Lucas Oskorep
92 lines
3.0 KiB
Rust
92 lines
3.0 KiB
Rust
use crate::models::MediaSource;
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/// 1. Resolution First: Higher resolution always wins (e.g., 1080p beats 720p)
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// 2. Quality-Optimized Codec Comparison: At the same resolution, it calculates an "effective bitrate" that accounts for codec efficiency:
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// - H.265/HEVC: 1.5x multiplier (50% more efficient than H.264)
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// - AV1: 2.0x multiplier (50% more efficient than H.264, ~30% better than H.265)
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// - H.264: 1.0x baseline
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// 3. Example Scenarios:
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// - File A: 1080p H.264 @ 8 Mbps = 8.0 effective bitrate
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// - File B: 1080p H.265 @ 6 Mbps = 9.0 effective bitrate (6 × 1.5) → File B selected
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// - File C: 1080p H.265 @ 4 Mbps = 6.0 effective bitrate → File A selected
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pub fn select_best_source(sources: &[MediaSource]) -> Option<usize> {
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if sources.is_empty() {
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return None;
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}
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let mut best_idx = 0;
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for (idx, source) in sources.iter().enumerate().skip(1) {
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if is_better_source(source, &sources[best_idx]) {
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best_idx = idx;
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}
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}
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Some(best_idx)
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}
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fn is_better_source(candidate: &MediaSource, current_best: &MediaSource) -> bool {
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let candidate_height = get_height(candidate);
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let best_height = get_height(current_best);
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// Higher resolution always wins
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if candidate_height > best_height {
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return true;
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}
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if candidate_height < best_height {
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return false;
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}
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let candidate_effective_bitrate = calculate_effective_bitrate(candidate);
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let best_effective_bitrate = calculate_effective_bitrate(current_best);
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candidate_effective_bitrate > best_effective_bitrate
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}
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fn calculate_effective_bitrate(source: &MediaSource) -> f64 {
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let bitrate = source.bitrate.unwrap_or(0) as f64;
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let codec = get_codec(source);
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let efficiency_multiplier = get_codec_efficiency_multiplier(&codec);
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bitrate * efficiency_multiplier
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}
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fn get_codec_efficiency_multiplier(codec: &str) -> f64 {
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let codec_lower = codec.to_lowercase();
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if codec_lower.contains("av1") {
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// AV1 is ~50% more efficient than H.264, or ~30% better than H.265
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// So same bitrate AV1 ≈ 2.0x the quality of H.264
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2.0
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} else if codec_lower.contains("hevc") || codec_lower.contains("h265") {
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// H.265 is ~50% more efficient than H.264
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// So same bitrate H.265 ≈ 1.5x the quality of H.264
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1.5
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} else {
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1.0
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}
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}
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fn get_height(source: &MediaSource) -> i32 {
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source.height.or_else(|| {
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source.media_streams.as_ref().and_then(|streams| {
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streams
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.iter()
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.find(|s| s.stream_type.as_deref() == Some("Video"))
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.and_then(|s| s.height)
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})
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}).unwrap_or(0)
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}
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fn get_codec(source: &MediaSource) -> String {
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source.media_streams
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.as_ref()
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.and_then(|streams| {
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streams
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.iter()
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.find(|s| s.stream_type.as_deref() == Some("Video"))
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.and_then(|s| s.codec.clone())
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})
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.unwrap_or_default()
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}
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