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>
18 #include <unordered_map>
21 #include "bmusb/bmusb.h"
28 typedef std::function<bool(const uint8_t *data, unsigned num_samples, bmusb::AudioFormat audio_format, int64_t frame_length)> audio_callback_t;
30 ALSAInput(const char *device, unsigned sample_rate, unsigned num_channels, audio_callback_t audio_callback, ALSAPool *parent_pool, unsigned internal_dev_index);
33 // If not called before start_capture_thread(), the capture thread
34 // will call it until it succeeds.
37 // Not valid before the device has been successfully opened.
38 // NOTE: Might very well be different from the sample rate given to the
39 // constructor, since the card might not support the one you wanted.
40 unsigned get_sample_rate() const { return sample_rate; }
42 void start_capture_thread();
43 void stop_capture_thread();
46 void capture_thread_func();
47 int64_t frames_to_pts(uint64_t n) const;
49 enum class CaptureEndReason {
54 CaptureEndReason do_capture();
57 unsigned sample_rate, num_channels, num_periods;
58 snd_pcm_uframes_t period_size;
59 snd_pcm_uframes_t buffer_frames;
60 bmusb::AudioFormat audio_format;
61 audio_callback_t audio_callback;
63 snd_pcm_t *pcm_handle = nullptr;
64 std::thread capture_thread;
65 std::atomic<bool> should_quit{false};
66 std::unique_ptr<uint8_t[]> buffer;
67 ALSAPool *parent_pool;
68 unsigned internal_dev_index;
71 // The class dealing with the collective of all ALSA cards in the system.
72 // In particular, it deals with enumeration of cards, and hotplug of new ones.
79 // There is no card here. (There probably used to be one,
80 // but it got removed.) We don't insert a card before
81 // we've actually probed it, ie., we know whether it
82 // can be captured from at all, and what its name is.
85 // This card is ready for capture, as far as we know.
86 // (It could still be used by someone else; we don't know
87 // until we try to open it.)
90 // We are trying to start capture from this card, but we are not
91 // streaming yet. Note that this could in theory go on forever,
92 // if the card is in use by some other process; in the UI,
93 // we will show this state as “(busy)”.
96 // The card is capturing and sending data. If there's a fatal error,
97 // it could go back to STARTING, or it could go to DEAD
98 // (depending on the error).
101 // The card is gone (e.g., unplugged). However, since there's
102 // still a bus using it, we can't just remove the entry.
103 // If the card comes back (ie., a new card is plugged in,
104 // and we believe it has the same configuration), it could be
105 // installed in place of this card, and then presumably be put
106 // back into STARTING or RUNNING.
108 } state = State::EMPTY;
110 std::string address; // E.g. “hw:0,0”.
111 std::string name, info;
112 unsigned num_channels;
113 ALSAInput *input = nullptr; // nullptr iff EMPTY or DEAD.
115 // Whether the AudioMixer is interested in this card or not.
116 // “Interested” could mean either of two things: Either it is part of
117 // a bus mapping, or it is in the process of enumerating devices
118 // (to show to the user). A card that is _not_ held can disappear
119 // at any given time as a result of an error or hotplug event;
120 // a card that is held will go to the DEAD state instead.
126 // Get the list of all current devices. Note that this will implicitly mark
127 // all of the returned devices as held, since the input mapping UI needs
128 // some kind of stability when the user is to choose. Thus, when you are done
129 // with the list and have set a new mapping, you must go through all the devices
130 // you don't want and release them using release_device().
131 std::vector<Device> get_devices();
133 void hold_device(unsigned index);
134 void release_device(unsigned index); // Note: index is allowed to go out of bounds.
136 // If device is held, start or restart capture. If device is not held,
137 // stop capture if it isn't already.
138 void reset_device(unsigned index);
140 // Note: The card must be held. Returns OUTPUT_FREQUENCY if the card is in EMPTY or DEAD.
141 unsigned get_capture_frequency(unsigned index);
143 // Note: The card must be held.
144 Device::State get_card_state(unsigned index);
146 // Only for ALSAInput.
147 void set_card_state(unsigned index, Device::State state);
149 // Just a short form for taking <mu> and then moving the card to
150 // EMPTY or DEAD state. Only for ALSAInput and for internal use.
151 void free_card(unsigned index);
153 // TODO: Add accessors and/or callbacks about changed state, so that
154 // the UI actually stands a chance in using that information.
157 mutable std::mutex mu;
158 std::vector<Device> devices; // Under mu.
159 std::vector<std::unique_ptr<ALSAInput>> inputs; // Under mu, corresponds 1:1 to devices.
161 // Keyed on device address (e.g. “hw:0,0”). If there's an entry here,
162 // it means we already have a thread doing retries, so we shouldn't
164 std::unordered_map<std::string, unsigned> add_device_tries_left; // Under add_device_mutex.
165 std::mutex add_device_mutex;
167 static constexpr int num_retries = 10;
169 void inotify_thread_func();
170 void enumerate_devices();
172 // Try to add an input at the given card/device. If it succeeds, return
173 // synchronously. If not, fire off a background thread to try up to
174 // <num_retries> times.
175 void probe_device_with_retry(unsigned card_index, unsigned dev_index);
176 void probe_device_retry_thread_func(unsigned card_index, unsigned dev_index);
178 enum class ProbeResult {
183 ProbeResult probe_device_once(unsigned card_index, unsigned dev_index);
185 void unplug_device(unsigned card_index, unsigned dev_index);
187 // Must be called with <mu> held. Will allocate a new entry if needed.
188 // The returned entry will be set to READY state.
189 unsigned find_free_device_index(const std::string &name,
190 const std::string &info,
191 unsigned num_channels,
192 const std::string &address);
194 friend class ALSAInput;
197 #endif // !defined(_ALSA_INPUT_H)