Scoreboards and Video Routing in Python
Scorekeeper
© Photo by Johnny Briggs on Unsplash
We look at a broadcast video system network that uses Python code to control a video router and check out another program that creates a scoreboard.
Each year my church hosts a basketball league, and several years ago we wanted to upgrade to digital scoreboards because our existing classic board was showing its age. The first version of this new scoreboard software was written in Python [1] and used the GTK toolkit to create the public display. A web page designed for an iPad allowed courtside control.
The gym is a shared space that also hosts a meeting room, party hall, and general-purpose room. To support these roles, two NUC small-form-factor computers drive the displays (100-inch LCD TVs). Windows was necessary to support all of the display software so that PowerPoint and ProPresenter would run natively.
In general, a video system has a hub-and-spoke-style network wherein each device has a dedicated home that runs to a video switcher (Figure 1). The video switcher, as its name implies, accepts all of the video inputs and allows the operator to pick which one should be displayed, overlaid, or otherwise presented to the final output (Figure 2).
Displays are slightly more complicated because they need to select the switched video program from the video switcher or the scoreboards at any given time, which is accomplished by a matrix router. See the "Matrix Routers" box for more details.
Matrix Routers
In the video world, a router is a really helpful device. It accepts some number of video signals in and can send them to any of its destinations. This example uses a small four-input by four-output version, but other versions are available with up to thousands of I/O points.
Think of the router as a grid with sources (video signals – see the "Video Signals and Conversions" box) coming in on the left and going out along the bottom. Each column (an output or destination) is allowed one connection. Inputs can connect to as many outputs as needed. To say it another way, all of the outputs can display a single input, but each output can only display one thing at a time. When a selection is made, the selected input and output are connected as if they were wired together directly. These connections are easily changed throughout the day as the needs of the basketball game dictate.
Video Signals and Conversions
Many different video formats can carry live video down a wire. You're probably familiar with HDMI because it has been widely adopted since its introduction. The video system discussed here primarily uses a serial digital interface (SDI), which is a digital standard for broadcast video. Hardware converters between these formats also exist, so changing between them is as easy as connecting a cable of each type. The cost for this conversion is a slight delay in the video signal that is normally not noticeable; however, if you have stacked several conversions, the delays can start to add up and become visible. This scenario generally presents itself as audio out of sync with its associated video.
The Scoreboard
In addition to team points, a scoreboard also offers other game information, such as time remaining, period of play, time outs, or player numbers. Figure 3 shows the general flow of the program. At program startup, the graphics initialize and the initial state of the scoreboard renders. Concurrently, the web server starts and the operator brings this page up on a courtside computer (Figure 4).
As the basketball game progresses, the operator uses the web interface to update the game score and other statistics. Each action on the web interface starts as a JavaScript function that runs in the browser, communicating with the CherryPy [2] server through background Ajax calls. When CherryPy receives these commands, it updates the graphics screen to reflect the change on the scoreboard itself and then sends the updated values back to the browser so that the operator's interface is also updated.
Listing 1 shows some of the code behind the scoreboard. (You can download the complete code online [3].) To begin, you must import the external libraries the program needs: The pygame, graphics library [4] draws the scoreboard; _thread allows multiple branches of the program to run at the same time, so you can run the scoreboard display and the web control interface at the same time; pymysql is the MySQL database library for Python; and cherrypy sets up the CherryPy framework.
