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"
25 class DeviceSpecProto;
29 typedef std::function<bool(const uint8_t *data, unsigned num_samples, bmusb::AudioFormat audio_format, int64_t frame_length)> audio_callback_t;
31 ALSAInput(const char *device, unsigned sample_rate, unsigned num_channels, audio_callback_t audio_callback, ALSAPool *parent_pool, unsigned internal_dev_index);
34 // If not called before start_capture_thread(), the capture thread
35 // will call it until it succeeds.
38 // Not valid before the device has been successfully opened.
39 // NOTE: Might very well be different from the sample rate given to the
40 // constructor, since the card might not support the one you wanted.
41 unsigned get_sample_rate() const { return sample_rate; }
43 void start_capture_thread();
44 void stop_capture_thread();
47 void capture_thread_func();
48 int64_t frames_to_pts(uint64_t n) const;
50 enum class CaptureEndReason {
55 CaptureEndReason do_capture();
58 unsigned sample_rate, num_channels, num_periods;
59 snd_pcm_uframes_t period_size;
60 snd_pcm_uframes_t buffer_frames;
61 bmusb::AudioFormat audio_format;
62 audio_callback_t audio_callback;
64 snd_pcm_t *pcm_handle = nullptr;
65 std::thread capture_thread;
66 std::atomic<bool> should_quit{false};
67 std::unique_ptr<uint8_t[]> buffer;
68 ALSAPool *parent_pool;
69 unsigned internal_dev_index;
72 // The class dealing with the collective of all ALSA cards in the system.
73 // In particular, it deals with enumeration of cards, and hotplug of new ones.
80 // There is no card here. (There probably used to be one,
81 // but it got removed.) We don't insert a card before
82 // we've actually probed it, ie., we know whether it
83 // can be captured from at all, and what its name is.
86 // This card is ready for capture, as far as we know.
87 // (It could still be used by someone else; we don't know
88 // until we try to open it.)
91 // We are trying to start capture from this card, but we are not
92 // streaming yet. Note that this could in theory go on forever,
93 // if the card is in use by some other process; in the UI,
94 // we will show this state as “(busy)”.
97 // The card is capturing and sending data. If there's a fatal error,
98 // it could go back to STARTING, or it could go to DEAD
99 // (depending on the error).
102 // The card is gone (e.g., unplugged). However, since there's
103 // still a bus using it, we can't just remove the entry.
104 // If the card comes back (ie., a new card is plugged in,
105 // and we believe it has the same configuration), it could be
106 // installed in place of this card, and then presumably be put
107 // back into STARTING or RUNNING.
109 } state = State::EMPTY;
111 std::string address; // E.g. “hw:0,0”.
112 std::string name, info;
113 unsigned num_channels;
114 ALSAInput *input = nullptr; // nullptr iff EMPTY or DEAD.
116 // Whether the AudioMixer is interested in this card or not.
117 // “Interested” could mean either of two things: Either it is part of
118 // a bus mapping, or it is in the process of enumerating devices
119 // (to show to the user). A card that is _not_ held can disappear
120 // at any given time as a result of an error or hotplug event;
121 // a card that is held will go to the DEAD state instead.
124 std::string display_name() const { return name + " (" + info + ")"; }
129 // Get the list of all current devices. Note that this will implicitly mark
130 // all of the returned devices as held, since the input mapping UI needs
131 // some kind of stability when the user is to choose. Thus, when you are done
132 // with the list and have set a new mapping, you must go through all the devices
133 // you don't want and release them using release_device().
134 std::vector<Device> get_devices();
136 void hold_device(unsigned index);
137 void release_device(unsigned index); // Note: index is allowed to go out of bounds.
139 // If device is held, start or restart capture. If device is not held,
140 // stop capture if it isn't already.
141 void reset_device(unsigned index);
143 // Note: The card must be held. Returns OUTPUT_FREQUENCY if the card is in EMPTY or DEAD.
144 unsigned get_capture_frequency(unsigned index);
146 // Note: The card must be held.
147 Device::State get_card_state(unsigned index);
149 // Only for ALSAInput.
150 void set_card_state(unsigned index, Device::State state);
152 // Just a short form for taking <mu> and then moving the card to
153 // EMPTY or DEAD state. Only for ALSAInput and for internal use.
154 void free_card(unsigned index);
156 // Create a new card, mark it immediately as DEAD and hold it.
157 // Returns the new index.
158 unsigned create_dead_card(const std::string &name, const std::string &info, unsigned num_channels);
160 // Make a protobuf representation of the given card, so that it can be
161 // matched against at a later stage. For AudioMixer only.
162 // The given card must be held.
163 void serialize_device(unsigned index, DeviceSpecProto *serialized);
166 mutable std::mutex mu;
167 std::vector<Device> devices; // Under mu.
168 std::vector<std::unique_ptr<ALSAInput>> inputs; // Under mu, corresponds 1:1 to devices.
170 // Keyed on device address (e.g. “hw:0,0”). If there's an entry here,
171 // it means we already have a thread doing retries, so we shouldn't
173 std::unordered_map<std::string, unsigned> add_device_tries_left; // Under add_device_mutex.
174 std::mutex add_device_mutex;
176 static constexpr int num_retries = 10;
178 void inotify_thread_func();
179 void enumerate_devices();
181 // Try to add an input at the given card/device. If it succeeds, return
182 // synchronously. If not, fire off a background thread to try up to
183 // <num_retries> times.
184 void probe_device_with_retry(unsigned card_index, unsigned dev_index);
185 void probe_device_retry_thread_func(unsigned card_index, unsigned dev_index);
187 enum class ProbeResult {
192 ProbeResult probe_device_once(unsigned card_index, unsigned dev_index);
194 void unplug_device(unsigned card_index, unsigned dev_index);
196 // Must be called with <mu> held. Will allocate a new entry if needed.
197 // The returned entry will be set to READY state.
198 unsigned find_free_device_index(const std::string &name,
199 const std::string &info,
200 unsigned num_channels,
201 const std::string &address);
203 friend class ALSAInput;
206 #endif // !defined(_ALSA_INPUT_H)