LibVLC SampleCode Thumbnailer

This sample code will generate a thumbnail from any media.

 /* Copyright Rafael Carre (licence WTFPL) */

#include <stdio.h>
#include <vlc/libvlc.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

static libvlc_exception_t ex;

static void catch (void)
{
    if (libvlc_exception_raised (&ex))
    {
        fprintf (stderr, "Exception: %s\n",
                 libvlc_exception_get_message (&ex));
        exit(1);
    }

    libvlc_exception_clear (&ex);
}

#define TEMP "/tmp/vlc-video-thumbnailer.png"

#define usage() \
        fprintf( stderr, \
            "Usage: %s input output\n" \
            "input being any video VLC can read, and output a png file\n" \
            , argv[0] )

int main( int argc, const char **argv )
{
    if( argc != 3 && argc != 5 )
    {
        usage();
        if( argc == 2 && ( !strcmp( argv[1], "-h" ) || strcmp( argv[1], "--help") ) )
            return 0;
        else
            return 1;
    }

    const char *input = argv[1];
    const char *output = argv[2];
    int i_width = 0;
    int i_height = 0;

    if( argc == 5 )
    {
        if( memcmp( argv[1], "-s", 3 ) != 0 )
        {
            usage();
            return 1;
        }
        i_width = atoi( argv[2] );
        input = argv[3];
        output = argv[4];
    }

    libvlc_exception_init( &ex );

    const char* const args[] = {
        "-I", "dummy",                      /* no interface */
        "--vout", "dummy",                  /* we don't want video */
        "--no-audio",                       /* we don't want audio */
        "--verbose=1",                      /* show only errors & warnings */
        "--no-media-library",               /* don't want that */
        "--services-discovery", "",         /* nor that */
        "--no-video-title-show",            /* nor the filename displayed */
        "--no-sub-autodetect",              /* don't want subtitles */
        "--control", "",                    /* don't want interface */
        "--extraintf", ""                   /* AT ALL ! */
    };

    int nargs = sizeof(args) / sizeof(args[0]);
    libvlc_instance_t *libvlc = libvlc_new( nargs, args, &ex );
    catch();

    libvlc_media_instance_t *mi;
    libvlc_media_descriptor_t *md;

    md = libvlc_media_descriptor_new( libvlc, input, &ex );
    catch();
   
    mi = libvlc_media_instance_new_from_media_descriptor( md, &ex );
    catch();
    
    libvlc_media_descriptor_release( md );

    libvlc_media_instance_play( mi, &ex );
    catch();

    /* go to position 30% to avoid introductions */
    libvlc_media_instance_set_position( mi, 0.30, &ex );
    catch();

    /* leave vlc some time to start playing */
    sleep(1); /* TODO: wait for a status change */

    libvlc_video_take_snapshot( mi, TEMP, i_width, i_height, &ex );
    catch();

    sleep(1);

    /* We use a destination snapshot with a .png extension, since libvlc use the extension to detect the encoder used */
    char *mv;
    if( asprintf( &mv, "mv %s %s", TEMP, output ) == -1 )
        return 1;
    system( mv );
    free( mv );

    libvlc_media_instance_stop( mi, &ex );
    catch();

    libvlc_media_instance_release( mi );

    libvlc_release( libvlc, &ex );
    catch();

    return 0;
}