Add render option to use x265 with lossless settings

manim/_config/utils.py

@@ -320,6 +320,7 @@ class MyScene(Scene): ...
         "force_window",
         "no_latex_cleanup",
         "preview_command",
+        "lossless",
     }
 
     def __init__(self) -> None:
@@ -591,6 +592,7 @@ def digest_parser(self, parser: configparser.ConfigParser) -> Self:
             "enable_wireframe",
             "force_window",
             "no_latex_cleanup",
+            "lossless",
         ]:
             setattr(self, key, parser["CLI"].getboolean(key, fallback=False))
 
@@ -767,6 +769,7 @@ def digest_args(self, args: argparse.Namespace) -> Self:
             "dry_run",
             "no_latex_cleanup",
             "preview_command",
+            "lossless",
         ]:
             if hasattr(args, key):
                 attr = getattr(args, key)
@@ -1491,6 +1494,15 @@ def zero_pad(self) -> int:
     def zero_pad(self, value: int) -> None:
         self._set_int_between("zero_pad", value, 0, 9)
 
+    @property
+    def lossless(self) -> bool:
+        """Whether to use lossless x265 encoding (mp4 format only)."""
+        return self._d["lossless"]
+
+    @lossless.setter
+    def lossless(self, value: bool) -> None:
+        self._set_boolean("lossless", value)
+
     def get_dir(self, key: str, **kwargs: Any) -> Path:
         """Resolve a config option that stores a directory.
 

manim/cli/render/render_options.py

@@ -212,4 +212,10 @@ def validate_resolution(
         help="Use shaders for OpenGLVMobject stroke which are compatible with transformation matrices.",
         default=None,
     ),
+    option(
+        "--lossless",
+        is_flag=True,
+        help="Render with lossless x265 encoding (mp4 format only).",
+        default=False,
+    ),
 )

manim/scene/scene_file_writer.py

@@ -536,12 +536,20 @@ def open_partial_movie_stream(self, file_path=None) -> None:
 
         fps = to_av_frame_rate(config.frame_rate)
 
-        partial_movie_file_codec = "libx264"
         partial_movie_file_pix_fmt = "yuv420p"
         av_options = {
             "an": "1",  # ffmpeg: -an, no audio
-            "crf": "23",  # ffmpeg: -crf, constant rate factor (improved bitrate)
         }
+        if config.lossless:
+            partial_movie_file_codec = "libx265"
+            av_options["x265-params"] = (
+                "lossless=1"  # ffmpeg: set lossless mode for x265
+            )
+        else:
+            partial_movie_file_codec = "libx264"
+            av_options["crf"] = (
+                "23"  # ffmpeg: -crf, constant rate factor (improved bitrate)
+            )
 
         if config.movie_file_extension == ".webm":
             partial_movie_file_codec = "libvpx-vp9"