High-capacity transcoding station and method
The invention provides a high-capacity transcoding station for concurrently transcoding multiple signal streams received from designated multimedia sources. The transcoding station employs a pool of heterogenous processing units of different types, referenced as “workers”, a pool of resources communicatively coupled to the pool of workers, and an orchestrator configured to communicate with the pool of workers and communicate with the multimedia sources through a network interface. The network interface receives transcoding requests and signal streams to be transcoded, directs control data components of the transcoding requests from different multimedia sources to the orchestrator and directs content data of the signal streams to the pool of workers. The content data is organized into groups of pictures (GOPs) and each worker is configured to process one GOP at a time. The GOPs are treated as independent entities, regardless of their stream affiliations. A worker may process a GOP belonging to any stream.
1 . A transcoding station, comprising:
a pool of heterogeneous workers configured to concurrently transcode a plurality of heterogeneous signal streams, wherein each signal stream is organized into groups of pictures (GOPs), each worker comprising a respective hardware processor, wherein the pool of workers is organized into a predefined number of worker groups, each worker group comprising workers of a respective transcoding stage;
an orchestrator configured to assign to each GOP a respective set of workers to produce a respective transcoded GOP, wherein the orchestrator is coupled to one or more transcoding-stage controllers, each transcoding-stage controller communicatively coupled to a respective worker group, wherein said respective set of workers comprises one worker from each worker group, wherein each worker of each worker group has a dual control channel to the orchestrator, a first content-transfer channel from a content-transfer mechanism, and a second content-transfer channel to said content-transfer mechanism, thereby enabling transfer of control data and content data from a worker of any worker group to a worker of another worker group, wherein said content-transfer mechanism comprises:
a worker-selection unit for each worker group having a respective upstream selector for transferring GOP content to a selected worker of said each worker group and a downstream selector for transferring output of the selected worker to a common memory;
a first cyclical selector for supplying GOP content data from a network interface and from said worker-selection units to said common memory; and
a second cyclical selector for transfer of GOP content data from said common memory to said worker-selection units and to said network interface;
the network interface, connecting to a telecommunication network, configured to:
communicate with a plurality of multimedia sources to receive transcoding requests and corresponding signal streams organized into GOPs;
attach a signal-stream identifier to each GOP;
direct the transcoding requests to the orchestrator; and
direct the signal streams to the pool of workers; and
a collator coupled to said network interface configured to collate transcoded GOPs according to respective signal-stream identifiers and arrange GOPs of each signal stream in proper sequential order to be communicated to respective destinations through the network interface.
2 . The transcoding station of claim 1 , wherein said plurality of heterogeneous signal streams comprises at least two signal streams formed according to different coding standards.
3 . The transcoding station of claim 1 , wherein each said transcoding request of a specific signal stream comprises metadata indicating a compression standard according to which the specific stream is formed and specifying a compression standard according to which a respective transcoded signal stream is to be formed.
4 . The transcoding station of claim 1 , wherein said orchestrator is configured to, for each transcoding stage:
define tasks to be performed for said each GOP according to metadata content of transcoding request;
present definitions of said tasks to compatible workers of said each transcoding stage; and
select a compatible worker of least workload.
5 . The transcoding station of claim 1 , wherein said content-transfer mechanism comprises:
a worker-selection unit for each worker group having a respective upstream selector for transferring GOP content to a selected worker of said each worker group and a downstream selector for transferring output of the selected worker to an intermediate content memory coupled to a subsequent worker-selection unit.
6 . The transcoding station of claim 1 , wherein said content-transfer mechanism comprises:
an input selector for transferring GOP content data received through said network interface to designated workers of a first-stage worker group;
(Ω−1) switching units each connecting a respective worker-group to a subsequent worker group; and
an output selector for transferring transcoded GOP content data to said network interface.
7 . The transcoding station of claim 1 , wherein at least one worker group comprises workers having respective dedicated resources.
8 . The transcoding station of claim 1 , wherein workers of at least one worker group connect to a shared pool of heterogenous resources through a resource-access mechanism where a resource of the shared pool is allocable to any worker of the at least one worker group on demand.
9 . The transcoding station of claim 1 , wherein the pool of workers is organized into three worker groups so that:
a first group of workers decodes received GOPs to produce respective decoded GOPs;
a second group of workers performs processes relevant to frame rate and frame dimension to organize frames of each GOP to be compatible with destination receivers; and
a third group of workers encodes output GOPs of the second group of workers according to a requisite coding standard at destination to produce a compressed signal modulating a downstream carrier directed to respective destinations.
