The VideoLAN Forums

I have been looking at the following Tutorial:

http://wiki.videolan.org/LibVLC_Tutorial

Is it possible to adjust brightness, contrast, hue and saturation using libVLC?

Has anyone found a solution for this question. I am using JVLC and would like to access the video effects that are available under the extended settings dialog in the VLC media player.

Well, you can change the values from the libvlc_new text parameters. But I doubt anyone implemented an API to change them afterward.

But what about the extended settings dialog in the VLC media player? is there a API for this?

Did you get the any of the Video Effects (e.g video scaling) to work?

Hello everybody!

I am currently trying to get brightness, contrast, hue and gamma filters working using libvlc-dev 1.1.1 in a c++ program under linux.

Here's what I do :

libvlc_video_set_adjust_int(mp,libvlc_adjust_Enable,1); // mp is libvlc_media_player_t

libvlc_video_set_adjust_float(mp,libvlc_adjust_Gamma,1.0f);

I found those 2 functions in libvlc_media_player.h

Unfortunately, the video remains exactly the same.

Could someone please tell me what I am doing wrong?

Thank you in advance.

Please...anybody?

libvlc_adjust_Enable( ?

Thanks a lot for answering.

However, from what I can see in libvlc_media_player.h, libvlc_adjust_Enable is declared as :

/** option values for libvlc_video_{get,set}_adjust_{int,float,bool} */
enum libvlc_video_adjust_option_t {
libvlc_adjust_Enable = 0,
libvlc_adjust_Contrast,
libvlc_adjust_Brightness,
libvlc_adjust_Hue,
libvlc_adjust_Saturation,
libvlc_adjust_Gamma,
};

And libvlc_video_set_adjust_int :

VLC_PUBLIC_API void libvlc_video_set_adjust_int( libvlc_media_player_t *p_mi,
unsigned option, int value );


So, correct me if I am wrong but libvlc_adjust_Enable is an argument, not a function.

Pardon me if my problem is confusing : I just want to filter the video and I thought libvlc_video_set_adjust was the right function for me but unfortunately, the video keeps playing unfiltered.

Is my problem clear enough?

Thanks again in advance

Is the video already playing when you call the video adjust functions?

I have those functions working in the Java bindings just fine, I just can't remember if the video has to be already playing or not.

Thanks for answering so fast.

I tried to call those 2 functions before and after : libvlc_media_player_play (mp) (mp is my libvlc_media_player_t ), but it doesn't seem to show any difference.

Should I try my code with a different computer or with a different libvlc-dev ? (currently 1.1.1-1~ppa1 under linux lucid)

Thanks a lot anyway.

libvlc_video_set_adjust_float(mp,libvlc_adjust_Gamma,1.0f);

Is that just an example? I thought 1.0f was the 'default' gamma value so setting it to that wouldn't change anything anyway.

What I do in my code is this:

1. libvlc_media_player_play
2. libvlc_video_set_adjust_int(mp, libvlc_adjust_Enable, 1);
3. libvlc_video_set_adjust_float(mp, libvlc_adjust_Gamma, gamma);

where gamma comes from a slider control that ranges from 0.01 to 10.0.

This has worked just fine for me with libvlc 1.1.1 onwards.

Indeed, 1.0f was just an example. I tried more often values between 0.0f and 1.0f because I was ignorant of the actual range of this parameter.

However, I am using these lines in the exact same order with different values of gamma and brightness and saturation...; I guess it's just bad luck then!

Are you aware of any example of vlc integration in c++ with that filter thingy?

Thank you one more time for your consideration and support.