Volume resets when play() is called

[EddieDover]

May be related to #2, but I'm facing the same issue. Once play() is called the volume is reset to 1.0. The only solution is to set the volume immediately after calling play().

[olivertwistor]

Can confirm running just_playback 0.1.8 with Python 3.9 on a Linux machine.

[cheofusi]

Hi @EddieDover,

I can't reproduce this. What sequence of playback calls are you making? The volume is tied to the lifetime of the playback object, being initialized only when that object is created and keeping its value across calls to load_file() or play(), unless changed by set_volume()

[EddieDover]

@cheofusi Honestly, you'll probably get better info out of @olivertwistor about this issue. After I ran into it, I wrote a function override/monkey-patch that just sets the volume immediately after play is called and just moved on. That project was marked finished, and I'm not too involved in it anymore.

[olivertwistor]

I just tested with a clean virtual environment with just Python 3.13 and just_playback built from source.

This does not produce the desired results:

from just_playback import Playback

playback = Playback("sound.ogg")
playback.set_volume(0.5)
playback.play()

But this will (set_volume() and play() switched places):

from just_playback import Playback

playback = Playback("sound.ogg")
playback.play()
playback.set_volume(0.5)

Additionally, calling set_volume again, and playing again does not change the volume.

[domdfcoding]

I think I am seeing the same. Setting the volume to zero before calling play() and the sound plays audibly. Setting it after works but is not ideal as it isn't immediate - you hear brief blip of sound.

[domdfcoding]

I went as far back as 39d42b6 trying to find when it worked, but I couldn't. I wonder if it has ever? Is it actually supported by miniaudio, or does that need a PR first?

[olivertwistor]

@domdfcoding According to the miniaudio docs, there is a function to set the volume.

A sound can have its volume changed with ma_sound_set_volume(). If you prefer decibel volume
control you can use ma_volume_db_to_linear() to convert from decibel representation to linear.

Source: https://miniaud.io/docs/manual/index.html#HighLevelAPI

[domdfcoding]

@olivertwistor Sorry, I meant does it support setting the volume before starting playing?, rather than only afterwards.

I think it does. With this patch (removing the check for active I can successfully set the volume before playing.

--- a/just_playback/playback.py
+++ b/just_playback/playback.py
@@ -147,8 +147,8 @@ class Playback:
         """
 
         self.__ma_attrs.playback_volume = min(max(volume, 0), 1)
-        if self.active:
-            self.__bind(lib.set_device_volume(self.__ma_attrs))
+        # if self.active:
+        self.__bind(lib.set_device_volume(self.__ma_attrs))
     
     def loop_at_end(self, loops_at_end: bool) -> None:
         """

Looking at the rest of the code the only other place lib.set_device_volume gets called is when loading the file - it's not called by play(). So even without the patch this way round also works, it's just slightly less elegant:

playback = Playback()
playback.set_volume(0.5)
playback.load_file("sound.ogg")
playback.play()

But I don't see why the call to lib.set_device_volume in set_volume() has to be gated with if self.active: - miniaudio's code doesn't seem to require that.