The MultiencodeWorkflowHandler is used to encode source media into multiple formats concurrently. The source recording are selected by source-flavors AND source-tags. Each source media selector (eg presenter or presentation) can have an independent set of encoding profile ids (one for each target recording) and target tags. Encoding of each source medium runs as one ffmpeg command. This operation will generate one multiencode operation per source medium, all of them running concurrently on the same or on different workers. In addition, the target media can be optionally tagged with the encoding profile ids.
This workflow handles each source selector independently as a section. The parameters for each configuration, such as flavors are separated positionally into sections by ";". The use of the semi-colon is optional. If it is absent, there is only one section.
One source selector means that all the matching recording will be processed the same way.
Two different source selectors means that all the matching recordings in the first selector will be processed according to the parameters in the first section and the all the matching recordings in the second selector will be processed according to the parameters in next section.
Each source selector can have only one corresponding section. If there is only one section in one parameter, eg: target-flavors, but multiple sections in another, eg: source-flavors, then the sections are collapsed into one. For example:
All targets are flavored the same way, using the example above, becomes "presenter/preview" and "presentation/preview"
Each source selector can have its own set of target tags and flavors, defined as a comma delimited list. For example:
Using the example above. "presenter/preview" is tagged with "engage-streaming,rss,atom". "presentation/preview" is tagged with "engage-download,rss,atom".
When a configuration has the same number of sections as the source, then the configurations for the operation are taken from the corresponding sections.
Each section runs independently as a parallel encoding job.
For example, if presenter/source is to encoded with "mp4-low.http,mp4-medium.http" and presentation/source is to be encoded with "mp4-hd.http,mp4-hd.http"
The target flavors are presenter/delivery and presentation/delivery and all are tagged "rss, archive". The target flavors are additionally tagged with encoding profiles, so that they can selected individually.
This workflow supports HLS adaptive streaming. By: 1) Using only H.264/HENV encodings in the list of encoding profiles. 2) In the encoding profile, use the "-
To make sure that stream switching works as expected, state the bitrates explicitly for each of mp4 encoding profiles used. For advices on how to pick bitrates see: https://developer.apple.com/documentation/http_live_streaming/hls_authoring_specification_for_apple_devices
For more details on HLS, see: https://tools.ietf.org/html/rfc8216 https://tools.ietf.org/html/draft-pantos-http-live-streaming-23
Without HLS, it will look like the following.
|source-flavors||presenter/source;presentation/source||Which media should be encoded|
|target-flavors||*/preview||Specifies the flavor of the new media|
|target-tags||rss,archive||Specifies the tags of the new media|
|encoding-profiles||mp4-low.http,mp4-medium.http;mp4-hd.http,mp4-hd.http||Encoding profiles for each source flavor|
|tag-with-profile||true (default to false)||target medium are tagged with coresponding encoding profile Id|
<operation id="multiencode" fail-on-error="true" exception-handler-workflow="error" description="Encoding presenter (camera) video to Flash download"> <configurations> <configuration key="source-flavors">presenter/work;presentation/work</configuration> <configuration key="target-flavors">*/delivery</configuration> <configuration key="target-tags">rss,archive</configuration> <configuration key="encoding-profiles">mp4-low.http;mp4-hd.http</configuration> <configuration key="tag-with-profile">true</configuration> </configurations> </operation>
Each source flavor generates all the target formats in one ffmpeg call by incorporating relevant parts of the encoding profile commands.
Care must be taken that no ffmpeg complex filters are used in the encoding profiles used for this workflow, as it can cause a conflict.
Encoded target recording are distinguished by the suffix, it is important that all the encoding profiles used have distinct suffixes to use "tag-with-profile" configuration, for example:
profile.mp4-vga-medium.http.suffix = -vga-medium.mp4 profile.mp4-medium.http.suffix = -medium.mp4