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我正在尝试使用 gstreamer appsrc 通过网络播放视频流。

我在这里找到了很好的例子。

gstreamer appsrc 测试应用程序

http://amarghosh.blogspot.kr/2012/01/gstreamer-appsrc-in-action.html

使用上面的示例，我可以使用 Xlib 在 X Window 中播放视频。当管道设置为 PLAYING 状态时，会以某种方式发出“need-data”信号，并在 start_feed 回调函数中从视频文件读取的数据注入到 appsrc GstBuffer 并播放示例视频。

我正在尝试从网络而不是文件获取数据，所以我认为简单的回显服务器以与上述完全相同的方式读取视频文件，并在发生连接时将数据发送到客户端。客户端应该获取这些数据并放入appsrc。

我的问题是如何将流数据放入 appsrc 管道？有没有人给出任何建议或好的参考？

这是使用上述链接示例的工作示例代码。

// http://amarghosh.blogspot.kr/2012/01/gstreamer-appsrc-in-action.html
// http://www.cs.odu.edu/~cs476/Xlib/xlines.c
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <stdio.h>
#include <unistd.h> // sleep()
#include <stdbool.h>

#include <gst/gst.h>
#include <gst/app/gstappsrc.h>
#include <gst/app/gstappbuffer.h>
#include <gst/interfaces/xoverlay.h>

#define BUFF_SIZE (640*480*3)//(1024)
#define BORDER_WIDTH    2

#define DEBUG   printf

typedef unsigned int  uint32;
typedef unsigned char uint8;

typedef struct {
    GstPipeline *pipeline;
    GstAppSrc *src;
    GstElement *sink;
    GstElement *decoder;
    GstElement *ffmpeg;
    GstElement *videosink;
    GMainLoop *loop;
    guint sourceid;
    FILE *file;
} gst_app_t;

static gst_app_t gst_app;

static Window child_window = 0;
static Window window = 0;

static gboolean read_data(gst_app_t *app)
{
    GstBuffer *buffer;
    guint8 *ptr;
    gint size;
    GstFlowReturn ret;

    ptr = g_malloc(BUFF_SIZE);
    g_assert(ptr);

    size = fread(ptr, 1, BUFF_SIZE, app->file);

    if(size == 0){
    ret = gst_app_src_end_of_stream(app->src);
    DEBUG("eos returned %d at %d\n", ret, __LINE__);
    return FALSE;
    }

    buffer = gst_buffer_new();
    GST_BUFFER_MALLOCDATA(buffer) = ptr;
    GST_BUFFER_SIZE(buffer) = size;
    GST_BUFFER_DATA(buffer) = GST_BUFFER_MALLOCDATA(buffer);

    ret = gst_app_src_push_buffer(app->src, buffer);

    if(ret !=  GST_FLOW_OK){
        DEBUG("push buffer returned %d for %d bytes \n", ret, size);
        return FALSE;
    }

    if(size != BUFF_SIZE){
        ret = gst_app_src_end_of_stream(app->src);
        DEBUG("eos returned %d at %d\n", ret, __LINE__);
        return FALSE;
    }

    return TRUE;
}

static void start_feed (GstElement * pipeline, guint size, gst_app_t *app)
{
    if (app->sourceid == 0) {
        DEBUG ("start feeding\n");
        app->sourceid = g_idle_add ((GSourceFunc) read_data, app);
    }
}

static void stop_feed (GstElement * pipeline, gst_app_t *app)
{
    if (app->sourceid != 0) {
        DEBUG ("stop feeding\n");
        g_source_remove (app->sourceid);
        app->sourceid = 0;
    }
}

static void on_pad_added(GstElement *element, GstPad *pad)
{
    GstCaps *caps;
    GstStructure *str;
    gchar *name;
    GstPad *ffmpegsink;
    GstPadLinkReturn ret;

    DEBUG("pad added\n");

    caps = gst_pad_get_caps(pad);
    str = gst_caps_get_structure(caps, 0);

    g_assert(str);

    name = (gchar*)gst_structure_get_name(str);