Listing 1
scoreboard.py
001 import pygame
002 import _thread
003 import cherrypy
004 import pymysql
005
006 class web:
007 def __init__ ( self , scoreboard ):
008 self.scoreboard = scoreboard
009 self.reconnect()
010 self.dbGameID = None
011
012 def reconnect ( self ):
013 self.db = pymysql.connect(
014 host='DB_HOSTNAME',
015 user='DB_USER',
016 password = "DB_PASSWORD",
017 db='DB_NAME',
018 )
019
020 def gameEvent ( self , event , value ):
021 if self.dbGameID == None: return
022
023 self.db.ping ( True )
024 period = self.scoreboard.period.value
025 time = self.scoreboard.clk.seconds
026
027 sql = "INSERT INTO `updates` ( `gameID` , `period` , `gameTime` , `event` , `value` ) VALUES ( " + str ( self.dbGameID ) + " , " + str ( period ) + " , " + str ( time ) + " , '" + event + "' , " + str ( value ) + " );"
028
029 cursor = self.db.cursor ( pymysql.cursors.DictCursor )
030 cursor.execute ( sql )
031 self.db.commit()
032
033 @cherrypy.expose
034 def index ( self ):
035 html = """
...
240 """.format (
241 self.scoreboard.court.value + " " + self.scoreboard.court.label,
242 self.scoreboard.scoreA.label,
243 self.scoreboard.scoreB.label,
244 self.scoreboard.scoreA.value,
245 self.scoreboard.scoreB.value,
246 self.scoreboard.clk.clockString,
247 self.scoreboard.timeoutA.value,
248 self.scoreboard.timeoutB.value,
249 self.scoreboard.posession.leftString,
250 self.scoreboard.posession.rightString,
251 self.scoreboard.period.value
252 )
253
254 return html
255
256 @cherrypy.expose
257 def teams ( self ):
258 cursor = self.db.cursor ( pymysql.cursors.DictCursor )
259 sql = "SELECT t1.teamName AS t1name , t2.teamName AS t2name , games.* FROM `games` LEFT JOIN `teams` t1 ON t1.ID=games.team1 LEFT JOIN `teams` t2 ON t2.ID=games.team2";
260 cursor.execute ( sql )
261
262 html = "<select id='gameSelect'>"
263 for game in cursor.fetchall():
264 html += "<option value='" + str ( game [ 'ID' ] ) + "'>" + str ( game [ 'date' ] ) + " | " + str ( game [ 'time' ] ) + " | " + game [ 't1name' ] + " | " + game [ 't2name' ] + "</option>"
265 html += "</select>"
266
267 return html
268
269 @cherrypy.expose
270 def processGameSelect ( self , gameID ):
271 cursor = self.db.cursor ( pymysql.cursors.DictCursor )
272 sql = "SELECT t1.teamName AS t1name , t2.teamName AS t2name , games.* FROM `games` LEFT JOIN `teams` t1 ON t1.ID=games.team1 LEFT JOIN `teams` t2 ON t2.ID=games.team2 WHERE games.ID = " + str ( gameID );
273 cursor.execute ( sql )
274 game = cursor.fetchone()
275
276 self.dbGameID = gameID
277
278 self.teamName ( "1" , game [ "t1name" ] )
279 self.teamName ( "2" , game [ "t2name" ] )
280
281 @cherrypy.expose
282 def teamName ( self , team , name ):
283 if team == "1": self.scoreboard.scoreA.label = name
284 if team == "2": self.scoreboard.scoreB.label = name
285
286 @cherrypy.expose
287 def score ( self , team1 , team2 ):
288 self.scoreboard.scoreA.value += int ( team1 )
289 self.scoreboard.scoreB.value += int ( team2 )
290
291 if team1 != "0": self.gameEvent ( "T1SCORE" , team1 )
292 if team2 != "0": self.gameEvent ( "T2SCORE" , team2 )
293
294 self.scoreboard.render()
295 return str ( self.scoreboard.scoreA.value ) + ":" + str ( self.scoreboard.scoreB.value );
296
297 @cherrypy.expose
298 def timeouts ( self , team1 , team2 ):
299 self.scoreboard.timeoutA.value += int ( team1 )
300 self.scoreboard.timeoutB.value += int ( team2 )
301
302 if team1 != "0": self.gameEvent ( "T1TIMEOUT" , team1 )
303 if team2 != "0": self.gameEvent ( "T2TIMEOUT" , team2 )
