decouple.xc sampResOut corrupted before calling check_and_signal_stream_event_to_audio

[fabriceo]

resulting in bad value for curSamRes_DAC in xua_audiohub.xc transmitted to AudioHwConfig
this can be reproduced (v5.1) using debug_printf, either in check_and_signal_stream_event_to_audio or AudioHwConfig.
it happens when stream start or stop is received from host. value can be very strange like 88, 48000 ... instead of 16 24 or 32

[xross]

Thanks for the report @fabriceo, we'll take a look at this. Were you building/running a particular build configuration?

[xross]

Also, what do you need this value for? Is it important? Its potentially on the list to be removed since its not known until stream time - which causes some issues as it means such events interrupt the AudioHub and therefore mixing of all channels - not just usb related ones.

[fabriceo]

Hi, I m running the project on the EVK_316. I have removed the lib_board_support and created my own sandbox with xmos dependencies. I have changed the lib_xua dependency to my own fork and branch but I have not yet made any big changes in it so I guess my code is not the cause of the problem :)

It is true that this information is not reliable till the start of the stream.
it is true that sending this to the audiohub breaks the mainloop and does not bring too much of value.
Still we need to create multiple STREAM_OUTPUT to support the host 16/24/32 especially for alsa/linux which is sensitive (unless using plug). The cascade of this information down in the Audiohub is questionable as most of the I2S are using 32bits anyway. I m still in favour of keeping this information and the ctrl command flow in audiohub as some product may use the information for audioconfig.
Don't hesitate to put this as low priority!

[fabriceo]

Hi, just to confirm that this issue exists with the vanilla sw_usb_audio 9.1 application for evk_316 board. using xrun --xscope file.xe, compiled with cmake/xmake. to replicate issue on macosx, just download the app, do not change usb settings in midi, launch REW, set the device in the parameter, with same sample rate, press the "level" to view the bar graph. this "start streaming" and audioconfig show the corruption.