[OTHER] Slow times of stopping the camera recording

[ilirosmanaj]

I am working on a module that uses two cameras connected to the board. Both of these cameras run on video stream mode (though for the sake of this mini example I've let one run in capture mode and one in video mode).

This is quite a time sensitive application so I need to make sure that the whole flow runs as quick as possible. However, in my main app I am noticing times when stoping the camera recording takes from 200-400ms, which seems to much.

Sample code:

import time
import io
from threading import Condition
from picamera2 import Picamera2
from picamera2.encoders import MJPEGEncoder, H264Encoder
from picamera2.outputs import FileOutput


def print_time(start_time: float, end_time: float, message: str) -> None:
    print(f"{message} took: {(end_time - start_time):.3f}s")

class StreamingOutput(io.BufferedIOBase):
    def __init__(self):
        self.frame = None
        self.condition = Condition()

    def write(self, buf):
        with self.condition:
            self.frame = buf
            self.condition.notify_all()


STREAMING_OUTPUT = StreamingOutput()

MJPEG_ENCODER = MJPEGEncoder(bitrate=14 * 1000000)
FILE_OUTPUT = FileOutput(STREAMING_OUTPUT)

camera1 = Picamera2(0)
camera2 = Picamera2(1)

start_time = time.perf_counter()
camera1.start_recording(MJPEG_ENCODER, FILE_OUTPUT)
print_time(start_time=start_time, end_time=time.perf_counter(), message="Camera 1 start duration")

start_time = time.perf_counter()
camera2.start()
print_time(start_time=start_time, end_time=time.perf_counter(), message="Camera 2 start duration")

start_time = time.perf_counter()
camera1.stop_recording()
print_time(start_time=start_time, end_time=time.perf_counter(), message="Camera 1 stop duration")

start_time = time.perf_counter()
camera2.stop()
print_time(start_time=start_time, end_time=time.perf_counter(), message="Camera 2 stop duration")

Sample output:

$ python picamera_stop.py 
[3:08:31.847773757] [143896]  INFO Camera camera_manager.cpp:297 libcamera v0.0.5+83-bde9b04f
[3:08:32.118285752] [143922]  INFO RPI vc4.cpp:437 Registered camera /base/soc/i2c0mux/i2c@0/imx708@1a to Unicam device /dev/media4 and ISP device /dev/media1
[3:08:32.118519752] [143922]  INFO RPI pipeline_base.cpp:1101 Using configuration file '/usr/share/libcamera/pipeline/rpi/vc4/rpi_apps.yaml'
[3:08:32.163806008] [143922]  INFO RPI vc4.cpp:437 Registered camera /base/soc/i2c0mux/i2c@1/imx708@1a to Unicam device /dev/media5 and ISP device /dev/media2
[3:08:32.164103342] [143922]  INFO RPI pipeline_base.cpp:1101 Using configuration file '/usr/share/libcamera/pipeline/rpi/vc4/rpi_apps.yaml'
[3:08:32.212697623] [143896]  INFO Camera camera.cpp:1033 configuring streams: (0) 1280x720-XBGR8888 (1) 1536x864-SBGGR10_CSI2P
[3:08:32.215352887] [143922]  INFO RPI vc4.cpp:565 Sensor: /base/soc/i2c0mux/i2c@0/imx708@1a - Selected sensor format: 1536x864-SBGGR10_1X10 - Selected unicam format: 1536x864-pBAA
Camera 1 start duration took: 0.410s
[3:08:32.624291895] [143896]  INFO Camera camera.cpp:1033 configuring streams: (0) 640x480-XBGR8888 (1) 1536x864-SBGGR10_CSI2P
[3:08:32.628214403] [143922]  INFO RPI vc4.cpp:565 Sensor: /base/soc/i2c0mux/i2c@1/imx708@1a - Selected sensor format: 1536x864-SBGGR10_1X10 - Selected unicam format: 1536x864-pBAA
Camera 2 start duration took: 0.305s
Camera 1 stop duration took: 0.206s
Camera 2 stop duration took: 0.019s

Notice how much quicker the stop is compared to stop_recording.

Any ideas?