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Merged
richiemcilroy merged 3 commits into from
Oct 18, 2026
Merged

perf(editor): avoid playback hitches during unrelated live edits #2507

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9df8106
perf(editor): avoid playback hitches during unrelated live edits
AksharP5 Oct 13, 2026
03ebccf
fix(editor): preserve live-edit toggles across benchmark presses
AksharP5 Oct 13, 2026
b01cda6
Merge branch 'main' into perf/playback-cursor-timeline-reuse
richiemcilroy Oct 18, 2026
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77 changes: 67 additions & 10 deletions crates/editor/examples/editor-playback-benchmark.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -89,6 +89,8 @@ struct BenchmarkSummary {
submitted_frames: u64,
rendered_frames: u64,
callback_frames: u64,
last_callback: Option<Instant>,
callback_gaps: DurationStats,
dropped_by_renderer: u64,
send_failures: u64,
skipped_frames: u64,
Expand Down Expand Up @@ -273,7 +275,12 @@ impl BenchmarkSummary {
}
}

fn record_callback_frame(&mut self, bytes: usize) {
fn record_callback_frame(&mut self, bytes: usize, received_at: Instant) {
if let Some(previous) = self.last_callback {
self.callback_gaps
.push(received_at.saturating_duration_since(previous));
}
self.last_callback = Some(received_at);
self.callback_frames += 1;
self.bytes_from_callback = self.bytes_from_callback.saturating_add(bytes as u64);
}
Expand Down Expand Up @@ -435,6 +442,12 @@ fn parse_resolution(args: &[String]) -> XY<u32> {
}
}

#[derive(Clone, Copy, Debug)]
enum LiveEdit {
Background,
CursorSpring,
}

#[tokio::main]
async fn main() {
tracing_subscriber::fmt()
Expand All @@ -447,6 +460,19 @@ async fn main() {
ffmpeg::init().expect("Failed to initialize FFmpeg");

let args: Vec<String> = std::env::args().collect();
let live_edit = arg_value(&args, "--live-edit").map(|kind| match kind {
"background" => LiveEdit::Background,
"cursor-spring" => LiveEdit::CursorSpring,
_ => panic!("--live-edit must be background or cursor-spring"),
});
let edit_interval_ms = arg_value(&args, "--edit-interval-ms")
.map(|value| {
value
.parse::<u64>()
.expect("--edit-interval-ms must be an integer")
})
.unwrap_or(50);
assert!(edit_interval_ms > 0, "--edit-interval-ms must be positive");

let recording_path = arg_value(&args, "--recording-path")
.map(PathBuf::from)
Expand Down Expand Up @@ -533,7 +559,7 @@ async fn main() {
let layers_rx = finish_renderer_layers_creation(layers_rx).await;

let (telemetry, mut telemetry_rx) = PlaybackTelemetry::channel();
let (frame_tx, mut frame_rx) = mpsc::unbounded_channel::<usize>();
let (frame_tx, mut frame_rx) = mpsc::unbounded_channel::<(usize, Instant)>();
let frame_cb = Box::new(move |output: EditorFrameOutput, _: FrameLayout| {
let bytes = match output {
EditorFrameOutput::Nv12(frame) => {
Expand All @@ -548,7 +574,7 @@ async fn main() {
#[cfg(target_os = "macos")]
EditorFrameOutput::Surface(_) => return,
};
let _ = frame_tx.send(bytes);
let _ = frame_tx.send((bytes, Instant::now()));
});

let renderer = match Renderer::spawn_with_telemetry(
Expand Down Expand Up @@ -586,14 +612,21 @@ async fn main() {
.collect()
};

let (_project_tx, project_rx) = watch::channel(project);
let base_padding = project.background.padding;
let base_tension = project.cursor.tension;
let (project_tx, project_rx) = watch::channel(project);

// One persistent output stream shared across presses, like the real app.
let audio_output = Arc::new(cap_editor::AudioOutput::new());
let audio_output = Arc::new(if args.iter().any(|arg| arg == "--headless") {
cap_editor::AudioOutput::new_headless(Box::new(|_, _| {}))
} else {
cap_editor::AudioOutput::new()
});
audio_output.prewarm();

let mut summary = BenchmarkSummary::default();
let mut measured_elapsed = 0.0f64;
let mut live_edit_high = false;

for (press_idx, (press_start_frame, press_frames)) in presses.iter().copied().enumerate() {
if press_idx > 0
Expand Down Expand Up @@ -628,6 +661,15 @@ async fn main() {
tokio::pin!(deadline);

let mut press_summary = BenchmarkSummary::default();
let mut live_edit_count = 0_u64;
Comment thread
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let mut edit_timer = live_edit.map(|_| {
let mut timer = tokio::time::interval_at(
tokio::time::Instant::now() + Duration::from_millis(500),
Duration::from_millis(edit_interval_ms),
);
timer.set_missed_tick_behavior(tokio::time::MissedTickBehavior::Skip);
timer
});

