[youtube|ffmpeg] Automatically correct video with non-square pixels (Fixes #4674)

youtube_dl/postprocessor/__init__.py

@@ -6,6 +6,7 @@ from .ffmpeg import (
     FFmpegAudioFixPP,
     FFmpegEmbedSubtitlePP,
     FFmpegExtractAudioPP,
+    FFmpegFixupStretchedPP,
     FFmpegMergerPP,
     FFmpegMetadataPP,
     FFmpegVideoConvertorPP,
@@ -24,6 +25,7 @@ __all__ = [
     'FFmpegAudioFixPP',
     'FFmpegEmbedSubtitlePP',
     'FFmpegExtractAudioPP',
+    'FFmpegFixupStretchedPP',
     'FFmpegMergerPP',
     'FFmpegMetadataPP',
     'FFmpegPostProcessor',

youtube_dl/postprocessor/ffmpeg.py

@@ -50,6 +50,10 @@ class FFmpegPostProcessor(PostProcessor):
         programs = ['avprobe', 'avconv', 'ffmpeg', 'ffprobe']
         return dict((p, get_exe_version(p, args=['-version'])) for p in programs)
 
+    @property
+    def available(self):
+        return self._executable is not None
+
     @property
     def _executable(self):
         if self._downloader.params.get('prefer_ffmpeg', False):
@@ -540,3 +544,22 @@ class FFmpegAudioFixPP(FFmpegPostProcessor):
         os.rename(encodeFilename(temp_filename), encodeFilename(filename))
 
         return True, info
+
+
+class FFmpegFixupStretchedPP(FFmpegPostProcessor):
+    def run(self, info):
+        stretched_ratio = info.get('stretched_ratio')
+        if stretched_ratio is None or stretched_ratio == 1:
+            return
+
+        filename = info['filepath']
+        temp_filename = prepend_extension(filename, 'temp')
+
+        options = ['-c', 'copy', '-aspect', '%f' % stretched_ratio]
+        self._downloader.to_screen('[ffmpeg] Fixing aspect ratio in "%s"' % filename)
+        self.run_ffmpeg(filename, temp_filename, options)
+
+        os.remove(encodeFilename(filename))
+        os.rename(encodeFilename(temp_filename), encodeFilename(filename))
+
+        return True, info