44 lines
2.0 KiB
Dart
44 lines
2.0 KiB
Dart
/// Represents the seekable capture buffer for a live TV transcode session.
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///
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/// Extracted from the `TranscodeSession` element in the tune response:
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/// - [startedAt] = `timeStamp` (epoch seconds, the buffer origin)
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/// - [seekStartSeconds] = `minOffsetAvailable` (earliest seekable offset)
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/// - [seekEndSeconds] = `maxOffsetAvailable` (latest seekable offset / live edge)
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class CaptureBuffer {
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final double startedAt;
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final double seekStartSeconds;
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final double seekEndSeconds;
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const CaptureBuffer({required this.startedAt, required this.seekStartSeconds, required this.seekEndSeconds});
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/// Absolute epoch second of the earliest seekable point.
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int get seekableStartEpoch => (startedAt + seekStartSeconds).round();
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/// Absolute epoch second of the latest seekable point (≈ live edge).
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int get seekableEndEpoch => (startedAt + seekEndSeconds).round();
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/// Duration of the seekable range in seconds.
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int get seekableDurationSeconds => (seekEndSeconds - seekStartSeconds).round();
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/// Parse from a TranscodeSession JSON map. Returns null if required fields are missing.
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/// Values may be num or String depending on whether the server returned JSON or XML.
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static CaptureBuffer? fromTranscodeSession(Map<String, dynamic> session) {
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final timeStamp = _parseDouble(session['timeStamp']);
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final minOffset = _parseDouble(session['minOffsetAvailable']);
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final maxOffset = _parseDouble(session['maxOffsetAvailable']);
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if (timeStamp == null || minOffset == null || maxOffset == null) return null;
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return CaptureBuffer(startedAt: timeStamp, seekStartSeconds: minOffset, seekEndSeconds: maxOffset);
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}
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static double? _parseDouble(dynamic value) {
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if (value is num) return value.toDouble();
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if (value is String) return double.tryParse(value);
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return null;
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}
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@override
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String toString() =>
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'CaptureBuffer(startedAt: $startedAt, seek: $seekStartSeconds..$seekEndSeconds, '
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'range: $seekableStartEpoch..$seekableEndEpoch)';
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}
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