more features

Content/Python/ue_workshop/video.py

@@ -5,7 +5,8 @@ import subprocess
 from .paths import executable
 
 
-def encode(frames, fps, output=None, ffmpeg=None, expected_frames=None):
+def encode(frames, fps, output=None, ffmpeg=None, expected_frames=None, audio=None):
+    """Encode PNG frames to MP4. Audio is cut to the film; shorter audio ends in silence."""
     frames = Path(frames).resolve()
     if fps <= 0:
         raise ValueError("FPS musi byc dodatni.")
@@ -17,10 +18,16 @@ def encode(frames, fps, output=None, ffmpeg=None, expected_frames=None):
         raise RuntimeError(f"Render zapisal {count} klatek zamiast {expected_frames}.")
     output = Path(output) if output else frames.parent / "film.mp4"
     output.parent.mkdir(parents=True, exist_ok=True)
+    audio_input, audio_output = [], []
+    if audio is not None:
+        if not Path(audio).is_file():
+            raise FileNotFoundError(audio)
+        audio_input = ["-i", str(audio)]
+        audio_output = ["-map", "0:v:0", "-map", "1:a:0", "-c:a", "aac", "-b:a", "192k", "-t", str(count / fps)]
     command = [executable("ffmpeg", ffmpeg), "-hide_banner", "-loglevel", "error", "-y",
-               "-framerate", str(fps), "-start_number", "0", "-i", str(frames / "frame_%04d.png"),
+               "-framerate", str(fps), "-start_number", "0", "-i", str(frames / "frame_%04d.png"), *audio_input,
                "-frames:v", str(count), "-c:v", "libx264", "-crf", "20", "-pix_fmt", "yuv420p",
-               "-vf", "pad=ceil(iw/2)*2:ceil(ih/2)*2", "-movflags", "+faststart", str(output)]
+               "-vf", "pad=ceil(iw/2)*2:ceil(ih/2)*2", *audio_output, "-movflags", "+faststart", str(output)]
     result = subprocess.run(command, capture_output=True, text=True)
     if result.returncode:
         raise RuntimeError("FFmpeg: " + result.stderr[-4000:])