Restore changes from the voicekit branch

Summary of changes:
- Fix instructions for using the Voice Kit on Stretch (#187)
- Make it easier to turn the LED off (#167)
- Fix crash with trigger sound (#163)
- Let user code control TTS (#185)
- Enable hotwording with Cloud Speech (0b4972b)

HACKING.md

@@ -31,10 +31,21 @@ on Raspbian 2017-07-05 and later. You'll also need to configure ALSA:
 
 ``` shell
 sudo scripts/configure-driver.sh
+sudo reboot
+```
+
+After your Pi has rebooted with the driver enabled, run:
+
+```
+cd ~/AIY-projects-python
 sudo scripts/install-alsa-config.sh
+python3 checkpoints/check_audio.py
 sudo reboot
 ```
 
+Don't skip running `check_audio.py` before rebooting, as it has an important
+effect on the state of ALSA, the sound architecture.
+
 ## Get cloud credentials
 
 To access the cloud services you need to register a project and generate

src/aiy/_drivers/_led.py

@@ -90,7 +90,7 @@ def _animate(self):
                 running = self.running
             if not running:
                 return
-            if state:
+            if state is not None:
                 if not self._parse_state(state):
                     raise ValueError('unsupported state: %d' % state)
             if self.iterator:

src/aiy/_drivers/_status_ui.py

@@ -53,6 +53,7 @@ def set_trigger_sound_wave(self, trigger_sound_wave):
         """
         if not trigger_sound_wave:
             self._trigger_sound_wave = None
+            return
         expanded_path = os.path.expanduser(trigger_sound_wave)
         if os.path.exists(expanded_path):
             self._trigger_sound_wave = expanded_path

src/aiy/_drivers/_tts.py

@@ -33,21 +33,24 @@ def create_say(player):
     return functools.partial(say, player, lang=lang)
 
 
-def say(player, words, lang='en-US'):
+def say(player, words, lang='en-US', volume=60, pitch=130):
     """Say the given words with TTS.
 
     Args:
       player: To play the text-to-speech audio.
       words: string to say aloud.
       lang: language for the text-to-speech engine.
+      volume: volume for the text-to-speech engine.
+      pitch: pitch for the text-to-speech engine.
     """
     try:
         (fd, tts_wav) = tempfile.mkstemp(suffix='.wav', dir=TMP_DIR)
     except IOError:
         logger.exception('Using fallback directory for TTS output')
         (fd, tts_wav) = tempfile.mkstemp(suffix='.wav')
     os.close(fd)
-    words = '<volume level="60"><pitch level="130">%s</pitch></volume>' % words
+    words = '<volume level="' + str(volume) + '"><pitch level="' + str(pitch) + \
+            '">' + words + '</pitch></volume>'
     try:
         subprocess.call(['pico2wave', '--lang', lang, '-w', tts_wav, words])
         player.play_wav(tts_wav)

src/aiy/audio.py

@@ -28,6 +28,8 @@
 _voicehat_recorder = None
 _voicehat_player = None
 _status_ui = None
+_tts_volume = 60
+_tts_pitch = 130
 
 
 class _WaveDump(object):
@@ -108,15 +110,24 @@ def play_audio(audio_data):
     player.play_bytes(audio_data, sample_width=AUDIO_SAMPLE_SIZE, sample_rate=AUDIO_SAMPLE_RATE_HZ)
 
 
-def say(words, lang=None):
+def say(words, lang=None, volume=None, pitch=None):
     """Says the given words in the given language with Google TTS engine.
 
-    If lang is specified, e.g. "en-US', it will be used to say the given words.
+    If lang is specified, e.g. "en-US", it will be used to say the given words.
     Otherwise, the language from aiy.i18n will be used.
+    volume (optional) volume used to say the given words.
+    pitch (optional) pitch to say the given words.
+    Example: aiy.audio.say('This is an example', lang="en-US", volume=75, pitch=135)
+    Any of the optional variables can be left out.
     """
+
     if not lang:
         lang = aiy.i18n.get_language_code()
-    aiy._drivers._tts.say(aiy.audio.get_player(), words, lang=lang)
+    if not volume:
+        volume = aiy.audio.get_tts_volume()
+    if not pitch:
+        pitch = aiy.audio.get_tts_pitch()
+    aiy._drivers._tts.say(aiy.audio.get_player(), words, lang=lang, volume=volume, pitch=pitch)
 
 
 def get_status_ui():
@@ -129,3 +140,23 @@ def get_status_ui():
     if not _status_ui:
         _status_ui = aiy._drivers._StatusUi()
     return _status_ui
+
+
+def set_tts_volume(volume):
+    global _tts_volume
+    _tts_volume = volume
+
+
+def get_tts_volume():
+    global _tts_volume
+    return _tts_volume
+
+
+def set_tts_pitch(pitch):
+    global _tts_pitch
+    _tts_pitch = pitch
+
+
+def get_tts_pitch():
+    global _tts_pitch
+    return _tts_pitch

src/aiy/cloudspeech.py

@@ -34,17 +34,51 @@ class _CloudSpeechRecognizer(object):
     def __init__(self, credentials_file):
         self._request = aiy._apis._speech.CloudSpeechRequest(credentials_file)
         self._recorder = aiy.audio.get_recorder()
+        self._hotwords = []
 
     def recognize(self):
         """Recognizes the user's speech and transcript it into text.
 
         This function listens to the user's speech via the VoiceHat speaker. Then it
         contacts Google CloudSpeech APIs and returns a textual transcript if possible.
+        If hotword list is populated this method will only respond if hotword is said.
         """
         self._request.reset()
         self._request.set_endpointer_cb(self._endpointer_callback)
         self._recorder.add_processor(self._request)
-        return self._request.do_request().transcript
+        text = self._request.do_request().transcript
+        if self._hotwords and text:
+            text = text.lower()
+            loc_min = len(text)
+            hotword_found = ''
+            for hotword in self._hotwords:
+                loc_temp = text.find(hotword)
+                if loc_temp > -1 and loc_min > loc_temp:
+                    loc_min = loc_temp
+                    hotword_found = hotword
+            if hotword_found:
+                parse_text = text.split(hotword_found)[1]
+                return parse_text.strip()
+            else:
+                return ''
+        else:
+            return '' if self._hotwords else text
+
+    def expect_hotword(self, hotword_list):
+        """Enables hotword detection for a selected list
+        This method is optional and populates the list of hotwords
+        to be used for hotword activation.
+
+        For example, to create a recognizer for Google:
+
+        recognizer.expect_hotword('Google')
+        recognizer.expect_hotword(['Google','Raspberry Pi'])
+        """
+        if isinstance(hotword_list, list):
+            for hotword in hotword_list:
+                self._hotwords.append(hotword.lower())
+        else:
+            self._hotwords.append(hotword_list.lower())
 
     def expect_phrase(self, phrase):
         """Explicitly tells the engine that the phrase is more likely to appear.