10 . The transcoding station of claim 9 , wherein:
said first group of workers comprises a predetermined number of decoding sub-groups, each decoding sub-group corresponding to a respective coding standard; and
said third group of workers comprises a predetermined number of encoding sub-groups, each encoding sub-group corresponding to a respective coding standard.
11 . The transcoding station of claim 1 , wherein said network interface comprises:
a network interface processor;
a source-characterization module configured to determine characteristics of each engaged multimedia source of said plurality of multimedia sources, with the help of a source-characteristics database; and
a destination interaction module configured to communicate notifications and respective transcoded content to all destinations of each transcoded stream.
12 . A method of signal-stream transcoding, implemented at a transcoding station employing a plurality of hardware processors, the method comprising:
employing a plurality of heterogeneous workers, each worker comprising a processor and configured to perform a respective set of tasks of a plurality of predefined tasks, wherein the plurality of heterogeneous workers is organized into a predefined number of worker groups, each worker group comprising workers of a respective transcoding stage;
receiving heterogeneous signal streams from multiple signal sources, each signal stream associated with respective metadata and organized into respective groups of pictures (GOPs), each GOP comprising a respective number of video frames;
assigning, by an orchestrator, a respective set of heterogeneous workers of the plurality of heterogeneous workers to each GOP, wherein the orchestrator is coupled to one or more transcoding-stage controllers, each transcoding-stage controller communicatively coupled to a respective worker group, wherein said respective set of heterogeneous workers comprises one worker from each worker group, wherein each worker of each worker group has a dual control channel to the orchestrator, a first content-transfer channel from a content-transfer mechanism, and a second content-transfer channel to said content-transfer mechanism, thereby enabling transfer of control data and content data from a heterogeneous worker of any worker group to a heterogeneous worker of another worker group, wherein said content-transfer mechanism comprises:
a worker-selection unit for each worker group having a respective upstream selector for transferring GOP content to a selected worker of said each worker group and a downstream selector for transferring output of the selected worker to a common memory;
a first cyclical selector for supplying GOP content data from a network interface and from said worker-selection units to said common memory; and
a second cyclical selector for transfer of GOP content data from said common memory to said worker-selection units and to said network interface;
concurrently processing individual GOPs of all of said heterogeneous signal streams as independent entities, said processing comprising:
identifying requisite tasks of said plurality of predefined tasks for each signal stream of said heterogenous signal streams according to said respective metadata; and
allocating and activating compatible workers to perform said requisite tasks for each GOP of said each signal stream to produce a respective transcoded GOP;
collating resulting transcoded GOPs according to signal-stream identity and sequential order within each signal-stream; and
transmitting transcoded GOPs of each stream to respective designated destinations.
13 . The method of claim 12 , wherein said plurality of workers comprises a number of specific workers performing functions pertinent to respective coding standards and each said specific worker comprises dedicated resources.
14 . The method of claim 12 , wherein said requisite tasks comprise generic processes of:
decoding received GOPs to produce respective decoded GOPs;
adjusting frame-dimensions and frame-rates of the decoded GOPs to produce respective edited GOPs compatible with target receivers;
encoding the edited GOPs to produce respective compressed GOPs compatible with said target receivers; and
modulating a downstream carrier signal directed to a network for distribution to said target receivers.
15 . The method of claim 12 , wherein said heterogeneous signal streams comprise signal streams formed according to different coding standards and said respective metadata of said each signal stream specify:
a first coding standard according to which said each signal stream is compressed at source;
frame dimensions and frame rate at source, and requisite frame dimensions and frame rate at destination;
and
a second coding standard according to which a respective transcoded signal stream is to be formed.
16 . The method of claim 12 , further comprising arranging said plurality of heterogeneous workers into:
a first group of workers for performing video-signal decompression functions;
a second group of workers for performing video-signal formatting; and
a third group of workers for performing video-signal compression functions.
17 . The method of claim 16 , further comprising:
partitioning said first group of workers into a predetermined number of decoding sub-groups, each decoding sub-group corresponding to a respective coding standard;
and
partitioning said third group of workers into a predetermined number of encoding sub-groups, each encoding sub-group corresponding to a respective coding standard;
thereby expediting allocation of said compatible workers.