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https://github.com/smittix/intercept.git
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ef7d8cca9f
slowrx is a GTK GUI app that doesn't support CLI usage, so the SSTV decoder was silently failing. This replaces it with a pure Python implementation using numpy and Pillow that supports Robot36/72, Martin1/2, Scottie1/2, and PD120/180 modes via VIS header auto-detection. Key implementation details: - Generalized Goertzel (DTFT) for exact-frequency tone detection - Vectorized batch Goertzel for real-time pixel decoding performance - Overlapping analysis windows for short-window frequency estimation - VIS header detection state machine with parity validation - Per-line sync re-synchronization for drift tolerance Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
251 lines
7.1 KiB
Python
251 lines
7.1 KiB
Python
"""SSTV mode specifications.
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Dataclass definitions for each supported SSTV mode, encoding resolution,
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color model, line timing, and sync characteristics.
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"""
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from __future__ import annotations
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import enum
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from dataclasses import dataclass, field
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class ColorModel(enum.Enum):
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"""Color encoding models used by SSTV modes."""
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RGB = 'rgb' # Sequential R, G, B channels per line
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YCRCB = 'ycrcb' # Luminance + chrominance (Robot modes)
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YCRCB_DUAL = 'ycrcb_dual' # Dual-luminance YCrCb (PD modes)
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class SyncPosition(enum.Enum):
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"""Where the horizontal sync pulse appears in each line."""
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FRONT = 'front' # Sync at start of line (Robot, Martin)
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MIDDLE = 'middle' # Sync between G and B channels (Scottie)
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FRONT_PD = 'front_pd' # PD-style sync at start
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@dataclass(frozen=True)
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class ChannelTiming:
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"""Timing for a single color channel within a scanline.
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Attributes:
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duration_ms: Duration of this channel's pixel data in milliseconds.
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"""
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duration_ms: float
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@dataclass(frozen=True)
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class SSTVMode:
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"""Complete specification of an SSTV mode.
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Attributes:
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name: Human-readable mode name (e.g. 'Robot36').
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vis_code: VIS code that identifies this mode.
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width: Image width in pixels.
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height: Image height in lines.
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color_model: Color encoding model.
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sync_position: Where the sync pulse falls in each line.
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sync_duration_ms: Horizontal sync pulse duration (ms).
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sync_porch_ms: Porch (gap) after sync pulse (ms).
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channels: Timing for each color channel per line.
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line_duration_ms: Total duration of one complete scanline (ms).
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has_half_rate_chroma: Whether chroma is sent at half vertical rate
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(Robot modes: Cr and Cb alternate every other line).
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"""
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name: str
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vis_code: int
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width: int
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height: int
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color_model: ColorModel
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sync_position: SyncPosition
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sync_duration_ms: float
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sync_porch_ms: float
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channels: list[ChannelTiming] = field(default_factory=list)
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line_duration_ms: float = 0.0
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has_half_rate_chroma: bool = False
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channel_separator_ms: float = 0.0 # Time gap between color channels (ms)
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# ---------------------------------------------------------------------------
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# Robot family
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# ---------------------------------------------------------------------------
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ROBOT_36 = SSTVMode(
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name='Robot36',
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vis_code=8,
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width=320,
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height=240,
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color_model=ColorModel.YCRCB,
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sync_position=SyncPosition.FRONT,
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sync_duration_ms=9.0,
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sync_porch_ms=3.0,
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channels=[
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ChannelTiming(duration_ms=88.0), # Y (luminance)
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ChannelTiming(duration_ms=44.0), # Cr or Cb (alternating)
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],
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line_duration_ms=150.0,
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has_half_rate_chroma=True,
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channel_separator_ms=6.0,
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)
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ROBOT_72 = SSTVMode(
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name='Robot72',
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vis_code=12,
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width=320,
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height=240,
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color_model=ColorModel.YCRCB,
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sync_position=SyncPosition.FRONT,
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sync_duration_ms=9.0,
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sync_porch_ms=3.0,
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channels=[
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ChannelTiming(duration_ms=138.0), # Y (luminance)
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ChannelTiming(duration_ms=69.0), # Cr
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ChannelTiming(duration_ms=69.0), # Cb
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],
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line_duration_ms=300.0,
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has_half_rate_chroma=False,
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channel_separator_ms=6.0,
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)
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# ---------------------------------------------------------------------------
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# Martin family
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# ---------------------------------------------------------------------------
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MARTIN_1 = SSTVMode(
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name='Martin1',
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vis_code=44,
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width=320,
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height=256,
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color_model=ColorModel.RGB,
