[YoutubeDL] Output avconv/ffmpeg versions if -v is given

3 files changed, 48 insertions, 14 deletions

diff --git a/youtube_dl/YoutubeDL.py b/youtube_dl/YoutubeDL.py
index 242affb5b..ecf426e37 100755
--- a/youtube_dl/YoutubeDL.py
+++ b/youtube_dl/YoutubeDL.py
@@ -62,7 +62,7 @@ from .utils import (
 from .cache import Cache
 from .extractor import get_info_extractor, gen_extractors
 from .downloader import get_suitable_downloader
-from .postprocessor import FFmpegMergerPP
+from .postprocessor import FFmpegMergerPP, FFmpegPostProcessor
 from .version import __version__
 
 
@@ -1311,8 +1311,18 @@ class YoutubeDL(object):
                 sys.exc_clear()
             except:
                 pass
-        self._write_string('[debug] Python version %s - %s' %
-                     (platform.python_version(), platform_name()) + '\n')
+        self._write_string('[debug] Python version %s - %s\n' % (
+            platform.python_version(), platform_name()))
+
+        exe_versions = FFmpegPostProcessor.get_versions()
+        exe_str = ', '.join(
+            '%s %s' % (exe, v)
+            for exe, v in sorted(exe_versions.items())
+            if v
+        )
+        if not exe_str:
+            exe_str = 'none'
+        self._write_string('[debug] exe versions: %s\n' % exe_str)
 
         proxy_map = {}
         for handler in self._opener.handlers:
diff --git a/youtube_dl/postprocessor/__init__.py b/youtube_dl/postprocessor/__init__.py
index 15aa0daa9..6ac67cbae 100644
--- a/youtube_dl/postprocessor/__init__.py
+++ b/youtube_dl/postprocessor/__init__.py
@@ -1,24 +1,26 @@
 
 from .atomicparsley import AtomicParsleyPP
 from .ffmpeg import (
+    FFmpegPostProcessor,
     FFmpegAudioFixPP,
+    FFmpegEmbedSubtitlePP,
+    FFmpegExtractAudioPP,
     FFmpegMergerPP,
     FFmpegMetadataPP,
     FFmpegVideoConvertor,
-    FFmpegExtractAudioPP,
-    FFmpegEmbedSubtitlePP,
 )
 from .xattrpp import XAttrMetadataPP
 from .execafterdownload import ExecAfterDownloadPP
 
 __all__ = [
     'AtomicParsleyPP',
+    'ExecAfterDownloadPP',
     'FFmpegAudioFixPP',
+    'FFmpegEmbedSubtitlePP',
+    'FFmpegExtractAudioPP',
     'FFmpegMergerPP',
     'FFmpegMetadataPP',
+    'FFmpegPostProcessor',
     'FFmpegVideoConvertor',
-    'FFmpegExtractAudioPP',
-    'FFmpegEmbedSubtitlePP',
     'XAttrMetadataPP',
-    'ExecAfterDownloadPP',
 ]
diff --git a/youtube_dl/postprocessor/ffmpeg.py b/youtube_dl/postprocessor/ffmpeg.py
index 6f010a9c7..867e75d80 100644
--- a/youtube_dl/postprocessor/ffmpeg.py
+++ b/youtube_dl/postprocessor/ffmpeg.py
@@ -1,4 +1,5 @@
 import os
+import re
 import subprocess
 import sys
 import time
@@ -18,6 +19,23 @@ from ..utils import (
 )
 
 
+def get_version(executable):
+    """ Returns the version of the specified executable,
+    or False if the executable is not present """
+    try:
+        out, err = subprocess.Popen(
+            [executable, '-version'],
+            stdout=subprocess.PIPE, stderr=subprocess.PIPE).communicate()
+    except OSError:
+        return False
+    firstline = out.partition(b'\n')[0].decode('ascii', 'ignore')
+    m = re.search(r'version\s+([0-9._-a-zA-Z]+)', firstline)
+    if not m:
+        return u'present'
+    else:
+        return m.group(1)
+
+
 class FFmpegPostProcessorError(PostProcessingError):
     pass
 
@@ -25,22 +43,26 @@ class FFmpegPostProcessorError(PostProcessingError):
 class FFmpegPostProcessor(PostProcessor):
     def __init__(self, downloader=None, deletetempfiles=False):
         PostProcessor.__init__(self, downloader)
-        self._exes = self.detect_executables()
+        self._versions = self.get_versions()
         self._deletetempfiles = deletetempfiles
 
     @staticmethod
-    def detect_executables():
+    def get_versions():
         programs = ['avprobe', 'avconv', 'ffmpeg', 'ffprobe']
-        return dict((program, check_executable(program, ['-version'])) for program in programs)
+        return dict((program, get_version(program)) for program in programs)
 
     def _get_executable(self):
         if self._downloader.params.get('prefer_ffmpeg', False):
-            return self._exes['ffmpeg'] or self._exes['avconv']
+            prefs = ('ffmpeg', 'avconv')
         else:
-            return self._exes['avconv'] or self._exes['ffmpeg']
+            prefs = ('avconv', 'ffmpeg')
+        for p in prefs:
+            if self._versions[p]:
+                return p
+        return None
 
     def _uses_avconv(self):
-        return self._get_executable() == self._exes['avconv']
+        return self._get_executable() == 'avconv'
 
     def run_ffmpeg_multiple_files(self, input_paths, out_path, opts):
         if not self._get_executable():