[UOS/PortAudio] Minimizing Audio Latency?

[Hobbit1972]

Hi!

I'm using UOS (with PortAudio lib) to route MicIn to SpkOut:

Code: Pascal  [Select][+][-]

1.   uos_CreatePlayer(0);
2.   uos_AddIntoDevOut(0);
3.   uos_AddFromDevIn(0);
4.   uos_Play(0);
5.  

This gives me quite audible latency between in and out. I Tried to fiddle with the paramters of AddFromDevIn like

Code: Pascal  [Select][+][-]

1.  uos_AddFromFrvIn(0,-1,4,-1,-1,-1,128,-1);

but this doesn't change much.

Is there some way to reduce latency here?

Tx!

[Fred vS]

Hello.

Please take a look at the examples in /uos/examples/.
There is also a uos-forum: http://uos-forum.108.s1.nabble.com/

Thanks.

Fre;D

[metis]

@Hobbit1972

Which OS, which SoundCard, which AudioDriver do You use ?

Did You try ASIO or JACK (JACK@GitHub) ?

On Windows, I use PortAudio together with ASIO4ALL to obtain incredible, crystal-clear low-latency Sound
with Audios and Videos(!) with my FFmpeg-based Audio/Video-RenderingEngine FFPlay4Laz.

[Hobbit1972]

@Fred vS: any particular example touching latency in mind?
The latency value is seconds? milliseconds? foo units? 

@metis:
Win11 64bit. Out-of-the-box card&driver of my mainboard. As the program should run on different platforms, general ideas would be appreciated.

Tx

[Fred vS]

@Fred vS: any particular example touching latency in mind?
The latency value is seconds? milliseconds? foo units? 

Please try SimplePlayer demo.
About latency: http://www.portaudio.com/docs/latency.html

Fre;D

[Fred vS]

Hi!

I'm using UOS (with PortAudio lib) to route MicIn to SpkOut:

Re-hello.

Did you try the simplerecorder.lpi example?
Is the sound ok?

[Hobbit1972]

@Fred vS:
Yes, SimplePlayer runs and is okay. Except "play revers" where it gets jumpy.

[Fred vS]

@Fred vS:
Yes, SimplePlayer runs and is okay. Except "play revers" where it gets jumpy.

Ha, ok, ( hum, jumpy with what kind of audio files, mp3, wav, ogg, ... ?)

And what about SimpleRecorder, is the mic-input to output sound ok ?

[Hobbit1972]

@Fred vS:
Yes, SimplePlayer runs and is okay. Except "play revers" where it gets jumpy.

Ha, ok, ( hum, jumpy with what kind of audio files, mp3, wav, ogg, ... ?)

And what about SimpleRecorder, is the mic-input to output sound ok ?

ogg. plays backwards till it reaches 0:00:00.743, jumps to 0:00:01.114, plays backwards... and so on...

Recorder: let me check that out...

[Hobbit1972]

And what about SimpleRecorder, is the mic-input to output sound ok ?

SimpleRecorder: I'd say latency is ~1/4s, just like in my program.

[Hobbit1972]

@Fred vS:
FYI: as the compiler threw an error not knowing which overloed function to use, I made this change in uos.pas:

Code: Pascal  [Select][+][-]

1.           if StreamIn[x].AACI.lwDataLen > (StreamIn[x].AACI.BitsPerSample div 8) then
2.             StreamIn[x].Data.outframes := trunc(comp(StreamIn[x].AACI.lwDataLen) Div (StreamIn[x].AACI.
3.                                           BitsPerSample Div 8))
4.  

I added comp() to get it to work.

[Fred vS]

ogg. plays backwards till it reaches 0:00:00.743, jumps to 0:00:01.114, plays backwards... and so on...

Ok, I will check this asap with ogg files, write you later.

[EDIT] Ha, ok, I see, it is wanted  .
If reverse-song reach to begin, there is a loop with first chunck.
This reverse effect is to show how to use the uos-dsp feature, feel free to adapt the code like you want.

SimpleRecorder: I'd say latency is ~1/4s, just like in my program.

Sorry but I did not understand. 
Is the sound ok or not?

[Fred vS]

@Fred vS:
FYI: as the compiler threw an error not knowing which overloed function to use, I made this change in uos.pas:

Code: Pascal  [Select][+][-]

1.           if StreamIn[x].AACI.lwDataLen > (StreamIn[x].AACI.BitsPerSample div 8) then
2.             StreamIn[x].Data.outframes := trunc(comp(StreamIn[x].AACI.lwDataLen) Div (StreamIn[x].AACI.
3.                                           BitsPerSample Div 8))
4.  

I added comp() to get it to work.

Please give the error you get from the compiler.

[Hobbit1972]

SimpleRecorder: I'd say latency is ~1/4s, just like in my program.

Sorry but I did not understand. 
Is the sound ok or not?

Sound is (and was alaways) okay, but processing time (=latency) is too long for my purposes. Between me speaking in the mic and hearing my voice in the speaker is ~250ms 

ofc Win was and is a pain in the a** concerning these kind of things. 

[Hobbit1972]

@Fred vS:
FYI: as the compiler threw an error not knowing which overloed function to use, I made this change in uos.pas:

Code: Pascal  [Select][+][-]

1.           if StreamIn[x].AACI.lwDataLen > (StreamIn[x].AACI.BitsPerSample div 8) then
2.             StreamIn[x].Data.outframes := trunc(comp(StreamIn[x].AACI.lwDataLen) Div (StreamIn[x].AACI.
3.                                           BitsPerSample Div 8))
4.  

I added comp() to get it to work.

Please give the error you get from the compiler.

Here you go:

Code: Pascal  [Select][+][-]

1. uos.pas(10381,43) Error: Can't determine which overloaded function to call