sox source: can't open: unsupported # of channels: expected=2 actual=1

[Ramblurr]

As discussed in matrix..

pi@dev1:~ $ roc-send -vvvv --input alsa://hw:1,0 --source rtp+rs8m://10.9.6.96:10001 --repair rs8m://10.9.6.96:10002
17:01:11.476 [5110] [dbg] roc_core: [slab_pool.cpp:38] slab pool: initializing: object_size=672 min_slab=0B(1S) max_slab=0B(0S) poison=0
17:01:11.477 [5110] [dbg] roc_core: [slab_pool.cpp:38] slab pool: initializing: object_size=2064 min_slab=0B(1S) max_slab=0B(0S) poison=0
17:01:11.477 [5110] [dbg] roc_core: [slab_pool.cpp:38] slab pool: initializing: object_size=4112 min_slab=0B(1S) max_slab=0B(0S) poison=0
17:01:11.477 [5111] [dbg] roc_netio: [network_loop.cpp:278] network loop: starting event loop
17:01:11.477 [5110] [dbg] roc_peer: [context.cpp:25] context: initializing
17:01:11.478 [5110] [dbg] roc_sndio: [pulseaudio_backend.cpp:19] pulseaudio backend: initializing
17:01:11.478 [5110] [dbg] roc_sndio: [sox_backend.cpp:164] sox backend: initializing
17:01:11.478 [5112] [dbg] roc_ctl: [control_task_queue.cpp:95] control task queue: starting event loop
17:01:11.478 [5112] [trc] roc_ctl: [control_task_queue.cpp:706] control task queue: ready task queue is empty or being pushed
17:01:11.478 [5112] [trc] roc_ctl: [control_task_queue.cpp:839] control task queue: updating wakeup deadline: deadline=-1
17:01:11.478 [5110] [dbg] roc_sndio: [backend_map.cpp:20] backend map: initialized: n_backends=2 n_drivers=58
17:01:11.478 [5110] [inf] roc_sndio: [sox_source.cpp:65] sox source: opening: driver=alsa path=hw:1,0
17:01:11.491 [5110] [trc] roc_sndio: [sox_backend.cpp:157] sox: alsa.c: select_format: trying #7
17:01:11.491 [5110] [trc] roc_sndio: [sox_backend.cpp:157] sox: alsa.c: select_format: trying #8
17:01:11.491 [5110] [trc] roc_sndio: [sox_backend.cpp:157] sox: alsa.c: select_format: trying #4
17:01:11.491 [5110] [trc] roc_sndio: [sox_backend.cpp:157] sox: alsa.c: select_format: trying #5
17:01:11.491 [5110] [trc] roc_sndio: [sox_backend.cpp:157] sox: alsa.c: select_format: trying #6
17:01:11.491 [5110] [trc] roc_sndio: [sox_backend.cpp:157] sox: alsa.c: select_format: trying #2
17:01:11.491 [5110] [dbg] roc_sndio: [sox_backend.cpp:157] sox: alsa.c: can't encode 32-bit Signed Integer PCM
17:01:11.491 [5110] [trc] roc_sndio: [sox_backend.cpp:157] sox: alsa.c: selecting format 2: S16_LE (Signed 16 bit Little Endian)
17:01:11.493 [5110] [err] roc_sndio: [sox_source.cpp:337] sox source: can't open: unsupported # of channels: expected=2 actual=1
17:01:11.494 [5110] [dbg] roc_sndio: [sox_backend.cpp:289] sox backend: open failed: driver=alsa path=hw:1,0
17:01:11.494 [5110] [inf] roc_sndio: [sox_source.cpp:361] sox source: closing input
17:01:11.495 [5110] [err] roc_sndio: [backend_dispatcher.cpp:208] backend dispatcher: failed to open source: type=device driver=alsa path=hw:1,0
17:01:11.495 [5110] [err] roc_send: [main.cpp:255] can't open input file or device: uri=alsa://hw:1,0 format=(null)
17:01:11.495 [5110] [dbg] roc_peer: [context.cpp:29] context: deinitializing
17:01:11.495 [5112] [trc] roc_ctl: [control_task_queue.cpp:706] control task queue: ready task queue is empty or being pushed
17:01:11.496 [5112] [trc] roc_ctl: [control_task_queue.cpp:839] control task queue: updating wakeup deadline: deadline=-1
17:01:11.496 [5112] [dbg] roc_ctl: [control_task_queue.cpp:105] control task queue: finishing event loop
17:01:11.496 [5111] [dbg] roc_netio: [network_loop.cpp:285] network loop: finishing event loop

Raspberry PI Zero 2 running 64bit raspbian PulseAudio 14.2

pi@dev1:~ $ roc-send  --version
roc-send 0.2.0 (ed92e21e98)```

[gavv]

To fix this, we should ask backend (source or sink) its channel layout and perform channel mapping. We already have channel mapper class, just need to apply it in right place.