stream description at an HTTP streamer from a media preparation unit, the adaptive transport stream description describing media content available from the media preparation unit as one or more adaptive transport streams, wherein each of said one or more adaptive transport streams are continuous streams comprising a plurality of switchable segments each comprising one or more delivery chunks, the switchable segments being marked with segment boundary points and the delivery chunks being marked with chunk boundary points, wherein positions between each of said plurality of switchable segments are positions at which a client device can switch to a different one of said one or more adaptive transport streams;
publishing a playlist with said HTTP streamer listing identifiers for one or more of said plurality of switchable segments, the switchable segments including delivery chunks;
receiving said one or more adaptive transport streams into a memory buffer at said HTTP streamer from said media preparation unit;
receiving a request at said HTTP streamer from said client device for a particular switchable segment identified on said playlist to be received at a requested bit rate;
responding to said request in the HTTP streamer by processing the received one of more adaptive transport streams on the fly in real time by;
continuing receipt of delivery chunks of a switchable segment prior to the particular switchable segment until the delivery chunks reach a segment boundary point;
identifying boundary marks of the one or more chunks in only the particular switchable segment; and
transmitting the one or more delivery chunks from said particular switchable segment at the requested bit rate to said client device using HTTP chunked transfer encoding until a terminating segment boundary point is reached,
wherein each of said one or more delivery chunks are portions of the particular switchable segment that are independently decodable by said client device, such that said HTTP streamer is configured to begin sending delivery chunks from a requested switchable segment so that said client device begins decoding and rendering received delivery chunks when said HTTP streamer has not yet received additional ones of the switchable segments from said media preparation unit.
2. The method of claim 1 , wherein said media content is a live broadcast.
3. The method of claim 1 , wherein said segment boundary points are encoder boundary points inserted in private data when said media content is encoded according to an OpenCable standard.
4. The method of claim 1 , wherein said segment boundary points are inserted in public data.
5. The method of claim 1 , wherein said HTTP streamer publishes virtual identifiers on said playlist, said virtual identifiers each pointing to the switchable segment most recently received in part or in full from said media preparation unit.
6. The method of claim 1 , wherein said HTTP streamer publishes segment identifiers on said playlist, said segment identifiers each pointing to a full or partial switchable segment identified by said HTTP streamer from opening and/or closing segment boundary points within said one or more adaptive transport streams.
7. The method of claim 6 , wherein said HTTP streamer adds a new segment identifier to said playlist when it encounters a beginning segment boundary point marking the start of a new switchable segment in said one or more adaptive transport streams.
8. The method of claim 1 , further comprising sending a terminating delivery chunk of length zero to said client device when said terminating segment boundary point is reached.
9. The method of claim 1 , further comprising sending each of said delivery chunks to said client device using zero-copy segmentation within said memory buffer, wherein bits in said memory buffer that correspond to a single delivery chunk as identified by opening and/or closing chunk boundary points are transmitted directly from said memory buffer to said client device.
10. The method of claim 1 , wherein the HTTP streamer receives the adaptive transport streams well prepared including all the boundary marks identified and labeled for the switchable segments, and wherein the HTTP streamer sends the chunks incrementally in response to the client's media request.