How to perform retrigger/restart sample in gstreamer without cutting the previous playback

Question

So I am trying to make a drum machine with gstreamer. For those who are not familiar with a drum machine have a look at:

https://www.youtube.com/watch?v=KC7UaUD5rEA

Basically you have a specific sample loaded to a track. Each track has 16 steps which you can enable or disable. When you press play the drum machine will loop over the steps and when a step is enabled it will play that sound.

I got it working with the current setup: 8 x (filesrc | wavparse | audioconvert | volume) | audiomixer | alsasink

I put the pipeline in play state and each step I perform a seek_simple back to the start of the pipeline. To trigger the sound I mute and demute the wav each step according to the wanted rhythm/pattern.

The issue: By performing the seek back to the start the tail of the wav sample/sound is cut off and this makes a choppy sound. Ideally I'd like to re-trigger a wav sample but the previous one should continue to play until done.

The question: How can I re trigger a sound without cutting of it's tail?

Ps: I've tried to play with the seek flags "flush", "keep_unit", ... but without success.

My loop:

    def run(self):
        startTime = time.time()
        while True:
            if self.running:
                self.player.set_state(Gst.State.NULL)
                self.player.seek_simple(Gst.Format.TIME, Gst.SeekFlags.FLUSH, 0)
                for track in self.tracks:
                    track.step()
                self.player.set_state(Gst.State.PLAYING)

            time.sleep(self.delayBmp -
                       ((time.time() - startTime) % self.delayBmp))

Thanks in advance

Answer 1

I managed to achieve my goal by using this C library: https://soundprogramming.net/programming/tutorial-using-sdl2-and-sdl_mixer-to-play-samples/

This example gives a way to play multiple sound simultaneously. I then made a python wrapper around it and push a wav file to it. Follow this tutorial:

https://docs.python.org/3/extending/index.html

Feel free to post the gstreamer solution.

thx