3
下面的代碼是使用updsink元素通過網絡傳輸mpeg4視頻（使用以下功能的v4l2src元素：width = 640，height = 480，frame rate = 30/1），並且能力值應變爲（width = 352，高度= 288，幀率= 15/1）後按下鍵盤上的「1」。我試圖通過在按下「1」之後暫停管道，然後重新將頂蓋設置爲新值然後再次使管道進入播放狀態，但這對我無效。暫停gstreamer管道並進行更改後返回到播放狀態時不應用任何操作？
我得到暫停管道之前打印的上限值後所做的更改，我可以看到更改上限乃做，但不是當管道被帶到播放狀態再次施加（）
請幫助.......
可以通過鍵入到一個新的終端下列命令回放該流只是運行下面的代碼之前：
GST-發射udpsrc多播組= 127.0.0.1端口= 8999！ mpeg4videoparse！ ffdec_mpeg4！ ffmpegcolorspace！ autovideosink
======================
#include <gst/gst.h>
#include <glib.h>
#include <stdio.h>
#include <glib-object.h>
static gboolean bus_call (GstBus *bus, GstMessage *msg, gpointer data)
{
GMainLoop *loop = (GMainLoop *) data;
switch (GST_MESSAGE_TYPE (msg)) {
case GST_MESSAGE_EOS:
g_print ("End of stream\n");
g_main_loop_quit (loop);
break;
case GST_MESSAGE_ERROR: {
gchar *debug;
GError *error;
gst_message_parse_error (msg, &error, &debug);
g_free (debug);
g_printerr ("Error: %s\n", error->message);
g_error_free (error);
g_main_loop_quit (loop);
break;
}
default: break;
}
return TRUE;
}
int main (int argc, char *argv[])
{
GMainLoop *loop;
GstElement *pipeline, *source, *filter, *vrate, *encoder, *conv, *sink;
GstBus *bus;
GstCaps *filtercaps;
gint width, height, num, denom;
const GstStructure *str;
/* Initialisation */
gst_init (&argc, &argv);
loop = g_main_loop_new (NULL, FALSE);
/* Check input arguments */
if (argc != 2) {
g_printerr ("Usage: %s <Ogg/Vorbis filename>\n", argv[0]);
return -1;
}
/* Create gstreamer elements */
pipeline = gst_pipeline_new ("video-player");
source = gst_element_factory_make ("v4l2src", "file-source");
vrate = gst_element_factory_make ("videorate", "video-rate");
filter = gst_element_factory_make ("capsfilter", "filter");
conv = gst_element_factory_make ("ffmpegcolorspace","converter");
encoder = gst_element_factory_make ("ffenc_mpeg4","mpeg-decoder");
sink = gst_element_factory_make ("udpsink","audio-output");
if (!pipeline || !source || !filter || !vrate || !conv || !encoder || !sink) {
g_printerr ("One element could not be created. Exiting.\n");
return -1;
}
/* Set up the pipeline */
/* we set the input filename to the source element */
filtercaps = gst_caps_new_simple ("video/x-raw-yuv",
"width", G_TYPE_INT, 640,
"height", G_TYPE_INT, 480,
"framerate", GST_TYPE_FRACTION, 30, 1,
NULL);
g_object_set (G_OBJECT (filter), "caps", filtercaps, NULL);
gst_caps_unref (filtercaps);
g_object_set (G_OBJECT (encoder), "bitrate" , 384 , NULL);
g_object_set (G_OBJECT (sink), "host" , argv[1] , NULL);
g_object_set (G_OBJECT (sink), "port" , 8999 , NULL);
g_object_set (G_OBJECT (sink), "async" , FALSE , NULL);
/* we add a message handler */
bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
gst_bus_add_watch (bus, bus_call, loop);
gst_object_unref (bus);
/* we add all elements into the pipeline */
/* file-source | ogg-demuxer | vorbis-decoder | converter | alsa-output */
gst_bin_add_many (GST_BIN (pipeline), source, vrate, filter, conv, encoder, sink, NULL);
/* we link the elements together */
/* file-source -> ogg-demuxer ~> vorbis-decoder -> converter -> alsa-output */
gst_element_link_many (source, vrate, filter, conv, encoder, sink, NULL);
/* Set the pipeline to "playing" state*/
g_print ("Now playing: \n");
gst_element_set_state (pipeline, GST_STATE_PLAYING);
/* Print out the frame size and rate */
str = gst_caps_get_structure (filtercaps, 0);
if (!gst_structure_get_int (str, "width", &width) || !gst_structure_get_int (str, "height", &height) ||
!gst_structure_get_fraction (str, "framerate", &num, &denom))
g_print ("No width/height available\n");
g_print ("The video size of this set of capabilities is %dx%d and the frame rate is %d/%d\n", width, height, num, denom);
/* Pausing the streame */
int in;
if (scanf ("%d", &in) == 1){
g_print ("Now pausing: \n");
gst_element_set_state (pipeline, GST_STATE_PAUSED);
g_assert (GST_STATE (pipeline) == GST_STATE_PAUSED);
g_assert (GST_STATE (source) == GST_STATE_PAUSED);
g_assert (GST_STATE (filter) == GST_STATE_PAUSED);
g_assert (GST_STATE (vrate) == GST_STATE_PAUSED);
g_assert (GST_STATE (encoder) == GST_STATE_PAUSED);
g_assert (GST_STATE (conv) == GST_STATE_PAUSED);
g_assert (GST_STATE (sink) == GST_STATE_PAUSED);
/* apply the alterations to the caps now */
gst_caps_set_simple (filtercaps, "width", G_TYPE_INT, 352, "height", G_TYPE_INT, 288, "framerate", GST_TYPE_FRACTION, 15, 1, NULL);
/* Print out the frame size and rate after alteration*/
str = gst_caps_get_structure (filtercaps, 0);
if (!gst_structure_get_int (str, "width", &width) || !gst_structure_get_int (str, "height", &height) ||
!gst_structure_get_fraction (str, "framerate", &num, &denom))
g_print ("No width/height available\n");
g_print ("The video size of this set of capabilities is %dx%d and the frame rate is %d/%d\n", width, height, num, denom);
/* set back to playing */
gst_element_set_state (pipeline, GST_STATE_PLAYING);
g_assert (GST_STATE (pipeline) == GST_STATE_PLAYING);
g_assert (GST_STATE (source) == GST_STATE_PLAYING);
g_assert (GST_STATE (filter) == GST_STATE_PLAYING);
g_assert (GST_STATE (vrate) == GST_STATE_PLAYING);
g_assert (GST_STATE (encoder) == GST_STATE_PLAYING);
g_assert (GST_STATE (conv) == GST_STATE_PLAYING);
g_assert (GST_STATE (sink) == GST_STATE_PLAYING);
}
/* Iterate */
g_print ("Running...\n");
g_main_loop_run (loop);
/* Out of the main loop, clean up nicely */
g_print ("Returned, stopping playback\n");
gst_element_set_state (pipeline, GST_STATE_NULL);
g_print ("Deleting pipeline\n");
gst_object_unref (GST_OBJECT (pipeline));
return 0;
}
乾杯。
伊布拉