Syncing Audio/Music

rbaffy · December 28, 2017, 4:53pm

Apologies if this has been answered before; I can’t find anything through search…

Has anyone built a rhythm-style game in Corona? I think the actual gameplay/timing part is somewhat simple – tracking the timing of “notes” traveling down the screen, and checking to see how close player input occurs relative to position/timing of those notes. BUT, I think the bigger issue might be ensuring that the music behind the logic is in sync, both throughout the entire song but also when OS interruptions happen, like calls, texts, etc.

I don’t see any functionality in the audio API for current millisecond count on a playing sound/stream, but maybe I’m missing something. Any push in the right direction or advice/experience you could share would be appreciated.

roaminggamer · December 28, 2017, 6:05pm

The API used to have some un-exposed features, but you’re right. The docs do not elaborate on how to determine the current position you are at in a song.

There used to be some unexposed OpenAL features, but they were never supported officially and I think they may be dead. NOT DEAD (see my posts below.)

That said, here is a code snippet to give you a starting point to research them (supply your own audio file):

local song = audio.loadStream( "Dub Eastern.mp3" ) print(song) local channel, source = audio.play( song ) print("Channel: " .. tostring(channel) ) print("Source: " .. tostring(source) ) for k,v in pairs( al ) do print( k, v) end --al.Source(source, al.PITCH, 1.5) -- Crashes?

That prints out this:

10:02:49.432 Channel: 1 10:02:49.432 Source: 177221568 10:02:49.432 GetEnumValue function: 0A8CC6E0 10:02:49.432 BITS 8194 10:02:49.432 VENDOR 45057 10:02:49.432 DIRECTION 4101 10:02:49.432 DISTANCE\_MODEL 53248 10:02:49.432 FALSE 0 10:02:49.432 GetError function: 0A8CC7C0 10:02:49.432 TRUE 1 10:02:49.432 INVERSE\_DISTANCE 53249 10:02:49.432 BUFFERS\_PROCESSED 4118 10:02:49.432 SOURCE\_TYPE 4135 10:02:49.432 IsEnabled function: 0A8CC580 10:02:49.432 FORMAT\_MONO16 4353 10:02:49.432 GetSource function: 0A8CC6A0 10:02:49.432 PLAYING 4114 10:02:49.432 FORMAT\_STEREO8 4354 10:02:49.432 INVALID\_OPERATION 40964 10:02:49.432 CONE\_OUTER\_ANGLE 4098 10:02:49.432 MIN\_GAIN 4109 10:02:49.432 FORMAT\_MONO8 4352 10:02:49.432 MAX\_DISTANCE 4131 10:02:49.432 DistanceModel function: 0A8CC800 10:02:49.432 DOPPLER\_FACTOR 49152 10:02:49.432 SIZE 8196 10:02:49.432 Source function: 0A8CC5E0 10:02:49.432 SOURCE\_STATE 4112 10:02:49.432 Enable function: 0A8CC680 10:02:49.432 FREQUENCY 8193 10:02:49.432 \_VERSION 1.1 10:02:49.432 INVERSE\_DISTANCE\_CLAMPED 53250 10:02:49.432 MAX\_GAIN 4110 10:02:49.432 ROLLOFF\_FACTOR 4129 10:02:49.432 VERSION 45058 10:02:49.432 DopplerVelocity function: 0A8CC840 10:02:49.432 SpeedOfSound function: 0A8CC7A0 10:02:49.432 STOPPED 4116 10:02:49.432 EXPONENT\_DISTANCE\_CLAMPED 53254 10:02:49.432 IsExtensionPresent function: 0A8CC720 10:02:49.432 VELOCITY 4102 10:02:49.432 SPEED\_OF\_SOUND 49155 10:02:49.432 EXPONENT\_DISTANCE 53253 10:02:49.432 GAIN 4106 10:02:49.432 LINEAR\_DISTANCE\_CLAMPED 53252 10:02:49.432 DopplerFactor function: 0A8CC6C0 10:02:49.432 LINEAR\_DISTANCE 53251 10:02:49.432 CHANNELS 8195 10:02:49.432 STATIC 4136 10:02:49.432 SEC\_OFFSET 4132 10:02:49.432 NONE 0 10:02:49.432 FORMAT\_STEREO16 4355 10:02:49.432 STREAMING 4137 10:02:49.432 RENDERER 45059 10:02:49.432 OUT\_OF\_MEMORY 40965 10:02:49.432 ILLEGAL\_ENUM 40962 10:02:49.432 SAMPLE\_OFFSET 4133 10:02:49.432 ILLEGAL\_COMMAND 40964 10:02:49.432 INVALID\_VALUE 40963 10:02:49.432 UNDETERMINED 4144 10:02:49.432 INVALID\_NAME 40961 10:02:49.432 PAUSED 4115 10:02:49.432 DOPPLER\_VELOCITY 49153 10:02:49.432 INVALID -1 10:02:49.432 GetListener function: 0A8CC760 10:02:49.432 BYTE\_OFFSET 4134 10:02:49.432 LOOPING 4103 10:02:49.432 POSITION 4100 10:02:49.432 Listener function: 0A8CC540 10:02:49.432 Disable function: 0A8CC620 10:02:49.432 BUFFERS\_QUEUED 4117 10:02:49.432 CONE\_INNER\_ANGLE 4097 10:02:49.432 BUFFER 4105 10:02:49.432 NO\_ERROR 0 10:02:49.432 CONE\_OUTER\_GAIN 4130 10:02:49.432 SOURCE\_RELATIVE 514 10:02:49.432 REFERENCE\_DISTANCE 4128 10:02:49.432 EXTENSIONS 45060 10:02:49.432 INITIAL 4113 10:02:49.432 PITCH 4099 10:02:49.432 ORIENTATION 4111

roaminggamer · December 28, 2017, 6:10pm

It occurred to me the crash was probably because I was using loadStream().

This code works fine (again, supply your own sound file):

local song = audio.loadSound( "Dub Eastern.mp3" ) local channel, source = audio.play( song ) print("Channel: " .. tostring(channel) ) print("Source: " .. tostring(source) ) al.Source(source, al.PITCH, 0.5 ) -- slow by 50%

This proves the openAL features still work in the simulator on Windows 10. So, if you’re willing to investigate and verify this works on your target devices you may have somewhere to start on this.

roaminggamer · December 28, 2017, 6:12pm

One last bit. I’m attaching the openAL programmers guide v1.0 It won’t apply directly, but will give you a place to work from.

roaminggamer · December 28, 2017, 6:28pm

https://github.com/roaminggamer/RG_FreeStuff/raw/master/AskEd/2017/12/audioTricks.zip

rbaffy · December 29, 2017, 3:57am

Wow, thanks @roaminggamer! I’ll post back here when I get a test working if it’s worth sharing. Thanks again!

roaminggamer · December 28, 2017, 6:05pm