问题描述
我有以下代码，它是对here找到的代码的修改。结合本教程here。
RcppC：/Users/user1/AndroidStudioProjects/Project/app/jni/tutorial-3.c：344： 未定义对“ gdk_pixbuf_new_from_data”的引用
C：/Users/user1/AndroidStudioProjects/Project/app/jni/tutorial-3.c：347： 未定义对`gdk_pixbuf_save'clang ++的引用：错误：链接器 命令失败，退出代码为1（使用-v查看调用）
我的文件顶部有static void * snapshot_function(void *userdata){
CustomData *data = (CustomData *) userdata;
gint width,height;
GstSample *sample;
GError *error = NULL;
GdkPixbuf *pixbuf;
gint64 duration,position;
GstStateChangeReturn ret;
gboolean res;
GstMapInfo map;
/* Build pipeline */
data->pipeline_snapshot = gst_parse_launch(pipeline_description_snapshot,&error);
if (error) {
gchar *message =
g_strdup_printf("Unable to build pipeline: %s",error->message);
g_clear_error(&error);
set_ui_message(message,data);
g_free(message);
return NULL;
}
if (error != NULL) {
g_print ("Could not construct pipeline: %s\n",error->message);
g_error_free (error);
exit (-1);
}
/* get sink */
data->snapshot_sink = gst_bin_get_by_name (GST_BIN (data->pipeline_snapshot),"sink");
/* set to PAUSED to make the first frame arrive in the sink */
ret = gst_element_set_state (data->pipeline_snapshot,GST_STATE_PAUSED);
switch (ret) {
case GST_STATE_CHANGE_FAILURE:
g_print ("Failed to play the file\n");
exit (-1);
case GST_STATE_CHANGE_NO_preroll:
/* for live sources,we need to set the pipeline to PLAYING before we can
* receive a buffer. We don't do that yet */
g_print ("live sources not supported yet\n");
exit (-1);
default:
break;
}
/* This can block for up to 5 seconds. If your machine is really overloaded,* it might time out before the pipeline prerolled and we generate an error. A
* better way is to run a mainloop and catch errors there. */
ret = gst_element_get_state (data->pipeline_snapshot,NULL,5 * GST_SECOND);
if (ret == GST_STATE_CHANGE_FAILURE) {
g_print ("Failed to play the file\n");
exit (-1);
}
/* get the duration */
gst_element_query_duration (data->pipeline_snapshot,GST_FORMAT_TIME,&duration);
if (duration != -1)
/* we have a duration,seek to 5% */
position = duration * 5 / 100;
else
/* no duration,seek to 1 second,this Could EOS */
position = 1 * GST_SECOND;
/* seek to the a position in the file. Most files have a black first frame so
* by seeking to somewhere else we have a bigger chance of getting something
* more interesting. An optimisation would be to detect black images and then
* seek a little more */
gst_element_seek_simple (data->pipeline_snapshot,GST_SEEK_FLAG_KEY_UNIT | GST_SEEK_FLAG_FLUSH,position);
/* get the preroll buffer from appsink,this block untils appsink really
* prerolls */
g_signal_emit_by_name (data->snapshot_sink,"pull-preroll",&sample,NULL);
gst_object_unref (data->snapshot_sink);
/* if we have a buffer Now,convert it to a pixbuf. It's possible that we
* don't have a buffer because we went EOS right away or had an error. */
if (sample) {
GstBuffer *buffer;
GdkPixbuf *pixbuf;
GstCaps *caps;
GstStructure *s;
/* get the snapshot buffer format Now. We set the caps on the appsink so
* that it can only be an rgb buffer. The only thing we have not specified
* on the caps is the height,which is dependent on the pixel-aspect-ratio
* of the source material */
caps = gst_sample_get_caps (sample);
if (!caps) {
g_print ("Could not get snapshot format\n");
exit (-1);
}
s = gst_caps_get_structure (caps,0);
/* we need to get the final caps on the buffer to get the size */
res = gst_structure_get_int (s,"width",&width);
res |= gst_structure_get_int (s,"height",&height);
if (!res) {
g_print ("Could not get snapshot dimension\n");
exit (-1);
}
/* create pixmap from buffer and save,gstreamer video buffers have a stride
* that is rounded up to the nearest multiple of 4 */
buffer = gst_sample_get_buffer (sample);
gst_buffer_map (buffer,&map,GST_MAP_READ);
pixbuf = gdk_pixbuf_new_from_data (map.data,GDK_COLORSPACE_RGB,FALSE,8,width,height,GST_ROUND_UP_4 (width * 3),NULL);
/* save the pixbuf */
gdk_pixbuf_save (pixbuf,"snapshot.png","png",&error,NULL);
gst_buffer_unmap (buffer,&map);
} else {
g_print ("Could not make snapshot");
}
/* cleanup and exit */
gst_element_set_state (data->pipeline_snapshot,GST_STATE_NULL);
gst_object_unref (data->pipeline_snapshot);
exit (0);
}
，有人知道我可能做错了什么吗？
解决方法
您在链接时遇到问题，因此您需要查看构建脚本，似乎您忘记了链接库。例如，如果使用cmake，它将如下所示：
target_link_libraries(tutorial-3 gdk_pixbuf-2.0)