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@startuml

autonumber

box "Container" #LightGreen
participant Client
participant rialtoClient
end box

box "Platform" #LightBlue
participant rialtoServer
participant GStreamer_server
end box


== Create Web Audio Player session ==

Client            ->  rialtoClient:     createWebAudioPlayer(client, pcm_params)
note right
This should only be called in when app is in ACTIVE
state. If client porting layer requires a persistent
web audio player it will need to manage creation &
destruction of the rialto object on state change.
end note
rialtoClient      ->  rialtoServer:     createWebAudioPlayer(client, pcm_params)
rialtoServer      ->  rialtoServer:     Check resource permissions that were granted to app and currently\nallocated pipelines permit this object to be created
note left: This check is (num_current_web_audio_sessions < resources.max_supported_web_audio)
rialtoServer      ->  rialtoServer:     Check pcm_params valid
note left: sampleSize is valid aslong as it is > CHAR_BIT (8 bits)
 

opt Permission & pcm_params checks passed
rialtoServer      ->  rialtoServer:     Store offset & size of media transfer buffer in shm
note left: This data comes from the getSharedMemory() API called when Rialto server entered ACTIVE state
rialtoServer      ->  GStreamer_server: Create rialto server PCM audio pipeline
GStreamer_server  --> rialtoServer:
rialtoServer      --> rialtoClient:     web_audio_session
rialtoClient      --> Client:           web_audio_session

rialtoServer      --/ rialtoClient:     notifyState(web_audio_session, IDLE)
rialtoClient      --/ Client:           notifyState(web_audio_session, IDLE)

else Checks failed

rialtoServer      --> rialtoClient:     nullptr
rialtoClient      --> Client:              nullptr

end


== Initialisation ==

Client            ->  rialtoClient:     getDeviceInfo()
rialtoClient      ->  rialtoServer:     getDeviceInfo()
rialtoServer      --> rialtoClient:     preferred_frames, max_frames, support_deferred_play
note right: preferred_frames=minimum of 640 or max_frames\nmax_frames=shm_region_size/bytes_per_frame (pcd(pcm_params.channels * pcm_params.sampleSize) \nsupport_deferred_play=true
rialtoClient      --> Client:           preferred_frames, max_frames, support_deferred_play


== Destroy Web Audio Player session ==

Client            ->  rialtoClient:     ~IWebAudioPlayer()
note right
This should be called in when app leaves ACTIVE
state or destroys it's web audio player.
end note
rialtoClient      ->  rialtoServer:     ~IWebAudioPlayer(client, pcm_params)
rialtoServer      ->  GStreamer_server: Destroy PCM audio pipeline
GStreamer_server  --> rialtoServer:
rialtoServer      --> rialtoClient:
rialtoClient      --> Client:


@enduml