working a bit faster

core/async_lowres_preprocessor.py

@@ -0,0 +1,337 @@
+"""
+Async low-resolution video preprocessor for parallel processing optimization.
+Creates low-resolution videos in background while main pipeline processes other segments.
+"""
+
+import os
+import asyncio
+import subprocess
+import logging
+import threading
+from pathlib import Path
+from typing import List, Dict, Any, Optional
+from concurrent.futures import ThreadPoolExecutor
+
+logger = logging.getLogger(__name__)
+
+class AsyncLowResPreprocessor:
+    """
+    Handles async pre-generation of low-resolution videos for SAM2 inference.
+    Uses FFmpeg subprocesses to bypass Python GIL limitations.
+    """
+    
+    def __init__(self, max_concurrent: int = 3, segments_ahead: int = 3, use_ffmpeg: bool = True):
+        """
+        Initialize async preprocessor.
+        
+        Args:
+            max_concurrent: Maximum number of concurrent FFmpeg processes
+            segments_ahead: How many segments to prepare in advance
+            use_ffmpeg: Use FFmpeg instead of OpenCV for better performance
+        """
+        self.max_concurrent = max_concurrent
+        self.segments_ahead = segments_ahead
+        self.use_ffmpeg = use_ffmpeg
+        self.preparation_tasks = {}  # segment_idx -> threading.Thread
+        self.completed_segments = set()  # Track completed preparations
+        self.active_threads = []  # Track active background threads
+        
+        logger.info(f"AsyncLowResPreprocessor initialized: max_concurrent={max_concurrent}, "
+                   f"segments_ahead={segments_ahead}, use_ffmpeg={use_ffmpeg}")
+    
+    async def create_lowres_ffmpeg(self, input_path: str, output_path: str, scale: float, semaphore: asyncio.Semaphore) -> bool:
+        """
+        Create low-resolution video using FFmpeg (bypasses Python GIL).
+        
+        Args:
+            input_path: Path to input video
+            output_path: Path to output low-res video
+            scale: Scale factor for resolution reduction
+            semaphore: Asyncio semaphore for limiting concurrent processes
+            
+        Returns:
+            True if successful
+        """
+        async with semaphore:  # Limit concurrent FFmpeg processes
+            try:
+                # Ensure output directory exists
+                os.makedirs(os.path.dirname(output_path), exist_ok=True)
+                
+                # FFmpeg command for fast low-res video creation
+                cmd = [
+                    'ffmpeg', '-y',  # Overwrite output
+                    '-i', input_path,
+                    '-vf', f'scale=iw*{scale}:ih*{scale}',
+                    '-c:v', 'libx264',
+                    '-preset', 'ultrafast',  # Fastest encoding
+                    '-crf', '28',  # Lower quality OK for inference
+                    '-an',  # No audio needed for inference
+                    output_path
+                ]
+                
+                logger.debug(f"Starting FFmpeg low-res creation: {os.path.basename(input_path)} -> {os.path.basename(output_path)}")
+                
+                # Run FFmpeg asynchronously
+                proc = await asyncio.create_subprocess_exec(
+                    *cmd,
+                    stdout=asyncio.subprocess.DEVNULL,
+                    stderr=asyncio.subprocess.PIPE
+                )
+                
+                stdout, stderr = await proc.wait(), await proc.communicate()
+                
+                if proc.returncode != 0:
+                    stderr_text = stderr[1].decode() if stderr and len(stderr) > 1 else "Unknown error"
+                    logger.error(f"FFmpeg failed for {input_path}: {stderr_text}")
+                    return False
+                
+                # Verify output file was created
+                if not os.path.exists(output_path) or os.path.getsize(output_path) == 0:
+                    logger.error(f"FFmpeg output file missing or empty: {output_path}")
+                    return False
+                
+                logger.debug(f"FFmpeg low-res creation completed: {os.path.basename(output_path)}")
+                return True
+                
+            except Exception as e:
+                logger.error(f"Error in FFmpeg low-res creation for {input_path}: {e}")
+                return False
+    
+    def create_lowres_opencv(self, input_path: str, output_path: str, scale: float) -> bool:
+        """
+        Fallback: Create low-resolution video using OpenCV (blocking operation).
+        Used when FFmpeg is not available or fails.
+        
+        Args:
+            input_path: Path to input video
+            output_path: Path to output low-res video
+            scale: Scale factor for resolution reduction
+            
+        Returns:
+            True if successful
+        """
+        try:
+            import cv2
+            
+            logger.debug(f"Creating low-res video with OpenCV: {os.path.basename(input_path)}")
+            
+            cap = cv2.VideoCapture(input_path)
