Gstreamer命令行管道到C++代码

Question

I have a gstreamer pipeline that works in the command line and I am trying to convert it to C++ code. I have most of it, except I need to be able to write the -e flag in C++ but I'm not sure how to add it to the pipeline. Here is the command line

gst-launch-1.0 -e udpsrc port=8000 ! application/x-rtp, encoding-name=H264, payload=109 ! tee name=t t. ! rtph264depay ! h264parse ! queue ! avdec_h264 ! videoconvert ! autovideosink t. ! rtph264depay ! h264parse ! queue ! mp4mux ! filesink location=!/camera.mp4"

Here is the C++ code I have. This works to display a live stream from a camera and write a mp4 file, however it is not readable. The -e flag makes the file able to be played.

// [1] Create Elements
pipeline = gst_pipeline_new("xvoverlay");
src = gst_element_factory_make("udpsrc", NULL);
caps = gst_element_factory_make("capsfilter", NULL);
tee = gst_element_factory_make("tee", "tee");

// Display
rtpDepay = gst_element_factory_make("rtph264depay", NULL);
h264Parse = gst_element_factory_make("h264parse", NULL);
displayQueue = gst_element_factory_make("queue", NULL);
decoder = gst_element_factory_make("avdec_h264", NULL);
videoConvert = gst_element_factory_make("videoconvert", NULL);
upload = gst_element_factory_make("d3d11upload", NULL);
sink = gst_element_factory_make("d3d11videosink", NULL);

// Record
recordRtpDepay = gst_element_factory_make("rtph264depay", NULL);
recordH264Parse = gst_element_factory_make("h264parse", NULL);
recordQueue = gst_element_factory_make("queue", "save_queue");
mux = gst_element_factory_make("mp4mux", NULL);
filesink = gst_element_factory_make("filesink", NULL);

// [2] Set element properties
g_object_set(src, "port", port, NULL);
g_object_set(caps, "caps", gst_caps_from_string("application/x-rtp, encoding-name=H264, payload=109"), NULL);
g_object_set(filesink, "location", "camera.mp4", NULL);
//g_object_set(mux, "faststart", true, NULL);

// [3] Add elements to pipeline and link together
//gst_bin_add_many(GST_BIN(pipeline), src, caps, rtpDepay, h264Parse, displayQueue, decoder, videoConvert, upload, sink, NULL);
//gst_element_link_many(src, caps, rtpDepay, h264Parse, displayQueue, decoder, videoConvert, upload, sink, NULL);
gst_bin_add_many(GST_BIN(pipeline), src, caps, tee, rtpDepay, h264Parse, displayQueue, decoder, videoConvert, upload, sink, recordRtpDepay, recordH264Parse, recordQueue, mux, filesink, NULL);
if (!gst_element_link_many(src, caps, tee, NULL)
    || !gst_element_link_many(tee, rtpDepay, h264Parse, displayQueue, decoder, videoConvert, upload, sink, NULL)
    || !gst_element_link_many(tee, recordRtpDepay, recordH264Parse, recordQueue, mux, filesink, NULL))
{
    qDebug() << "Failed to link elements";
}

How do I add a -e flag as a GstElement? I've searched online and I can't find anyone trying to do this programatically with that flag.

Answer 1

The -e flag sends and EOS at the end of the stream. While processing the EOS message, the video writer will write the header information needed for the video to be playable.

The solution is to change the way you stop your pipeline. Instead of however you currently do it (you did not include that code), you should get access to the srcpad of your udpsrc object, and then send a GST_EVENT_EOS . This will signal to the application that you have ended the stream. Each element will process what it needs to, and then forward that event further down the pipeline. It will reach the video writer, which will then write the needed header information to your videofile, before entering a paused state.

Answer 2

On shutdown, call

gst_element_send_event(src, gst_event_new_eos ())

This will send EOS event downstream and write the required meta data.

Answer 3

it's easier to use gst_parse_launch and then gst_bin_get_by_name on elements you want to do fancy things with.

The -e flags can be given in gst_init