20200514-Virtual-Technical-Summit-AASIG-AudioHAL-Workshop-Minutes

Philippe Robin welcomed everyone and handover to Wassim

60 attendees

Wassim describes the agenda (slide #2)

slide deck for this workshop is here

## Project overview & proof-of-concept demo

Project overview presented by Wassim (slides #4 to #6)

• Two strategies for system level audio
• Combining both of them
• Expecting to take opinion from the people on what topics are currently relevant

Topics relevant for all strategies and pre-requisites for the proof-of-concept for further discussion today (slides #7 to #9)

Proof-of-concept presented by Piotr (slides #13 to #15)

• Presentation about the PoC and what have been done
• Presentation of the demo
• Lesson learned

Q&A on Proof-of-concept

• Q: What about low latency streams ?
  
  • (not captured)
• Q: CPU offloading, what do you mean exactly by this ? Is it considered ?
  • For now the POC is not considering CPU offloading, we know it's feasible but it's not yet considered in this POC
  • CPU offloading is when the DSP can take care of some action instead of the CPU
  • Android has such a feature that allows the DSP to directly decode some streams
  • Android would like to isolate 3rd party developers for such decisions and they inform that such streams can be offloaded.
• Q: if audio is played by Android application but external mixer for some reason does not given priority due to other sources , how app layer gets notified about error ?
  
  • The external mixer can be used for chimes and warnings, usually they are mixed on top (they play along music)
• Q: Can you please explain the diagram on the right?
  • (not captured)
• Q: What are the socket kind of ports shown in the lower block of slide #13 ?
  • One of the first findings we made is that the network sockets cannot be used directly by Audio HAL.
  • So the sockets are deprecated (they are realized by 3rd service and audio relays)
• Q. How does this Proof-of-concept work in case of fail-safe scenario ? Can you explain more on System Proxy part considering start-up and shutdown use case?
  • The fail-safe scenario solution is as follows: during the start-up the audio can be available already because the ALSA is already available