+            if not cap.isOpened():
+                logger.error(f"Could not open video with OpenCV: {input_path}")
+                return False
+            
+            # Get video properties
+            frame_width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH) * scale)
+            frame_height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT) * scale)
+            fps = cap.get(cv2.CAP_PROP_FPS) or 30.0
+            
+            # Ensure output directory exists
+            os.makedirs(os.path.dirname(output_path), exist_ok=True)
+            
+            # Create video writer
+            fourcc = cv2.VideoWriter_fourcc(*'mp4v')
+            out = cv2.VideoWriter(output_path, fourcc, fps, (frame_width, frame_height))
+            
+            if not out.isOpened():
+                logger.error(f"Could not create video writer for: {output_path}")
+                cap.release()
+                return False
+            
+            # Process frames
+            frame_count = 0
+            while True:
+                ret, frame = cap.read()
+                if not ret:
+                    break
+                
+                # Resize frame
+                low_res_frame = cv2.resize(frame, (frame_width, frame_height), 
+                                         interpolation=cv2.INTER_LINEAR)
+                out.write(low_res_frame)
+                frame_count += 1
+            
+            # Cleanup
+            cap.release()
+            out.release()
+            
+            logger.debug(f"OpenCV low-res creation completed: {frame_count} frames -> {os.path.basename(output_path)}")
+            return True
+            
+        except Exception as e:
+            logger.error(f"Error in OpenCV low-res creation for {input_path}: {e}")
+            return False
+    
+    async def create_lowres_video_async(self, input_path: str, output_path: str, scale: float, semaphore: asyncio.Semaphore) -> bool:
+        """
+        Create low-resolution video using the configured method (FFmpeg or OpenCV).
+        
+        Args:
+            input_path: Path to input video
+            output_path: Path to output low-res video
+            scale: Scale factor for resolution reduction
+            semaphore: Asyncio semaphore for limiting concurrent processes
+            
+        Returns:
+            True if successful
+        """
+        # Skip if already exists
+        if os.path.exists(output_path) and os.path.getsize(output_path) > 0:
+            logger.debug(f"Low-res video already exists: {os.path.basename(output_path)}")
+            return True
+        
+        if self.use_ffmpeg:
+            # Try FFmpeg first
+            success = await self.create_lowres_ffmpeg(input_path, output_path, scale, semaphore)
+            if success:
+                return True
+            
+            logger.warning(f"FFmpeg failed for {input_path}, falling back to OpenCV")
+        
+        # Fallback to OpenCV (run in thread pool to avoid blocking)
+        loop = asyncio.get_event_loop()
+        with ThreadPoolExecutor(max_workers=1) as executor:
+            success = await loop.run_in_executor(
+                executor, self.create_lowres_opencv, input_path, output_path, scale
+            )
+        
+        return success
+    
+    async def prepare_segment_lowres(self, segment_info: Dict[str, Any], scale: float, 
+                                   separate_eye_processing: bool = False, semaphore: asyncio.Semaphore = None) -> bool:
+        """
+        Prepare low-resolution videos for a segment (regular or eye-specific).
+        
+        Args:
+            segment_info: Segment information dictionary
+            scale: Scale factor for resolution reduction
+            separate_eye_processing: Whether to prepare eye-specific videos
+            semaphore: Asyncio semaphore for limiting concurrent processes
+            
+        Returns:
+            True if all videos were prepared successfully
+        """
+        segment_idx = segment_info['index']
+        segment_dir = segment_info['directory']
+        
+        try:
+            if separate_eye_processing:
+                # Prepare low-res videos for left and right eyes
+                success_left = success_right = True
+                
+                left_eye_path = os.path.join(segment_dir, "left_eye.mp4")
+                right_eye_path = os.path.join(segment_dir, "right_eye.mp4")
+                
+                if os.path.exists(left_eye_path):
+                    lowres_left_path = os.path.join(segment_dir, "low_res_left_eye_video.mp4")
+                    success_left = await self.create_lowres_video_async(left_eye_path, lowres_left_path, scale, semaphore)
+                
+                if os.path.exists(right_eye_path):
+                    lowres_right_path = os.path.join(segment_dir, "low_res_right_eye_video.mp4")
+                    success_right = await self.create_lowres_video_async(right_eye_path, lowres_right_path, scale, semaphore)
+                
