GStreamer设置pipeline的状态返回GST_STATE_CHANGE_ASYNC。

[neicole]

GStreamer设置pipeline的状态返回GST_STATE_CHANGE_ASYNC。
程序一直在loop运行（不结束），但是却在bus上最后的消息是元素的状态改为PAUSED。

本来想实现mp4的截取功能，filesrc->qtdemux->mp4mux->filesink
打算下一步是通过seek实现（不确定可以不可以）控制qtdemux的时间。

本程序运行后，不能自动结束，按理来说，当文件完全读取完毕后，能自动结束程序。
以下是Debug信息：

/root/QtProgram/GStreamer/video_cut/video_cut 启动中...
STATE CHANGE:  NAME:  "mp4filesink"  Old State:  "NULL"  New State:  "READY" 
STATE CHANGE:  NAME:  "mp4mux"  Old State:  "NULL"  New State:  "READY" 
STATE CHANGE:  NAME:  "qtdemux"  Old State:  "NULL"  New State:  "READY" 
STATE CHANGE:  NAME:  "mp4filesrc"  Old State:  "NULL"  New State:  "READY" 
STATE CHANGE:  NAME:  "my-pipeline"  Old State:  "NULL"  New State:  "READY" 
STATE CHANGE:  NAME:  "mp4mux"  Old State:  "READY"  New State:  "PAUSED" 
STREAM_STATUS  Element: "qtdemux"  Status:  "GST_STREAM_STATUS_TYPE_CREATE" 
STATE CHANGE:  NAME:  "qtdemux"  Old State:  "READY"  New State:  "PAUSED" 
STATE CHANGE:  NAME:  "mp4filesrc"  Old State:  "READY"  New State:  "PAUSED" 
STREAM_STATUS  Element: "qtdemux"  Status:  "GST_STREAM_STATUS_TYPE_ENTER" 
In->S_CbPadAdded(...) 
caps: "video/x-h264, stream-format=(string)avc, alignment=(string)au, level=(string)4, profile=(string)high, codec_data=(buffer)01640028ffe1001867640028acb402802dd808800000030080000019478c195001000568cf32c8b0, width=(int)1280, height=(int)720, framerate=(fraction)25/1, pixel-aspect-ratio=(fraction)1/1" 
video/x-h264   padSink 0x10c0b20 
pad link success 
In->S_CbPadAdded(...) 
caps: "audio/mpeg, mpegversion=(int)4, framed=(boolean)true, stream-format=(string)raw, level=(string)2, base-profile=(string)lc, profile=(string)lc, codec_data=(buffer)1210, rate=(int)44100, channels=(int)2" 
audio/mpeg   padSink 0x10c0f80 
pad link success 

以下是源码：

#include <gst/gst.h>
#include <glib.h>

#include <QDebug>
#include <QString>

#define IF_NULL_REUTRN(OBJECT) if (NULL == OBJECT) { qDebug() << "OBJECT==NULL"; return -1;}


/// help class
class CPipeElem
{
public:
    GMainLoop*      loop;
    GstElement*     elemPipeline;
    GstBus*         bus;
    GstElement*     elemFileSrc;
    GstElement*     elemQtDemux;
    GstElement*     elemMp4mux;
    GstElement*     elemFileSink;

public:
    CPipeElem():loop(NULL), elemPipeline(NULL), bus(NULL),
        elemFileSrc(NULL), elemQtDemux(NULL), elemMp4mux(NULL),elemFileSink(NULL)
    {
    }
};


/// function declaration
static void S_CallBackMessage(GstBus *bus, GstMessage *message, gpointer user_data);
static void S_CbPadAdded(GstElement *element, GstPad *pad, gpointer user_data);


/// main function
gint main (gint argc, gchar *argv[])
{
    CPipeElem pipeElem;


    ///////////////////////////////////////////             init          //////////////////////////////////////////////////


    /// init gstreamer
    gst_init (&argc, &argv);


    ///////////////////////////////////////////          init  elem        //////////////////////////////////////////////////


