How to Set an In/Out Render Range with the DaVinci Resolve Python API

import os
import sys
import time
from pathlib import Path


def import_resolve_module():
    try:
        import DaVinciResolveScript as dvr
        return dvr
    except ImportError:
        search_paths = [
            os.environ.get("RESOLVE_SCRIPT_API", ""),
            os.environ.get("RESOLVE_MODULES", ""),
            r"C:\ProgramData\Blackmagic Design\DaVinci Resolve\Support\Developer\Scripting\Modules",
            "/opt/resolve/Developer/Scripting/Modules",
            "/opt/BlackmagicDesign/DaVinciResolve/Developer/Scripting/Modules",
            "/Library/Application Support/Blackmagic Design/DaVinci Resolve/Developer/Scripting/Modules",
            str(Path.home() / "Library/Application Support/Blackmagic Design/DaVinci Resolve/Developer/Scripting/Modules"),
        ]
        for path in search_paths:
            if path and os.path.isdir(path) and path not in sys.path:
                sys.path.append(path)
        import DaVinciResolveScript as dvr
        return dvr


def safe_call(obj, name, *args, **kwargs):
    try:
        fn = getattr(obj, name, None)
        if callable(fn):
            return fn(*args, **kwargs)
    except Exception:
        return None
    return None


def get_project_and_timeline():
    dvr = import_resolve_module()
    resolve = dvr.scriptapp("Resolve")
    if not resolve:
        raise RuntimeError("DaVinci Resolve API is unavailable")

    project_manager = safe_call(resolve, "GetProjectManager")
    project = safe_call(project_manager, "GetCurrentProject") if project_manager else None
    if not project:
        raise RuntimeError("No DaVinci Resolve project is open")

    timeline = safe_call(project, "GetCurrentTimeline")
    if not timeline:
        raise RuntimeError("No active Timeline")

    return resolve, project, timeline


FALLBACK_FPS = 24.0


def frames_to_tc(frame: int, fps: float):
    fps_i = int(round(fps)) or int(FALLBACK_FPS)
    f = int(frame)
    hh = f // (fps_i * 3600)
    f %= fps_i * 3600
    mm = f // (fps_i * 60)
    f %= fps_i * 60
    ss = f // fps_i
    ff = f % fps_i
    return f"{hh:02d}:{mm:02d}:{ss:02d}:{ff:02d}"


def set_render_range_by_frames(project, timeline, start_frame: int, end_frame: int):
    if end_frame <= start_frame:
        raise ValueError("end_frame must be greater than start_frame")

    try:
        fps = float(safe_call(project, "GetSetting", "timelineFrameRate") or FALLBACK_FPS)
    except Exception:
        fps = FALLBACK_FPS

    start_tc = frames_to_tc(start_frame, fps)
    end_tc = frames_to_tc(end_frame, fps)

    if not safe_call(timeline, "SetInOutPoints", start_tc, end_tc):
        raise RuntimeError("Timeline did not accept the In/Out points")

    safe_call(project, "SetRenderRange", "In/Out Range")
    return start_tc, end_tc


resolve, project, timeline = get_project_and_timeline()
start_tc, end_tc = set_render_range_by_frames(project, timeline, 0, 240)
print("Render range:", start_tc, end_tc)