cutter,restreamer: Set stream=True for full cuts when appropriate

And also default to a new ffmpeg encoding setting for high-quality mpegts
(ie. still streamable) that is encoded very quickly.

common/common/segments.py

@@ -414,7 +414,7 @@ def feed_input(segments, pipe):
 			try:
 				shutil.copyfileobj(f, pipe)
 			except OSError as e:
-				# ignore EPIPE, as this just means the end cut meant we didn't need all i>
+				# ignore EPIPE, as this just means the end cut meant we didn't need all it
 				if e.errno != errno.EPIPE:
 					raise
 	pipe.close()

cutter/cutter/main.py

@@ -294,8 +294,14 @@ class Cutter(object):
 			self.logger.debug("No encoding settings, using fast cut")
 			cut = fast_cut_segments(job.segments, job.video_start, job.video_end)
 		else:
-			self.logger.debug("Using encoding settings for cut: {}".format(upload_backend.encoding_settings))
-			cut = full_cut_segments(job.segments, job.video_start, job.video_end, upload_backend.encoding_settings)
+			self.logger.debug("Using encoding settings for {} cut: {}".format(
+				"streamable" if upload_backend.encoding_streamable else "non-streamable",
+				upload_backend.encoding_settings,
+			))
+			cut = full_cut_segments(
+				job.segments, job.video_start, job.video_end,
+				upload_backend.encoding_settings, stream=upload_backend.encoding_streamable,
+			)
 
 		# This flag tracks whether we've told requests to finalize the upload,
 		# and serves to detect whether errors from the request call are recoverable.

cutter/cutter/upload_backends.py

@@ -67,12 +67,17 @@ class UploadBackend(object):
 	under the 'encoding_settings' attribute.
 	If this is None, instead uses the 'fast cut' strategy where nothing
 	is transcoded.
+
+	In addition, if the output format doesn't need a seekable file,
+	you should set encoding_streamable = True so we know we can stream the output directly.
 	"""
 
 	needs_transcode = False
 
-	# reasonable default if settings don't otherwise matter
-	encoding_settings = ['-f', 'mp4']
+	# reasonable default if settings don't otherwise matter:
+	# high-quality mpegts, without wasting too much cpu on encoding
+	encoding_args = ['-c:v', 'libx264', '-preset', 'ultrafast', '-crf', '0', '-f', 'mpegts']
+	encoding_streamable = True
 
 	def upload_video(self, title, description, tags, data):
 		raise NotImplementedError
@@ -92,10 +97,14 @@ class Youtube(UploadBackend):
 		language:
 			The language code to describe all videos as.
 			Default is "en", ie. English. Set to null to not set.
+		use_yt_recommended_encoding:
+			Default False. If True, use the ffmpeg settings that Youtube recommends for
+			fast processing once uploaded. We suggest not bothering, as it doesn't appear
+			to make much difference.
 	"""
 
 	needs_transcode = True
-	encoding_settings = [
+	recommended_settings = [
 		# Youtube's recommended settings:
 		'-codec:v', 'libx264', # Make the video codec x264
 		'-crf', '21', # Set the video quality, this produces the bitrate range that YT likes
@@ -108,7 +117,7 @@ class Youtube(UploadBackend):
 		'-movflags', 'faststart', # put MOOV atom at the front of the file, as requested
 	]
 
-	def __init__(self, credentials, hidden=False, category_id=23, language="en"):
+	def __init__(self, credentials, hidden=False, category_id=23, language="en", use_yt_recommended_encoding=False):
 		self.logger = logging.getLogger(type(self).__name__)
 		self.client = GoogleAPIClient(
 			credentials['client_id'],
@@ -118,6 +127,9 @@ class Youtube(UploadBackend):
 		self.hidden = hidden
 		self.category_id = category_id
 		self.language = language
+		if use_yt_recommended_encoding:
+			self.encoding_settings = self.recommended_settings
+			self.encoding_streamable = False
 
 	def upload_video(self, title, description, tags, data):
 		json = {

restreamer/restreamer/main.py

@@ -237,7 +237,6 @@ def cut(channel, quality):
 			Even if holes are allowed, a 406 may result if the resulting video would be empty.
 		type: One of "fast" or "full". Default to "fast".
 			A fast cut is much faster but minor artifacting may be present near the start and end.
-			A fast cut is encoded as MPEG-TS, a full as mp4.
 	"""
 	start = dateutil.parse_utc_only(request.args['start']) if 'start' in request.args else None
 	end = dateutil.parse_utc_only(request.args['end']) if 'end' in request.args else None
@@ -272,8 +271,9 @@ def cut(channel, quality):
 	if type == 'fast':
 		return Response(fast_cut_segments(segments, start, end), mimetype='video/MP2T')
 	elif type == 'full':
-		# output as mp4 with no more specific encoding args
-		return Response(full_cut_segments(segments, start, end, ['-f', 'mp4']), mimetype='video/mp4')
+		# output as high-quality mpegts, without wasting too much cpu on encoding
+		encoding_args = ['-c:v', 'libx264', '-preset', 'ultrafast', '-crf', '0', '-f', 'mpegts']
+		return Response(full_cut_segments(segments, start, end, encoding_args, stream=True), mimetype='video/MP2T')
 	else:
 		return "Unknown type {!r}. Must be 'fast' or 'full'.".format(type), 400