Gstreamer Python Documentation

Gstreamer python library Docs

from UAV.imports import *   # TODO why is this relative import on nbdev_export?
import cv2
import gi
import numpy as np
from imutils import resize

from PIL import Image


import time
# from dataloader import LoadImages, resize
from pathlib import Path
# import logging

# gi.require_version('Gst', '1.0')

from gstreamer import GstPipeline, GstContext, GstVidSrcValve, GstApp, Gst, GstVideo
import gstreamer.utils as gst_utils
from UAV.utils import *
from UAV.imports import *   # TODO why is this relative import on nbdev_export?
import time

---

GstVidSrcValve

 GstVidSrcValve (command:str, leaky:bool=False, max_buffers_size:int=100,
                 loglevel:gstreamer.gst_tools.LogLevels=20)

GstVideoSourceValve is a wrapper around a GStreamer pipeline that provides get and set methods for valve states.

	Type	Default	Details
command	str		Gst_launch string
leaky	bool	False	If True -> use LeakyQueue
max_buffers_size	int	100	Max queue size
loglevel	LogLevels	20

Setup the pipeline commands

The valve is used to pause the video, this way we can multiplex the video stream so to conserve bandwidth

---

GstVidSrcValve.set_valve_state

 GstVidSrcValve.set_valve_state (valve_name:str, dropstate:bool)

Set the state of a valve in the pipeline

	Type	Details
valve_name	str	Name of the valve in the pipeline
dropstate	bool	True = drop, False = pass

The valve is used to pause the video, this way we can multiplex the video stream so to conserve bandwidth

---

GstVidSrcValve.get_valve_state

 GstVidSrcValve.get_valve_state (valve_name:str)

Get the state of a valve in the pipeline

	Type	Details
valve_name	str	Name of the valve in the pipeline

DEFAULT_PIPELINE = gst_utils.to_gst_string([
            'videotestsrc pattern=ball is-live=true num-buffers=1000 ! tee name=t',
            't.',
            'queue leaky=2 ! valve name=myvalve drop=False ! video/x-raw,format=I420,width=640,height=480',
            'videoconvert',
            # 'x264enc tune=zerolatency noise-reduction=10000 bitrate=2048 speed-preset=superfast',
            'x264enc tune=zerolatency',
            'rtph264pay ! udpsink host=127.0.0.1 port=5000',
            't.',
            'queue leaky=2 ! videoconvert ! videorate drop-only=true ! video/x-raw,framerate=5/1,format=(string)BGR',
            'videoconvert ! appsink name=mysink emit-signals=true  sync=false async=false  max-buffers=2 drop=true ',
        ])

command = DEFAULT_PIPELINE
width, height, num_buffers = 1920, 1080, 40
with GstVidSrcValve(command, leaky=True) as pipeline:
    buffers = []
    count = 0
    dropstate = False
    while len(buffers) < num_buffers:
        time.sleep(0.1)
        count += 1
        if count % 10 == 0:
            dropstate = not dropstate
            pipeline.set_valve_state("myvalve", dropstate)
            print(f' {dropstate = }, {count = }')
        buffer = pipeline.pop()
        if buffer:
            buffers.append(buffer)
            # if len(buffers) % 10 == 0:
            #     print(f'Got: {len(buffers)} buffers of {pipeline.queue_size}')
    print('Got: {} buffers'.format(len(buffers)))
    
_,axs = plt.subplots(2,2,figsize=(12,10))
for i,ax in enumerate(axs.flatten()): show_image(buffers[i*5].data, ax=ax, title=f'image {i*5}')

 dropstate = True, count = 10
 dropstate = False, count = 20
 dropstate = True, count = 30
 dropstate = False, count = 40
Got: 40 buffers

Show the video on screen using two pipelines

SRC_PIPELINE = gst_utils.to_gst_string([
            'videotestsrc pattern=ball is-live=true num-buffers=1000 ! video/x-raw,framerate=5/1 !  tee name=t',
            't.',
            'queue leaky=2 ! valve name=myvalve drop=False ! video/x-raw,format=I420,width=640,height=480',
            # 'textoverlay text="Frame: " valignment=top halignment=left shaded-background=true',
            # 'timeoverlay valignment=top halignment=right shaded-background=true',

            'videoconvert',
            # 'x264enc tune=zerolatency noise-reduction=10000 bitrate=2048 speed-preset=superfast',
            'x264enc tune=zerolatency',
            'rtph264pay ! udpsink host=127.0.0.1 port=5000',
            't.',
            'queue leaky=2 ! videoconvert ! videorate drop-only=true ! video/x-raw,framerate=5/1,format=(string)BGR',
            'videoconvert ! appsink name=mysink emit-signals=true  sync=false async=false  max-buffers=2 drop=true ',
        ])
print(SRC_PIPELINE)
SINK_PIPELINE = gst_utils.to_gst_string([
            'udpsrc port=5000 ! application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264, payload=(int)96',
            'rtph264depay ! avdec_h264',
            'fpsdisplaysink',
            # 'autovideosink',
        ])

videotestsrc pattern=ball is-live=true num-buffers=1000 ! video/x-raw,framerate=5/1 !  tee name=t t. ! queue leaky=2 ! valve name=myvalve drop=False ! video/x-raw,format=I420,width=640,height=480 ! videoconvert ! x264enc tune=zerolatency ! rtph264pay ! udpsink host=127.0.0.1 port=5000 t. ! queue leaky=2 ! videoconvert ! videorate drop-only=true ! video/x-raw,framerate=5/1,format=(string)BGR ! videoconvert ! appsink name=mysink emit-signals=true  sync=false async=false  max-buffers=2 drop=true 

num_buffers = 40
with GstPipeline(SINK_PIPELINE) as rcv_pipeline:
    with GstVidSrcValve(SRC_PIPELINE, leaky=True) as pipeline:
        buffers = []
        count = 0
        dropstate = False
        while len(buffers) < num_buffers:
            time.sleep(0.1)
            count += 1
            if count % 10 == 0:
                print(f'Count = : {count}')
                dropstate = not dropstate
                pipeline.set_valve_state("myvalve", dropstate)
            buffer = pipeline.pop()
            if buffer:

                buffers.append(buffer)
                if len(buffers) % 10 == 0:
                    print(f'Got: {len(buffers)} buffers of {pipeline.queue_size}')
        print('Got: {} buffers'.format(len(buffers)))

Count = : 10
Got: 10 buffers of 0
Count = : 20
Got: 20 buffers of 0
Count = : 30
Got: 30 buffers of 0
Count = : 40
Got: 40 buffers of 0
Got: 40 buffers

# assert False, 'stop here'