Extract and convert audio using ffmpeg or avconv

src/python/rpitx/_hidden.py

@@ -1,42 +1,57 @@
 """Hides imports and other irrelevant things so that ipython works nicely."""
 
-from pydub import AudioSegment
 import _rpitx
-import io
-import array
+import ffmpegwrapper
+import libavwrapper
 import logging
-import wave
+import os
+import subprocess
+import threading
 
 
-def broadcast_fm(file_, frequency):
-    """Play a music file over FM."""
+def broadcast_fm(media_file_name, frequency):
+    """Play a media file's audio over FM."""
 
     logging.basicConfig()
     logger = logging.getLogger('rpitx')
 
-    def _reencode(file_name):
-        """Returns an AudioSegment file reencoded to the proper WAV format."""
-        original = AudioSegment.from_file(file_name)
-        if original.channels > 2:
-            raise ValueError('Too many channels in sound file')
-        if original.channels == 2:
-            # TODO: Support stereo. For now, just overlay into mono.
-            logger.info('Reducing stereo channels to mono')
-            left, right = original.split_to_mono()
-            original = left.overlay(right)
+    if subprocess.call(('which', 'ffmpeg')) == 1:
+        Input = ffmpegwrapper.Input
+        Output = ffmpegwrapper.Output
+        VideoCodec = ffmpegwrapper.VideoCodec
+        AudioCoded = ffmpegwrapper.AudioCodec
+        Stream = ffmpegwrapper.FFmpeg
+        command = 'ffmpeg'
+    elif subprocess.call(('which', 'avconv')) == 1:
+        Input = libavwrapper.Input
+        Output = libavwrapper.Output
+        VideoCodec = libavwrapper.VideoCodec
+        AudioCoded = libavwrapper.AudioCodec
+        Stream = libavwrapper.AVConv
+        command = 'avconv'
+    else:
+        raise NotImplementedError(
+            'Broadcasting audio requires either avconv or ffmpeg to be installed'
+        )
 
-        return original
+    logger.debug('Using {}'.format(command))
 
-    raw_audio_data = _reencode(file_)
+    pipe_name = '/tmp/rpitx-fifo.wav'
+    if not os.path.exists(pipe_name):
+        os.mkfifo(pipe_name)
 
-    wav_data = io.BytesIO()
-    wav_writer = wave.open(wav_data, 'w')
-    wav_writer.setnchannels(1)
-    wav_writer.setsampwidth(2)
-    wav_writer.setframerate(48000)
-    wav_writer.writeframes(raw_audio_data.raw_data)
-    wav_writer.close()
+    def convert():
+        """Runs the conversion command and writes to a FIFO."""
+        input_media = Input(media_file_name)
+        codec = AudioCodec('pcm_s16le').frequence(48000).channels(1)
+        output_audio = Output(pipe_name, pipe_out)
+        stream = Stream(command, input_media, output_audio)
+        stream.add_option('-y', '')  # Force overwriting existing file
+        logger.debug('Extracting and converting audio')
+        stream.run()
 
-    raw_array = array.array('b', wav_data.getvalue())
-    array_address, length = raw_array.buffer_info()
-    _rpitx.broadcast_fm(array_address, length, frequency)
+    thread = threading.Thread(target=convert)
+    thread.start()
+    logger.debug('Calling broadcast_fm')
+    _rpitx.broadcast_fm(pipe_name, frequency)
+    thread.join()