+                success = success_left and success_right
+                if success:
+                    logger.info(f"Pre-generated low-res eye videos for segment {segment_idx}")
+                else:
+                    logger.warning(f"Failed to pre-generate some eye videos for segment {segment_idx}")
+            else:
+                # Prepare regular low-res video
+                input_path = segment_info['video_file']
+                lowres_path = os.path.join(segment_dir, "low_res_video.mp4")
+                
+                success = await self.create_lowres_video_async(input_path, lowres_path, scale, semaphore)
+                if success:
+                    logger.info(f"Pre-generated low-res video for segment {segment_idx}")
+                else:
+                    logger.warning(f"Failed to pre-generate low-res video for segment {segment_idx}")
+            
+            if success:
+                self.completed_segments.add(segment_idx)
+            
+            return success
+            
+        except Exception as e:
+            logger.error(f"Error preparing low-res videos for segment {segment_idx}: {e}")
+            return False
+    
+    def start_background_preparation(self, segments_info: List[Dict[str, Any]], scale: float, 
+                                   separate_eye_processing: bool = False, current_segment: int = 0):
+        """
+        Start preparing upcoming segments in background using threads.
+        
+        Args:
+            segments_info: List of all segment information
+            scale: Scale factor for resolution reduction  
+            separate_eye_processing: Whether to prepare eye-specific videos
+            current_segment: Index of currently processing segment
+        """
+        def background_worker():
+            """Background thread worker that prepares upcoming segments."""
+            try:
+                # Prepare segments ahead of current processing
+                start_idx = current_segment + 1
+                end_idx = min(len(segments_info), start_idx + self.segments_ahead)
+                
+                segments_to_prepare = []
+                for i in range(start_idx, end_idx):
+                    if i not in self.completed_segments and i not in self.preparation_tasks:
+                        segments_to_prepare.append((i, segments_info[i]))
+                
+                if segments_to_prepare:
+                    logger.info(f"Starting background preparation for {len(segments_to_prepare)} segments (indices {start_idx}-{end_idx-1})")
+                    
+                    # Run async work in new event loop
+                    loop = asyncio.new_event_loop()
+                    asyncio.set_event_loop(loop)
+                    
+                    try:
+                        # Create semaphore in this event loop
+                        semaphore = asyncio.Semaphore(self.max_concurrent)
+                        
+                        tasks = []
+                        for segment_idx, segment_info in segments_to_prepare:
+                            task = self.prepare_segment_lowres(segment_info, scale, separate_eye_processing, semaphore)
+                            tasks.append(task)
+                        
+                        # Run all preparation tasks
+                        results = loop.run_until_complete(asyncio.gather(*tasks, return_exceptions=True))
+                        
+                        # Mark completed segments
+                        for i, (segment_idx, _) in enumerate(segments_to_prepare):
+                            if i < len(results) and results[i] is True:
+                                self.completed_segments.add(segment_idx)
+                                logger.debug(f"Background preparation completed for segment {segment_idx}")
+                        
+                    finally:
+                        loop.close()
+                else:
+                    logger.debug(f"No segments need preparation (current: {current_segment})")
+                    
+            except Exception as e:
+                logger.error(f"Error in background preparation worker: {e}")
+        
+        # Start background thread
+        thread = threading.Thread(target=background_worker, daemon=True)
+        thread.start()
+        self.active_threads.append(thread)
+    
+    def is_segment_ready(self, segment_idx: int) -> bool:
+        """
+        Check if low-res videos for a segment are ready.
+        
+        Args:
+            segment_idx: Index of segment to check
+            
+        Returns:
+            True if segment is ready
+        """
+        return segment_idx in self.completed_segments
+    
+    def cleanup(self):
+        """Clean up any running threads."""
+        # Note: daemon threads will be cleaned up automatically when main process exits
+        # We just clear our tracking structures
+        self.active_threads.clear()
+        self.preparation_tasks.clear()
+        
+        logger.debug("AsyncLowResPreprocessor cleanup completed")

