Add MJPEG streaming

Signed-off-by: Krayon <krayon.git@qdnx.org>

webcam.py

@@ -21,30 +21,83 @@ def index(req, resp):
     flash = req.form.get('flash', 'false')
     if flash == 'true':
         led.on()
+    stream = req.form.get('stream', 'false')
+    stream = True if stream == 'true' else False
 
     # Camera resilience - if we fail to init try to deinit and init again
-    if (not camera.init()):
+    if (not camera.init()): #{
         camera.deinit()
         await asyncio.sleep(1)
         # If we fail to init, return a 503
-        if (not camera.init()):
+        if (not camera.init()): #{
             yield from picoweb.start_response(resp, status=503)
             yield from resp.awrite('ERROR: Failed to initialise camera\r\n\r\n')
             return
+        #}
+    #}
 
     # wait for sensor to start and focus before capturing image
     await asyncio.sleep(2)
-    buf = camera.capture()
 
-    led.off()
-    camera.deinit()
+    n_frame = 0
+    while True: #{
+        n_try = 0
+        buf = False
+        while (n_try < 10 and buf == False): #{
+            # wait for sensor to start and focus before capturing image
+            buf = camera.capture()
+            if (buf == False): await asyncio.sleep(2)
+            n_try = n_try + 1
+        #}
 
-    if type(buf) is bytes and len(buf) > 0:
-        yield from picoweb.start_response(resp, "image/jpeg")
-        yield from resp.awrite(buf)
-    else:
-        picoweb.http_error(resp, 503)
+        if (not stream): #{
+            led.off()
+            camera.deinit()
+        #}
 
+        if (type(buf) is bytes and len(buf) > 0): #{
+            try:
+                if (not stream): #{
+                    yield from picoweb.start_response(resp, "image/jpeg")
+                    yield from resp.awrite(buf)
+                    print('JPEG: Output frame')
+                    break
+                #}
+
+                if (n_frame == 0): #{
+                    yield from picoweb.start_response(resp, "multipart/x-mixed-replace; boundary=myboundary")
+                #}
+
+                yield from resp.awrite('--myboundary\r\n')
+                yield from resp.awrite('Content-Type:   image/jpeg\r\n')
+                yield from resp.awrite('Content-length: ' + str(len(buf)) + '\r\n\r\n')
+                yield from resp.awrite(buf)
+
+            except:
+                # Connection gone?
+                print('Connection closed by client')
+                led.off()
+                camera.deinit()
+                return
+
+        else: #}{
+            if (stream): #{
+                led.off()
+                camera.deinit()
+            #}
+
+            #picoweb.http_error(resp, 503)
+            yield from picoweb.start_response(resp, status=503)
+            if (stream and n_frame > 0): #{
+                yield from resp.awrite('Content-Type:   text/html; charset=utf-8\r\n\r\n')
+            #}
+            yield from resp.awrite('Issues:\r\n\r\n' + str(buf))
+            return
+        #}
+
+        print('MJPEG: Output frame ' + str(n_frame))
+        n_frame = n_frame + 1
+    #}
 
 def run():
     app.run(host='0.0.0.0', port=80, debug=True)