304
305 return str ( self.scoreboard.timeoutA.value ) + ":" + str ( self.scoreboard.timeoutB.value )
306
307 @cherrypy.expose
308 def period ( self , period ):
309 self.gameEvent ( "PERIOD" , period )
310
311 self.scoreboard.period.value += int ( period )
312 return str ( self.scoreboard.period.value )
313
314 @cherrypy.expose
315 def getClock ( self ):
316 return self.scoreboard.clk.clockString
317
318 @cherrypy.expose
319 def clockRun ( self ):
320 self.scoreboard.clk.running = True
321
322 @cherrypy.expose
323 def clockStop ( self ):
324 self.scoreboard.clk.running = False
325 self.gameEvent ( "CLOCKSTOP" , 0 )
326
327 @cherrypy.expose
328 def clockSet ( self , seconds ):
329 self.scoreboard.clk.seconds = int ( seconds ) + 1
330 self.scoreboard.clk.tick ( manual = True )
331 return self.scoreboard.clk.clockString
332
333 @cherrypy.expose
334 def posession ( self ):
335 self.scoreboard.posession.toggle()
336 if self.scoreboard.posession.leftString == "<": self.gameEvent ( "POSESSION" , 1 )
337 if self.scoreboard.posession.rightString == ">": self.gameEvent ( "POSESSION" , 2 )
338
339 return self.scoreboard.posession.leftString + ":" + self.scoreboard.posession.rightString
340
341 class clock:
342 def __init__ ( self , screen ):
343 self.screen = screen
344 self.width = self.screen.get_width()
345 self.height = 250
346 self.seconds = 6 * 60
347 self.clockSurf = pygame.surface.Surface ( ( self.width , self.height ) )
348 self.clockFont = pygame.font.Font ( "open24.ttf" , self.height )
349 self.running = False
350
351 mins = int ( float ( self.seconds ) / 60.0 )
352 secs = self.seconds % 60
353
354 self.clockString = "{0}:{1:02d}".format ( mins , secs )
355
356 def tick ( self , manual = False ):
357 if self.seconds > 0 and ( self.running == True or manual == True ):
358 self.seconds -= 1
359
360 mins = int ( float ( self.seconds ) / 60.0 )
361 secs = self.seconds % 60
362
363 self.clockString = "{0}:{1:02d}".format ( mins , secs )
364
365 def render ( self ):
366 timeSurf = self.clockFont.render ( self.clockString , True , ( 0 , 255 , 0 ) )
367
368 x = self.width / 2 - int ( timeSurf.get_width() / 2 )
369 self.clockSurf.fill ( ( 0 , 0 , 0 ) )
370 self.clockSurf.blit ( timeSurf , ( x , -25 ) )
371 return self.clockSurf
372
373 class posession:
374 def __init__ ( self ):
375 self.width = 300
376 self.height = 100
377 self.font = None
378 self.direction = "<"
379 self.posSurf = pygame.surface.Surface ( ( self.width , self.height ) )
380 self.leftString = ""
381 self.rightString = ""
382 self.makeSurfaces()
383
384 def makeSurfaces ( self ):
385 self.leftSurf = self.font.render ( "<" , True , ( 255 , 0 , 0 ) )
386 self.rightSurf = self.font.render ( ">" , True , ( 255 , 0 , 0 ) )
387
388 def toggle ( self ):
389 if self.direction == "<":
390 self.direction = ">"
391 self.leftString = ""
392 self.rightString = ">"
393 else:
394 self.direction = "<"
395 self.leftString = "<"
396 self.rightString = ""
397
398 def render ( self ):
399 self.posSurf.fill ( ( 0 , 0 , 0 ) )
400 label = self.font.render ( "POSESSION" , True , ( 255 , 0 , 0 ) )
401 x = self.width / 2 - int ( label.get_width() / 2 )
402 self.posSurf.blit ( label , ( x , 0 ) )
403
404 if self.direction == "<": self.posSurf.blit ( self.leftSurf , ( 0 , 0 ) )
405 else: self.posSurf.blit ( self.rightSurf , ( self.width - self.rightSurf.get_width() , 0 ) )
406 return self.posSurf
407
408 class label:
409 def __init__ ( self ):
410 self.width = 250
