Added ability to join together multiple renders

manim/__init__.py

@@ -100,6 +100,7 @@ from .utils.sounds import *
 from .utils.space_ops import *
 from .utils.tex import *
 from .utils.tex_templates import *
+from .utils.join_scenes import *
 
 try:
     from IPython import get_ipython

manim/utils/join_scenes.py

@@ -0,0 +1,121 @@
+from pathlib import Path
+import subprocess
+
+from manim._config import config, tempconfig, logger
+from manim.constants import QUALITIES
+from manim.scene.scene import Scene
+from manim.__main__ import __version__
+
+__all__ = ["render_multiple_scenes"]
+
+def combine_renders(
+        dir: Path,
+        input_files: list[str],
+        output_file: Path,
+    ) -> None:
+    """Make ffmpeg do all the hard work of combining video files"""
+
+    file_list = dir / "partial_scenes_file_list.txt"
+    logger.debug(
+        f"Renders to combine ({len(input_files)} files): %(p)s",
+        {"p": input_files[:5]},
+    )
+    with file_list.open("w", encoding="utf-8") as fp:
+        fp.write("# This file is used internally by FFMPEG.\n")
+        for pf_path in input_files:
+            pf_path = Path(pf_path).as_posix()
+            fp.write(f"file 'file:{pf_path}'\n")
+    commands = [
+        config.ffmpeg_executable,
+        "-y",  # overwrite output file if it exists
+        "-f",
+        "concat",
+        "-safe",
+        "0",
+        "-i",
+        str(file_list),
+        "-loglevel",
+        config.ffmpeg_loglevel.lower(),
+        "-metadata",
+        f"comment=Rendered with Manim Community v{__version__}",
+        "-nostdin",
+        "-c",
+        "copy",
+        str(output_file)
+    ]
+
+    combine_process = subprocess.Popen(commands)
+    combine_process.wait()
+
+def combine_scenes(
+        *classes: type[Scene],
+        output: Path | None = None
+    ) -> Path:
+    """
+    Combine scenes produced by different renders. This function is mostly Path stuff.
+
+    Returns:
+    --------
+        The location of the final file
+    """
+    quality_dict = QUALITIES[config.quality] # type: ignore
+    quality_folder = f"{quality_dict['pixel_height']}p{quality_dict['frame_rate']}"
+
+    dir = Path(config.media_dir) / f"videos/{quality_folder}"
+
+    files = [
+        str(dir / f"{cls.__name__}.mp4")
+        for cls in classes
+    ]
+
+    output = dir/"final.mp4" if output is None else output
+
+    combine_renders(
+        dir,
+        files,
+        output
+    )
+    return output
+
+def render_multiple_scenes(
+        *scenes: type[Scene],
+        dir: Path | str = config.media_dir,
+        user_config: dict = {},
+        output_file: Path | str | None = None
+    ) -> None:
+    """
+    Render and concatenate multiple `Scene`s together.
+
+    Parameters:
+    -----------
+        *scenes
+            The classes to combine
+        dir
+            The location of the media files
+        user_config
+            Other configuration options, like transparency and stuff. Some features (like turning into a GIF) may not work
+        output_file
+            Where to keep the final file
+    """
+    if not scenes:
+        raise ValueError("Must be at least one scene to render!")
+
+    if not Path(dir).exists():
+        Path(dir).mkdir()
+    config.media_dir = str(dir)
+
+    config.update(user_config)
+
+    for scene in scenes:
+        # use tempconfig to prevent bugs
+        # with multiple renders in one file
+        with tempconfig({}):
+            scene().render()
+    
+    if output_file is not None:
+        output_file = Path(output_file)
+    final = combine_scenes(*scenes, output=output_file)
+    
+    logger.info(f"Concatenated Scene can be found at \'{final.absolute()}\'")
+
+