2 #define _ALSA_INPUT_H 1
4 // ALSA sound input, running in a separate thread and sending audio back
7 // Note: “frame” here generally refers to the ALSA definition of frame,
8 // which is a set of samples, exactly one for each channel.
10 #include <alsa/asoundlib.h>
18 #include "bmusb/bmusb.h"
19 #include "quittable_sleeper.h"
25 typedef std::function<bool(const uint8_t *data, unsigned num_samples, bmusb::AudioFormat audio_format, std::chrono::steady_clock::time_point ts)> audio_callback_t;
27 ALSAInput(const char *device, unsigned sample_rate, unsigned num_channels, audio_callback_t audio_callback, ALSAPool *parent_pool, unsigned internal_dev_index);
30 // If not called before start_capture_thread(), the capture thread
31 // will call it until it succeeds.
34 // Not valid before the device has been successfully opened.
35 // NOTE: Might very well be different from the sample rate given to the
36 // constructor, since the card might not support the one you wanted.
37 unsigned get_sample_rate() const { return sample_rate; }
39 void start_capture_thread();
40 void stop_capture_thread();
42 // Set access, sample rate and format parameters on the given ALSA PCM handle.
43 // Returns the computed parameter set and the chosen sample rate. Note that
44 // sample_rate is an in/out parameter; you send in the desired rate,
45 // and ALSA picks one as close to that as possible.
46 static bool set_base_params(const char *device_name, snd_pcm_t *pcm_handle, snd_pcm_hw_params_t *hw_params, unsigned *sample_rate);
49 bool done_init = false;
50 void capture_thread_func();
52 enum class CaptureEndReason {
57 CaptureEndReason do_capture();
60 unsigned sample_rate, num_channels, num_periods;
61 snd_pcm_uframes_t period_size;
62 snd_pcm_uframes_t buffer_frames;
63 bmusb::AudioFormat audio_format;
64 audio_callback_t audio_callback;
66 snd_pcm_t *pcm_handle = nullptr;
67 std::thread capture_thread;
68 QuittableSleeper should_quit;
69 std::unique_ptr<uint8_t[]> buffer;
70 ALSAPool *parent_pool;
71 unsigned internal_dev_index;
74 #endif // !defined(_ALSA_INPUT_H)