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Posted: **27 Jan 2021 13:32**

Hello, everyone! I make a small videoplayer using libvlc. But I stucked in finding way to rotate video (for example 90 degrees clockwise). I found module vls_es.h with difinition of function making transformation with video. Also I found enum:
TRANSFORM_IDENTITY = ORIENT_NORMAL,
TRANSFORM_HFLIP = ORIENT_HFLIPPED,
TRANSFORM_VFLIP = ORIENT_VFLIPPED,
TRANSFORM_R180 = ORIENT_ROTATED_180,
TRANSFORM_R270 = ORIENT_ROTATED_270,
TRANSFORM_R90 = ORIENT_ROTATED_90,
TRANSFORM_TRANSPOSE = ORIENT_TRANSPOSED,
TRANSFORM_ANTI_TRANSPOSE = ORIENT_ANTI_TRANSPOSED
that matches with option in VLC player->Tools->Effects and Filters->VideoEffects->Geometry->Transform

I used libvlc_media_player_t for media control.
How can I use video_format_t to send format to libvlc_media_player_t? Is it possible? Or maybe there is other way to make rotation?

Posted: **01 Feb 2021 03:21**

See https://wiki.videolan.org/VLC_command-line_help

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Video transformation filter (transform)
 Rotate or flip the video
      --transform-type={90,180,270,hflip,vflip,transpose,antitranspose} 
                                 Transform type

You could give this to `libvlc_new`

Posted: **05 Feb 2021 04:56**

I meet the same question , and i found a way to get and modify the parameter of transform filter , but it seems does not take effect . Steps ars as follows:

1) start vlc instance with transform fiter :

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    const char *vlc_args[] =
    {
        "--video-filter=transform",
        "--transform-type=0",
    };

    if (m_vlcInstance == Q_NULLPTR) {
        m_vlcInstance = libvlc_new(sizeof(vlc_args)/sizeof(vlc_args[0]), vlc_args);
    }

2) find the filter:

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vlc_object_t* p_filter2 = vlc_object_find_name((vlc_object_t*)m_mediaPlayer, "transform");

3) read , modify and re-read parameter :

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QString s_degree1 = var_GetString(p_filter2,"transform-type");
var_SetString(p_filter2, "transform-type","180");
QString s_degree2 = var_GetString(p_filter2, "transform-type");

As if new parameter is in the cache??? Anyone know how to make new parameter take effect???

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