View source for LibVLC SampleCode Thumbnailer

This sample code will generate a thumbnail from any media.
It can be used by nautilus instead of totem-video-thumbnailer
  /* Copyright [[User:Funman|Rafaël Carré]] (licence [http://en.wikipedia.org/wiki/WTFPL WTFPL]) */
<pre>
/* A video thumbnailer compatible with nautilus */
/* Copyright © 2007-2008 Rafaël Carré <funman@videolanorg> */

#include <stdio.h>
#include <vlc/libvlc.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <locale.h>
#include <sys/types.h>
#include <sys/stat.h>

/* gcc -ansi -Wall -Werror -lvlc-control vlc-video-thumbnailer.c */

#if 1
#   define DEBUG( s ) fprintf( stderr, s"\n" );
#else
#   define DEBUG( s )
#endif

/* position to seek to (out of 1.) */
#define POS 0.3

/* delay before aborting ( real delay will be * 2 ) */
#define MAX_DELAY 5.0

/* for the callback to notify the main thread that the position changed */
static int fini = 0;

/* to catch problems */
static libvlc_exception_t ex;

/* "position changed" callback */
static void callback( const libvlc_event_t *ev, void *param )
{
    if( ev->type == libvlc_MediaInstancePositionChanged )
    {
        float new_pos;
        new_pos = ev->u.media_instance_position_changed.new_position;
        if( new_pos >= POS - ( POS / 10 ) )
        {
            DEBUG( "Position set" );
            fini = 1; /* now we can take the snapshot */
        }
    }
    else
    {
        fprintf( stderr, "Error: catched event %s\n", 
                libvlc_event_type_name( ev->type ) );
        exit(1);
    }
}

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);
}

/* nautilus doesn't use .png extension, and vlc detects the filetype with the
 * extension, so we use a temporary file to be sure we'll use png */
#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;
    }

    /* mandatory to support UTF-8 filenames (provided the locale is well set)*/
    setlocale( LC_ALL, getenv( "LANG" ) );

    const char const *input, *output;
    int i_width, i_height = 0;

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

    libvlc_exception_init( &ex );

    /* libvlc settings */
    const char* const args[] = {
        "-I", "dummy",                      /* no interface */
        "--vout", "dummy",                  /* we don't want video (output) */
        "--no-audio",                       /* we don't want audio */
        "--verbose=0",                      /* show only errors */
        "--no-media-library",               /* don't want that */
        "--services-discovery", "",         /* nor that */
        "--no-video-title-show",            /* nor the filename displayed */
        "--no-stats",                       /* no stats */
        "--config", "/dev/null",            /* don't overwrite the config */
        "--no-sub-autodetect",              /* don't want subtitles */
        "--control", "",                    /* don't want interface (again) */
        "--no-inhibit",                     /* i say no interface ! */
        "--no-disable-screensaver",         /* wanna fight ? */
        "--extraintf", ""                   /* ok, it will be a piece of cake */
    };

    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();

    /* avoid introduction */
    libvlc_media_instance_set_position( mi, POS, &ex );
    catch();

    libvlc_event_manager_t *em;
    em = libvlc_media_instance_event_manager( mi, &ex );
    catch();

    libvlc_event_attach( em, libvlc_MediaInstancePositionChanged,
                         callback, NULL, &ex );
    catch();

    float max = MAX_DELAY;   /* don't wait more MAX_DELAY seconds */
    while( !fini && ( max -= .2 ) > 0 )  /* wait for the position changed event */
        usleep( 200000 );

    libvlc_event_detach( em, libvlc_MediaInstancePositionChanged,
                         callback, NULL, &ex );
    catch();

    DEBUG( "Taking snapshot" );
    libvlc_video_take_snapshot( mi, TEMP, i_width, i_height, &ex );
    catch();

    sleep( 1 ); /* be sure that the snapshot has been written */

    DEBUG( "Stopping" );
    libvlc_media_instance_stop( mi, &ex );
    catch();

    max = MAX_DELAY;
    while( ( max -= .2 ) > 0 )
    {
        struct stat st;
        if( stat( TEMP, &st ) == 0 )
            break;
        DEBUG( TEMP" doesn't exist" );
        if( max <= .2 )
        {
            DEBUG( "Snapshot has not been written :(" );
            goto end;
        }
        usleep( 200000 );
    }

    DEBUG( "Moving snapshot" );
    char *mv;
    if( asprintf( &mv, "mv \"%s\" \"%s\"", TEMP, output ) == -1 )
        return 1;
    system( mv );
    free( mv );

end:
    libvlc_media_instance_release( mi );

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

    return 0;
}</pre>