我试图使用gstreamer从一个来源拍摄几张快照。使用以下代码,我成功地获取了9个文件但是从源代码中获得了EOS(这实际上是正常的,它是由num-buffers参数引起的):
m
但我的问题是我希望在这9个快照之后继续直播。我在发球台和排队能力方面寻找,但我无法做任何事情。我想我必须用一个我暂停和播放的multifilesink元素做一个动态管道,但是如何告诉它只做9个文件? (max-files = 9不起作用导致生成的文件被覆盖)
由于
答案 0 :(得分:0)
当然,您需要在计数缓冲区中添加探针,并在您不需要时删除一些元素。
我在你的结构中添加了几个字段:
int count;
GstPad *blockpad;
GstElement *fakesink;
一旦我们保存了9个快照,我又创建了一个接收器来替换管道末端:
data.fakesink = gst_element_factory_make ("fakesink", "fakesink");
我将探测添加到data.convert
的srcpad:
data.count = 0;
data.blockpad = gst_element_get_static_pad (data.convert, "src");
gst_pad_add_probe (data.blockpad, GST_PAD_PROBE_TYPE_BLOCK_DOWNSTREAM | GST_PAD_PROBE_TYPE_BUFFER,
pad_probe_cb, &data, NULL);
我使用了GStreamer 1.x,因此我将ffenc_pgm
元素替换为avenc_pgm
,将ffmpegcolorspace
元素替换为identity
:
#include <stdio.h>
#include <gst/gst.h>
/* Structure to contain all our information, so we can pass it to callbacks */
typedef struct _CustomData {
int count;
GstPad *blockpad;
GstElement *pipeline;
GstElement *source;
GstElement *convert;
GstElement *sink;
GstElement *fakesink;
GstElement *encode;
} CustomData;
static GstPadProbeReturn
pad_probe_cb (GstPad * pad, GstPadProbeInfo * info, gpointer user_data) {
CustomData *data = user_data;
data->count++;
printf("%d\n", data->count);
if (data->count > 9)
{
gst_element_set_state (data->encode, GST_STATE_NULL);
gst_bin_remove (GST_BIN (data->pipeline), data->encode);
gst_element_set_state (data->sink, GST_STATE_NULL);
gst_bin_remove (GST_BIN (data->pipeline), data->sink);
gst_bin_add (GST_BIN (data->pipeline), data->fakesink);
gst_element_link (data->convert, data->fakesink);
gst_element_set_state (data->fakesink, GST_STATE_PLAYING);
gst_pad_remove_probe (pad, GST_PAD_PROBE_INFO_ID (info));
return GST_PAD_PROBE_REMOVE;
}
else
return GST_PAD_PROBE_PASS;
}
int main(int argc, char *argv[]) {
CustomData data;
GstBus *bus;
GstMessage *msg;
GstStateChangeReturn ret;
gboolean terminate = FALSE;
/* Initialize GStreamer */
gst_init (&argc, &argv);
/* Create the elements */
data.source = gst_element_factory_make ("videotestsrc", "source");
data.convert = gst_element_factory_make ("identity", "convert");
data.encode = gst_element_factory_make ("avenc_pgm", "encode");
data.sink = gst_element_factory_make ("multifilesink", "sink");
data.fakesink = gst_element_factory_make ("fakesink", "fakesink");
/* Create the empty pipeline */
data.pipeline = gst_pipeline_new ("test-pipeline");
if (!data.pipeline || !data.source || !data.convert || !data.sink) {
g_printerr ("Not all elements could be created.\n");
return -1;
}
/* Build the pipeline. Note that we are NOT linking the source at this
* point. We will do it later. */
gst_bin_add_many (GST_BIN (data.pipeline), data.source, data.convert , data.encode, data.sink, NULL);
if (!gst_element_link_many (data.source, data.convert, data.encode, data.sink, NULL)) {
g_printerr ("Elements could not be linked.\n");
gst_object_unref (data.pipeline);
return -1;
}
/* Modify the source's properties */
g_object_set (data.source, "pattern", 0, NULL);
g_object_set (data.source, "num-buffers", 20, NULL);
g_object_set (data.sink, "location", "frame%05d.pgm", NULL);
data.count = 0;
data.blockpad = gst_element_get_static_pad (data.convert, "src");
gst_pad_add_probe (data.blockpad, GST_PAD_PROBE_TYPE_BLOCK_DOWNSTREAM | GST_PAD_PROBE_TYPE_BUFFER,
pad_probe_cb, &data, NULL);
/* Start playing */
ret = gst_element_set_state (data.pipeline, GST_STATE_PLAYING);
if (ret == GST_STATE_CHANGE_FAILURE) {
g_printerr ("Unable to set the pipeline to the playing state.\n");
gst_object_unref (data.pipeline);
return -1;
}
/* Wait until error or EOS */
bus = gst_element_get_bus (data.pipeline);
msg = gst_bus_timed_pop_filtered (bus, GST_CLOCK_TIME_NONE, GST_MESSAGE_ERROR | GST_MESSAGE_EOS);
/* Parse message */
if (msg != NULL) {
GError *err;
gchar *debug_info;
switch (GST_MESSAGE_TYPE (msg)) {
case GST_MESSAGE_ERROR:
gst_message_parse_error (msg, &err, &debug_info);
g_printerr ("Error received from element %s: %s\n", GST_OBJECT_NAME (msg->src), err->message);
g_printerr ("Debugging information: %s\n", debug_info ? debug_info : "none");
g_clear_error (&err);
g_free (debug_info);
break;
case GST_MESSAGE_EOS:
g_print ("End-Of-Stream reached.\n");
break;
default:
/* We should not reach here because we only asked for ERRORs and EOS */
g_printerr ("Unexpected message received.\n");
break;
}
gst_message_unref (msg);
}
/* Free resources */
gst_object_unref (bus);
gst_element_set_state (data.pipeline, GST_STATE_NULL);
gst_object_unref (data.pipeline);
return 0;
}