Add a setting for debug logging

This is very primitive logging, with no control over output filenames,
paths, or log rotation.  As such, it is only meant for debugging.

To enable, set debug_logs: true in the pipeline config.

Issue #12

Change-Id: I16696b5cea54579b921ff8186c944e8e5a5939fc

streamer/default_config.py

@@ -65,6 +65,10 @@
   # If true, reduce the level of output.  Only errors will be shown in quiet
   # mode.
   'quiet': False,
+  # If true, output simple log files from each node.  No control is given over
+  # log filenames.  Logs are written to the current working directory.  We do
+  # not yet support log rotation.  This is meant only for debugging.
+  'debug_logs': False,
 
   'transcoder': {
     # A list of resolutions to encode.

streamer/loop_input_node.py

@@ -64,5 +64,15 @@ def start(self):
         self._output_path,
     ]
 
-    self._process = self._create_process(args)
+    env = {}
+    if self._config.debug_logs:
+      # A safe version of the input path that we can put into a log filename.
+      sanitized_input = self._input_path.replace('/', '-').replace('\\', '-')
+      # Use this environment variable to turn on ffmpeg's logging.  This is
+      # independent of the -loglevel switch above.  The log file will have the
+      # input filename in it, in case there are multiple LoopInputNodes.
+      env['FFREPORT'] = 'file=LoopInputNode-{}.log:level=32'.format(
+          sanitized_input)
+
+    self._process = self._create_process(args, env)
 

streamer/packager_node.py

@@ -15,6 +15,7 @@
 """A module that feeds information from two named pipes into shaka-packager."""
 
 import os
+import subprocess
 
 from . import metadata
 from . import node_base
@@ -124,8 +125,16 @@ def start(self):
     if self._config.encryption['enable']:
       args += self._setup_encryption()
 
-    self._process = self._create_process(args)
+    stdout = None
+    if self._config.debug_logs:
+      # Log by writing all Packager output to a file.  Unlike the logging
+      # system in ffmpeg, this will stop any Packager output from getting to
+      # the screen.
+      stdout = open('PackagerNode.log', 'w')
 
+    self._process = self._create_process(args,
+                                         stderr=subprocess.STDOUT,
+                                         stdout=stdout)
 
   def _create_text(self, dict, language):
     # TODO: Format using text Metadata objects, which don't exist yet

streamer/pipeline_configuration.py

@@ -19,6 +19,7 @@
 
 MODE = 'streaming_mode'
 QUIET = 'quiet'
+DEBUG_LOGS = 'debug_logs'
 TRANSCODER = 'transcoder'
 PACKAGER = 'packager'
 ENCRYPTION = 'encryption'
@@ -32,6 +33,7 @@ def __init__(self, user_config,
     self.dict = user_config
     self.mode = self.dict[MODE]
     self.quiet = self.dict[QUIET]
+    self.debug_logs = self.dict[DEBUG_LOGS]
     self.transcoder = self.dict[TRANSCODER]
     self.packager = self.dict[PACKAGER]
     self.encryption = self.packager[ENCRYPTION]

streamer/transcoder_node.py

@@ -109,7 +109,13 @@ def start(self):
           args += map_args
           args += self._encode_video(video, input)
 
-    self._process = self._create_process(args)
+    env = {}
+    if self._config.debug_logs:
+      # Use this environment variable to turn on ffmpeg's logging.  This is
+      # independent of the -loglevel switch above.
+      env['FFREPORT'] = 'file=TranscoderNode.log:level=32'
+
+    self._process = self._create_process(args, env)
 
   def _live_input(self, input_object):
     args = []