implement ALSA period/cycle setting

diff --git a/libs/backends/alsa/alsa_audiobackend.cc b/libs/backends/alsa/alsa_audiobackend.cc
index b0997a6202bbb2524f2db4844d767b1a6a69a5c7..d0236327f3b475f532b7e9c039235b292f49d00f 100644 (file)
--- a/libs/backends/alsa/alsa_audiobackend.cc
+++ b/libs/backends/alsa/alsa_audiobackend.cc
@@ -330,6 +330,15 @@ AlsaAudioBackend::available_output_channel_count (const std::string& device) con
        return 128;
 }
 
+std::vector<uint32_t>
+AlsaAudioBackend::available_period_sizes (const std::string& driver) const
+{
+       std::vector<uint32_t> ps;
+       ps.push_back (2);
+       ps.push_back (3);
+       return ps;
+}
+
 bool
 AlsaAudioBackend::can_change_sample_rate_when_running () const
 {
@@ -422,6 +431,19 @@ AlsaAudioBackend::set_sample_rate (float sr)
        return 0;
 }
 
+int
+AlsaAudioBackend::set_peridod_size (uint32_t n)
+{
+       if (n == 0 || n > 3) {
+               return -1;
+       }
+       if (_run) {
+               return -1;
+       }
+       _periods_per_cycle = n;
+       return 0;
+}
+
 int
 AlsaAudioBackend::set_buffer_size (uint32_t bs)
 {
@@ -526,6 +548,12 @@ AlsaAudioBackend::buffer_size () const
        return _samples_per_period;
 }
 
+uint32_t
+AlsaAudioBackend::period_size () const
+{
+       return _periods_per_cycle;
+}
+
 bool
 AlsaAudioBackend::interleaved () const
 {
@@ -1208,6 +1236,8 @@ AlsaAudioBackend::register_system_audio_ports()
        const int a_ins = _n_inputs;
        const int a_out = _n_outputs;
 
+       // TODO set latency depending on _periods_per_cycle and  _samples_per_period
+
        /* audio ports */
        lr.min = lr.max = (_measure_latency ? 0 : _systemic_audio_input_latency);
        for (int i = 1; i <= a_ins; ++i) {
@@ -1282,7 +1312,7 @@ AlsaAudioBackend::register_system_midi_ports()
                                LatencyRange lr;
                                lr.min = lr.max = (_measure_latency ? 0 : nfo->systemic_output_latency);
                                set_latency_range (p, false, lr);
-                               static_cast<AlsaMidiPort*>(p)->set_n_periods(2);
+                               static_cast<AlsaMidiPort*>(p)->set_n_periods(_periods_per_cycle); // TODO check MIDI alignment
                                _system_midi_out.push_back(static_cast<AlsaPort*>(p));
                                _rmidi_out.push_back (mout);
                        }

diff --git a/libs/backends/alsa/alsa_audiobackend.h b/libs/backends/alsa/alsa_audiobackend.h
index c95593c349b75638daa07fe2ea76c581a32ec5da..1dca7ec14989f0a410d574ffdf8a41d61dcb5781 100644 (file)
--- a/libs/backends/alsa/alsa_audiobackend.h
+++ b/libs/backends/alsa/alsa_audiobackend.h
@@ -148,10 +148,10 @@ class AlsaMidiPort : public AlsaPort {
                const AlsaMidiBuffer * const_buffer () const { return & _buffer[_bufperiod]; }
 
                void next_period() { if (_n_periods > 1) { get_buffer(0); _bufperiod = (_bufperiod + 1) % _n_periods; } }
-               void set_n_periods(int n) { if (n > 0 && n < 3) { _n_periods = n; } }
+               void set_n_periods(int n) { if (n > 0 && n < 4) { _n_periods = n; } }
 
        private:
-               AlsaMidiBuffer _buffer[2];
+               AlsaMidiBuffer _buffer[3];
                int _n_periods;
                int _bufperiod;
 }; // class AlsaMidiPort
@@ -168,6 +168,8 @@ class AlsaAudioBackend : public AudioBackend {
                bool is_realtime () const;
 
                bool use_separate_input_and_output_devices () const { return true; }
+               bool can_set_period_size () const { return true; }
+
                std::vector<DeviceStatus> enumerate_devices () const;
                std::vector<DeviceStatus> enumerate_input_devices () const;
                std::vector<DeviceStatus> enumerate_output_devices () const;
@@ -175,6 +177,7 @@ class AlsaAudioBackend : public AudioBackend {
                std::vector<float> available_sample_rates2 (const std::string&, const std::string&) const;
                std::vector<uint32_t> available_buffer_sizes (const std::string& device) const;
                std::vector<uint32_t> available_buffer_sizes2 (const std::string&, const std::string&) const;
+               std::vector<uint32_t> available_period_sizes (const std::string& driver) const;
                uint32_t available_input_channel_count (const std::string& device) const;
                uint32_t available_output_channel_count (const std::string& device) const;
 
@@ -186,6 +189,7 @@ class AlsaAudioBackend : public AudioBackend {
                int set_output_device_name (const std::string&);
                int set_sample_rate (float);
                int set_buffer_size (uint32_t);
+               int set_peridod_size (uint32_t);
                int set_interleaved (bool yn);
                int set_input_channels (uint32_t);
                int set_output_channels (uint32_t);
@@ -202,6 +206,7 @@ class AlsaAudioBackend : public AudioBackend {
                std::string  output_device_name () const;
                float        sample_rate () const;
                uint32_t     buffer_size () const;
+               uint32_t     period_size () const;
                bool         interleaved () const;
                uint32_t     input_channels () const;
                uint32_t     output_channels () const;