core/mask_processor.py

@@ -459,41 +459,12 @@ class MaskProcessor:
         
         return colored_mask
     
-    def _precompute_upscaled_masks(self, video_segments: Dict[int, Dict[int, np.ndarray]], 
-                                  target_width: int, target_height: int) -> Dict[int, Dict[int, np.ndarray]]:
-        """
-        Pre-compute all upscaled masks to avoid per-frame upscaling.
 
-        Args:
-            video_segments: Dictionary of frame masks from SAM2
-            target_width: Target frame width
-            target_height: Target frame height
-            
-        Returns:
-            Dictionary with pre-upscaled masks
-        """
-        logger.info(f"Pre-computing upscaled masks for {len(video_segments)} frames")
-        upscaled_segments = {}
-        
-        for frame_idx, frame_masks in video_segments.items():
-            upscaled_frame_masks = {}
-            for obj_id, mask in frame_masks.items():
-                mask = mask.squeeze()
-                if mask.shape != (target_height, target_width):
-                    upscaled_mask = cv2.resize(mask.astype(np.uint8), 
-                                             (target_width, target_height), 
-                                             interpolation=cv2.INTER_NEAREST)
-                    upscaled_frame_masks[obj_id] = upscaled_mask
-                else:
-                    upscaled_frame_masks[obj_id] = mask.astype(np.uint8)
-            upscaled_segments[frame_idx] = upscaled_frame_masks
-        
-        logger.info(f"Pre-computed upscaled masks for {len(upscaled_segments)} frames")
-        return upscaled_segments
 
     def process_and_save_output_video(self, video_path: str, output_video_path: str, 
                                      video_segments: Dict[int, Dict[int, np.ndarray]], 
-                                     use_nvenc: bool = False, bitrate: str = "50M") -> bool:
+                                     use_nvenc: bool = False, bitrate: str = "50M",
+                                     batch_size: int = 16) -> bool:
         """
         Process high-resolution frames, apply upscaled masks, and save the output video.
         
@@ -503,6 +474,7 @@ class MaskProcessor:
             video_segments: Dictionary of frame masks
             use_nvenc: Whether to use NVIDIA hardware encoding
             bitrate: Output video bitrate
+            batch_size: Number of frames to process in a single batch
             
         Returns:
             True if successful
@@ -520,18 +492,15 @@ class MaskProcessor:
             
             logger.info(f"Processing video: {frame_width}x{frame_height} @ {fps}fps, {total_frames} frames")
             
-            # Pre-compute all upscaled masks (Phase 1 optimization)
-            upscaled_segments = self._precompute_upscaled_masks(video_segments, frame_width, frame_height)
-            
             # Setup VideoWriter
+            out_writer = None
             if self.output_mode == "alpha_channel":
-                # For alpha channel, we need a codec that supports transparency
                 success = self._setup_alpha_encoder(output_video_path, frame_width, frame_height, fps, bitrate)
                 if not success:
                     logger.error("Failed to setup alpha channel encoder")
                     cap.release()
                     return False
-                use_nvenc = False  # Override NVENC for alpha channel
+                use_nvenc = False
             elif use_nvenc:
                 success = self._setup_nvenc_encoder(output_video_path, frame_width, frame_height, fps, bitrate)
                 if not success:
@@ -539,106 +508,101 @@ class MaskProcessor:
                     use_nvenc = False
             
             if not use_nvenc and self.output_mode != "alpha_channel":
-                # Use OpenCV VideoWriter
+                fourcc = cv2.VideoWriter_fourcc(*'mp4v')
-                fourcc = cv2.VideoWriter_fourcc(*'mp4v')  # Use mp4v for better compatibility
+                out_writer = cv2.VideoWriter(output_video_path, fourcc, fps, (frame_width, frame_height))
-                out = cv2.VideoWriter(output_video_path, fourcc, fps, (frame_width, frame_height))
+                if not out_writer.isOpened():
-                if not out.isOpened():
                     logger.error("Failed to create output video writer")
                     cap.release()
                     return False
 
-            # Process frames with batch reading (Phase 1 optimization)
+            # Process frames in batches
             frame_idx = 0
             processed_frames = 0
-            batch_size = 10  # Process frames in batches for better I/O performance
-            frame_buffer = []
             
-            # Pre-fill frame buffer
+            while frame_idx < total_frames:
-            for _ in range(min(batch_size, len(upscaled_segments))):
+                batch_frames = []
+                batch_masks = []
+                
+                # Read a batch of frames
+                for _ in range(batch_size):
                     ret, frame = cap.read()
-                if ret:
+                    if not ret:
-                    frame_buffer.append(frame)
+                        break
-                else:
+                    batch_frames.append(frame)
+                
+                if not batch_frames:
                     break
                 
-            buffer_idx = 0
+                # Get masks for the current batch and perform just-in-time upscaling
-            while frame_idx < len(upscaled_segments) and buffer_idx < len(frame_buffer):
+                for i in range(len(batch_frames)):
-                frame = frame_buffer[buffer_idx]
+                    current_frame_idx = frame_idx + i
-                
+                    if current_frame_idx in video_segments:
-                if frame_idx in upscaled_segments:
+                        frame_masks = video_segments[current_frame_idx]
-                    # Get pre-computed upscaled masks for this frame (Phase 1 optimization)
+                        upscaled_masks = []
-                    upscaled_masks = [upscaled_segments[frame_idx][obj_id] 
+                        for obj_id, mask in frame_masks.items():
-                                    for obj_id in upscaled_segments[frame_idx]]
+                            mask = mask.squeeze()
-                    
+                            if mask.shape != (frame_height, frame_width):
-                    # Apply mask based on output mode (no upscaling needed - already done)
+                                upscaled_mask = cv2.resize(mask.astype(np.uint8), 
-                    if self.output_mode == "alpha_channel":
+                                                         (frame_width, frame_height), 
-                        result_frame = self.apply_mask_with_alpha(frame, upscaled_masks)
+                                                         interpolation=cv2.INTER_NEAREST)
+                                upscaled_masks.append(upscaled_mask)
                             else:
-                        result_frame = self.apply_green_mask(frame, upscaled_masks)
+                                upscaled_masks.append(mask.astype(np.uint8))
+                        batch_masks.append(upscaled_masks)
+                    else:
+                        batch_masks.append([]) # No masks for this frame
+                
+                # Process the batch
+                result_batch = []
+                for i, frame in enumerate(batch_frames):
+                    masks = batch_masks[i]
+                    if masks:
+                        if self.output_mode == "alpha_channel":
+                            result_frame = self.apply_mask_with_alpha(frame, masks)
+                        else:
+                            result_frame = self.apply_green_mask(frame, masks)
                     else:
                         # No mask for this frame
                         if self.output_mode == "alpha_channel":
-                        # Create fully transparent frame for alpha channel mode
                             bgra_frame = cv2.cvtColor(frame, cv2.COLOR_BGR2BGRA)
-                        bgra_frame[:, :, 3] = 0  # Fully transparent
+                            bgra_frame[:, :, 3] = 0
                             result_frame = bgra_frame
-                        logger.warning(f"No mask for frame {frame_idx}, using transparent frame")
                         else:
-                        # Use original frame for green screen mode
-                        logger.warning(f"No mask for frame {frame_idx}, using original")
                             result_frame = frame
+                    result_batch.append(result_frame)
                 
-                # Write frame
+                # Write the processed batch
+                for result_frame in result_batch:
                     if self.output_mode == "alpha_channel" and hasattr(self, 'alpha_process'):
                         self.alpha_process.stdin.write(result_frame.tobytes())
                     elif use_nvenc and hasattr(self, 'nvenc_process'):
                         self.nvenc_process.stdin.write(result_frame.tobytes())
                     else:
-                    out.write(result_frame)
+                        out_writer.write(result_frame)
                 
-                processed_frames += 1
+                processed_frames += len(batch_frames)
-                frame_idx += 1
+                frame_idx += len(batch_frames)
-                buffer_idx += 1
                 
-                # Refill buffer when needed
+                if processed_frames % 100 < batch_size:
-                if buffer_idx >= len(frame_buffer) and frame_idx < len(upscaled_segments):
-                    frame_buffer.clear()
-                    buffer_idx = 0
-                    # Read next batch
-                    for _ in range(min(batch_size, len(upscaled_segments) - frame_idx)):
-                        ret, frame = cap.read()
-                        if ret:
-                            frame_buffer.append(frame)
-                        else:
-                            break
-                
-                # Progress logging
-                if processed_frames % 100 == 0:
                     logger.info(f"Processed {processed_frames}/{total_frames} frames")
 
             # Cleanup
             cap.release()
-            
             if self.output_mode == "alpha_channel" and hasattr(self, 'alpha_process'):
                 self.alpha_process.stdin.close()
                 self.alpha_process.wait()
-                if self.alpha_process.returncode != 0:
-                    logger.error("Alpha channel encoding failed")
-                    return False
             elif use_nvenc and hasattr(self, 'nvenc_process'):
                 self.nvenc_process.stdin.close()
                 self.nvenc_process.wait()
-                if self.nvenc_process.returncode != 0:
-                    logger.error("NVENC encoding failed")
-                    return False
             else:
-                out.release()
+                if out_writer:
+                    out_writer.release()
             
             logger.info(f"Successfully processed {processed_frames} frames to {output_video_path}")
             return True
             
         except Exception as e:
-            logger.error(f"Error processing video: {e}")
+            logger.error(f"Error processing video: {e}", exc_info=True)
             return False
     
     def _setup_nvenc_encoder(self, output_path: str, width: int, height: int, 
@@ -751,6 +715,14 @@ class MaskProcessor:
         
         if success:
             logger.info(f"Successfully created {self.output_mode} video: {output_video}")
+            # Mark segment as completed only after video is successfully written
+            try:
+                output_done_file = os.path.join(segment_info['directory'], "output_frames_done")
+                with open(output_done_file, 'w') as f:
+                    f.write(f"Segment {segment_info['index']} processed and saved successfully.")
+                logger.debug(f"Created completion marker for segment {segment_info['index']}")
+            except Exception as e:
+                logger.error(f"Failed to create completion marker for segment {segment_info['index']}: {e}")
         else:
             logger.error(f"Failed to process segment {segment_info['index']}")
         

core/sam2_processor.py

@@ -8,6 +8,7 @@ import cv2
 import numpy as np
 import torch
 import logging
+import subprocess
 import gc
 from typing import Dict, List, Any, Optional, Tuple
 from sam2.build_sam import build_sam2_video_predictor
@@ -19,7 +20,8 @@ class SAM2Processor:
     """Handles SAM2-based video segmentation for human tracking."""
     
     def __init__(self, checkpoint_path: str, config_path: str, vos_optimized: bool = False, 
-                 separate_eye_processing: bool = False, eye_overlap_pixels: int = 0):
+                 separate_eye_processing: bool = False, eye_overlap_pixels: int = 0,
+                 async_preprocessor=None):
         """
         Initialize SAM2 processor.
         
@@ -29,11 +31,13 @@ class SAM2Processor:
             vos_optimized: Enable VOS optimization for speedup (requires PyTorch 2.5.1+)
             separate_eye_processing: Enable VR180 separate eye processing mode
             eye_overlap_pixels: Pixel overlap between eyes for blending
+            async_preprocessor: Optional async preprocessor for background low-res video generation
         """
         self.checkpoint_path = checkpoint_path
         self.config_path = config_path
         self.vos_optimized = vos_optimized
         self.separate_eye_processing = separate_eye_processing
+        self.async_preprocessor = async_preprocessor
         self.predictor = None
         
         # Initialize eye processor if separate eye processing is enabled
@@ -120,13 +124,64 @@ class SAM2Processor:
     
     def create_low_res_video(self, input_video_path: str, output_video_path: str, scale: float):
         """
-        Create a low-resolution version of the input video for inference.
+        Create a low-resolution version of the input video for inference using FFmpeg
+        with hardware acceleration for improved performance.
         
         Args:
             input_video_path: Path to input video
             output_video_path: Path to output low-res video  
             scale: Scale factor for resolution reduction
         """
+        try:
+            # Get video properties using OpenCV
+            cap = cv2.VideoCapture(input_video_path)
+            if not cap.isOpened():
+                raise ValueError(f"Could not open video: {input_video_path}")
+            
+            original_width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
+            original_height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
+            fps = cap.get(cv2.CAP_PROP_FPS) or 30.0
+            frame_count = int(cap.get(cv2.CAP_PROP_FRAME_COUNT))
+            cap.release()
+
+            target_width = int(original_width * scale)
+            target_height = int(original_height * scale)
+
+            # Ensure dimensions are even, as required by many codecs
+            target_width = target_width if target_width % 2 == 0 else target_width + 1
+            target_height = target_height if target_height % 2 == 0 else target_height + 1
+
+            # Construct FFmpeg command with hardware acceleration
+            command = [
+                'ffmpeg',
+                '-y',
+                '-hwaccel', 'auto',  # Auto-detect hardware acceleration
+                '-i', input_video_path,
+                '-vf', f'scale={target_width}:{target_height}',
+                '-c:v', 'h264_nvenc', # Use NVIDIA's hardware encoder
+                '-preset', 'fast',
+                '-crf', '23',
+                output_video_path
+            ]
+            
+            logger.info(f"Executing FFmpeg command: {' '.join(command)}")
+            
+            # Execute FFmpeg command
+            process = subprocess.run(command, check=True, capture_output=True, text=True)
+            
+            if process.returncode != 0:
+                logger.error(f"FFmpeg failed with error: {process.stderr}")
+                raise RuntimeError(f"FFmpeg process failed: {process.stderr}")
+
+            logger.info(f"Created low-res video with {frame_count} frames: {output_video_path}")
+
+        except (subprocess.CalledProcessError, FileNotFoundError) as e:
+            logger.warning(f"Hardware-accelerated FFmpeg failed: {e}. Falling back to OpenCV.")
+            # Fallback to original OpenCV implementation if FFmpeg fails
+            self._create_low_res_video_opencv(input_video_path, output_video_path, scale)
+
+    def _create_low_res_video_opencv(self, input_video_path: str, output_video_path: str, scale: float):
+        """Original OpenCV-based implementation for creating low-resolution video."""
         cap = cv2.VideoCapture(input_video_path)
         if not cap.isOpened():
             raise ValueError(f"Could not open video: {input_video_path}")
@@ -151,7 +206,42 @@ class SAM2Processor:
         cap.release()
         out.release()
         
-        logger.info(f"Created low-res video with {frame_count} frames: {output_video_path}")
+        logger.info(f"Created low-res video with {frame_count} frames using OpenCV: {output_video_path}")
+    
+    def ensure_low_res_video(self, input_video_path: str, output_video_path: str, 
+                                 scale: float, segment_idx: Optional[int] = None) -> bool:
+        """
+        Ensure low-resolution video exists, using async preprocessor if available.
+        
+        Args:
+            input_video_path: Path to input video
+            output_video_path: Path to output low-res video
+            scale: Scale factor for resolution reduction
+            segment_idx: Optional segment index for async coordination
+            
+        Returns:
+            True if low-res video is ready
+        """
+        # Check if already exists
+        if os.path.exists(output_video_path) and os.path.getsize(output_video_path) > 0:
+            return True
+        
+        # Use async preprocessor if available and segment index provided
+        if self.async_preprocessor and segment_idx is not None:
+            if self.async_preprocessor.is_segment_ready(segment_idx):
+                if os.path.exists(output_video_path) and os.path.getsize(output_video_path) > 0:
+                    logger.debug(f"Async preprocessor provided segment {segment_idx}")
+                    return True
+            else:
+                logger.debug(f"Async preprocessor hasn't completed segment {segment_idx} yet")
+        
+        # Fallback to synchronous creation
+        try:
+            self.create_low_res_video(input_video_path, output_video_path, scale)
+            return os.path.exists(output_video_path) and os.path.getsize(output_video_path) > 0
+        except Exception as e:
+            logger.error(f"Failed to create low-res video {output_video_path}: {e}")
+            return False
     
     def add_yolo_prompts_to_predictor(self, inference_state, prompts: List[Dict[str, Any]]) -> bool:
         """
@@ -341,13 +431,10 @@ class SAM2Processor:
         
         logger.info(f"Processing segment {segment_idx} with SAM2")
         
-        # Create low-resolution video for inference
+        # Create low-resolution video for inference (async-aware)
         low_res_video_path = os.path.join(segment_dir, "low_res_video.mp4")
-        if not os.path.exists(low_res_video_path):
+        if not self.ensure_low_res_video(video_path, low_res_video_path, inference_scale, segment_idx):
-            try:
+            logger.error(f"Failed to create low-res video for segment {segment_idx}")
-                self.create_low_res_video(video_path, low_res_video_path, inference_scale)
-            except Exception as e:
-                logger.error(f"Failed to create low-res video for segment {segment_idx}: {e}")
             return None
         
         try:
@@ -387,13 +474,7 @@ class SAM2Processor:
             except Exception as e:
                 logger.warning(f"Could not remove low-res video: {e}")
             
-            # Mark segment as completed (for resume capability)
+
-            try:
-                with open(output_done_file, 'w') as f:
-                    f.write(f"Segment {segment_idx} completed successfully\n")
-                logger.debug(f"Marked segment {segment_idx} as completed")
-            except Exception as e:
-                logger.warning(f"Could not create completion marker: {e}")
             
             return video_segments
             
@@ -698,13 +779,10 @@ class SAM2Processor:
             logger.error(f"Eye video not found: {eye_video_path}")
             return None
         
-        # Create low-resolution eye video for inference
+        # Create low-resolution eye video for inference (async-aware)
         low_res_eye_video_path = os.path.join(segment_dir, f"low_res_{eye_side}_eye_video.mp4")
-        if not os.path.exists(low_res_eye_video_path):
+        if not self.ensure_low_res_video(eye_video_path, low_res_eye_video_path, inference_scale, segment_idx):
-            try:
+            logger.error(f"Failed to create low-res {eye_side} eye video for segment {segment_idx}")
-                self.create_low_res_video(eye_video_path, low_res_eye_video_path, inference_scale)
-            except Exception as e:
-                logger.error(f"Failed to create low-res {eye_side} eye video for segment {segment_idx}: {e}")
             return None
         
         try:

core/video_splitter.py

@@ -44,6 +44,14 @@ class VideoSplitter:
         segments_dir = os.path.join(output_dir, f"{video_name}_segments")
         ensure_directory(segments_dir)
         
+        # Check for completion marker to avoid re-splitting
+        completion_marker = os.path.join(segments_dir, ".splitting_done")
+        if os.path.exists(completion_marker):
+            logger.info(f"Video already split, skipping splitting process. Found completion marker: {completion_marker}")
+            segment_dirs = [d for d in os.listdir(segments_dir) if os.path.isdir(os.path.join(segments_dir, d)) and d.startswith("segment_")]
+            segment_dirs.sort(key=lambda x: int(x.split("_")[1]))
+            return segments_dir, segment_dirs
+        
         logger.info(f"Splitting video {input_video} into {self.segment_duration}s segments")
         
         # Split video using ffmpeg
@@ -83,6 +91,11 @@ class VideoSplitter:
         # Create file list for later concatenation
         self._create_file_list(segments_dir, segment_dirs)
         
+        # Create completion marker
+        completion_marker = os.path.join(segments_dir, ".splitting_done")
+        with open(completion_marker, 'w') as f:
+            f.write("Video splitting completed successfully.")
+        
         logger.info(f"Successfully split video into {len(segment_dirs)} segments")
         return segments_dir, segment_dirs
     

main.py

@@ -475,8 +475,8 @@ def process_segment_with_separate_eyes(segment_info, detector, sam2_processor, m
     
     return success, left_masks, right_masks
 
-def main():
+async def main_async():
-    """Main processing pipeline."""
+    """Main processing pipeline with async optimizations."""
     args = parse_arguments()
     
     try:
@@ -568,6 +568,24 @@ def main():
         eye_overlap_pixels = config.get('processing.eye_overlap_pixels', 0)
         enable_greenscreen_fallback = config.get('processing.enable_greenscreen_fallback', True)
         
+        # Initialize async preprocessor if enabled
+        async_preprocessor = None
+        if config.get('advanced.enable_background_lowres_generation', False):
+            from core.async_lowres_preprocessor import AsyncLowResPreprocessor
+            
+            max_concurrent = config.get('advanced.max_concurrent_lowres', 3)
+            segments_ahead = config.get('advanced.lowres_segments_ahead', 3)
+            use_ffmpeg = config.get('advanced.use_ffmpeg_lowres', True)
+            
+            async_preprocessor = AsyncLowResPreprocessor(
+                max_concurrent=max_concurrent,
+                segments_ahead=segments_ahead,
+                use_ffmpeg=use_ffmpeg
+            )
+            logger.info(f"Async low-res preprocessing: ENABLED (max_concurrent={max_concurrent}, segments_ahead={segments_ahead})")
+        else:
+            logger.info("Async low-res preprocessing: DISABLED")
+        
         if separate_eye_processing:
             logger.info("VR180 Separate Eye Processing: ENABLED")
             logger.info(f"Eye overlap pixels: {eye_overlap_pixels}")
@@ -578,7 +596,8 @@ def main():
             config_path=config.get_sam2_config(),
             vos_optimized=config.get('models.sam2_vos_optimized', False),
             separate_eye_processing=separate_eye_processing,
-            eye_overlap_pixels=eye_overlap_pixels
+            eye_overlap_pixels=eye_overlap_pixels,
+            async_preprocessor=async_preprocessor
         )
         
         # Initialize mask processor with quality enhancements
@@ -593,6 +612,16 @@ def main():
         logger.info("Step 4: Processing segments sequentially")
         total_humans_detected = 0
         
+        # Start background low-res video preprocessing if enabled
+        if async_preprocessor:
+            logger.info("Starting background low-res video preprocessing")
+            async_preprocessor.start_background_preparation(
+                segments_info, 
+                config.get_inference_scale(), 
+                separate_eye_processing, 
+                current_segment=0
+            )
+        
         # Initialize previous masks for separate eye processing
         previous_left_masks = None
         previous_right_masks = None
@@ -602,6 +631,15 @@ def main():
             
             logger.info(f"Processing segment {segment_idx}/{len(segments_info)-1}")
             
+            # Start background preparation for upcoming segments
+            if async_preprocessor and i < len(segments_info) - 1:
+                async_preprocessor.start_background_preparation(
+                    segments_info, 
+                    config.get_inference_scale(), 
+                    separate_eye_processing, 
+                    current_segment=i
+                )
+            
             # Reset temporal history for new segment
             mask_processor.reset_temporal_history()
             
@@ -1012,6 +1050,16 @@ def main():
     except Exception as e:
         logger.error(f"Pipeline failed: {e}", exc_info=True)
         return 1
+    finally:
+        # Cleanup async preprocessor if it was used
+        if async_preprocessor:
+            async_preprocessor.cleanup()
+            logger.debug("Async preprocessor cleanup completed")
+
+def main():
+    """Main entry point - wrapper for async main."""
+    import asyncio
+    return asyncio.run(main_async())
 
 if __name__ == "__main__":
     exit_code = main()