我正在学习Gstreamer,无论我通过Gstreamer工具取得了什么成就,我都在尝试使用C语言在gstreamer应用程序中实现同样的功能。
以下命令成功流式传输了mp4视频文件: gst-launch-1.0.exe -v filesrc location = file.mp4! qtdemux! h264parse! avdec_h264!视频转换!自动视频接收器
我用C代码尝试了同样的操作,还使用了“添加了填充”的Elements Signals创建填充并链接到下一个元素,即解析器(h264parser)。
因此,它因流停止而失败,原因未经协商。
完整输出: 现在播放:file.mp4 跑步... 为解复用器创建了一个新的打击垫视频_0 元素多路分配将链接到解析器 错误:内部数据流错误。 调试信息:../gst/isomp4/qtdemux.c(6607):gst_qtdemux_loop():/ GstPipeline:video-play / GstQTDemux:demux: 流停止,原因未协商(-4) 返回,正在停止播放... 正在释放管道... 已完成。再见!
#include <gst/gst.h>
#include <stdlib.h>
#include <string.h>
#define INPUT_FILE "file.mp4"
static gboolean bus_call(GstBus *bus, GstMessage *msg, gpointer data)
{
GMainLoop *loop = (GMainLoop *)data;
switch (GST_MESSAGE_TYPE(msg)) {
gchar *debug;
GError *error;
case GST_MESSAGE_EOS:
g_print("End of stream\n");
g_main_loop_quit(loop);
break;
case GST_MESSAGE_ERROR:
gst_message_parse_error(msg, &error, &debug);
g_free(debug);
g_printerr("Error: %s\n", error->message);
g_printerr("Debug Information: %s\n", debug);
g_error_free(error);
g_main_loop_quit(loop);
break;
default:
break;
}
return TRUE;
}
static void on_pad_added(GstElement *element, GstPad *pad, gpointer data)
{
gchar *name;
GstElement *parse = (GstElement *)data;
name = gst_pad_get_name(pad);
g_print("A new pad %s was created for %s\n", name, gst_element_get_name(element));
g_free(name);
g_print("element %s will be linked to %s\n",
gst_element_get_name(element),
gst_element_get_name(parse));
gst_element_link(element, parse);
}
int main(int argc, char *argv[])
{
GMainLoop *loop;
GstElement *pipeline, *source, *demux, *parser, *decoder, *sink, *fpssink;
GstBus *bus;
guint bus_watch_id;
const gchar *input_file = INPUT_FILE;
/* Initialization */
gst_init(&argc, &argv);
loop = g_main_loop_new(NULL, FALSE);
/* Create gstreamer elements */
pipeline = gst_pipeline_new("video-play");
source = gst_element_factory_make("filesrc", "file-source");
demux = gst_element_factory_make("qtdemux", "demux");
parser = gst_element_factory_make("h264parse", "h264-parser");
decoder = gst_element_factory_make("avdec_h264", "decoder");
sink = gst_element_factory_make("d3dvideosink", "video-output");
if (!pipeline || !source || !demux || !parser || !decoder || !sink) {
g_printerr("One element could not be created. Exiting.\n");
return -1;
}
/* Set input video file for source element */
g_object_set(G_OBJECT(source), "location", input_file, NULL);
/* we add a message handler */
bus = gst_pipeline_get_bus(GST_PIPELINE(pipeline));
bus_watch_id = gst_bus_add_watch(bus, bus_call, loop);
gst_object_unref(bus);
/* Add all elements into the pipeline */
/* pipeline---[ filesrc + qtdemux + h264parse + avdec_h264 + d3dvideosink ] */
gst_bin_add_many(GST_BIN(pipeline), source, demux, parser, decoder, sink, NULL);
/* Link the elements filesrc->demux together */
if (gst_element_link(source, demux) != TRUE) {
g_printerr("Element source->demux could not be linked.\n");
gst_object_unref(pipeline);
return -1;
}
