| """ffmpeg encoders for the published video streams. |
| |
| RGB / tactile -> H.264 yuv444p CRF18 (visually lossless, seekable) |
| depth -> FFV1 gray16le (mathematically lossless, millimetres) |
| """ |
| from __future__ import annotations |
|
|
| import subprocess |
| from pathlib import Path |
|
|
| import numpy as np |
|
|
| from .config import CRF, FPS, H, W |
|
|
|
|
| class VideoWriter: |
| """Streaming ffmpeg writer. Use as a context manager and `write()` blocks.""" |
|
|
| def __init__(self, path: Path, pix_fmt="bgr24", codec="libx264", |
| width=W, height=H, fps=FPS): |
| self.path = Path(path) |
| self.path.parent.mkdir(parents=True, exist_ok=True) |
| self._cmd = self._build(pix_fmt, codec, width, height, fps) |
| self._proc = None |
|
|
| def _build(self, pix_fmt, codec, width, height, fps): |
| cmd = ["ffmpeg", "-y", "-hide_banner", "-loglevel", "error", |
| "-f", "rawvideo", "-pix_fmt", pix_fmt, |
| "-s", f"{width}x{height}", "-r", str(fps), "-i", "-"] |
| if codec == "libx264": |
| cmd += ["-c:v", "libx264", "-profile:v", "high444", "-preset", "medium", |
| "-crf", CRF, "-pix_fmt", "yuv444p", "-movflags", "+faststart"] |
| elif codec == "ffv1": |
| cmd += ["-c:v", "ffv1", "-level", "3", "-pix_fmt", "gray16le"] |
| else: |
| raise ValueError(f"unknown codec {codec!r}") |
| return cmd + ["-an", str(self.path)] |
|
|
| def __enter__(self): |
| self._proc = subprocess.Popen(self._cmd, stdin=subprocess.PIPE) |
| return self |
|
|
| def write(self, block: np.ndarray) -> None: |
| self._proc.stdin.write(np.ascontiguousarray(block).tobytes()) |
|
|
| def __exit__(self, exc_type, exc, tb): |
| if self._proc.stdin: |
| self._proc.stdin.close() |
| rc = self._proc.wait() |
| if rc != 0 and exc_type is None: |
| raise RuntimeError(f"ffmpeg failed ({rc}) writing {self.path}") |
| return False |
|
|
|
|
| def rgb_writer(path: Path) -> VideoWriter: |
| """8-bit colour stream. Feed BGR blocks (ffmpeg's native order).""" |
| return VideoWriter(path, pix_fmt="bgr24", codec="libx264") |
|
|
|
|
| def depth_writer(path: Path) -> VideoWriter: |
| """16-bit depth stream, lossless. Feed uint16 millimetre blocks.""" |
| return VideoWriter(path, pix_fmt="gray16le", codec="ffv1") |
|
|