411 self.height = 350
412 self.label = ""
413 self.value = ""
414 self.labelFont = None
415 self.valueFont = None
416 self.labelColor = ( 200 , 200 , 200 )
417 self.valueColor = ( 200 , 200 , 200 )
418 self.countSurf = pygame.surface.Surface ( ( self.width , self.height ) )
419
420 def render ( self ):
421 self.countSurf.fill ( ( 0 , 0 , 0 ) )
422 valSurf = self.valueFont.render ( str ( self.value ) , True , self.valueColor )
423 x = self.width / 2 - int ( valSurf.get_width() / 2 )
424 self.countSurf.blit ( valSurf , ( x , 0 ) )
425
426 labelSurf = self.labelFont.render ( str ( self.label ) , True , self.labelColor )
427 x = self.width / 2 - int ( labelSurf.get_width() / 2 )
428 self.countSurf.blit ( labelSurf , ( x , valSurf.get_height() - 10 ) )
429
430 return self.countSurf
431
432 class counter:
433 def __init__ ( self ):
434 self.width = 250
435 self.height = 350
436 self.label = ""
437 self.value = 0
438 self.labelFont = None
439 self.valueFont = None
440 self.labelColor = ( 200 , 200 , 200 )
441 self.valueColor = ( 200 , 200 , 200 )
442 self.countSurf = pygame.surface.Surface ( ( self.width , self.height ) )
443
444 def render ( self ):
445 self.countSurf.fill ( ( 0 , 0 , 0 ) )
446 valSurf = self.valueFont.render ( str ( self.value ) , True , self.valueColor )
447 x = self.width / 2 - int ( valSurf.get_width() / 2 )
448 self.countSurf.blit ( valSurf , ( x , 0 ) )
449
450 labelSurf = self.labelFont.render ( str ( self.label ) , True , self.labelColor )
451 x = self.width / 2 - int ( labelSurf.get_width() / 2 )
452 self.countSurf.blit ( labelSurf , ( x , valSurf.get_height() - 10 ) )
453
454 return self.countSurf
455
456 class board:
457 def __init__ ( self ):
458 pygame.display.init()
459 self.screen = pygame.display.set_mode ( ( 1280 , 720 ) , display = 1 , flags = pygame.FULLSCREEN )
460 pygame.font.init()
461 self.scoreFont = pygame.font.Font ( "font.ttf" , 200 )
462 self.labelFont = pygame.font.Font ( "font.ttf" , 50 )
463 self.timeoutFont = pygame.font.Font ( "font.ttf" , 50 )
464 self.posFont = pygame.font.Font ( "font2.otf" , 50 )
465
466 self.logo = pygame.image.load ( "upwardBlack.jpg" ).convert()
467
468 self.clk = clock ( self.screen )
469
...
The Web Class
The web class (lines 6-339) connects to a MySQL database that will be used to retrieve team names, determine which team plays which, and record game history. When the class is instantiated, the __init__ function is called automatically to set up a few things needed later. Line 8 creates a class variable self.scoreboard and saves the reference to the scoreboard class that's passed in as an argument.
The reconnect function is really only one call split up across multiple lines for easier readability (lines 12-18). pymysql.connect creates self.db, the local reference to the database. Each line supplies the appropriate credential.
The gameEvent function (lines 20-31) logs any change to the scoreboard. In a future version, this function will allow for recovering the scoreboard after a crash and exporting a game report. To begin, the code checks whether self.dbGameID (which was initialized to None in line 10) is set. If not, then you don't have a database ID, so you just return.
The self.db.ping convenience function, with an argument of True, checks whether the database connection is live and, if not, reconnects automatically in the next line. The two lines that follow get the game period and time in seconds. These two values pinpoint a unique time within the game.
