Greetings, everyone.

I would like to create a PD patch that would load and play an audio file and send OSC messages at specific points during playback. Playing the audio file and sending OSC messages are straightforward individually, but I've not discovered an elegant why to synchronize them. Would I use an array crated by soundfiler to create a sort of timeline, then trigger an OSC message based on the index of the sample being played? Suggestions would be most appreciated.

@earlyjp There might well be a better way than the two options that I can think of straight away.

You could play the audio file from disk, and send a bang into [delay] objects as you start playback, with the delays set to trigger the messages at the correct time.
I am not sure how long a [delay] you can create though because of the precision limit of a number size that can be saved in Pd. You might need to use [timer] banged by a [metro]

Or as you say you could load the file into RAM using [soundfiler] and play the track in the array using [phasor~] and trigger the messages as the output of [phasor~] reaches certain values.
Using [phasor~] the sample will loop though.
To play just once you could use [line~] or [vline~]
You would need to catch the values from [phasor~] [line~] or [vline~] using [snapshot~].
[<=] followed by [once] would be a good idea for catching, as catching the exact value would likely be unreliable...... once.pd
The same will be true if you use [timer] as the [metro] will not make [timer] output every value.

Again, number precision for catching the value could be a problem with long audio files.

Help for the second method....... https://forum.pdpatchrepo.info/topic/9151/for-phasor-and-vline-based-samplers-how-can-we-be-sure-all-samples-are-being-played

The [soundfiler] method will use much more cpu if that is a problem.
If there is a playback object that outputs it's index then use that, but I have not seen one.
David.

@earlyjp I had to do something vaguely similar for a show last summer. I loaded the file I wanted to playback into REAPER, and then added automation and/or MIDI in relation to the audio file--all DAWs excel at that kind of thing. I triggered REAPER playback using OSC, and had a Pd patch running as a VST3 in plugdata (or maybe Camomile) that was reading the automation/MIDI and doing stuff in response.

BTW, since learning that's it's easy to encode arbitrary Pd messages as sysex, I've been using REAPER a lot more to record, edit, and playback Pd message sequences. To me, with my limited patience and imagination, It's more pleasant than doing it in Pd alone, although it's also true that I have to write myself plenty of notes regarding how. things are set up.

@whale-av - This is very helpful indeed, thank you! I will experiment with the suggested objects and report back.

@jameslo -- Thank you for the suggestion to use a DAW to synchronize the audio with the OSC messages. I considered this option, but I am trying to see how far I can get using only Pd. I didn't mention in my original post that my system runs on a Raspberry Pi 4, and I'm concerned that running a DAW would strain the resources needed by Pd. However, I will investigate this further and report back. Thanks again.