95 lines
3.6 KiB
Python
95 lines
3.6 KiB
Python
#!/usr/bin/env python3
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"""
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Extracts the first 1.5 minutes of a video into:
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- a video-only file (no audio)
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- an audio-only file (no video)
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Output goes into an 'extracted' folder next to this script.
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Requires: ffmpeg installed and on PATH.
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"""
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import subprocess
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import os
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import sys
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import shutil
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# ─── Hardcoded input (relative to this script's directory) ───
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inputs = [
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"/path/to/movie_b.mp4",
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"/path/to/movie_a.mkv"
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]
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INPUT_FILES = []
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for input_file in inputs:
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INPUT_FILES.append(os.path.join(os.path.dirname(os.path.abspath(__file__)), input_file))
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DURATION = 90 # 1.5 minutes in seconds
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OUT_DIR = os.path.join(os.path.dirname(os.path.abspath(__file__)), "extracted")
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# ─── Analysis-friendly codecs (NOT GPU) ───
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# Video: FFV1 (lossless, intra-only) in MKV. Every frame stands alone, no
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# P/B-frame prediction, no blocking artifacts -> exact frames for similarity
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# (SSIM/pHash/features) + fast random access. Decoded with -pix_fmt yuv444p
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# to avoid 4:2:0 chroma-subsampling noise.
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# Audio: PCM float32 WAV, 48 kHz mono. Bit-exact waveform preserves phase for
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# cross-correlation / GCC-PHAT. Never MP3/AAC/Opus here (MDCT + padding
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# smears transients and shifts correlation peaks). FLAC is the only
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# acceptable compressed alternative (lossless).
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# GPU (RX 7900 XTX via VAAPI/AMF: h264_vaapi/hevc_vaapi/h264_amf): deliberately
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# NOT used. Those encoders are lossy delivery codecs, lower quality per bit,
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# inter-frame only, and FFV1/PCM/ProRes/DNxHR have no GPU implementation.
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# GPU only makes sense for preview proxies, not for measurement. CPU encode
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# of 90 s clips is fast enough and bit-exact.
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VIDEO_CODEC = ["-c:v", "ffv1", "-level", "3", "-pix_fmt", "yuv444p"]
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AUDIO_CODEC = ["-c:a", "pcm_f32le", "-ar", "48000", "-ac", "1"]
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# ─── Check ffmpeg ───
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if shutil.which(f"ffmpeg") is None:
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sys.exit(f"ERROR: 'ffmpeg' not found on PATH. Install it and try again.")
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# ─── Prepare output folder ───
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os.makedirs(OUT_DIR, exist_ok=True)
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for INPUT_FILE in INPUT_FILES:
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# ─── Derive output filenames ───
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stem = os.path.splitext(os.path.basename(INPUT_FILE))[0]
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video_out = os.path.join(OUT_DIR, f"{stem}_video.mkv") # FFV1
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audio_out = os.path.join(OUT_DIR, f"{stem}_audio.wav") # PCM f32
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print(f"Input : {INPUT_FILE}")
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print(f"Video → {video_out}")
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print(f"Audio → {audio_out}")
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print(f"-" * 50)
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# ─── Extract video-only (first 90s, no audio, CPU FFV1 re-encode) ───
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cmd_video = [
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"ffmpeg",
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"-y", # overwrite output
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"-i", INPUT_FILE,
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"-t", str(DURATION),
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"-an", # no audio
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*VIDEO_CODEC, # ffv1 lossless intra-only, CPU (no GPU equiv.)
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video_out
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]
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print(f"[video: {stem}] running ffmpeg…")
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r = subprocess.run(cmd_video, capture_output=True, text=True)
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if r.returncode != 0:
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sys.exit(f"ffmpeg (video) failed:\n{r.stderr}")
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print(f"[video: {stem}] done ✔")
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# ─── Extract audio-only (first 90s, no video, CPU PCM re-encode) ───
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cmd_audio = [
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"ffmpeg",
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"-y",
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"-i", INPUT_FILE,
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"-t", str(DURATION),
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"-vn", # no video
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*AUDIO_CODEC, # pcm_f32le 48kHz mono, CPU (no GPU equiv.)
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audio_out
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]
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print(f"[audio: {stem}] running ffmpeg…")
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r = subprocess.run(cmd_audio, capture_output=True, text=True)
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if r.returncode != 0:
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sys.exit(f"ffmpeg (audio) failed:\n{r.stderr}")
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print(f"[audio: {stem}] done ✔")
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print(f"-" * 50)
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print(f"All done. Files are in:", OUT_DIR)
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