从 tee 中删除分支时将 EoS 发送到文件接收器

Question

我写了一个v4l2src同时显示和录制的代码。我的管道看起来像：

               / [queue] ! [videosink]
v4l2src ! tee !  
               \ [queue] ! [filesink]

目前我可以同时显示+记录，也可以随意动态启动和停止记录分支（使用ctrl+c sigint handler for start/stop）。我在 answer, and parts of this 文章中使用了@thiagoss 的建议。

问题：

我面临的唯一问题是在取消链接时将 EoS 发送到 filesink 分支。我将 gst_element_send_event(-->?<--, gst_event_new_eos()); 事件发送到哪个元素？我无法将它发送到整个管道，因为 1. 分支现在已取消链接，并且 2. 即使我这样做，它也会关闭视频接收器。

我尝试过的：删除 mp4mux 并保存 h264 编码视频后，我可以使用 gst-playbin 观看视频，这意味着分支创建和取消链接正在正确进行。

以下是我的代码。

#include <string.h>
#include <gst/gst.h>
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>

// v4l2src ! tee name=t t. ! x264enc ! mp4mux ! filesink location=/home/rish/Desktop/okay.264 t. ! videoconvert ! autovideosink

static GMainLoop *loop;
static GstElement *pipeline, *src, *tee, *encoder, *muxer, *filesink, *videoconvert, *videosink, *queue_record, *queue_display;
static GstBus *bus;
static GstPad *teepad;
static gboolean recording = FALSE;
static gint counter = 0;

static gboolean
message_cb (GstBus * bus, GstMessage * message, gpointer user_data)
{
switch (GST_MESSAGE_TYPE (message)) {
case GST_MESSAGE_ERROR:{
  GError *err = NULL;
  gchar *name, *debug = NULL;

  name = gst_object_get_path_string (message->src);
  gst_message_parse_error (message, &err, &debug);

  g_printerr ("ERROR: from element %s: %s\n", name, err->message);
  if (debug != NULL)
    g_printerr ("Additional debug info:\n%s\n", debug);

  g_error_free (err);
  g_free (debug);
  g_free (name);

  g_main_loop_quit (loop);
  break;
}
case GST_MESSAGE_WARNING:{
    GError *err = NULL;
    gchar *name, *debug = NULL;

    name = gst_object_get_path_string (message->src);
    gst_message_parse_warning (message, &err, &debug);

    g_printerr ("ERROR: from element %s: %s\n", name, err->message);
    if (debug != NULL)
    g_printerr ("Additional debug info:\n%s\n", debug);

    g_error_free (err);
    g_free (debug);
    g_free (name);
    break;
}
case GST_MESSAGE_EOS:{
    g_print ("Got EOS\n");
    g_main_loop_quit (loop);
    gst_element_set_state (pipeline, GST_STATE_NULL);
    g_main_loop_unref (loop);
    gst_object_unref (pipeline);
    exit(0);
    break;
}
default:
    break;
}

return TRUE;
}

static GstPadProbeReturn unlink_cb(GstPad *pad, GstPadProbeInfo *info, gpointer user_data) {
g_print("Unlinking...");
GstPad *sinkpad;
sinkpad = gst_element_get_static_pad (queue_record, "sink");
gst_pad_unlink (teepad, sinkpad);
gst_object_unref (sinkpad);

gst_element_send_event(filesink, gst_event_new_eos());

sleep(1);
gst_bin_remove(GST_BIN (pipeline), queue_record);
gst_bin_remove(GST_BIN (pipeline), encoder);
// gst_bin_remove(GST_BIN (pipeline), muxer);
gst_bin_remove(GST_BIN (pipeline), filesink);

gst_element_set_state(queue_record, GST_STATE_NULL);
gst_element_set_state(encoder, GST_STATE_NULL);
// gst_element_set_state(muxer, GST_STATE_NULL);
gst_element_set_state(filesink, GST_STATE_NULL);

gst_object_unref(queue_record);
gst_object_unref(encoder);
// gst_object_unref(muxer);
gst_object_unref(filesink);

gst_element_release_request_pad (tee, teepad);
gst_object_unref (teepad);

g_print("Unlinked\n");

