VideoReceiver.cc

/*=====================================================================

QGroundControl Open Source Ground Control Station

(c) 2009, 2015 QGROUNDCONTROL PROJECT <http://www.qgroundcontrol.org>

This file is part of the QGROUNDCONTROL project

    QGROUNDCONTROL is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    QGROUNDCONTROL is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with QGROUNDCONTROL. If not, see <http://www.gnu.org/licenses/>.

======================================================================*/

/**
 * @file
 *   @brief QGC Video Receiver
 *   @author Gus Grubba <mavlink@grubba.com>
 */

#include "VideoReceiver.h"
#include <QDebug>

VideoReceiver::VideoReceiver(QObject* parent)
    : QObject(parent)
    , _pipeline(NULL)
    , _videoSink(NULL)
{

}

VideoReceiver::~VideoReceiver()
{
    stop();
    setVideoSink(NULL);
}

void VideoReceiver::setVideoSink(GstElement* sink)
{
    if (_videoSink) {
        gst_object_unref(_videoSink);
        _videoSink = NULL;
    }
    if (sink) {
        _videoSink = sink;
        gst_object_ref_sink(_videoSink);
    }
}

void VideoReceiver::start()
{
    if (_uri.isEmpty()) {
        qCritical() << "VideoReceiver::start() failed because URI is not specified";
        return;
    }

    if (_videoSink == NULL) {
        qCritical() << "VideoReceiver::start() failed because video sink is not set";
        return;
    }

    stop();

    bool running = false;

    GstElement*     dataSource  = NULL;
    GstCaps*        caps        = NULL;
    GstElement*     demux       = NULL;
    GstElement*     parser      = NULL;
    GstElement*     decoder     = NULL;

    do {
        if ((_pipeline = gst_pipeline_new("receiver")) == NULL) {
            break;
        }

        if ((dataSource = gst_element_factory_make("udpsrc", "udp-source")) == NULL) {
            break;
        }

        if ((caps = gst_caps_from_string("application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264")) == NULL) {
            break;
        }

        g_object_set(G_OBJECT(dataSource), "uri", qPrintable(_uri), "caps", caps, NULL);

        if ((demux = gst_element_factory_make("rtph264depay", "rtp-h264-depacketizer")) == NULL) {
            break;
        }

        if ((parser = gst_element_factory_make("h264parse", "h264-parser")) == NULL) {
            break;
        }

        if ((decoder = gst_element_factory_make("avdec_h264", "h264-decoder")) == NULL) {
            break;
        }

        gst_bin_add_many(GST_BIN(_pipeline), dataSource, demux, parser, decoder, _videoSink, NULL);

        if (gst_element_link_many(dataSource, demux, parser, decoder, _videoSink, NULL) != TRUE) {
            break;
        }

        dataSource = demux = parser = decoder = NULL;

        GstBus* bus = NULL;

        if ((bus = gst_pipeline_get_bus(GST_PIPELINE(_pipeline))) != NULL) {
            gst_bus_add_watch(bus, _onBusMessage, this);
            gst_object_unref(bus);
            bus = NULL;
        }

        running = gst_element_set_state(_pipeline, GST_STATE_PLAYING) != GST_STATE_CHANGE_FAILURE;

    } while(0);

    if (caps != NULL) {
        gst_caps_unref(caps);
        caps = NULL;
    }

    if (!running) {
        qCritical() << "VideoReceiver::start() failed";

        if (decoder != NULL) {
            gst_object_unref(decoder);
            decoder = NULL;
        }

        if (parser != NULL) {
            gst_object_unref(parser);
            parser = NULL;
        }

        if (demux != NULL) {
            gst_object_unref(demux);
            demux = NULL;
        }

        if (dataSource != NULL) {
            gst_object_unref(dataSource);
            dataSource = NULL;
        }

        if (_pipeline != NULL) {
            gst_object_unref(_pipeline);
            _pipeline = NULL;
        }
    }
}

void VideoReceiver::stop()
{
    if (_pipeline != NULL) {
        gst_element_set_state(_pipeline, GST_STATE_NULL);
        gst_object_unref(_pipeline);
        _pipeline = NULL;
    }
}

void VideoReceiver::setUri(const QString & uri)
{
    stop();
    _uri = uri;
}

void VideoReceiver::_onBusMessage(GstMessage* msg)
{
    switch (GST_MESSAGE_TYPE(msg)) {
    case GST_MESSAGE_EOS:
        stop();
        break;
    case GST_MESSAGE_ERROR:
        do {
            gchar* debug;
            GError* error;
            gst_message_parse_error(msg, &error, &debug);
            g_free(debug);
            qCritical() << error->message;
            g_error_free(error);
        } while(0);
        stop();
        break;
    default:
        break;
    }
}

gboolean VideoReceiver::_onBusMessage(GstBus* bus, GstMessage* msg, gpointer data)
{
    Q_UNUSED(bus)
    Q_ASSERT(msg != NULL && data != NULL);
    VideoReceiver* pThis = (VideoReceiver*)data;
    pThis->_onBusMessage(msg);
    return TRUE;
}