1 files changed, 154 insertions, 0 deletions
diff --git a/audio.py b/audio.py
new file mode 100755
index 0000000..37b0f7d
--- /dev/null
+++ b/audio.py
@@ -0,0 +1,154 @@
+#!/usr/bin/env python3
+
+"""Audio module for BLC.
+
+This module defines an AudioPlayer interface which allows for various audio backends to be used 
+interchangeably. It also defines a bare-bones better-than-nothing "FFPlayer" implementation and 
+a better "MPVPlayer" implementation.
+
+"DefaultAudioPlayer" should be used in general and will refer to MPVPlayer if available and 
+FFPlayer otherwise.
+"""
+
+import atexit
+import subprocess as subp
+import time
+import warnings
+
+from abc import ABC, abstractmethod, abstractproperty
+
+def ttoti(t):
+    """Convert seconds to milliseconds."""
+    return int(1000*t + 0.5)
+
+def titot(ti):
+    """Convert milliseconds to seconds."""
+    return ti/1000
+
+class AudioPlayer(ABC):
+    """Class for playing audio.
+    
+    All time indices must be integers in milliseconds.
+    """
+    @abstractmethod
+    def play(self, start=-1):
+        """Play the audio from the given time.
+        
+        If start is -1, play it from the current time index (e.g. if paused). If the player is 
+        already playing, throw an error.
+        """
+        return
+
+    @abstractmethod
+    def seek(self, t):
+        """Seek to the given time index."""
+        return
+
+    @abstractmethod
+    def pause(self):
+        """Pause the player."""
+        return
+
+    @abstractmethod
+    def stop(self):
+        """Stop the player and reset to the first time index."""
+        return
+
+    @abstractproperty
+    def volume(self):
+        """Get or set the current volume."""
+        return 
+
+    @abstractproperty
+    def position(self) -> int:
+        """The current position in milliseconds."""
+        return
+
+    @abstractproperty
+    def playing(self) -> bool:
+        """Return if the player is playing or not."""
+        return
+
+    def __init__(self, fname, args=()):
+        self.fname = fname
+        self.args = args
+
+class FFPlayer(AudioPlayer):
+    """Audio player using ffplay.
+    
+    Note that this is incredibly bad: the current position is guessed based on the start time of
+    the subprocess (meaning startup time of the ffplay process is counted in the current 
+    position), no preloading of files is done, seeking is inaccurate and requires killing and 
+    restarting the ffplay process, volume is ignored, and more. This is due to the fact that you 
+    can't provide input to ffplay because it uses SDL exclusively for input (even though it can 
+    be run without SDL?) so any change requires restarting the process. Use MPVPlayer if
+    possible.
+    """
+    def play(self, start=-1):
+        if self.playing:
+            raise ValueError("Already playing")
+
+        if start != -1:
+            self.start = titot(start)
+        self.player = subp.Popen(["ffplay", "-nodisp", "-autoexit", "-ss", str(self.start), *self.args, self.fname],
+                                 stdin=subp.DEVNULL, stdout=subp.DEVNULL, stderr=subp.DEVNULL)
+        atexit.register(self.stop)
+        self.start_time = time.monotonic()
+
+    def stop(self):
+        if not self.playing:
+            return
+        self.player.terminate()
+        atexit.unregister(self.stop)
+        self.player = None
+        self.start = 0
+
+    def seek(self, t):
+        if self.playing:
+            self.stop()
+            self.start = titot(t)
+            self.play()
+        else:
+            self.start = titot(t)
+
+    def pause(self):
+        if not self.playing:
+            return
+        self.stop()
+        self.start = self.start + time.monotonic()
+
+    @property
+    def position(self):
+        if not self.playing:
+            return self.start
+        return ttoti(self.start + time.monotonic() - self.start_time)
+
+    @property
+    def volume(self):
+        return 100
+
+    @volume.setter
+    def volume(self, vol):
+        return
+
+    @property
+    def playing(self):
+        if self.player is not None:
+            if self.player.poll() is not None:
+                self.player = None
+
+        return self.player is not None
+
+    def __init__(self, fname, args=()):
+        super().__init__(fname, args=args)
+        
+        self.player = None
+        self.start = 0
+        self.start_time = 0
+        
+try:
+    import mpv
+except (OSError, ImportError):
+    warnings.warn("mpv backend unavailable, falling back to ffplay", RuntimeWarning)
+
+    DefaultAudioPlayer = FFPlayer