brightness, contrast, hue and saturation in libVLC

[GunnarK]

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?

[duppenkamp]

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.

[Rémi Denis-Courmont]

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

[GunnarK]

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

[kryptonite]

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

[zamensis]

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.

[zamensis]

Please...anybody?

[Jean-Baptiste Kempf]

libvlc_adjust_Enable( ?

[zamensis]

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

[sherington]

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.

[zamensis]

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.

[sherington]

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.

[zamensis]

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.