Hello, I’m trying to create a dynamic pipeline that has a trunk that encodes the framebuffer with the omxh264enc element and multiple branches, one for writing to a file and one for sending the encoded data over UDP. The pipeline will look something like this:
gst-launch-1.0 multifilesrc location=/dev/fb0 ! \
rawvideoparse format=8 width=1024 height=768 framerate=25/1 ! \
videoconvert ! \
video/x-raw,format=NV12 ! \
omxh264enc target-bitrate=16384 qp-mode=auto entropy-mode=CABAC min-qp=10 max-qp=51 periodicity-idr=4 ! \
video/x-h264,profile=high ! \
tee name=t ! \
queue ! \
identity eos-after=512 ! \
h264parse ! \
mp4mux ! \
filesink location=test.mp4 \
t. ! \
queue ! \
rtph264pay name=pay0 pt=96 ! \
udpsink host=192.168.1.10 port=6666
This works fine with gst-launch-1.0. I created a C++ application to create the trunk and add branches to the tee after the pipeline was playing. When I attach a branch consisting of queue ! fakesink to the tee, the pipeline gets paused and the omxh264enc element won’t push any more buffers when the pipeline is set back to playing. I think this is an issue with the omxh264enc element, if I remove the omxh264enc element I can add and remove branches and everything works.
This is running on an embedded system using a Zynq Ultrascale+ and the omxh264enc element is using the embedded VCU hardware.
If I set the pipeline to NULL before adding the branch and back to playing after everything works ok, but it sometimes takes ~5s to set the pipeline to NULL which is unacceptable in our use case. Also, I can’t put the omxh264enc element after the tee because the hardware we’re using doesn’t have enough memory bandwidth to support more than one encoding stream at a time.
Here is a code snippet showing how I attach a branch to the tee.
bool GStreamerBranch::attachToPipeline(GstElement *pipeline, GstElement *tee) {
// Get src pad from trunk tee
PLOG_DEBUG << "Attaching branch " << m_Name.toStdString() << " to pipeline";
// Here only for the dot dump
m_Pipeline = pipeline;
m_Tee = tee;
// Get src pad from trunk tee
GstPadTemplate *templ =
gst_element_class_get_pad_template(GST_ELEMENT_GET_CLASS(tee), "src_%u");
m_TeeSrcPad = gst_element_request_pad(tee, templ, NULL, NULL);
GST_DEBUG_BIN_TO_DOT_FILE_WITH_TS(GST_BIN(m_Pipeline), GST_DEBUG_GRAPH_SHOW_ALL,
QString("%1_request_pad").arg(m_Name).toUtf8());
// Add all elements to the pipeline
if (!gst_bin_add(GST_BIN(pipeline), m_Queue)) {
PLOG_ERROR << "Failed to add element " << GST_OBJECT_NAME(m_Queue);
return false;
}
for (GstElement *element : m_Elements) {
if (!gst_bin_add(GST_BIN(pipeline), element)) {
PLOG_ERROR << "Failed to add element " << GST_OBJECT_NAME(element);
return false;
}
}
GST_DEBUG_BIN_TO_DOT_FILE_WITH_TS(GST_BIN(m_Pipeline), GST_DEBUG_GRAPH_SHOW_ALL,
QString("%1_add_elements").arg(m_Name).toUtf8());
// Link our elemets together
// Get first element
GstElement *prevElement = m_Queue;
for (GstElement *element : m_Elements) {
gst_element_link(prevElement, element);
prevElement = element;
}
GST_DEBUG_BIN_TO_DOT_FILE_WITH_TS(GST_BIN(m_Pipeline), GST_DEBUG_GRAPH_SHOW_ALL,
QString("%1_link_elements").arg(m_Name).toUtf8());
// Sync elements with parent
if (!gst_element_sync_state_with_parent(m_Queue)) {
PLOG_ERROR << "Failed to sync queue with parent";
return false;
}
for (GstElement *element : m_Elements) {
if (!gst_element_sync_state_with_parent(element)) {
PLOG_ERROR << "Failed to sync " << gst_element_get_name(element) << " with parent";
return false;
}
}
GST_DEBUG_BIN_TO_DOT_FILE_WITH_TS(GST_BIN(m_Pipeline), GST_DEBUG_GRAPH_SHOW_ALL,
QString("%1_sync_elements").arg(m_Name).toUtf8());
// Attach tee src pad to queue sink pad
GstPad *queueSinkPad = gst_element_get_static_pad(m_Queue, "sink");
gst_pad_link(m_TeeSrcPad, queueSinkPad);
gst_object_unref(queueSinkPad);
GST_DEBUG_BIN_TO_DOT_FILE_WITH_TS(GST_BIN(m_Pipeline), GST_DEBUG_GRAPH_SHOW_ALL,
QString("%1_link_tee_queue").arg(m_Name).toUtf8());
return true;
}
The dot file created after the gst_element_sync_state_with_parent calls shows that the pipeline is paused ([=]->[=]), with the newly added fakesink showing [-]->[>].
Is there any way to not pause the pipeline when adding a branch to the tee?
Maybe I’m missing a step adding the branch?
Thanks for any help!