return GST_PAD_PROBE_REMOVE;
}

void stopRecording() {
    g_print("stopRecording\n");
    gst_pad_add_probe(teepad, GST_PAD_PROBE_TYPE_IDLE, unlink_cb, NULL, (GDestroyNotify) g_free);
    recording = FALSE;
}

 void startRecording() {
g_print("startRecording\n");
GstPad *sinkpad;
GstPadTemplate *templ;

templ = gst_element_class_get_pad_template(GST_ELEMENT_GET_CLASS(tee), "src_%u");
teepad = gst_element_request_pad(tee, templ, NULL, NULL);
queue_record = gst_element_factory_make("queue", "queue_record");
encoder = gst_element_factory_make("x264enc", NULL);
// muxer = gst_element_factory_make("mp4mux", NULL);
filesink = gst_element_factory_make("filesink", NULL);
char *file_name = (char*) malloc(100*sizeof(char));
sprintf(file_name, "/home/rish/Desktop/rec%d.mp4", counter++);
g_print(file_name);
g_object_set(filesink, "location", file_name, NULL);
g_object_set(encoder, "tune", 4, NULL);
free(file_name);

gst_bin_add_many(GST_BIN(pipeline), gst_object_ref(queue_record), gst_object_ref(encoder), gst_object_ref(filesink), NULL);
gst_element_link_many(queue_record, encoder, filesink, NULL);

gst_element_sync_state_with_parent(queue_record);
gst_element_sync_state_with_parent(encoder);
// gst_element_sync_state_with_parent(muxer);
gst_element_sync_state_with_parent(filesink);

sinkpad = gst_element_get_static_pad(queue_record, "sink");
gst_pad_link(teepad, sinkpad);
gst_object_unref(sinkpad);

recording = TRUE;
}

int sigintHandler(int unused) {
g_print("You ctrl-c!\n");
if (recording)
    stopRecording();
else
    startRecording();
return 0;
}

int main(int argc, char *argv[])
{
signal(SIGINT, sigintHandler);
gst_init (&argc, &argv);

pipeline = gst_pipeline_new(NULL);
src = gst_element_factory_make("v4l2src", NULL);
tee = gst_element_factory_make("tee", "tee");
queue_display = gst_element_factory_make("queue", "queue_display");
videoconvert = gst_element_factory_make("videoconvert", NULL);
videosink = gst_element_factory_make("autovideosink", NULL);

if (!pipeline || !src || !tee || !videoconvert || !videosink || !queue_display) {
    g_error("Failed to create elements");
    return -1;
}

gst_bin_add_many(GST_BIN(pipeline), src, tee, queue_display, videoconvert, videosink, NULL);
if (!gst_element_link_many(src, tee, NULL) 
    || !gst_element_link_many(tee, queue_display, videoconvert, videosink, NULL)) {
    g_error("Failed to link elements");
    return -2;
}

startRecording();
loop = g_main_loop_new(NULL, FALSE);

bus = gst_pipeline_get_bus(GST_PIPELINE (pipeline));
gst_bus_add_signal_watch(bus);
g_signal_connect(G_OBJECT(bus), "message", G_CALLBACK(message_cb), NULL);
gst_object_unref(GST_OBJECT(bus));

gst_element_set_state(pipeline, GST_STATE_PLAYING);

g_print("Starting loop\n");
g_main_loop_run(loop);

return 0;
}

Answer 1

你应该把它发送给编码器，这样他们就可以正确地完成他们的工作，他们会把它转发给 muxer，muxer 也需要通过编写 headers 的部分来包装文件只能写在最后。

此外，删除睡眠，您将需要确保 filesink posted 一条 EOS 消息以确保它已全部处理并且可以安全地删除它们。您可能需要为管道启用 message-forward，否则它会保留 EOS 消息，直到所有接收器 post 他们的 EOS（由于视频接收器，这在您的情况下不会发生）。

Answer 2

我在单独的垃圾箱中安装了带有编码器的文件接收器，并覆盖了 handle_message (How to override handle_message in GstBin?) 以忽略 EOS 并将其转换为自定义消息。

初始EOS被发送到那个bin的ghostpad。该 pad 连接到编码器（该 bin 包含编码器、多路复用器和文件接收器）。

从 tee 中删除分支时将 EoS 发送到文件接收器

Sending EoS to filesink while removing branch from tee

gstreamer