举几个代码中使用shmsrc的例子

1. 使用GStreamer中的shmsrc读取共享内存数据：

import gi
gi.require_version('Gst', '1.0')
from gi.repository import Gst

Gst.init(None)

# 创建GStreamer的pipeline
pipeline = Gst.Pipeline()

# 创建shmsrc element
shmsrc = Gst.ElementFactory.make("shmsrc", None)
shmsrc.set_property("socket-path", "/tmp/shm")
shmsrc.set_property("is-live", True)

# 添加shmsrc到pipeline中
pipeline.add(shmsrc)

# 创建appsink element，用于处理shmsrc读取的数据
appsink = Gst.ElementFactory.make("appsink", None)
appsink.set_property("emit-signals", True)

# 添加appsink到pipeline中
pipeline.add(appsink)

# 连接shmsrc和appsink
shmsrc.link(appsink)

# 启动pipeline
pipeline.set_state(Gst.State.PLAYING)

# 从appsink中读取shmsrc读取的数据
def on_new_sample(appsink):
    sample = appsink.emit("pull-sample")
    buffer = sample.get_buffer()
    data = buffer.extract_dup(0, buffer.get_size())
    print("Received data:", data)

appsink.connect("new-sample", on_new_sample)

2. 使用OpenCV中的VideoCapture和shmsrc读取共享内存中的视频数据：

import cv2
import numpy as np

# 定义共享内存的大小和格式
shm_size = 640 * 480 * 3
shm_format = "BGR"

# 创建GStreamer的pipeline
cap = cv2.VideoCapture("shmsrc socket-path=/tmp/shm do-timestamp=true ! video/x-raw,format={0},width=640,height=480,framerate=30/1 ! decodebin ! videoconvert ! appsink".format(shm_format), cv2.CAP_GSTREAMER)

while True:
    # 从shmsrc读取数据
    ret, frame = cap.read()

    # 处理读取的数据
    if ret:
        cv2.imshow("frame", frame)
        if cv2.waitKey(1) & 0xFF == ord('q'):
            break
    else:
        break

cap.release()
cv2.destroyAllWindows()