media/audio/linux/alsa_input.h

   1 // Copyright (c) 2012 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_LINUX_ALSA_INPUT_H_
   6 #define MEDIA_AUDIO_LINUX_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 AudioManagerLinux;
  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(AudioManagerLinux* audio_manager,
  38                      const std::string& device_name,
  39                      const AudioParameters& params,
  40                      AlsaWrapper* wrapper);
  41
  42   virtual ~AlsaPcmInputStream();
  43
  44   // Implementation of AudioInputStream.
  45   virtual bool Open() OVERRIDE;
  46   virtual void Start(AudioInputCallback* callback) OVERRIDE;
  47   virtual void Stop() OVERRIDE;
  48   virtual void Close() OVERRIDE;
  49   virtual double GetMaxVolume() OVERRIDE;
  50   virtual void SetVolume(double volume) OVERRIDE;
  51   virtual double GetVolume() OVERRIDE;
  52
  53  private:
  54   // Logs the error and invokes any registered callbacks.
  55   void HandleError(const char* method, int error);
  56
  57   // Reads one or more buffers of audio from the device, passes on to the
  58   // registered callback and schedules the next read.
  59   void ReadAudio();
  60
  61   // Recovers from any device errors if possible.
  62   bool Recover(int error);
  63
  64   // Utility function for talking with the ALSA API.
  65   snd_pcm_sframes_t GetCurrentDelay();
  66
  67   // Non-refcounted pointer back to the audio manager.
  68   // The AudioManager indirectly holds on to stream objects, so we don't
  69   // want circular references.  Additionally, stream objects live on the audio
  70   // thread, which is owned by the audio manager and we don't want to addref
  71   // the manager from that thread.
  72   AudioManagerLinux* audio_manager_;
  73   std::string device_name_;
  74   AudioParameters params_;
  75   int bytes_per_buffer_;
  76   AlsaWrapper* wrapper_;
  77   base::TimeDelta buffer_duration_;  // Length of each recorded buffer.
  78   AudioInputCallback* callback_;  // Valid during a recording session.
  79   base::TimeTicks next_read_time_;  // Scheduled time for next read callback.
  80   snd_pcm_t* device_handle_;  // Handle to the ALSA PCM recording device.
  81   snd_mixer_t* mixer_handle_; // Handle to the ALSA microphone mixer.
  82   snd_mixer_elem_t* mixer_element_handle_; // Handle to the capture element.
  83   base::WeakPtrFactory<AlsaPcmInputStream> weak_factory_;
  84   scoped_ptr<uint8[]> audio_buffer_;  // Buffer used for reading audio data.
  85   bool read_callback_behind_schedule_;
  86
  87   DISALLOW_COPY_AND_ASSIGN(AlsaPcmInputStream);
  88 };
  89
  90 }  // namespace media
  91
  92 #endif  // MEDIA_AUDIO_LINUX_ALSA_INPUT_H_