loop {
if press_summary.submitted_frames >= press_frames {
Expand All @@ -643,11 +685,20 @@ async fn main() {
break;
}
}
bytes = frame_rx.recv() => {
if let Some(bytes) = bytes {
press_summary.record_callback_frame(bytes);
frame = frame_rx.recv() => {
if let Some((bytes, received_at)) = frame {
press_summary.record_callback_frame(bytes, received_at);
}
}
_ = async { edit_timer.as_mut().unwrap().tick().await }, if edit_timer.is_some() => {
live_edit_high = !live_edit_high;
let offset = if live_edit_high { 1.0 } else { 0.0 };
project_tx.send_modify(|project| match live_edit.unwrap() {
LiveEdit::Background => project.background.padding = base_padding + offset,
LiveEdit::CursorSpring => project.cursor.tension = base_tension + offset as f32,
});
live_edit_count += 1;
}
_ = &mut deadline => {
break;
}
Expand All @@ -662,8 +713,13 @@ async fn main() {
while let Ok(event) = telemetry_rx.try_recv() {
press_summary.record_event(event);
}
while let Ok(bytes) = frame_rx.try_recv() {
press_summary.record_callback_frame(bytes);
while let Ok((bytes, received_at)) = frame_rx.try_recv() {
press_summary.record_callback_frame(bytes, received_at);
}
if let Some(kind) = live_edit {
println!(
"Live edits: kind={kind:?} interval_ms={edit_interval_ms} sent={live_edit_count}"
);
}

let press_time_secs = press_start_frame as f64 / fps as f64;
Expand Down Expand Up @@ -761,6 +817,7 @@ async fn main() {
summary.render_finish_submit.print("finish submit");
summary.render_immediate_flush.print("immediate flush");
summary.callback.print("callback packing");
summary.callback_gaps.print("callback gap");
DurationStats::print_values("render steady", steady_render_values);

println!("\nRenderer prepare stages:");
Expand Down
26 changes: 17 additions & 9 deletions crates/editor/src/editor_instance.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,19 @@ pub(super) const PREVIEW_RENDER_MAX_ATTEMPTS: u32 = 3;
pub(super) const PREVIEW_RENDER_RETRY_DELAY_MS: u64 = 120;
const PREVIEW_CURSOR_CACHE_CAPACITY: usize = 2;

pub(super) fn cursor_timeline_settings(cursor: &cap_project::CursorConfiguration) -> [u32; 7] {
let click_spring = cursor.click_spring_config();
[
u32::from(cursor.raw),
cursor.tension.to_bits(),
cursor.mass.to_bits(),
cursor.friction.to_bits(),
click_spring.tension.to_bits(),
click_spring.mass.to_bits(),
click_spring.friction.to_bits(),
]
}

#[derive(Default)]
pub(super) struct PreviewCursorCache {
entries: Vec<PreviewCursorCacheEntry>,
Expand Down Expand Up @@ -73,15 +86,7 @@ impl PreviewCursorCache {
friction: project.cursor.friction,
};
let click_spring = project.cursor.click_spring_config();
let settings = [
u32::from(project.cursor.raw),
smoothing.tension.to_bits(),
smoothing.mass.to_bits(),
smoothing.friction.to_bits(),
click_spring.tension.to_bits(),
click_spring.mass.to_bits(),
click_spring.friction.to_bits(),
];
let settings = cursor_timeline_settings(&project.cursor);

if let Some(index) = self.entries.iter().position(|entry| {
entry.recording_clip == recording_clip
Expand Down Expand Up @@ -1985,6 +1990,9 @@ mod tests {
project.cursor.rotation_amount += 0.1;
project.cursor.stop_movement_in_last_seconds = Some(0.5);
project.cursor.click_spring = Some(project.cursor.click_spring_config());
project.background.padding += 1.0;
project.audio.mic_volume_db += 1.0;
project.cursor.motion_blur += 0.1;
let repeated = cache.get(0, &Arc::clone(&cursor), &project).unwrap();

assert!(Arc::ptr_eq(&first, &repeated));
Expand Down
8 changes: 6 additions & 2 deletions crates/editor/src/playback.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -25,7 +25,7 @@ use tracing::{info, warn};
use crate::{
audio_output::{AudioOutput, PlaySpec},
editor,
editor_instance::SegmentMedia,
editor_instance::{SegmentMedia, cursor_timeline_settings},
segments::get_audio_segments,
telemetry::{
PlaybackFrameSource, PlaybackSkipReason, PlaybackTelemetry, PlaybackTelemetryEvent,
Expand Down Expand Up @@ -1458,6 +1458,8 @@ impl Playback {
let next_project = self.project.borrow_and_update().clone();
let audio_changed = cached_project.audio != next_project.audio
|| clip_audio_changed(&cached_project, &next_project);
let cursor_changed = cursor_timeline_settings(&cached_project.cursor)
!= cursor_timeline_settings(&next_project.cursor);
cached_project = next_project;
if adopted.is_none()
&& audio_changed
Expand All @@ -1475,7 +1477,9 @@ impl Playback {
generation,
);
}
cursor_timelines = build_cursor_timelines(&cached_project);
if cursor_changed {
cursor_timelines = build_cursor_timelines(&cached_project);
}
zoom_timelines = build_zoom_timelines(&cached_project);
outgoing_zoom_timelines = build_outgoing_zoom_timelines(&cached_project);
}
Expand Down
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