Gstreamer1.0：将decodebin链接到video会话

我有以下管道工作正常：

gst-launch-1.0 -v filesrc location = / home / Videos / sample_h264.mov！ decodebin！ video转换！ autovideosink

我想写一个C程序来做同样的事情。 所以我将以前的管道转换为以下代码：

pipeline = gst_pipeline_new ("video_pipeline"); if (!pipeline) { g_print("Failed to create the pipeline\n"); return -1; } bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline)); watch_id = gst_bus_add_watch (bus, bus_call, loop); gst_object_unref (bus); source = gst_element_factory_make ("filesrc", "file-source"); decoder = gst_element_factory_make ("decodebin", "standard-decoder"); converter = gst_element_factory_make ("videoconvert", "converter"); sink = gst_element_factory_make ("autovideosink", "video-sink"); if (!source || !decoder || !converter || !sink) { g_print("Failed to create one or more pipeline elements\n"); return -1; } g_object_set(G_OBJECT(source), "location", file_name, NULL); gst_bin_add_many (GST_BIN (pipeline), source, decoder, converter, sink, NULL); if (!gst_element_link_many (source, decoder, converter, sink, NULL)) { g_print ("Failed to link some elements!\n"); return -1; } /* run */ ret = gst_element_set_state (pipeline, GST_STATE_PLAYING); if (ret == GST_STATE_CHANGE_FAILURE) { GstMessage *msg; g_print ("Failed to start up pipeline!\n"); /* check if there is an error message with details on the bus */ msg = gst_bus_poll (bus, GST_MESSAGE_ERROR, 0); if (msg) { GError *err = NULL; gst_message_parse_error (msg, &err, NULL); g_print ("ERROR: %s\n", err->message); g_error_free (err); gst_message_unref (msg); } return -1; } 

但是当我尝试将解码器连接到转换器时，我收到错误。 为什么它在命令行中工作正常但不能用C代码工作？

Answer 1

解码器使用称为“有时垫”的东西，它基本上是在满足某个条件时出现的填充，在解码媒体的解码箱中。 gst-launch将自动执行此类操作，但在代码中，您需要注册回调，然后在该回调中链接pad。 另请参阅： GStreamer：如何连接动态焊盘

Answer 2

正如@HarvardGraff所说， decodebin没有静态src pad（参见gst-inspect decodebin ）。

但您也可以在应用中使用启动字符串。 这样GStreamer应该处理所有链接）：

 GstError *error = NULL; GstElement *pipeline = gst_parse_launch("filesrc name=src ! decodebin ! videoconvert ! autovideosink", &error); if (!error) { GstElement filesrc = gst_bin_get_by_name(GST_BIN(pipeline), "src"); g_object_set(filesrc, "location", "/home/Videos/sample_h264.mov", NULL); }