Using VLC feature for my experiment

[maggiegirl123]

Hi all, bonjour!

I am a graduate student at York University (Canada) working in the autism research lab.
I am doing a project to test subjects awareness of audio asynchrony to video. I want users to be able to adjust an out-of-sync movie by pressing keys (like the function of 'g' and 'h' in VLC) until they decide the audio is in sync.

I know VLC can allow for dynamic manipulation of the audio sync using g and h keys to delay or skip ahead 50ms, but I need to formalize and randomize the experimental trials using a program such as E-prime, Presentation or PsychPy2 (similar to Matlab).

MY QUESTION IS>>>

Is there a way to use the functionality or code of VLC audio delay/advance in another program's media player? Or alternatively, is there a way I can use another program to open movies in VLC and send commands 'g' and 'h' to VLC?

I hope my question is clear, but if not, I'll try and clarify.

Thanks.

Maggie

[Rémi Denis-Courmont]

1/ No. 2/ It depends.

[maggiegirl123]

'It depends.'
I guess you mean it depends on the program? I would be calling VLC from E-prime, Presentation or PsychPy2 (similar to Matlab). I am looking into whether these can simply pass keypress information to VLC, but if not, I thought there might be specific parameters dealing with sound shifting in VLC that I could use to control VLC through code in one of the above mentioned programs.

[Greg]

There is a VLC command called audio-desync=xx This can be + or -
This command can preset the VLC output stream with a specific audio desynchronisation. Therefore, you can in effect alter the audio desync as it appears on another player streamed from VLC, but not on the fly with this command.
See
http://wiki.videolan.org/VLC_command-line_help
Note:
The caching value in the output stream needs to be set greater than the audio-desync value.

[Rémi Denis-Courmont]

It depends on the program, on the operating system, and on the method used. You should be able to change the audio sync with the HTTP interface, with a custom LUA script, or possibly even by sending fake key presses to the player (that latter option is ugly and OS-specific).

[maggiegirl123]

One more feature question. Pressing 'g' and 'h' allows for steps of 50ms delay or advance in audi.

Is there a way to change the 50ms to 25ms or 20ms, for finer adjustments?

Thanks again

Maggie