add support in JACK backend for specifying number of input and output channels to use

3 files changed, 14 insertions, 0 deletions

diff --git a/libs/ardour/ardour/jack_utils.h b/libs/ardour/ardour/jack_utils.h
index bc94da3361..7565353198 100644
--- a/libs/ardour/ardour/jack_utils.h
+++ b/libs/ardour/ardour/jack_utils.h
@@ -216,6 +216,8 @@ namespace ARDOUR {
 		uint32_t         num_periods;
 		uint32_t         period_size;
 		uint32_t         samplerate;
+		uint32_t         input_channels;
+		uint32_t         output_channels;
 		uint32_t         input_latency;
 		uint32_t         output_latency;
 		bool             hardware_metering;
diff --git a/libs/ardour/jack_audiobackend.cc b/libs/ardour/jack_audiobackend.cc
index a95242ba4b..8f3dffa40d 100644
--- a/libs/ardour/jack_audiobackend.cc
+++ b/libs/ardour/jack_audiobackend.cc
@@ -428,6 +428,8 @@ JACKAudioBackend::setup_jack_startup_command ()
 	options.output_device = _target_device;
 	options.input_latency = _target_systemic_input_latency;
 	options.output_latency = _target_systemic_output_latency;
+	options.input_channels = _target_input_channels;
+	options.output_channels = _target_output_channels;
 	if (_target_sample_format == FormatInt16) {
 		options.force16_bit = _target_sample_format;
 	}
diff --git a/libs/ardour/jack_utils.cc b/libs/ardour/jack_utils.cc
index c16270b261..4e2392aced 100644
--- a/libs/ardour/jack_utils.cc
+++ b/libs/ardour/jack_utils.cc
@@ -789,6 +789,16 @@ ARDOUR::get_jack_command_line_string (const JackCommandLineOptions& options, str
 		}
 	}
 
+	if (options.input_channels) {
+		args.push_back ("-i");
+		args.push_back (to_string (options.input_channels, std::dec));
+	}
+
+	if (options.output_channels) {
+		args.push_back ("-o");
+		args.push_back (to_string (options.output_channels, std::dec));
+	}
+
 	if (get_jack_audio_driver_supports_setting_period_count (options.driver)) {
 		args.push_back ("-n");
 		args.push_back (to_string (options.num_periods, std::dec));