vlc-thumb: video thumbnailer for nautilus

doc/libvlc/vlc-thumb.c

+/* Copyright Rafaël Carré (licence WTFPL) */
+/* A video thumbnailer compatible with nautilus */
+/* Copyright © 2007-2011 Rafaël Carré <funman@videolanorg> */
+
+/* Works with : libvlc 1.2.0
+   gcc -pedantic -Wall -Werror -Wextra `pkg-config --cflags --libs libvlc`
+
+  # to register the thumbnailer:
+  list=`grep ^Mime vlc.desktop|cut -d= -f2-|sed -e s/";"/\\\n/g -e s,/,@,g`
+  vid=`echo $mimes|grep ^vid`
+  for i in $vid
+  do 
+    key=/desktop/gnome/thumbnailers/$i/enable
+    gconftool-2 -t boolean -s $key true
+    gconftool-2 -t string  -s $key "vlc-thumb -s %s %u %o"
+  done
+ */
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <locale.h>
+
+#include <vlc/vlc.h>
+
+/* position at which the snapshot is taken */
+#define VLC_THUMBNAIL_POSITION (30./100.)
+
+static void usage(const char *name, int ret)
+{
+    fprintf(stderr, "Usage: %s [-s width] <video> <output.png>\n", name);
+    exit(ret);
+}
+
+/* extracts options from command line */
+static void cmdline(int argc, const char **argv, const char **in,
+                    char **out, char **out_with_ext, int *w)
+{
+    int idx = 1;
+    size_t len;
+
+    if (argc != 3 && argc != 5)
+        usage(argv[0], argc != 2 || strcmp(argv[1], "-h"));
+
+    *w = 0;
+
+    if (argc == 5) {
+        if (strcmp(argv[1], "-s"))
+            usage(argv[0], 1);
+
+        idx += 2; /* skip "-s width" */
+        *w = atoi(argv[2]);
+    }
+
+    *in  = argv[idx++];
+    *out = strdup(argv[idx++]);
+    assert(*out);
+
+    len = strlen(*out);
+    if (len >= 4 && !strcmp(*out + len - 4, ".png")) {
+        *out_with_ext = *out;
+        return;
+    }
+
+    /* We need to add .png extension to filename,
+     * VLC relies on it to detect output format,
+     * and nautilus doesn't give filenames ending in .png */
+
+    *out_with_ext = malloc(len + sizeof ".png");
+    assert(*out_with_ext);
+    strcpy(*out_with_ext, *out);
+    strcat(*out_with_ext, ".png");
+}
+
+static libvlc_instance_t *create_libvlc(void)
+{
+    static const char* const args[] = {
+        "--intf", "dummy",                  /* no interface                   */
+        "--vout", "dummy",                  /* we don't want video (output)   */
+        "--no-audio",                       /* we don't want audio (decoding) */
+        "--no-video-title-show",            /* nor the filename displayed     */
+        "--no-stats",                       /* no stats                       */
+        "--no-sub-autodetect-file",         /* we don't want subtitles        */
+        "--no-inhibit",                     /* we don't want interfaces       */
+        "--no-disable-screensaver",         /* we don't want interfaces       */
+        "--no-snapshot-preview",            /* no blending in dummy vout      */
+#if 1
+        "--verbose=2",                      /* full log                       */
+#endif
+    };
+
+    return libvlc_new(sizeof args / sizeof *args, args);
+}
+
+static void callback(const libvlc_event_t *ev, void *param)
+{
+    float new_position = ev->u.media_player_position_changed.new_position;
+
+    switch (ev->type) {
+
+    case libvlc_MediaPlayerPositionChanged:
+        if (new_position >= VLC_THUMBNAIL_POSITION * .9) { /* 90% margin */
+            *(int*)param = 1;
+        }
+        break;
+    case libvlc_MediaPlayerSnapshotTaken:
+        *(int*)param = 1;
+        break;
+
+    default:
+        assert(0);
+    }
+}
+
+/* FIXME: should use pthread notification */
+static void event_wait(const char *error, int *f)
+{
+#define VLC_THUMBNAIL_TIMEOUT   5.0 /* 5 secs */
+#define VLC_THUMBNAIL_LOOP_STEP 0.2 /* 200 ms */
+
+    float max = VLC_THUMBNAIL_TIMEOUT;
+    while ((max -= VLC_THUMBNAIL_LOOP_STEP) > 0.) {
+        if (*f)
+            return;
+
+        usleep(VLC_THUMBNAIL_LOOP_STEP * 1000000);
+    }
+
+    fprintf(stderr,
+            "%s (timeout after %.2f secs!\n", error, VLC_THUMBNAIL_TIMEOUT);
+    exit(1);
+}
+
+static void set_position(libvlc_media_player_t *mp)
+{
+    int f = 0;
+    libvlc_event_manager_t *em = libvlc_media_player_event_manager(mp);
+    assert(em);
+
+    libvlc_event_attach(em, libvlc_MediaPlayerPositionChanged, callback, &f);
+    libvlc_media_player_set_position(mp, VLC_THUMBNAIL_POSITION);
+    event_wait("Couldn't set position", &f);
+    libvlc_event_detach(em, libvlc_MediaPlayerPositionChanged, callback, &f);
+}
+
+static void snapshot(libvlc_media_player_t *mp, int width, char *out_with_ext)
+{
+    int f = 0;
+    libvlc_event_manager_t *em = libvlc_media_player_event_manager(mp);
+    assert(em);
+
+    libvlc_event_attach(em, libvlc_MediaPlayerSnapshotTaken, callback, &f);
+    libvlc_video_take_snapshot(mp, 0, out_with_ext, width, 0);
+    event_wait("Snapshot has not been written", &f);
+    libvlc_event_detach(em, libvlc_MediaPlayerSnapshotTaken, callback, &f);
+}
+
+int main(int argc, const char **argv)
+{
+    const char *in;
+    char *out, *out_with_ext;
+    int width;
+    libvlc_instance_t *libvlc;
+    libvlc_media_player_t *mp;
+    libvlc_media_t *m;
+
+    /* mandatory to support UTF-8 filenames (provided the locale is well set)*/
+    setlocale(LC_ALL, getenv("LANG"));
+
+    cmdline(argc, argv, &in, &out, &out_with_ext, &width);
+
+    /* starts vlc */
+    libvlc = create_libvlc();
+    assert(libvlc);
+
+    m = libvlc_media_new_path(libvlc, in);
+    assert(m);
+
+    mp = libvlc_media_player_new_from_media(m);
+    assert(mp);
+
+    libvlc_media_player_play(mp);
+
+    /* takes snapshot */
+    set_position(mp);
+    snapshot(mp, width, out_with_ext);
+
+    libvlc_media_player_stop(mp);
+
+    /* clean up */
+    if (out != out_with_ext) {
+        rename(out_with_ext, out);
+        free(out_with_ext);
+    }
+    free(out);
+
+    libvlc_media_player_release(mp);
+    libvlc_media_release(m);
+    libvlc_release(libvlc);
+
+    return 0;
+}