[downloader/external] Add curl and aria2c (Closes #182)

youtube_dl/downloader/external.py

@@ -97,13 +97,22 @@ class ExternalFD(FileDownloader):
         self._debug_cmd(cmd, subprocess_encoding)
 
         p = subprocess.Popen(
-            cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-        stdout, stderr = p.communicate()
+            cmd, stderr=subprocess.PIPE)
+        _, stderr = p.communicate()
         if p.returncode != 0:
             self.to_stderr(stderr)
         return p.returncode
 
 
+class CurlFD(ExternalFD):
+    def _make_cmd(self, tmpfilename, info_dict):
+        cmd = [self.exe, '-o', tmpfilename]
+        for key, val in self._calc_headers(info_dict).items():
+            cmd += ['--header', '%s: %s' % (key, val)]
+        cmd += ['--', info_dict['url']]
+        return cmd
+
+
 class WgetFD(ExternalFD):
     def _make_cmd(self, tmpfilename, info_dict):
         cmd = [self.exe, '-O', tmpfilename, '-nv', '--no-cookies']
@@ -113,6 +122,20 @@ class WgetFD(ExternalFD):
         return cmd
 
 
+class Aria2cFD(ExternalFD):
+    def _make_cmd(self, tmpfilename, info_dict):
+        cmd = [
+            self.exe, '-c',
+            '--min-split-size', '1M', '--max-connection-per-server', '4']
+        dn = os.path.dirname(tmpfilename)
+        if dn:
+            cmd += ['--dir', dn]
+        cmd += ['--out', os.path.basename(tmpfilename)]
+        for key, val in self._calc_headers(info_dict).items():
+            cmd += ['--header', '%s: %s' % (key, val)]
+        cmd += ['--', info_dict['url']]
+        return cmd
+
 _BY_NAME = dict(
     (klass.get_basename(), klass)
     for name, klass in globals().items()