Merge pull request #246 from Holzhaus/google-stt-engine-fixes

Improve Google STT engine.

1 files changed, 86 insertions, 29 deletions

diff --git a/client/stt.py b/client/stt.py
index bdf9d4e..aeaae0b 100644
--- a/client/stt.py
+++ b/client/stt.py
@@ -1,11 +1,12 @@
 #!/usr/bin/env python2
 # -*- coding: utf-8-*-
 import os
-import traceback
 import wave
 import json
 import tempfile
 import logging
+import urllib
+import urlparse
 from abc import ABCMeta, abstractmethod
 import requests
 import yaml
@@ -180,16 +181,55 @@ class GoogleSTT(AbstractSTTEngine):
 
     SLUG = 'google'
 
-    def __init__(self, api_key=None):
+    def __init__(self, api_key=None, language='en-us'):
         # FIXME: get init args from config
         """
         Arguments:
         api_key - the public api key which allows access to Google APIs
         """
-        if not api_key:
-            raise ValueError("No Google API Key given")
+        self._logger = logging.getLogger(__name__)
+        self._request_url = None
+        self._language = None
+        self._api_key = None
+        self._http = requests.Session()
+        self.language = language
         self.api_key = api_key
-        self.http = requests.Session()
+
+    @property
+    def request_url(self):
+        return self._request_url
+
+    @property
+    def language(self):
+        return self._language
+
+    @language.setter
+    def language(self, value):
+        self._language = value
+        self._regenerate_request_url()
+
+    @property
+    def api_key(self):
+        return self._api_key
+
+    @api_key.setter
+    def api_key(self, value):
+        self._api_key = value
+        self._regenerate_request_url()
+
+    def _regenerate_request_url(self):
+        if self.api_key and self.language:
+            query = urllib.urlencode({'output': 'json',
+                                      'client': 'chromium',
+                                      'key': self.api_key,
+                                      'lang': self.language,
+                                      'maxresults': 6,
+                                      'pfilter': 2})
+            self._request_url = urlparse.urlunparse(
+                ('https', 'www.google.com', '/speech-api/v2/recognize', '',
+                 query, ''))
+        else:
+            self._request_url = None
 
     @classmethod
     def get_config(cls):
@@ -214,36 +254,53 @@ class GoogleSTT(AbstractSTTEngine):
         audio_file_path -- the path to the .wav file to be transcribed
         """
 
+        if not self.api_key:
+            self._logger.critical('API key missing, transcription request ' +
+                                  'aborted.')
+            return []
+        elif not self.language:
+            self._logger.critical('Language info missing, transcription ' +
+                                  'request aborted.')
+            return []
+
         wav = wave.open(fp, 'rb')
         frame_rate = wav.getframerate()
         wav.close()
-
-        url = (("https://www.google.com/speech-api/v2/recognize?output=json" +
-                "&client=chromium&key=%s&lang=%s&maxresults=6&pfilter=2") %
-               (self.api_key, "en-us"))
-
         data = fp.read()
 
+        headers = {'content-type': 'audio/l16; rate=%s' % frame_rate}
+        r = self._http.post(self.request_url, data=data, headers=headers)
         try:
-            headers = {'Content-type': 'audio/l16; rate=%s' % frame_rate}
-            response = self.http.post(url, data=data, headers=headers)
-            response.encoding = 'utf-8'
-            response_read = response.text
-
-            response_parts = response_read.strip().split("\n")
-            decoded = json.loads(response_parts[-1])
-            if decoded['result']:
-                texts = [alt['transcript'] for alt in
-                         decoded['result'][0]['alternative']]
-                if texts:
-                    print "==================="
-                    print "JASPER: " + ', '.join(texts)
-                    print "==================="
-                return texts
-            else:
-                return []
-        except Exception:
-            traceback.print_exc()
+            r.raise_for_status()
+        except requests.exceptions.HTTPError:
+            self._logger.critical('Request failed with http status %d',
+                                  r.status_code)
+            if r.status_code == requests.codes['forbidden']:
+                self._logger.warning('Status 403 is probably caused by an ' +
+                                     'invalid Google API key.')
+            return []
+        r.encoding = 'utf-8'
+        try:
+            # We cannot simply use r.json() because Google sends invalid json
+            # (i.e. multiple json objects, seperated by newlines. We only want
+            # the last one).
+            response = json.loads(list(r.text.strip().split('\n', 1))[-1])
+            if len(response['result']) == 0:
+                # Response result is empty
+                raise ValueError('Nothing has been transcribed.')
+            results = [alt['transcript'] for alt
+                       in response['result'][0]['alternative']]
+        except ValueError as e:
+            self._logger.warning('Empty response: %s', e.args[0])
+            results = []
+        except (KeyError, IndexError):
+            self._logger.warning('Cannot parse response.', exc_info=True)
+            results = []
+        else:
+            # Convert all results to uppercase
+            results = tuple(result.upper() for result in results)
+            self._logger.info('Transcribed: %r', results)
+        return results
 
     @classmethod
     def is_available(cls):