Moving from audsrv to audio

There are two ways to use the audio library from code that calls audsrv.

• Keep the audsrv calls and link the audsrv-compat package. Nothing in the source changes.
• Call the audio library directly, using the table below for the equivalents.

Build setup for unchanged code

targets:
  - name: game
    type: ee
    sources: [main.c]
    libs: [audsrv-compat]
    embed_irx: [libsd, "audio:audsrv"]

audsrv-compat links the audio library itself. "audio:audsrv" embeds audio.irx under the symbol names audsrv_irx and size_audsrv_irx, which code that loaded the audsrv module expects. The application keeps loading libsd.irx and then that module before calling audsrv_init(), as before.

Calls

audsrv	audio	Notes
audsrv_init()	audio_init()	Calling it again returns 0.
audsrv_quit()	audio_shutdown()
audsrv_get_error(), audsrv_get_error_string()	audio_get_error_message()	The compatibility layer keeps the last error code itself.
audsrv_set_format()	audio_stream_start()
audsrv_wait_audio()	audio_stream_wait_until_writable()
audsrv_play_audio()	audio_stream_wait_until_writable() and audio_stream_queue_pcm()	The compatibility call waits for space in chunks of 4096 bytes, so all data is accepted. audio_stream_queue_pcm() returns what fits.
audsrv_stop_audio()	audio_stream_stop_and_clear()
audsrv_set_volume()	audio_stream_set_volume()	Affects the stream only. audio_set_master_volume() scales everything.
audsrv_available(), audsrv_queued()	audio_stream_get_free_bytes(), audio_stream_get_queued_bytes()
audsrv_on_fillbuf()	audio_stream_set_low_data_callback()	The threshold is the stream size minus the requested free space. The stream must be started.
audsrv_adpcm_init()	audio_sound_free_all()	Stops every channel; the stream keeps playing.
audsrv_load_adpcm()	audio_sound_load_apcm()	The compatibility call fills the descriptor from the file header.
audsrv_ch_play_adpcm()	audio_channel_play_sound(), audio_play_sound()	See the differences below.
audsrv_adpcm_set_volume_and_pan()	audio_channel_set_volume_and_pan()
audsrv_adpcm_set_volume()	audio_channel_set_volume_and_pan() with pan 0	Matches the audsrv macro, which sets the pan to center. audio_channel_set_volume() leaves the pan unchanged.
audsrv_is_adpcm_playing()	audio_channel_get_playing_sound()
audsrv_free_adpcm()	audio_sound_free()
CD audio calls		Not supported; they return -AUDSRV_ERR_NO_DISC.

Differences

• Channel already playing. audsrv_ch_play_adpcm() on a channel that is playing replaces the sound there and returns the channel. audsrv documents -AUDSRV_ERR_NO_MORE_CHANNELS for that case.
• Channel outside 0 to 23. Plays on the first free channel, as audsrv does. That channel is reset to volume 100, centered, normal pitch; channels played on by number keep their settings.
• Stream volume and sample volume are separate. audsrv_set_volume() and the channel volumes do not scale each other.
• Volume and pan before the first play are kept and used when the channel plays.
• Stream start. audsrv_on_fillbuf() needs a started stream, so call audsrv_set_format() first.
• Sample files. audsrv_load_adpcm() takes APCM (.adp) images, as audsrv does. See Sound files (.adp).