better backend selection and additional documentation

Author: RetiredWizard

Fruit_Jam/Fruit_Jam_Spell_Jam/code.py

@@ -1,5 +1,7 @@
 # SPDX-FileCopyrightText: 2025 Tim Cocks for Adafruit Industries
 # SPDX-License-Identifier: MIT
+
+import os
 import sys
 import time
 import supervisor
@@ -12,12 +14,12 @@
 
 from launcher_config import LauncherConfig
 
-# If tts_local.py exists, use that instead of tts_aws.py
-try:
+# choose AWS TTS engine if AWS credentials are set in environment variables
+if os.getenv("AWS_ACCESS_KEY") is not None and os.getenv("AWS_SECRET_KEY") is not None:
+    from tts_aws import WordFetcherTTS
+else:
     # tts_local defines WordFetcherTTS for TTS engine running on local network server
     from tts_local import WordFetcherTTS
-except ImportError:
-    from tts_aws import WordFetcherTTS
 
 # read the user settings
 launcher_config = LauncherConfig()

Fruit_Jam/Fruit_Jam_Spell_Jam/tts_local.py

@@ -1,6 +1,33 @@
 # SPDX-FileCopyrightText: 2025 RetiredWizard
 # SPDX-License-Identifier: MIT
 
+"""
+    Kani TTS engine for Fruit Jam Spell Jam. Install and run the kani-tts AI server on your
+    local network following the instructions at: https://github.com/nineninesix-ai/kani-tts
+
+    The server.py script from the kani-tts repo needs to be modified to create 16bit WAV files
+    instead of the default 32bit WAV files. Change the following lines in server.py
+
+        # Convert to WAV bytes
+        wav_buffer = io.BytesIO()
+        wav_write(wav_buffer, 22050, full_audio)
+        wav_buffer.seek(0)
+    to:
+        # Convert float32 audio (-1.0 to 1.0) to 16-bit PCM
+        audio_int16 = np.clip(full_audio, -1.0, 1.0)
+        audio_int16 = (audio_int16 * 32767).astype(np.int16)
+
+        # Write as 16-bit WAV
+        wav_buffer = io.BytesIO()
+        wav_write(wav_buffer, 22050, audio_int16)
+        wav_buffer.seek(0)
+
+    Then configure the server endpoint in launcher.conf.json, e.g.:
+    "spell_jam": {
+        "tts_server_endpoint": "http://myserver.local:8000"
+    }
+"""
+
 # tts_kani.py
 import json
 import adafruit_connection_manager