review: allow manual start selection

* return start video
* use ubuntu instead of alpine because ffmpeg in alpine lacks drawtext support
* only cache if inputs are exactly the same, preventing accidents (prev scheme too weak)
* fix a bug where end range is wrong if start_range doesn't start at 0
	conceptually, this was a more serious bug as time_offset was wrong, but luckily the bug applied
	equally to both racers so there was no net effect

restreamer/Dockerfile

@@ -1,7 +1,6 @@
-FROM alpine:3.7
+FROM ubuntu:18.04
 # dependencies needed for compiling c extensions
-# also busybox-extras for telnet for easier use of backdoor
-RUN apk --update add py2-pip gcc python-dev musl-dev file make busybox-extras
+RUN chmod 1777 /tmp && apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install --yes python-pip python-dev file gcc make ffmpeg
 
 # Install gevent so that we don't need to re-install it when common changes
 RUN pip install gevent
@@ -11,7 +10,6 @@ COPY common /tmp/common
 RUN pip install /tmp/common && rm -r /tmp/common
 
 # Install actual application
-RUN apk add ffmpeg
 COPY restreamer /tmp/restreamer
 RUN pip install /tmp/restreamer && rm -r /tmp/restreamer
 

restreamer/restreamer/main.py

@@ -365,20 +365,32 @@ def review_race(match_id, race_number):
 			race start time to look for the start signal. Default 0,5.
 		finish_range: As start_range, but how long to make the final review video before/after
 			the nominal duration. Default -5,10.
+		racer1_start, racer2_start: Explicit start times, as float.
 	"""
 	if app.condor_db is None:
 		return "Reviews are disabled", 501
 	start_range = map(float, request.args.get('start_range', '0,5').split(','))
 	finish_range = map(float, request.args.get('finish_range', '-5,10').split(','))
+	racer1_start = float(request.args['racer1_start']) if 'racer1_start' in request.args else None
+	racer2_start = float(request.args['racer2_start']) if 'racer2_start' in request.args else None
 	try:
-		review_path = review(match_id, race_number, app.static_folder, app.condor_db, start_range, finish_range)
+		review_path = review(
+			match_id, race_number, app.static_folder, app.condor_db, start_range, finish_range,
+			racer1_start, racer2_start,
+		)
 	except RaceNotFound as e:
 		return str(e), 404
 	except NoSegments:
 		logging.warning("Failed review due to no segments", exc_info=True)
 		return "Video content is missing - cannot review automatically", 400
 	except CantFindStart as e:
-		return str(e), 400
+		return (
+			"{}\n"
+			"Please check start video and adjust start_range or set racer{}_start: {}\n"
+			"Note timestamps in that video are only valid for the current start_range.\n"
+		).format(
+			e, e.racer_number, os.path.join(app.static_url_path, os.path.relpath(e.path, app.static_folder))
+		), 400
 
 	relative_path = os.path.relpath(review_path, app.static_folder)
 	review_url = os.path.join(app.static_url_path, relative_path)

restreamer/restreamer/review.py

@@ -3,6 +3,7 @@ import datetime
 import logging
 import os
 import subprocess
+from hashlib import sha256
 from urlparse import urlparse
 from uuid import uuid4
 
@@ -21,14 +22,16 @@ class RaceNotFound(Exception):
 
 
 class CantFindStart(Exception):
-	def __init__(self, racer, found):
+	def __init__(self, racer, racer_number, found, path):
 		self.racer = racer
+		self.racer_number = racer_number
 		self.found = found
+		self.path = path
 	def __str__(self):
 		if self.found > 0:
-			return "Found multiple ({}) possible start points for {}".format(self.found, self.racer)
+			return "Found multiple ({}) possible start points for racer {} ({})".format(self.found, self.racer_number, self.racer)
 		else:
-			return "Failed to find start point for {}".format(self.racer)
+			return "Failed to find start point for racer {} ({})".format(self.racer_number, self.racer)
 
 
 def ts(dt):
@@ -77,7 +80,10 @@ def conn_from_url(url):
 	)
 
 
-def review(match_id, race_number, base_dir, db_url, start_range=(0, 5), finish_range=(-5, 10)):
+def review(
+	match_id, race_number, base_dir, db_url, start_range=(0, 5), finish_range=(-5, 10),
+	racer1_start=None, racer2_start=None,
+):
 	logger = logging.getLogger("review").getChild("{}-{}".format(match_id, race_number))
 
 	conn = conn_from_url(db_url)
@@ -111,11 +117,15 @@ def review(match_id, race_number, base_dir, db_url, start_range=(0, 5), finish_r
 	(racer1, racer2, start, duration), = data
 	end = start + datetime.timedelta(seconds=duration/100.)
 
+	# cache hash encapsulates all input args
+	cache_hash = sha256(str((match_id, race_number, start_range, finish_range, racer1_start, racer2_start)))
+	cache_str = cache_hash.digest().encode('base64')[:12]
+
 	output_name = "{}-{}-{}-{}".format(match_id, racer1, racer2, race_number)
 	output_dir = os.path.join(base_dir, "reviews", output_name)
 	if not os.path.exists(output_dir):
 		os.makedirs(output_dir)
-	result_name = "review_{}_{}.mp4".format(*finish_range)
+	result_name = "review_{}.mp4".format(cache_str)
 	result_path = os.path.join(output_dir, result_name)
 	if os.path.exists(result_path):
 		logger.info("Result already exists for {}, reusing".format(result_path))
@@ -123,10 +133,12 @@ def review(match_id, race_number, base_dir, db_url, start_range=(0, 5), finish_r
 
 	finish_paths = []
 
-	for racer_number, racer in enumerate((racer1, racer2)):
+	for racer_index, (racer, time_offset) in enumerate(((racer1, racer1_start), (racer2, racer2_start))):
 		nonce = str(uuid4())
-		start_path = os.path.join(output_dir, "start-{}-{}.mp4".format(racer_number, nonce))
+		racer_number = racer_index + 1
 
+		if time_offset is None:
+			start_path = os.path.join(output_dir, "start-{}-{}.mp4".format(racer_number, nonce))
 			logger.info("Cutting start for racer {} ({})".format(racer_number, racer))
 			start_start, start_end = add_range(start, start_range)
 			cut_to_file(logger, start_path, base_dir, racer, start_start, start_end)
@@ -153,9 +165,10 @@ def review(match_id, race_number, base_dir, db_url, start_range=(0, 5), finish_r
 				time_offset = float(black_end.split(':')[1])
 			else:
 				found = len(lines)
-			logger.warning("Unable to detect start (expected 1 black interval, but found {})".format(found))
-			raise CantFindStart(racer, found)
-		time_offset = datetime.timedelta(seconds=time_offset)
+				logger.warning("Unable to detect start (expected 1 black interval, but found {}), re-cutting with timestamps".format(found))
+				cut_to_file(logger, start_path, base_dir, racer, start_start, start_end, frame_counter=True)
+				raise CantFindStart(racer, racer_number, found, start_path)
+		time_offset = datetime.timedelta(seconds=time_offset - start_range[0])
 
 		# start each racer's finish video at TIME_OFFSET later, so they are the same
 		# time since their actual start.