    DEBUG("pad name %s\n", name);

    if(g_strrstr(name, "video")){

        ffmpegsink = gst_element_get_pad(gst_app.ffmpeg, "sink");
        g_assert(ffmpegsink);
        ret = gst_pad_link(pad, ffmpegsink);
        DEBUG("pad_link returned %d\n", ret);
        gst_object_unref(ffmpegsink);
    }
    gst_caps_unref(caps);
}

static gboolean bus_callback(GstBus *bus, GstMessage *message, gpointer *ptr)
{
    gst_app_t *app = (gst_app_t*)ptr;

    switch(GST_MESSAGE_TYPE(message))
    {
    case GST_MESSAGE_ELEMENT: {
        gst_x_overlay_set_window_handle (GST_X_OVERLAY (GST_MESSAGE_SRC(message)), child_window);
        }
        break;

    case GST_MESSAGE_ERROR:
        {
        gchar *debug;
        GError *err;

        gst_message_parse_error(message, &err, &debug);
        DEBUG("Error %s\n", err->message);
        g_error_free(err);
        g_free(debug);
        g_main_loop_quit(app->loop);
        }
        break;

    case GST_MESSAGE_WARNING:
        {
        gchar *debug;
        GError *err;
        gchar *name;

        gst_message_parse_warning(message, &err, &debug);
        DEBUG("Warning %s\nDebug %s\n", err->message, debug);

        name = GST_MESSAGE_SRC_NAME(message);

        DEBUG("Name of src %s\n", name ? name : "nil");
        g_error_free(err);
        g_free(debug);
        }
        break;

    case GST_MESSAGE_EOS:
        DEBUG("End of stream\n");
        g_main_loop_quit(app->loop);
        break;

    case GST_MESSAGE_STATE_CHANGED:
        break;

    default:
        DEBUG("got message %s\n", \
        gst_message_type_get_name (GST_MESSAGE_TYPE (message)));
        break;
    }

    return TRUE;
}

static gboolean terminate_playback (GstElement * loop)
{
    DEBUG ("Terminating playback\n");
    g_main_loop_quit ((GMainLoop *)loop);
    return FALSE;
}

int gstreamer_init(int argc, char *argv[])
{
    gst_app_t *app = &gst_app;

    GstBus *bus;
    GstStateChangeReturn state_ret;

    app->file = fopen(argv[1], "r");

    g_assert(app->file);

    /* initialization */
    gst_init((int)0, NULL);

    app->loop = g_main_loop_new(NULL, FALSE);

    /* create elements */
    app->pipeline = (GstPipeline *)gst_pipeline_new("my_pipeline");

    app->src = (GstAppSrc *)gst_element_factory_make("appsrc", "myappsrc");
    app->decoder = gst_element_factory_make("decodebin2", "mydecoder");
    app->ffmpeg = gst_element_factory_make("ffmpegcolorspace", "myffmpeg");
    app->videosink = gst_element_factory_make("autovideosink", "myvideosink");

    if (!app->videosink) {
        DEBUG ("output could not be found - check your install\n");
    }

    g_assert(app->src);
    g_assert(app->decoder);
    g_assert(app->ffmpeg);
    g_assert(app->videosink);

    bus = gst_pipeline_get_bus(GST_PIPELINE(app->pipeline));
    gst_bus_add_watch(bus, (GstBusFunc)bus_callback, app);
    gst_object_unref(bus);

    g_signal_connect(app->decoder, "pad-added",
                G_CALLBACK(on_pad_added), app->ffmpeg);

    //gst_app_src_set_emit_signals(app->src, true);
    g_signal_connect(app->src, "need-data", G_CALLBACK(start_feed), app);
    g_signal_connect(app->src, "enough-data", G_CALLBACK(stop_feed), app);

    gst_bin_add_many (GST_BIN (app->pipeline), (GstElement *)app->src,
                app->decoder, app->ffmpeg, app->videosink, NULL);

    /* link everything together */
    if (!gst_element_link((GstElement *)app->src, app->decoder)) {

