diff --git a/lib/render_job.py b/lib/render_job.py
index 4ba22eb..3da21de 100644
--- a/lib/render_job.py
+++ b/lib/render_job.py
@@ -33,6 +33,7 @@ class RenderJob:
 
         self.worker = RenderWorkerFactory.create_worker(renderer, input_path, output_path, args)
         self.worker.log_path = os.path.join(os.path.dirname(input_path), self.name + '.log')
+        self.worker.validate()
 
         self.file_hash = None
         threading.Thread(target=self.__get_file_hash).start()  # get file hash on bg thread
diff --git a/lib/render_workers/aerender_worker.py b/lib/render_workers/aerender_worker.py
index 79ae63a..57f446c 100644
--- a/lib/render_workers/aerender_worker.py
+++ b/lib/render_workers/aerender_worker.py
@@ -47,7 +47,7 @@ class AERenderWorker(BaseRenderWorker):
             logging.error(f'Failed to get {cls.renderer} version: {e}')
         return version
 
-    def _generate_subprocess(self):
+    def generate_worker_subprocess(self):
 
         if os.path.exists('nexrender-cli-macos'):
             logging.info('nexrender found')
diff --git a/lib/render_workers/blender_worker.py b/lib/render_workers/blender_worker.py
index 101349f..e78b8b1 100644
--- a/lib/render_workers/blender_worker.py
+++ b/lib/render_workers/blender_worker.py
@@ -21,7 +21,8 @@ class BlenderRenderWorker(BaseRenderWorker):
         self.engine = self.args.get('engine', 'BLENDER_EEVEE').upper()
         self.export_format = self.args.get('export_format', None) or 'JPEG'
         self.camera = self.args.get('camera', None)
-        self.render_all_frames = self.args.get('render_all_frames', False)
+        self.render_all_frames = self.args.get('render_all_frames', False) or \
+                                 '-a' in (self.args.get('raw', None) or "").split(' ')
         self.frame_to_render = 0
 
         # Stats
@@ -45,7 +46,7 @@ class BlenderRenderWorker(BaseRenderWorker):
             logging.error(f'Failed to get {cls.renderer} version: {e}')
         return version
 
-    def _generate_subprocess(self):
+    def generate_worker_subprocess(self):
 
         cmd = [self.renderer_path()]
         if self.args.get('background', True):  # optionally run render not in background
diff --git a/lib/render_workers/ffmpeg_worker.py b/lib/render_workers/ffmpeg_worker.py
index a3448d9..36aa102 100644
--- a/lib/render_workers/ffmpeg_worker.py
+++ b/lib/render_workers/ffmpeg_worker.py
@@ -35,7 +35,7 @@ class FFMPEGRenderWorker(BaseRenderWorker):
             logger.error("Failed to get FFMPEG version: {}".format(e))
         return version
 
-    def _generate_subprocess(self):
+    def generate_worker_subprocess(self):
 
         cmd = [self.renderer_path(), '-y', '-stats', '-i', self.input_path]
 
diff --git a/lib/render_workers/render_worker.py b/lib/render_workers/render_worker.py
index 8ab8ccf..6c68ec7 100644
--- a/lib/render_workers/render_worker.py
+++ b/lib/render_workers/render_worker.py
@@ -92,8 +92,28 @@ class BaseRenderWorker(object):
             logging.exception(e)
         return path
 
-    def _generate_subprocess(self):
-        raise NotImplementedError("_generate_subprocess not implemented")
+    def validate(self):
+        if not os.path.exists(self.input_path):
+            raise FileNotFoundError(f"Cannot find input path: {self.input_path}")
+        self.generate_subprocess()
+
+    def generate_subprocess(self):
+        # Convert raw args from string if available and catch conflicts
+        cmd = self.generate_worker_subprocess()
+        raw_args = self.args.get('raw', None)
+        if raw_args:
+            import shlex
+            args_split = shlex.split(raw_args)
+            flags = [x for x in args_split if x.startswith('-')]
+            conflict = any(element in flags for element in args_split)
+            if conflict:
+                raise ValueError("Custom args conflicts set parameters")
+            else:
+                cmd.extend(args_split)
+        return cmd
+
+    def generate_worker_subprocess(self):
+        raise NotImplementedError("generate_worker_subprocess not implemented")
 
     def start(self):
 
diff --git a/scheduler_gui.py b/scheduler_gui.py
index d5f452f..87c585b 100755
--- a/scheduler_gui.py
+++ b/scheduler_gui.py
@@ -16,7 +16,7 @@ from lib.utilities.server_helper import post_job_to_server
 logger = logging.getLogger()
 
 prefs_name = 'config/.scheduler_prefs'
-label_width = 7
+label_width = 9
 header_padding = 6
 server_setup_timeout = 5
 
@@ -137,6 +137,13 @@ class ScheduleJob(Frame):
         self.blender_multiple_cameras = BooleanVar(value=False)
         self.blender_cameras_list = None
 
+        # custom args frame
+        custom_args_frame = Frame(self)
+        custom_args_frame.pack(fill=X)
+        Label(custom_args_frame, text="Custom Args", width=label_width).pack(side=LEFT, padx=5, pady=5)
+        self.custom_args_entry = Entry(custom_args_frame)
+        self.custom_args_entry.pack(side=LEFT, padx=5, expand=True, fill=X)
+
         # Submit Button
         self.submit_frame = None
 
@@ -311,7 +318,7 @@ class ScheduleJob(Frame):
                     'renderer': renderer,
                     'client': client,
                     'output_path': os.path.join(os.path.dirname(self.chosen_file), self.output_entry.get()),
-                    'args': {},
+                    'args': {'raw': self.custom_args_entry.get()},
                     'name': None}
         job_list = []