update gstreamer recommended pipeline (#1682)

README.md

@@ -737,31 +737,47 @@ Videos can be published with `VideoWriter`:
 ```python
 import cv2
 import numpy as np
-from time import sleep
+from time import sleep, time
 
-fps = 20
+fps = 15
 width = 800
 height = 600
+colors = [
+    (0, 0, 255),
+    (255, 0, 0),
+    (0, 255, 0),
+]
 
 out = cv2.VideoWriter('appsrc ! videoconvert' + \
-    ' ! x264enc speed-preset=ultrafast bitrate=600 key-int-max=40' + \
+    ' ! x264enc speed-preset=ultrafast bitrate=600 key-int-max=' + str(fps * 2) + \
+    ' ! video/x-h264,profile=baseline' + \
     ' ! rtspclientsink location=rtsp://localhost:8554/mystream',
     cv2.CAP_GSTREAMER, 0, fps, (width, height), True)
 if not out.isOpened():
     raise Exception("can't open video writer")
 
+curcolor = 0
+start = time()
+
 while True:
     frame = np.zeros((height, width, 3), np.uint8)
 
-    # create a red rectangle
+    # create a rectangle
+    color = colors[curcolor]
+    curcolor += 1
+    curcolor %= len(colors)
     for y in range(0, int(frame.shape[0] / 2)):
         for x in range(0, int(frame.shape[1] / 2)):
-            frame[y][x] = (0, 0, 255)
+            frame[y][x] = color
 
     out.write(frame)
     print("frame written to the server")
 
-    sleep(1 / fps)
+    now = time()
+    diff = (1 / fps) - now - start
+    if diff > 0:
+        sleep(diff)
+    start = now
 ```
 
 ### From a UDP stream
@@ -770,7 +786,7 @@ The server supports ingesting UDP/MPEG-TS packets (i.e. MPEG-TS packets sent wit
 
 ```
 gst-launch-1.0 -v mpegtsmux name=mux alignment=1 ! udpsink host=238.0.0.1 port=1234 \
-videotestsrc ! video/x-raw,width=1280,height=720 ! x264enc speed-preset=ultrafast bitrate=6000 key-int-max=40 ! mux. \
+videotestsrc ! video/x-raw,width=1280,height=720 ! x264enc speed-preset=ultrafast bitrate=3000 key-int-max=60 ! video/x-h264,profile=high ! mux. \
 audiotestsrc ! audioconvert ! avenc_aac ! mux.
 ```