        DEBUG ("Failed to link one or more elements!\n");
        return -1;
    }

    if(!gst_element_link(app->ffmpeg, app->videosink)){
        DEBUG("failed to link ffmpeg and videosink");
        return -1;
    }

    state_ret = gst_element_set_state((GstElement *)app->pipeline, GST_STATE_PLAYING);
    if (state_ret == GST_STATE_CHANGE_FAILURE) {

        DEBUG("Failed to start up pipeline!\n");
        return 1;
    }

    DEBUG("set state returned %d\n", state_ret);

    //g_timeout_add (15000, (GSourceFunc) terminate_playback, app->loop);

    g_main_loop_run(app->loop);

    state_ret = gst_element_set_state((GstElement *)app->pipeline, GST_STATE_NULL);
    DEBUG("set state null returned %d\n", state_ret);
    gst_object_unref(app->pipeline);

    return 1;
}

/* 
 * gst-launch filesrc location=test.avi ! decodebin2 ! ffmpegcolorspace ! autovideosink
 *
 * 1. dependency library install
 *    $ sudo apt-get install gstreamer0.10-plugins-bad
 *    $ sudo apt-get install gstreamer0.10-ffmpeg
 *
 * 2. compile
 *    $ gcc hello.c -o hello -lX11 `pkg-config --cflags --libs gstreamer-0.10 gstreamer-app-0.10` -lgstinterfaces-0.10
 *
 * 3. how to run program 
 *    $ ./hello <video_file_name>
 *    $  GST_DEBUG=appsrc:5 ./hello ./hbo_dtc_sd.ts 
 */

int main(int argc, char *argv[])
{
    Display *disp;
    Window root;
    long fgcolor, bgcolor;

    GC gc;
    XGCValues gc_val;
    XEvent event;
    char *msg = "Hello, World!";
    int screen;

    disp = XOpenDisplay(NULL);
    if (disp == NULL) {
        fprintf(stderr, "Cannot open display\n");
        exit(1);
    }

    screen = DefaultScreen(disp);

    root = RootWindow(disp, screen);
    fgcolor = BlackPixel(disp, screen);
    bgcolor = WhitePixel(disp, screen);

    window = XCreateSimpleWindow(disp, root, 100, 100, 1000, 840, 1,
                    fgcolor, bgcolor);

    child_window = XCreateSimpleWindow(disp, window, 100, 100, 800, 600, 1,
                    fgcolor, bgcolor);

    gc_val.foreground = fgcolor;
    gc_val.background = bgcolor;
    gc = XCreateGC(disp, child_window, GCForeground|GCBackground, &gc_val);

    XSelectInput(disp, child_window, ExposureMask | KeyPressMask);

    g_warning("map xwindow");
    //XMapWindow(disp, window);
    XMapWindow(disp, window);
    XMapWindow(disp, child_window);
    XSync(disp, FALSE);

    //XDrawLine (disp, window, gc, 0, 0, 1000, 800); 
    //XDrawLine (disp, child_window, gc, 0, 0, 800, 600); 

    gstreamer_init(argc, argv);

    XDestroyWindow( disp, window );
    XDestroyWindow( disp, child_window );

    XCloseDisplay( disp );

    return 0;
}
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1 回答 1

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您将希望至少有一个其他线程（在每一端）来处理通过套接字（如 TCP 或 UDP，如果在本地网络上）的通信。这通常有一个阻塞调用来等待数据包。要发送数据，您可以形成一个 gstreamer tee 和队列，然后是一个 appsrc 来缓冲/发送数据到一个套接字。要接收，您可以将数据从套接字拉到缓冲区。请记住，操作系统的套接字缓冲区相对较小，如果您不能足够快地从中拉出数据包，或者推入一个太快，则会丢弃数据包。因此缓冲区。

在一个NEED_DATA信号上，您使用pushBuffer(). 在一个ENOUGH_DATA信号上，您可以继续缓冲或处理它，无论您的应用程序需要做什么。

于 2013-02-20T15:36:08.997 回答