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. The only exception
9 // is in frame_length, where it means the TIMEBASE length of the buffer
10 // as a whole, since that's what AudioMixer::add_audio() wants.
12 #include <alsa/asoundlib.h>
20 #include "bmusb/bmusb.h"
25 typedef std::function<bool(const uint8_t *data, unsigned num_samples, bmusb::AudioFormat audio_format, int64_t frame_length)> audio_callback_t;
27 ALSAInput(const char *device, unsigned sample_rate, unsigned num_channels, audio_callback_t audio_callback);
30 // NOTE: Might very well be different from the sample rate given to the
31 // constructor, since the card might not support the one you wanted.
32 unsigned get_sample_rate() const { return sample_rate; }
34 void start_capture_thread();
35 void stop_capture_thread();
38 void capture_thread_func();
39 int64_t frames_to_pts(uint64_t n) const;
40 void die_on_error(const char *func_name, int err);
43 unsigned sample_rate, num_channels, num_periods;
44 snd_pcm_uframes_t period_size;
45 snd_pcm_uframes_t buffer_frames;
46 bmusb::AudioFormat audio_format;
47 audio_callback_t audio_callback;
49 snd_pcm_t *pcm_handle;
50 std::thread capture_thread;
51 std::atomic<bool> should_quit{false};
52 std::unique_ptr<uint8_t[]> buffer;
55 // The class dealing with the collective of all ALSA cards in the system.
56 // In particular, it deals with enumeration of cards, and hotplug of new ones.
63 // There is no card here. (There probably used to be one,
64 // but it got removed.) We don't insert a card before
65 // we've actually probed it, ie., we know whether it
66 // can be captured from at all, and what its name is.
69 // This card is ready for capture, as far as we know.
70 // (It could still be used by someone else; we don't know
71 // until we try to open it.)
74 // We are trying to start capture from this card, but we are not
75 // streaming yet. Note that this could in theory go on forever,
76 // if the card is in use by some other process; in the UI,
77 // we will show this state as “(busy)”.
80 // The card is capturing and sending data. If there's a fatal error,
81 // it could go back to STARTING, or it could go to DEAD
82 // (depending on the error).
85 // The card is gone (e.g., unplugged). However, since there's
86 // still a bus using it, we can't just remove the entry.
87 // If the card comes back (ie., a new card is plugged in,
88 // and we believe it has the same configuration), it could be
89 // installed in place of this card, and then presumably be put
90 // back into STARTING or RUNNING.
94 std::string address; // E.g. “hw:0,0”.
95 std::string name, info;
96 unsigned num_channels;
97 ALSAInput *input = nullptr; // nullptr iff EMPTY or DEAD.
99 // Whether the AudioMixer is interested in this card or not.
100 // “Interested” could mean either of two things: Either it is part of
101 // a bus mapping, or it is in the process of enumerating devices
102 // (to show to the user). A card that is _not_ held can disappear
103 // at any given time as a result of an error or hotplug event;
104 // a card that is held will go to the DEAD state instead.
110 // Get the list of all current devices. Note that this will implicitly mark
111 // all of the returned devices as held, since the input mapping UI needs
112 // some kind of stability when the user is to choose. Thus, when you are done
113 // with the list and have set a new mapping, you must go through all the devices
114 // you don't want and release them using release_device().
115 std::vector<Device> get_devices();
117 void hold_device(unsigned index);
118 void release_device(unsigned index); // Note: index is allowed to go out of bounds.
120 // If device is held, start or restart capture. If device is not held,
121 // stop capture if it isn't already.
122 void reset_device(unsigned index);
124 // Note: The card must be held. Returns OUTPUT_FREQUENCY if the card is in EMPTY or DEAD.
125 unsigned get_capture_frequency(unsigned index);
127 // TODO: Add accessors and/or callbacks about changed state, so that
128 // the UI actually stands a chance in using that information.
131 mutable std::mutex mu;
132 std::vector<Device> devices; // Under mu.
133 std::vector<std::unique_ptr<ALSAInput>> inputs; // Under mu, corresponds 1:1 to devices.
135 void enumerate_devices();
136 bool add_device(unsigned card_index, unsigned dev_index);
139 #endif // !defined(_ALSA_INPUT_H)