Line 27 builds a SQL statement. The INSERT INTO command names the table followed by a list of columns separated by commas. The VALUES keyword assigns the values for each column, provided in the same order. Line 29 creates a database cursor that interacts with an SQL statement. In this case (line 30), it just executes the SQL line created in line 27, but it has many more capabilities, especially when retrieving records. Line 31 calls commit to confirm that you want to write the data.
The cherrypy decorator (lines 33-339) creates a small web server for controlling the scoreboard. Each Python function becomes a web address that returns its designated content to the browser that has called it.
The index function acts just like index.html in a traditional web server. In the absence of another address, it is the default item returned. Most of this function is a very large multiline string (not shown here, grab the full code online [3]) enclosed by triple quotes (""") that instructs Python to ignore any newlines or other special characters until it encounters another triple quote. The enclosed string is the HTML5 [5] and JavaScript of the control web page. After the massive text string, the Python format command inserts all of the current variables into the web page (lines 240-251).
The @cherrypy.expose decorator tells CherryPy that it should allow this function to be reachable through its web server. Without this decorator the function remains private from anyone on the web, which allows the program to be structured with additional functions as needed, with only those specifically designed to be web-accessible published. You'll see this decorator before each function in the web class, so it's only described once here.
The teams function (lines 257-267) is somewhat of a misnomer in that it generates a game selector. For the purposes of this database, a game is a pair of teams at a specific date and time on a specific court. This function retrieves all of the games and returns an HTML select widget.
The function begins by creating an SQL cursor and statement and then executing it (as in lines 29-31). However, now it's retrieving records, so the cursor has the results of the query, which is data instead of just a message that the query succeeded.
After starting the HTML select widget on line 262, the program loops over the SQL results. As the name implies, cursor.fetchall gives all of the results as an iterator. game will contain one row from the database for each time through the loop. Each pass creates an HTML option and lists the game date, time, and teams.
The processGameSelect function (lines 270-279) is called when the scoreboard operator selects a game from the drop-down just generated. It receives the gameID argument and uses that to get the game details from the database. Line 272 is an almost identical SQL statement to line 259, but with a WHERE clause added to the end with the gameID.
After doing the SQL dance one more time, line 274 calls cursor.fetchone. The last time, all of the records were retrieved, but this time only one is needed, which is saved into game. gameID is saved into a class variable, and self.teamName sets the names retrieved from the database.
The teamName function (lines 281-284) accepts a team number and name as arguments. Each of two if statements determines which team is being named and then saves the new name to a variable in the scoreboard class.
Housekeeping
The score, timeouts, and period functions (lines 286-312) accept the team1 and team2 arguments (period only accepts a period number) which are the amounts to change each value. Negative values are allowed so that values can be corrected or reset for the next game or period. Note also that the variables are preceded with int. All arguments from CherryPy come in as strings, so they have to be converted to integers before they can be used algebraically.
Finally, the two newly adjusted values are returned, separated by a colon, to go back to the JavaScript function and be split into the two scores so that the control screen is updated properly.
The JavaScript versions of these functions are generated in the index function (not included in the listing). The score function, for example, creates a JavaScript object and adds obj.team1 and obj.team2:
function score ( team1 , team2 )
{{
obj = new Object();
obj.team1 = team1
obj.team2 = team2These are the score deltas (amounts to change) for each team. jQuery [6] (represented by the $) then posts the object to the address score (the Python CherryPy function described above):
$.post ( "score" , obj , function ( data ) {{
scoreParts = data.split ( ":" );
$ ( "#team1score" ).html ( scoreParts [ 0 ] );
$ ( "#team2score" ).html ( scoreParts [ 1 ] );
}} );obj has the values to send that were set up earlier. When post finishes and receives a response, function ( data ) is called, where data is the returned string with the newly updated scores (or timeouts or period). First, the data is split into its two parts with data.split, and then the score on the control page is updated with jQuery.
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