Project Apollo currently has a very simple system for adding timed audio to Apollo missions. Currently you can set up any audio file to play at a specific mission time; generally it will play if either the time acceleration is 1.0x, or AUTOSLOW is set so that the time acceleration will be cut back to 1.0x automatically when the audio plays. Note that switching to a higher time acceleration will stop the audio playback.
Configuration is by a simple text file 'csmsound.csv' in Sound/ProjectApollo/ApolloNN where NN is the mission number specified in the APOLLONO variable.
A typical line in this file will be of this format:
The first parameter is the mission time at which we start playing the sound. Note that if you are using a high time acceleration when the time is reached then the playback will start on the next timestep, which may be tens of seconds out relative to the time you specified.
The second parameter is 'l' for time relative to launch. Currently this is the only option, but in future it will be expanded to allow times relative to other events, and flags to ensure that they only play in certain cases (e.g. you don't want to play normal mission audio in the event of an abort).
The third parameter is the priority. 9 will always be played, low values (1 or 2) will never be played if time acceleration is over 1.0, and intermediate (3 to 8) will be played at high time accelerations if AUTOSLOW is enabled (and will slow to 1.0).
The final parameter is the name of the sound file, without the .wav extension. The code will first look for the file in the current mission directory, and then try Sound/ProjectApollo for a generic file if no mission-specific file is found.
Be aware that you will need the latest version of OrbiterSound in order to play this timed audio, as there is a bug in earlier versions which prevents playback of sounds loaded dynamically in the Orbiter timestep function.