Option to choose different downloader for different protocols

* Renamed `--external-downloader-args` to `--downloader-args`
* Added `native` as an option for the downloader
* Use similar syntax to `--downloader-args` etc. Eg: `--downloader dash:native --downloader aria2c`
* Deprecated `--hls-prefer-native` and `--hls-prefer-ffmpeg` since the same can now be done with `--downloader "m3u8:native"` and `m3u8:ffmpeg` respectively
* Split `frag_urls` protocol into `m3u8_frag_urls` and `dash_frag_urls`
* Standardize shortening of protocol names with `downloader.shorten_protocol_name`

yt_dlp/downloader/__init__.py

@@ -1,5 +1,6 @@
 from __future__ import unicode_literals
 
+from ..compat import compat_str
 from ..utils import (
     determine_protocol,
 )
@@ -42,6 +43,23 @@ PROTOCOL_MAP = {
 }
 
 
+def shorten_protocol_name(proto, simplify=False):
+    short_protocol_names = {
+        'm3u8_native': 'm3u8_n',
+        'http_dash_segments': 'dash',
+        'niconico_dmc': 'dmc',
+    }
+    if simplify:
+        short_protocol_names.update({
+            'https': 'http',
+            'ftps': 'ftp',
+            'm3u8_native': 'm3u8',
+            'm3u8_frag_urls': 'm3u8',
+            'dash_frag_urls': 'dash',
+        })
+    return short_protocol_names.get(proto, proto)
+
+
 def get_suitable_downloader(info_dict, params={}, default=HttpFD):
     """Get the downloader class that can handle the info dict."""
     protocol = determine_protocol(info_dict)
@@ -50,8 +68,14 @@ def get_suitable_downloader(info_dict, params={}, default=HttpFD):
     # if (info_dict.get('start_time') or info_dict.get('end_time')) and not info_dict.get('requested_formats') and FFmpegFD.can_download(info_dict):
     #     return FFmpegFD
 
-    external_downloader = params.get('external_downloader')
-    if external_downloader is not None:
+    downloaders = params.get('external_downloader')
+    external_downloader = (
+        downloaders if isinstance(downloaders, compat_str)
+        else downloaders.get(shorten_protocol_name(protocol, True), downloaders.get('default')))
+    if external_downloader and external_downloader.lower() == 'native':
+        external_downloader = 'native'
+
+    if external_downloader not in (None, 'native'):
         ed = get_external_downloader(external_downloader)
         if ed.can_download(info_dict, external_downloader):
             return ed
@@ -59,6 +83,8 @@ def get_suitable_downloader(info_dict, params={}, default=HttpFD):
     if protocol.startswith('m3u8'):
         if info_dict.get('is_live'):
             return FFmpegFD
+        elif external_downloader == 'native':
+            return HlsFD
         elif _get_real_downloader(info_dict, 'frag_urls', params, None):
             return HlsFD
         elif params.get('hls_prefer_native') is True:
@@ -70,6 +96,7 @@ def get_suitable_downloader(info_dict, params={}, default=HttpFD):
 
 
 __all__ = [
-    'get_suitable_downloader',
     'FileDownloader',
+    'get_suitable_downloader',
+    'shorten_protocol_name',
 ]

yt_dlp/downloader/dash.py

@@ -20,7 +20,7 @@ from ..utils import (
 class DashSegmentsFD(FragmentFD):
     """
     Download segments in a DASH manifest. External downloaders can take over
-    the fragment downloads by supporting the 'frag_urls' protocol
+    the fragment downloads by supporting the 'dash_frag_urls' protocol
     """
 
     FD_NAME = 'dashsegments'
@@ -30,7 +30,7 @@ class DashSegmentsFD(FragmentFD):
         fragments = info_dict['fragments'][:1] if self.params.get(
             'test', False) else info_dict['fragments']
 
-        real_downloader = _get_real_downloader(info_dict, 'frag_urls', self.params, None)
+        real_downloader = _get_real_downloader(info_dict, 'dash_frag_urls', self.params, None)
 
         ctx = {
             'filename': filename,

yt_dlp/downloader/external.py

@@ -81,11 +81,15 @@ class ExternalFD(FileDownloader):
 
     @property
     def exe(self):
-        return self.params.get('external_downloader')
+        return self.get_basename()
 
     @classmethod
     def available(cls, path=None):
-        return check_executable(path or cls.get_basename(), [cls.AVAILABLE_OPT])
+        path = check_executable(path or cls.get_basename(), [cls.AVAILABLE_OPT])
+        if path:
+            cls.exe = path
+            return path
+        return False
 
     @classmethod
     def supports(cls, info_dict):
@@ -259,7 +263,7 @@ class WgetFD(ExternalFD):
 
 class Aria2cFD(ExternalFD):
     AVAILABLE_OPT = '-v'
-    SUPPORTED_PROTOCOLS = ('http', 'https', 'ftp', 'ftps', 'frag_urls')
+    SUPPORTED_PROTOCOLS = ('http', 'https', 'ftp', 'ftps', 'dash_frag_urls', 'm3u8_frag_urls')
 
     @staticmethod
     def supports_manifest(manifest):
@@ -310,9 +314,11 @@ class Aria2cFD(ExternalFD):
 
 
 class HttpieFD(ExternalFD):
+    AVAILABLE_OPT = '--version'
+
     @classmethod
     def available(cls, path=None):
-        return check_executable(path or 'http', ['--version'])
+        return ExternalFD.available(cls, path or 'http')
 
     def _make_cmd(self, tmpfilename, info_dict):
         cmd = ['http', '--download', '--output', tmpfilename, info_dict['url']]
@@ -327,7 +333,8 @@ class FFmpegFD(ExternalFD):
     SUPPORTED_PROTOCOLS = ('http', 'https', 'ftp', 'ftps', 'm3u8', 'rtsp', 'rtmp', 'mms')
 
     @classmethod
-    def available(cls, path=None):  # path is ignored for ffmpeg
+    def available(cls, path=None):
+        # TODO: Fix path for ffmpeg
         return FFmpegPostProcessor().available
 
     def _call_downloader(self, tmpfilename, info_dict):
@@ -484,4 +491,4 @@ def get_external_downloader(external_downloader):
         downloader . """
     # Drop .exe extension on Windows
     bn = os.path.splitext(os.path.basename(external_downloader))[0]
-    return _BY_NAME[bn]
+    return _BY_NAME.get(bn)

yt_dlp/downloader/hls.py

@@ -32,7 +32,7 @@ from ..utils import (
 class HlsFD(FragmentFD):
     """
     Download segments in a m3u8 manifest. External downloaders can take over
-    the fragment downloads by supporting the 'frag_urls' protocol and
+    the fragment downloads by supporting the 'm3u8_frag_urls' protocol and
     re-defining 'supports_manifest' function
     """
 
@@ -95,7 +95,7 @@ class HlsFD(FragmentFD):
             #     fd.add_progress_hook(ph)
             return fd.real_download(filename, info_dict)
 
-        real_downloader = _get_real_downloader(info_dict, 'frag_urls', self.params, None)
+        real_downloader = _get_real_downloader(info_dict, 'm3u8_frag_urls', self.params, None)
         if real_downloader and not real_downloader.supports_manifest(s):
             real_downloader = None
         if real_downloader: