Checks performed on ffmpeg encoder functionality

Author: alifuaziz

GUI/camera_setup_tab.py

@@ -13,7 +13,9 @@
     QSizePolicy,
     QHeaderView,
 )
-from PyQt6.QtCore import QTimer
+from PyQt6.QtCore import QTimer, Qt
+from PyQt6.QtGui import QIcon
+
 from dataclasses import asdict
 
 from config.config import paths_config, default_camera_config

GUI/camera_widget.py

@@ -2,6 +2,7 @@
 import csv
 import json
 import subprocess
+import signal
 import numpy as np
 from datetime import datetime
 from collections import deque
@@ -52,8 +53,6 @@ def __init__(self, parent, label, subject_id):
         self.label = label
         self.settings = self.camera_setup_tab.get_camera_settings_from_label(label)
         self.camera_api = init_camera_api_from_module(settings=self.settings)
-        self.cam_width = self.camera_api.get_width()
-        self.cam_height = self.camera_api.get_height()
         self._image_data = None
         self.frame_timestamps = deque(maxlen=10)
         self.controls_visible = True
@@ -174,6 +173,8 @@ def fetch_image_data(self) -> None:
         if self.recording:
             self.recorded_frames += len(new_images["images"])
             for frame in new_images["images"]:  # Send new images to FFMPEG for encoding.
+                # Downsample frame
+                frame = frame[::self.settings.downsampling_factor, ::self.settings.downsampling_factor]
                 self.ffmpeg_process.stdin.write(frame.tobytes())
             for gpio_pinstate in new_images["gpio_data"]:  # Write GPIO pinstate to file.
                 self.gpio_writer.writerow(gpio_pinstate)
@@ -199,28 +200,28 @@ def start_recording(self) -> None:
             "subject_ID": self.subject_id,
             "camera_unique_id": self.settings.unique_id,
             "recorded_frames": 0,
+            "downsampling_factor":self.settings.downsampling_factor,
             "begin_time": self.record_start_time.isoformat(timespec="milliseconds"),
             "end_time": None,
         }
         with open(self.metadata_filepath, "w") as meta_data_file:
             json.dump(self.metadata, meta_data_file, indent=4)
 
         # Initalise ffmpeg process
-        downsampled_width = int(self.cam_width / self.settings.downsampling_factor)
-        downsampled_height = int(self.cam_height / self.settings.downsampling_factor)
+        self.downsampled_width = int(self.camera_api.get_width() / self.settings.downsampling_factor)
+        self.downsampled_height = int(self.camera_api.get_height() / self.settings.downsampling_factor)
         ffmpeg_command = " ".join(
             [
                 self.ffmpeg_path,  # Path to binary
-                "-y",  # overwrite output file if it exists
                 "-f rawvideo",  # Input codec (raw video)
-                "-pix_fmt gray",  # Input Pixel format?
-                f"-s {downsampled_width}x{downsampled_height}",  # Input resolution
+                "-pix_fmt gray",  # Input Pixel Format: 8-bit grayscale input to ffmpeg process. Input array 1D
+                f"-s {self.downsampled_width}x{self.downsampled_height}",  # Input resolution
                 f"-r {self.settings.fps}",  # Frame rate
                 "-i -",  # input comes from a pipe (stdin)
-                f"-vcodec {self.video_capture_tab.ffmpeg_encoder_map[ffmpeg_config['compression_standard']]}",  # Output codec
+                f"-c:v {self.video_capture_tab.ffmpeg_encoder_map[ffmpeg_config['compression_standard']]}",  # Output codec
                 "-pix_fmt yuv420p",  # Output pixel format
                 f"-preset {ffmpeg_config['encoding_speed']}",  # Encoding speed [fast, medium, slow]
-                f"-crf {ffmpeg_config['crf']}",  # Controls quality vs filesize
+                f"-qp {ffmpeg_config['crf']}",  # Controls quality vs filesize 
                 f'"{self.video_filepath}"',  # Output file path
             ]
         )
@@ -253,6 +254,7 @@ def stop_recording(self) -> None:
         # Close FFMPEG process
         self.ffmpeg_process.stdin.close()
         self.ffmpeg_process.wait()
+
         # Update GUI
         self.stop_recording_button.setEnabled(False)
         self.start_recording_button.setEnabled(True)

GUI/icons/refresh.svg

@@ -14,9 +14,9 @@
 
 ffmpeg_config = {
     # "pxl_fmt": {"Mono8": "yuv420p", "Mono16": "?"},
-    "crf": 23,  # between 1 - 51
+    "crf": 23,  # between 1 - 51 https://slhck.info/video/2017/02/24/crf-guide.html 
     "encoding_speed": "slow",  # ["fast", "medium", "slow"]
-    "compression_standard": "h265",  # ["h265" , "h264"]
+    "compression_standard": "h264",  # ["h265" , "h264"]
 }
 
 # Paths -------------------------------------------------------------------------------