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sync_position=SyncPosition.FRONT,
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sync_duration_ms=4.862,
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sync_porch_ms=0.572,
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channels=[
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ChannelTiming(duration_ms=146.432), # Green
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ChannelTiming(duration_ms=146.432), # Blue
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ChannelTiming(duration_ms=146.432), # Red
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],
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line_duration_ms=446.446,
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)
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MARTIN_2 = SSTVMode(
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name='Martin2',
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vis_code=40,
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width=320,
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height=256,
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color_model=ColorModel.RGB,
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sync_position=SyncPosition.FRONT,
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sync_duration_ms=4.862,
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sync_porch_ms=0.572,
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channels=[
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ChannelTiming(duration_ms=73.216), # Green
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ChannelTiming(duration_ms=73.216), # Blue
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ChannelTiming(duration_ms=73.216), # Red
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],
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line_duration_ms=226.798,
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)
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# ---------------------------------------------------------------------------
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# Scottie family
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# ---------------------------------------------------------------------------
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SCOTTIE_1 = SSTVMode(
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name='Scottie1',
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vis_code=60,
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width=320,
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height=256,
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color_model=ColorModel.RGB,
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sync_position=SyncPosition.MIDDLE,
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sync_duration_ms=9.0,
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sync_porch_ms=1.5,
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channels=[
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ChannelTiming(duration_ms=138.240), # Green
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ChannelTiming(duration_ms=138.240), # Blue
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ChannelTiming(duration_ms=138.240), # Red
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],
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line_duration_ms=428.220,
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)
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SCOTTIE_2 = SSTVMode(
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name='Scottie2',
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vis_code=56,
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width=320,
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height=256,
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color_model=ColorModel.RGB,
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sync_position=SyncPosition.MIDDLE,
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sync_duration_ms=9.0,
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sync_porch_ms=1.5,
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channels=[
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ChannelTiming(duration_ms=88.064), # Green
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ChannelTiming(duration_ms=88.064), # Blue
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ChannelTiming(duration_ms=88.064), # Red
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],
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line_duration_ms=277.692,
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)
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# ---------------------------------------------------------------------------
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# PD (Pasokon) family
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# ---------------------------------------------------------------------------
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PD_120 = SSTVMode(
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name='PD120',
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vis_code=93,
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width=640,
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height=496,
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color_model=ColorModel.YCRCB_DUAL,
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sync_position=SyncPosition.FRONT_PD,
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sync_duration_ms=20.0,
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sync_porch_ms=2.080,
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channels=[
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ChannelTiming(duration_ms=121.600), # Y1 (even line luminance)
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ChannelTiming(duration_ms=121.600), # Cr
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ChannelTiming(duration_ms=121.600), # Cb
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ChannelTiming(duration_ms=121.600), # Y2 (odd line luminance)
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],
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line_duration_ms=508.480,
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)
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PD_180 = SSTVMode(
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name='PD180',
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vis_code=95,
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width=640,
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height=496,
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color_model=ColorModel.YCRCB_DUAL,
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sync_position=SyncPosition.FRONT_PD,
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sync_duration_ms=20.0,
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sync_porch_ms=2.080,
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channels=[
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ChannelTiming(duration_ms=183.040), # Y1
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ChannelTiming(duration_ms=183.040), # Cr
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ChannelTiming(duration_ms=183.040), # Cb
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ChannelTiming(duration_ms=183.040), # Y2
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],
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line_duration_ms=754.240,
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)
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# ---------------------------------------------------------------------------
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# Mode registry
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# ---------------------------------------------------------------------------
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ALL_MODES: dict[int, SSTVMode] = {
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m.vis_code: m for m in [
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ROBOT_36, ROBOT_72,
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MARTIN_1, MARTIN_2,
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SCOTTIE_1, SCOTTIE_2,
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PD_120, PD_180,
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]
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}
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MODE_BY_NAME: dict[str, SSTVMode] = {m.name: m for m in ALL_MODES.values()}
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def get_mode(vis_code: int) -> SSTVMode | None:
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"""Look up an SSTV mode by its VIS code."""
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return ALL_MODES.get(vis_code)
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def get_mode_by_name(name: str) -> SSTVMode | None:
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"""Look up an SSTV mode by name."""
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return MODE_BY_NAME.get(name)
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