Segmentation Fault with Caps Filter in DeepStream Pipeline + RGBA Color Format Issue

• Hardware Platform (Jetson / GPU) - DGPU
• DeepStream Version - 7
• JetPack Version (valid for Jetson only) - NA
• TensorRT Version - 8.6.1
• NVIDIA GPU Driver Version (valid for DGPU only) - 535.216.01
• Issue Type( questions, new requirements, bugs) - questions

Hello @yuweiw,

I am facing an issue while trying to save frames from the DeepStream pipeline. I am encountering the following error:

Error: “Currently we only support RGBA color format.”

To resolve this, I added a caps filter before the pgie (primary inference) element, as suggested in some previous threads. However, this leads to a segmentation fault (core dumped) issue every time I try to use the caps filter.

And also I tried adding the caps-filter at different stages.

Here is the part of the code where I am working with the caps filter:


import sys
sys.path.append('../')
import platform
import configparser

import gi
gi.require_version('Gst', '1.0')
from gi.repository import GLib, Gst
#from common.platform_info import PlatformInfo
from common.bus_call import bus_call
import numpy as np
import pyds
import cv2

MUXER_BATCH_TIMEOUT_USEC = 33000





def pgie_src_pad_buffer_probe(pad, info, u_data):
    gst_buffer = info.get_buffer()
    if not gst_buffer:
        print("Unable to get GstBuffer")
        return

    batch_meta = pyds.gst_buffer_get_nvds_batch_meta(hash(gst_buffer))
    l_frame = batch_meta.frame_meta_list
    while l_frame is not None:
        try:
            frame_meta = pyds.NvDsFrameMeta.cast(l_frame.data)
        except StopIteration:
            break

        n_frame = pyds.get_nvds_buf_surface(hash(gst_buffer), frame_meta.batch_id)
        frame_copy = np.array(n_frame, copy=True, order='C')
        frame_copy = cv2.cvtColor(frame_copy, cv2.COLOR_RGBA2BGR)

        l_obj = frame_meta.obj_meta_list
        while l_obj is not None:
            try:
                obj_meta = pyds.NvDsObjectMeta.cast(l_obj.data)
                print(f"Detected Object: {obj_meta.obj_label}, Confidence: {obj_meta.confidence:.2f}")
            except StopIteration:
                break
            try:
                l_obj = l_obj.next
            except StopIteration:
                break
        try:
            l_frame = l_frame.next
        except StopIteration:
            break

    return Gst.PadProbeReturn.OK



def main(args):
    if len(args) < 1:
        sys.stderr.write(f"usage: {args[0]} <h264_elementary_stream>\n")
        sys.exit(1)

    #platform_info = PlatformInfo()
    Gst.init(None)

    # Create Pipeline
    pipeline = Gst.Pipeline()
    if not pipeline:
        sys.stderr.write("Unable to create Pipeline\n")
        sys.exit(1)

    def on_pad_added(demuxer, pad, h264parser):
    # Only link if not already linked
        if not h264parser.get_static_pad("sink").is_linked():
            pad.link(h264parser.get_static_pad("sink"))

    # Elements
    source = Gst.ElementFactory.make("filesrc", "file-source")
    demuxer = Gst.ElementFactory.make("qtdemux", "qt-demuxer")  
    h264parser = Gst.ElementFactory.make("h264parse", "h264-parser")
    decoder = Gst.ElementFactory.make("nvv4l2decoder", "nvv4l2-decoder")
    streammux = Gst.ElementFactory.make("nvstreammux", "stream-muxer")
    pgie = Gst.ElementFactory.make("nvinfer", "primary-inference")
    nvvidconv = Gst.ElementFactory.make("nvvideoconvert", "nvvideo-converter")
    # capsfilter = Gst.ElementFactory.make("capsfilter", "capsfilter")
    # caps = Gst.Caps.from_string("video/x-raw(memory:NVMM), format=RGBA")
    # capsfilter.set_property("caps", caps)

    nvosd = Gst.ElementFactory.make("nvdsosd", "nv-onscreendisplay")
    sink = Gst.ElementFactory.make("nveglglessink", "nvvideo-renderer")

    if not all([source, h264parser, decoder, streammux, pgie, nvvidconv, nvosd, sink]):
        sys.stderr.write("Unable to create one or more elements\n")
        sys.exit(1)

    # Set Properties
    source.set_property("location", args[1])
    streammux.set_property("width", 1920)
    streammux.set_property("height", 1080)
    streammux.set_property("batch-size", 1)
    streammux.set_property("batched-push-timeout", MUXER_BATCH_TIMEOUT_USEC)
    pgie.set_property("config-file-path", "/home/dstream/Documents/Detection_Deep_Stream_App/configs/cofig_infer_yolov8_forum.txt")  # Ensure this file exists

    # Add Elements to Pipeline
    pipeline.add(source)
    pipeline.add(demuxer)
    pipeline.add(h264parser)
    pipeline.add(decoder)
    pipeline.add(streammux)
    pipeline.add(pgie)
    pipeline.add(nvvidconv)
    #pipeline.add(capsfilter)
    pipeline.add(nvosd)
    pipeline.add(sink)

    # Link Elements
    source.link(demuxer)
    source.link(demuxer)
    #demuxer.connect("pad-added", lambda demux, pad: pad.link(h264parser.get_static_pad("sink")))
    demuxer.connect("pad-added", lambda d, p: on_pad_added(d, p, h264parser))
    h264parser.link(decoder)  
    #h264parser.link(decoder)

    # Link decoder to streammux
    sinkpad = streammux.get_request_pad("sink_0")
    srcpad = decoder.get_static_pad("src")
    srcpad.link(sinkpad)

    # Link the rest
    streammux.link(pgie)
    pgie.link(nvvidconv)
    nvvidconv.link(nvosd)

    #capsfilter.link(nvosd)
    nvosd.link(sink)

    # Add Probe for Detection Metadata
    pgie_src_pad = pgie.get_static_pad("src")
    if pgie_src_pad:
        pgie_src_pad.add_probe(Gst.PadProbeType.BUFFER, pgie_src_pad_buffer_probe, 0)

    # Event Loop and Bus Handling
    loop = GLib.MainLoop()
    bus = pipeline.get_bus()
    bus.add_signal_watch()
    bus.connect("message", bus_call, loop)

    # Start Pipeline
    pipeline.set_state(Gst.State.PLAYING)
    try:
        loop.run()
    except KeyboardInterrupt:
        pass
    finally:
        pipeline.set_state(Gst.State.NULL)

if __name__ == "__main__":
    sys.exit(main(sys.argv))


When I don’t use the caps filter, I receive the error message: “Currently we only support RGBA color format.” But if I try to use the caps filter, the pipeline crashes with a segmentation fault.

Issue:

  • Without caps filter: I am receiving the error “Currently we only support RGBA color format.”
  • With caps filter: The pipeline crashes with a segmentation fault (core dumped).

Request for Guidance:

  • How can I solve the issue and successfully save frames from the DeepStream pipeline?
  • At which specific stage of the DeepStream pipeline can I save frames?
  • Is there a specific approach for saving frames in any format from the DeepStream pipeline?

Could you refer to our deepstream_imagedata-multistream.py to learn how to save images? You can run this sample first, then do some customization youself.