media/audio/alsa/alsa_input.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef MEDIA_AUDIO_ALSA_ALSA_INPUT_H_
   6 #define MEDIA_AUDIO_ALSA_ALSA_INPUT_H_
   7
   8 #include <alsa/asoundlib.h>
   9
  10 #include <string>
  11
  12 #include "base/compiler_specific.h"
  13 #include "base/memory/scoped_ptr.h"
  14 #include "base/memory/weak_ptr.h"
  15 #include "base/time/time.h"
  16 #include "media/audio/agc_audio_stream.h"
  17 #include "media/audio/audio_io.h"
  18 #include "media/audio/audio_parameters.h"
  19
  20 namespace media {
  21
  22 class AlsaWrapper;
  23 class AudioManagerBase;
  24
  25 // Provides an input stream for audio capture based on the ALSA PCM interface.
  26 // This object is not thread safe and all methods should be invoked in the
  27 // thread that created the object.
  28 class AlsaPcmInputStream : public AgcAudioStream<AudioInputStream> {
  29  public:
  30   // Pass this to the constructor if you want to attempt auto-selection
  31   // of the audio recording device.
  32   static const char kAutoSelectDevice[];
  33
  34   // Create a PCM Output stream for the ALSA device identified by
  35   // |device_name|. If unsure of what to use for |device_name|, use
  36   // |kAutoSelectDevice|.
  37   AlsaPcmInputStream(AudioManagerBase* audio_manager,
  38                      const std::string& device_name,
  39                      const AudioParameters& params,
  40                      AlsaWrapper* wrapper);
  41
  42   ~AlsaPcmInputStream() override;
  43
  44   // Implementation of AudioInputStream.
  45   bool Open() override;
  46   void Start(AudioInputCallback* callback) override;
  47   void Stop() override;
  48   void Close() override;
  49   double GetMaxVolume() override;
  50   void SetVolume(double volume) override;
  51   double GetVolume() override;
  52   bool IsMuted() override;
  53
  54  private:
  55   // Logs the error and invokes any registered callbacks.
  56   void HandleError(const char* method, int error);
  57
  58   // Reads one or more buffers of audio from the device, passes on to the
  59   // registered callback and schedules the next read.
  60   void ReadAudio();
  61
  62   // Recovers from any device errors if possible.
  63   bool Recover(int error);
  64
  65   // Utility function for talking with the ALSA API.
  66   snd_pcm_sframes_t GetCurrentDelay();
  67
  68   // Non-refcounted pointer back to the audio manager.
  69   // The AudioManager indirectly holds on to stream objects, so we don't
  70   // want circular references.  Additionally, stream objects live on the audio
  71   // thread, which is owned by the audio manager and we don't want to addref
  72   // the manager from that thread.
  73   AudioManagerBase* audio_manager_;
  74   std::string device_name_;
  75   AudioParameters params_;
  76   int bytes_per_buffer_;
  77   AlsaWrapper* wrapper_;
  78   base::TimeDelta buffer_duration_;  // Length of each recorded buffer.
  79   AudioInputCallback* callback_;  // Valid during a recording session.
  80   base::TimeTicks next_read_time_;  // Scheduled time for next read callback.
  81   snd_pcm_t* device_handle_;  // Handle to the ALSA PCM recording device.
  82   snd_mixer_t* mixer_handle_; // Handle to the ALSA microphone mixer.
  83   snd_mixer_elem_t* mixer_element_handle_; // Handle to the capture element.
  84   scoped_ptr<uint8[]> audio_buffer_;  // Buffer used for reading audio data.
  85   bool read_callback_behind_schedule_;
  86   scoped_ptr<AudioBus> audio_bus_;
  87
  88   // NOTE: Weak pointers must be invalidated before all other member variables.
  89   base::WeakPtrFactory<AlsaPcmInputStream> weak_factory_;
  90
  91   DISALLOW_COPY_AND_ASSIGN(AlsaPcmInputStream);
  92 };
  93
  94 }  // namespace media
  95
  96 #endif  // MEDIA_AUDIO_ALSA_ALSA_INPUT_H_