/* h264parse -> avdec_h264 -> d3dvideosink */
if (gst_element_link_many(parser, decoder, sink, NULL) != TRUE) {
g_printerr("Many Elements could not be linked.\n");
gst_object_unref(pipeline);
return -1;
}
g_signal_connect(demux, "pad-added", G_CALLBACK(on_pad_added), parser);
/* Set the pipeline to "playing" state */
g_print("Now playing: %s\n", input_file);
if (gst_element_set_state(pipeline,
GST_STATE_PLAYING) == GST_STATE_CHANGE_FAILURE) {
g_printerr("Unable to set the pipeline to the playing state.\n");
gst_object_unref(pipeline);
return -1;
}
g_print("Running...\n");
g_main_loop_run(loop);
/* Free resources and change state to NULL */
gst_object_unref(bus);
g_print("Returned, stopping playback...\n");
gst_element_set_state(pipeline, GST_STATE_NULL);
g_print("Freeing pipeline...\n");
gst_object_unref(GST_OBJECT(pipeline));
g_print("Completed. Goodbye!\n");
return 0;
}
请让我知道如何将这些键盘链接到h264parser元素以流式传输视频文件。如有可能,请说明这些键盘在Gstreamer工具和应用程序中如何工作
答案 0 :(得分:0)
以下命令成功流式传输了mp4视频文件: gst-launch-1.0.exe -v filesrc location = file.mp4! qtdemux! h264parse ! avdec_h264!视频转换!自动视频接收器
理想情况下,您的管道应该是:
gst-launch-1.0.exe -v filesrc location = file.mp4! qtdemux名称= d d.video_0!排队! h264parse! avdec_h264!视频转换! 自动视频接收器
如果您检查qtdemux (gst-inspect-1.0 qtdemux),您会注意到SINK垫具有以下上限:
功能: 视频/快速时间 视频/ mj2 音频/ x-m4a application / x-3gp
如果检查h264parse (gst-inspect-1.0 h264parse),您会注意到SRC垫具有以下上限:
SRC模板:“ src” 可用性:始终 能力: 视频/ x-h264 解析为:true 流格式:{(string)avc,(string)avc3,(string)byte-stream} 对齐方式:{(string)au,(string)nal}
当您尝试将Qtdemux的水槽垫链接到h264parse的src垫时,可能必须收集视频盖才能与h264parse连接。
我已使用以下代码在“添加了键盘的”信号中将qtdemux与h264parse链接起来:
static void pad_added_handler(GstElement *src, GstPad *new_pad, App *data) {
GstPadLinkReturn ret;
GstCaps *new_pad_caps = NULL;
GstStructure *new_pad_struct = NULL;
const gchar *new_pad_type = NULL;
/* Check the new pad's type */
new_pad_caps = gst_pad_get_current_caps(new_pad);
new_pad_struct = gst_caps_get_structure(new_pad_caps, 0);
new_pad_type = gst_structure_get_name(new_pad_struct);
GST_PAD_NAME(new_pad), new_pad_type, gst_caps_to_string(new_pad_caps));
if (g_str_has_prefix(new_pad_type, "video/x-h264")) {
ret = gst_pad_link(new_pad, sink_pad_video);
}
}
注意: 您可能需要链接大写过滤器,以过滤视频源所需的视频功能,或者仅尝试以下条件: if(g_str_has_prefix(new_pad_type,“ 视频”)){}
但是我不确定添加队列如何解决您的问题。
希望这会有所帮助。
答案 1 :(得分:0)
我刚刚编辑并修复了Shafeer的答案。
这是有效的代码:
static void pad_added_handler(GstElement *src, GstPad *new_pad, gpointer *data) {
GstPadLinkReturn ret;
GstCaps *new_pad_caps = nullptr;
GstStructure *new_pad_struct = nullptr;
const gchar *new_pad_type = nullptr;
GstElement *h264parse = (GstElement *) data;
/* Check the new pad's type */
new_pad_caps = gst_pad_get_current_caps(new_pad);
new_pad_struct = gst_caps_get_structure(new_pad_caps, 0);
new_pad_type = gst_structure_get_name(new_pad_struct);
if (g_str_has_prefix(new_pad_type, "video/x-h264")) {
GstPad *sink_pad_video = gst_element_get_static_pad (h264parse, "sink");
ret = gst_pad_link(new_pad, sink_pad_video);
}
}