    /// loop
    pipeElem.loop = g_main_loop_new(NULL, FALSE);
    IF_NULL_REUTRN(pipeElem.loop);

    /// pipeline
    pipeElem.elemPipeline = gst_pipeline_new("my-pipeline");
    IF_NULL_REUTRN(pipeElem.elemPipeline);

    /// bus
    pipeElem.bus = gst_pipeline_get_bus (GST_PIPELINE (pipeElem.elemPipeline));
    IF_NULL_REUTRN(pipeElem.bus);
    gst_bus_add_signal_watch(pipeElem.bus);
    g_signal_connect (pipeElem.bus, "message", (GCallback)S_CallBackMessage, &pipeElem); ///// pipeline的message

    /// filesrc elem (mp4 file)
    pipeElem.elemFileSrc = gst_element_factory_make("filesrc", "filesrc");
    IF_NULL_REUTRN(pipeElem.elemFileSrc);
    g_object_set (G_OBJECT(pipeElem.elemFileSrc), "name", "mp4filesrc", NULL);
    g_object_set (G_OBJECT(pipeElem.elemFileSrc), "location", "/root/QtProgram/GStreamer/video_cut/wildlife_h264.mp4", NULL);

    /// demux elem
    pipeElem.elemQtDemux = gst_element_factory_make("qtdemux", "qtdemux");
    IF_NULL_REUTRN(pipeElem.elemQtDemux);
    g_object_set (G_OBJECT(pipeElem.elemQtDemux), "name", "qtdemux", NULL);

    /// mux elem
    pipeElem.elemMp4mux = gst_element_factory_make("mp4mux", "mp4mux");
    IF_NULL_REUTRN(pipeElem.elemMp4mux);
    g_object_set (G_OBJECT(pipeElem.elemMp4mux), "name", "mp4mux", NULL);

    /// file sink elem
    pipeElem.elemFileSink = gst_element_factory_make("filesink", "mp4filesink");
    IF_NULL_REUTRN(pipeElem.elemFileSink);
    g_object_set (G_OBJECT(pipeElem.elemFileSink), "name", "mp4filesink", NULL);
    g_object_set (G_OBJECT(pipeElem.elemFileSink), "location", "/root/QtProgram/GStreamer/video_cut/cut.mp4", NULL);


    ///////////////////////////////////////////        create pipeline       //////////////////////////////////////////////////

    /// add to pipeline
    gst_bin_add_many(GST_BIN (pipeElem.elemPipeline),
                     pipeElem.elemFileSrc, pipeElem.elemQtDemux,
                     pipeElem.elemMp4mux, pipeElem.elemFileSink,
                     NULL);

    /// link in pipeline
    gst_element_link_many(pipeElem.elemFileSrc, pipeElem.elemQtDemux, NULL);
    gst_element_link_many(pipeElem.elemMp4mux, pipeElem.elemFileSink, NULL);

    g_signal_connect(pipeElem.elemQtDemux, "pad-added", (GCallback)S_CbPadAdded, &pipeElem);


    ///////////////////////////////////////////        run pipeline       //////////////////////////////////////////////////

    int nRes = gst_element_set_state(pipeElem.elemPipeline, GST_STATE_PLAYING);
    if (!(nRes == GST_STATE_CHANGE_ASYNC || nRes == GST_STATE_CHANGE_SUCCESS))
    {
            qDebug() << "Set State Error:" << nRes;
    }

    g_main_loop_run(pipeElem.loop);


    ///////////////////////////////////////////        uninit pipeline       //////////////////////////////////////////////////

    gst_element_set_state (pipeElem.elemPipeline, GST_STATE_NULL);
    gst_object_unref(pipeElem.bus);
    gst_object_unref(pipeElem.elemPipeline);
    g_main_loop_unref(pipeElem.loop);

    return 0;
}


static void S_CallBackMessage(GstBus *, GstMessage *message, gpointer user_data)
{
    CPipeElem* pPipeElem = (CPipeElem*)user_data;

    switch (GST_MESSAGE_TYPE (message))
    {

    case GST_MESSAGE_ERROR:
    {
        gchar *pDebug;
        GError *pError;

