init

tools/process_badapple.py

@@ -0,0 +1,130 @@
+#!/usr/bin/env python3
+"""Convert a Bad Apple source video into firmware-ready assets.
+
+This tool requires ffmpeg in PATH. It produces:
+- video.baa : 1-bit packed frames with custom header.
+- audio.pdm : 1-bit sigma-delta encoded PCM data with custom header.
+"""
+
+import argparse
+import math
+import struct
+import subprocess
+import tempfile
+from pathlib import Path
+
+VIDEO_MAGIC = b"BAA\0"
+AUDIO_MAGIC = b"BAP\0"
+
+
+def run_ffmpeg(args):
+    process = subprocess.run(args, check=False)
+    if process.returncode != 0:
+        raise RuntimeError(f"ffmpeg failed: {' '.join(args)}")
+
+
+def pcm_to_pdm(samples):
+    # First-order sigma-delta modulation.
+    acc = 0
+    threshold = 0
+    bitstream = bytearray((len(samples) + 7) // 8)
+    for idx, sample in enumerate(samples):
+        acc += sample - threshold
+        if acc >= 0:
+            threshold = 32767
+            bit = 1
+        else:
+            threshold = -32768
+            bit = 0
+        if bit:
+            bitstream[idx // 8] |= 1 << (idx % 8)
+    return bitstream
+
+
+def encode_video(raw_path, width, height, frame_count, fps, threshold):
+    stride_bits = width * height
+    stride_bytes = (stride_bits + 7) // 8
+    output = bytearray()
+    output += VIDEO_MAGIC
+    output += struct.pack('<H', width)
+    output += struct.pack('<H', height)
+    output += struct.pack('<H', fps)
+    output += struct.pack('<I', frame_count)
+    output += b"\x00\x00"
+
+    frame_size = width * height
+    with open(raw_path, 'rb') as fh:
+        for frame_idx in range(frame_count):
+            buf = fh.read(frame_size)
+            if len(buf) != frame_size:
+                raise RuntimeError(f"unexpected EOF at frame {frame_idx}")
+            bits = bytearray(stride_bytes)
+            for i, value in enumerate(buf):
+                if value >= threshold:
+                    bits[i // 8] |= 1 << (i % 8)
+            output.extend(bits)
+    return output
+
+
+def encode_audio(raw_path, sample_rate, start_offset_samples=0):
+    data = Path(raw_path).read_bytes()
+    samples = struct.iter_unpack('<h', data)
+    pcm = [value for (value,) in samples]
+    if start_offset_samples > 0:
+        pcm = pcm[start_offset_samples:]
+    bitstream = pcm_to_pdm(pcm)
+
+    header = bytearray()
+    header += AUDIO_MAGIC
+    header += struct.pack('<I', sample_rate)
+    header += struct.pack('<B', 1)  # bits per sample
+    header += struct.pack('<B', 1)  # mono
+    header += b"\x00\x00"
+    header += struct.pack('<I', len(pcm))
+    return bytes(header) + bytes(bitstream)
+
+
+parser = argparse.ArgumentParser(description=__doc__)
+parser.add_argument('--input', required=True, help='Path to Bad Apple video (any ffmpeg-supported format).')
+parser.add_argument('--output-dir', required=True, help='Directory to place generated assets.')
+parser.add_argument('--width', type=int, default=320)
+parser.add_argument('--height', type=int, default=240)
+parser.add_argument('--fps', type=int, default=30)
+parser.add_argument('--sample-rate', type=int, default=44100)
+parser.add_argument('--threshold', type=int, default=128, help='Luma threshold (0-255) for 1-bit conversion.')
+parser.add_argument('--audio-start-delay', type=float, default=0.0, help='Seconds to delay audio relative to video.')
+args = parser.parse_args()
+
+output_dir = Path(args.output_dir)
+output_dir.mkdir(parents=True, exist_ok=True)
+
+with tempfile.TemporaryDirectory() as tmpdir:
+    tmpdir = Path(tmpdir)
+    raw_video = tmpdir / 'frames.raw'
+    raw_audio = tmpdir / 'audio.raw'
+
+    run_ffmpeg([
+        'ffmpeg', '-y', '-i', args.input,
+        '-vf', f'scale={args.width}:{args.height},fps={args.fps},format=gray',
+        '-an', '-f', 'rawvideo', str(raw_video)
+    ])
+
+    run_ffmpeg([
+        'ffmpeg', '-y', '-i', args.input,
+        '-vn', '-ac', '1', '-ar', str(args.sample_rate), '-f', 's16le', str(raw_audio)
+    ])
+
+    frame_size = args.width * args.height
+    video_size = raw_video.stat().st_size
+    frame_count = video_size // frame_size
+    if frame_count == 0:
+        raise RuntimeError("ffmpeg produced zero frames - check input file")
+
+    video_blob = encode_video(raw_video, args.width, args.height, frame_count, args.fps, args.threshold)
+    audio_offset = int(args.audio_start_delay * args.sample_rate)
+    audio_blob = encode_audio(raw_audio, args.sample_rate, audio_offset)
+
+    (output_dir / 'video.baa').write_bytes(video_blob)
+    (output_dir / 'audio.pdm').write_bytes(audio_blob)
+
+    print(f"Generated {frame_count} frames @ {args.width}x{args.height} and audio track {args.sample_rate} Hz")