Conditionally use certain GStreamer plugins

In old versions of GStreamer gstvideoconvertscale was split into two
plugins, gstvideoscale and gstvideoconvert. This change makes the use of
these three plugins conditional on their existence and has Windows use
the two plugins from the older version of GStreamer. In addition, it
starts to clean up the gstreamer.py file which is responsible for
managing GStreamer libraries and plugins. This is the first change in a
series of changes that seek to clean up the way these libraries are
managed during the build.

1 files changed, 112 insertions, 97 deletions

diff --git a/python/servo/gstreamer.py b/python/servo/gstreamer.py
index 5eb491c98e5..1b7739d0f62 100644
--- a/python/servo/gstreamer.py
+++ b/python/servo/gstreamer.py
@@ -12,109 +12,113 @@ import sys
 import platform
 
 GSTREAMER_DYLIBS = [
-    ("gstapp", "gst-plugins-base"),
-    ("gstaudio", "gst-plugins-base"),
-    ("gstbase", "gstreamer"),
-    ("gstcodecparsers", "gst-plugins-bad"),
-    ("gstcontroller", "gstreamer"),
-    ("gstfft", "gst-plugins-base"),
-    ("gstgl", "gst-plugins-base"),
-    ("gstnet", "gstreamer"),
-    ("gstpbutils", "gst-plugins-base"),
-    ("gstplayer", "gst-plugins-bad"),
-    ("gstreamer", "gstreamer"),
-    ("gstriff", "gst-plugins-base"),
-    ("gstrtp", "gst-plugins-base"),
-    ("gstrtsp", "gst-plugins-base"),
-    ("gstsctp", "gst-plugins-bad"),
-    ("gstsdp", "gst-plugins-base"),
-    ("gsttag", "gst-plugins-base"),
-    ("gstvideo", "gst-plugins-base"),
-    ("gstwebrtc", "gst-plugins-bad"),
-]
-
-NON_UWP_DYLIBS = [
+    # gstreamer
+    "gstbase",
+    "gstcontroller",
     "gstnet",
+    "gstreamer",
+    # gst-plugins-base
+    "gstapp",
+    "gstaudio",
+    "gstfft",
+    "gstgl",
+    "gstpbutils",
+    "gstriff",
+    "gstrtp",
+    "gstrtsp",
     "gstsctp",
+    "gstsdp",
+    "gsttag",
+    "gstvideo",
+    # gst-plugins-bad
+    "gstcodecparsers",
+    "gstplayer",
+    "gstwebrtc",
 ]
 
-GSTREAMER_PLUGINS = [
-    ("gstapp", "gst-plugins-base"),
-    ("gstaudiobuffersplit", "gst-plugins-bad"),
-    ("gstaudioconvert", "gst-plugins-base"),
-    ("gstaudiofx", "gst-plugins-good"),
-    ("gstaudioparsers", "gst-plugins-good"),
-    ("gstaudioresample", "gst-plugins-base"),
-    ("gstautodetect", "gst-plugins-good"),
-    ("gstcoreelements", "gstreamer"),
-    ("gstdeinterlace", "gst-plugins-good"),
-    ("gstdtls", "gst-plugins-bad"),
-    ("gstgio", "gst-plugins-base"),
-    ("gstid3tag", "gst-plugins-bad"),
-    ("gstid3demux", "gst-plugins-good"),
-    ("gstinterleave", "gst-plugins-good"),
-    ("gstisomp4", "gst-plugins-good"),
-    ("gstlibav", "gst-libav"),
-    ("gstmatroska", "gst-plugins-good"),
-    ("gstogg", "gst-plugins-base"),
-    ("gstopengl", "gst-plugins-base"),
-    ("gstopus", "gst-plugins-base"),
-    ("gstplayback", "gst-plugins-base"),
-    ("gstproxy", "gst-plugins-bad"),
-    ("gstrtp", "gst-plugins-good"),
-    ("gstrtpmanager", "gst-plugins-good"),
-    ("gsttheora", "gst-plugins-base"),
-    ("gsttypefindfunctions", "gst-plugins-base"),
-    ("gstvideoconvertscale", "gst-plugins-base"),
-    ("gstvideofilter", "gst-plugins-good"),
-    ("gstvideoparsersbad", "gst-plugins-bad"),
-    ("gstvorbis", "gst-plugins-base"),
-    ("gstvolume", "gst-plugins-base"),
-    ("gstvpx", "gst-plugins-good"),
-    ("gstwebrtc", "gst-plugins-bad"),
-]
-
-WINDOWS_PLUGINS = [
-    "gstnice",
-    "gstwasapi",
-]
-
-MACOS_PLUGINS = [
-    # Temporarily disabled until CI is using Mojave.
-    # https://github.com/servo/saltfs/issues/1011
-    # ("gstapplemedia", "gst-plugins-bad"),
-    ("gstosxaudio", "gst-plugins-good"),
-    ("gstosxvideo", "gst-plugins-good"),
-]
 