        gst_message_parse_error (message, &pError, &pDebug);
        g_free (pDebug);
        qDebug() << "Error: " << QString(pError->message);
        g_error_free(pError);
        g_main_loop_quit(pPipeElem->loop);

        break;
    }

    case GST_MESSAGE_EOS:
    {
        qDebug() << "GST_MESSAGE_EOS";

        g_main_loop_quit (pPipeElem->loop);

        break;
    }

    case GST_MESSAGE_STATE_CHANGED:
    {
        GstState stateOld;
        GstState stateNew;

        gst_message_parse_state_changed(message, &stateOld, &stateNew, NULL);
        qDebug() << "STATE CHANGE: "
                 << "NAME: " << QString(GST_OBJECT_NAME (message->src))
                 << " Old State: "  << QString(gst_element_state_get_name (stateOld))
                 << " New State: "  << QString(gst_element_state_get_name (stateNew));
        break;
    }

    case GST_MESSAGE_STREAM_STATUS:
    {
        QMap<GstStreamStatusType, QString> mapStreamStatus;
        mapStreamStatus[GST_STREAM_STATUS_TYPE_CREATE] = "GST_STREAM_STATUS_TYPE_CREATE";
        mapStreamStatus[GST_STREAM_STATUS_TYPE_ENTER] = "GST_STREAM_STATUS_TYPE_ENTER";
        mapStreamStatus[GST_STREAM_STATUS_TYPE_LEAVE] = "GST_STREAM_STATUS_TYPE_LEAVE";
        mapStreamStatus[GST_STREAM_STATUS_TYPE_DESTROY] = "GST_STREAM_STATUS_TYPE_DESTROY";

        mapStreamStatus[GST_STREAM_STATUS_TYPE_START] = "GST_STREAM_STATUS_TYPE_START";
        mapStreamStatus[GST_STREAM_STATUS_TYPE_PAUSE] = "GST_STREAM_STATUS_TYPE_PAUSE";
        mapStreamStatus[GST_STREAM_STATUS_TYPE_STOP] = "GST_STREAM_STATUS_TYPE_STOP";

        GstStreamStatusType statusType;
        GstElement          *elemOwner;

        gst_message_parse_stream_status(message, &statusType, &elemOwner);
        qDebug() << "STREAM_STATUS "
                 << "Element:" << QString(gst_element_get_name(elemOwner))
                 << " Status: " << mapStreamStatus[statusType];

        break;
    }


    default:

        break;
    }

    return;
}



static void S_CbPadAdded(GstElement *, GstPad *padSrc, gpointer user_data)
{
    qDebug() << "In->S_CbPadAdded(...)";

    CPipeElem* pPipeElem = (CPipeElem*) user_data;


    //// Get the pads string
    GstCaps *capsQuery = gst_pad_query_caps(padSrc, NULL);
    gchar *cstrCaps = gst_caps_to_string(capsQuery);

    QString strCaps(cstrCaps);
    qDebug() << "caps:" << strCaps;

    g_free(cstrCaps);
    gst_caps_unref(capsQuery);

    GstPad* padSink = NULL;

    /// 视频处理
    if(strCaps.contains("video/x-h264"))
    {
        padSink = gst_element_get_request_pad(pPipeElem->elemMp4mux, "video_%u");
        qDebug() << "video/x-h264   padSink" << padSink;
    }

    /// 音频处理
    else if(strCaps.contains("audio/mpeg"))
    {
        padSink = gst_element_get_request_pad(pPipeElem->elemMp4mux, "audio_%u");
        qDebug() << "audio/mpeg   padSink" << padSink;
    }

    int nRes = 500;
    if (padSink != NULL)
    {
        nRes = gst_pad_link(padSrc, padSink);
    }
    if (nRes == 500)
    {
        qDebug() << "no pad to link";
    }
    else if (GST_PAD_LINK_OK != nRes)
    {
        qDebug() << "pad link error: " << nRes; /// GST_PAD_LINK_WAS_LINKED
    }
    else
    {
        qDebug() << "pad link success";
    }

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

    return;
}