-NON_UWP_PLUGINS = [
-    "gstdtls",
-    "gstmatroska",
+GSTREAMER_PLUGINS = [
+    # gstreamer
+    "gstcoreelements",
     "gstnice",
+    # gst-plugins-base
+    "gstapp",
+    "gstaudioconvert",
+    "gstaudioresample",
+    "gstgio",
     "gstogg",
     "gstopengl",
     "gstopus",
-    "gstrtp",
-    "gstrtpmanager",
+    "gstplayback",
     "gsttheora",
+    "gsttypefindfunctions",
+    "gstvolume",
     "gstvorbis",
+    # gst-plugins-good
+    "gstaudiofx",
+    "gstaudioparsers",
+    "gstautodetect",
+    "gstdeinterlace",
+    "gstid3demux",
+    "gstinterleave",
+    "gstisomp4",
+    "gstmatroska",
+    "gstrtp",
+    "gstrtpmanager",
+    "gstvideofilter",
     "gstvpx",
+    # gst-plugins-bad
+    "gstaudiobuffersplit",
+    "gstdtls",
+    "gstid3tag",
+    "gstproxy",
+    "gstvideoparsersbad",
     "gstwebrtc",
+    # gst-libav
+    "gstlibav",
 ]
 
 
 def windows_dlls(uwp):
-    dlls = [x for x, _ in GSTREAMER_DYLIBS]
+    libs = list(GSTREAMER_DYLIBS)
+    NON_UWP_DYLIBS = [
+        "gstnet",
+        "gstsctp",
+    ]
     if uwp:
-        dlls = filter(lambda x: x not in NON_UWP_DYLIBS, dlls)
-    return [x + "-1.0-0.dll" for x in dlls]
+        libs = filter(lambda x: x not in NON_UWP_DYLIBS, libs)
+    return [f"{lib}-1.0-0.dll" for lib in libs]
 
 
 def windows_plugins(uwp):
-    dlls = [x for x, _ in GSTREAMER_PLUGINS] + WINDOWS_PLUGINS
+    # FIXME: We should support newer gstreamer versions here that replace
+    # gstvideoconvert and gstvideoscale with gstvideoconvertscale.
+    libs = [
+        *GSTREAMER_PLUGINS,
+        "gstvideoconvert",
+        "gstvideoscale",
+        "gstwasapi"
+    ]
+    NON_UWP_PLUGINS = [
+        "gstnice",
+        # gst-plugins-base
+        "gstogg",
+        "gstopengl",
+        "gstopus",
+        "gstrtp",
+        "gsttheora",
+        "gstvorbis",
+        # gst-plugins-good
+        "gstmatroska",
+        "gstrtpmanager",
+        "gstvpx",
+        # gst-plugins-bad
+        "gstdtls",
+        "gstwebrtc",
+    ]
     if uwp:
-        dlls = filter(lambda x: x not in NON_UWP_PLUGINS, dlls)
-    return [x + ".dll" for x in dlls]
+        libs = filter(lambda x: x not in NON_UWP_PLUGINS, libs)
+    return [f"{lib}.dll" for lib in libs]
 
 
 def macos_lib_dir():
@@ -125,27 +129,38 @@ def macos_lib_dir():
 
 
 def macos_dylibs():
-    return [
-        os.path.join(
-            macos_lib_dir(),
-            "lib" + name + "-1.0.0.dylib"
-        ) for name, path in GSTREAMER_DYLIBS
-    ] + [
-        os.path.join(macos_lib_dir(), "libnice.dylib"),
-        os.path.join(macos_lib_dir(), "libnice.10.dylib"),
+    dylibs = [
+        *[f"lib{lib}-1.0.0.dylib" for lib in GSTREAMER_DYLIBS],
+        "libnice.dylib",
+        "libnice.10.dylib",
     ]
+    return [os.path.join(macos_lib_dir(), lib) for lib in dylibs]
 
 
 def macos_plugins():
-    return [
-        os.path.join(
-            macos_lib_dir(),
-            'gstreamer-1.0',
-            "lib" + name + ".dylib"
-        ) for name, path in GSTREAMER_PLUGINS + MACOS_PLUGINS
-    ] + [
-        os.path.join(macos_lib_dir(), "gstreamer-1.0", "libgstnice.dylib"),
+    plugins = [
+        *GSTREAMER_PLUGINS,
+        # gst-plugins-good
+        "gstosxaudio",
+        "gstosxvideo",
+        # gst-plugins-bad
+        "gstapplemedia",
+    ]
+
+    def plugin_path(plugin):
+        return os.path.join(macos_lib_dir(), 'gstreamer-1.0', f"lib{plugin}.dylib")
+
+    # These plugins depend on the particular version of GStreamer that is installed
+    # on the system that is building servo.
+    conditional_plugins = [
+        # gst-plugins-base
+        plugin_path("gstvideoconvert"),
+        plugin_path("gstvideoscale"),
+        plugin_path("gstvideoconvertscale")
     ]
+    conditional_plugins = list(filter(lambda path: os.path.exists(path),
+                                      conditional_plugins))
+    return [plugin_path(plugin) for plugin in plugins] + conditional_plugins
 
 
 def write_plugin_list(target):