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html: Track the script/UA initiated media seek request (#40981)

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The low-level media `seek` request could be initiated by script (DOM
method call or setting of an IDL attribute), by the user agent (seeking
data) or by the media engine itself (e.g. gst_play_set_rate()).
And to distinguish between them we will use the latest seek position (in
seconds) to be able abort processing the `seek` algorithm steps (13-17)
for a `seek` request initiated by the media engine.

See https://html.spec.whatwg.org/multipage/#dom-media-seek

If the `seeking` is in progress, any callback which affects the current
playback position (`position changed`, `end of the playback`) shouldn't
be processed (event marshalling over IPC router is non-state
conditional).

Testing: Regression in the following test causes by gstreamer issue when
the `gst_play_set_rate()` overrides the latest seek requested position
unconditionally and the user agent receives the `seek completion` event
with the unexpected seek position (0.5+ instead of 0.0).
- html/semantics/embedded-content/media-elements/preserves-pitch.html

See https://gitlab.freedesktop.org/gstreamer/gstreamer/-/issues/4762

Fixes: https://github.com/servo/servo/issues/37057

Signed-off-by: Andrei Volykhin <andrei.volykhin@gmail.com>
This commit is contained in:
Andrei Volykhin
2025-12-02 14:27:21 +03:00
committed by GitHub
parent 02ed2af193
commit d539ac8cf3
2 changed files with 62 additions and 30 deletions
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80
components/script/dom/html/htmlmediaelement.rs
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@@ -548,6 +548,10 @@ pub(crate) struct HTMLMediaElement {
volume: Cell<f64>,
/// <https://html.spec.whatwg.org/multipage/#dom-media-seeking>
seeking: Cell<bool>,
/// The latest seek position (in seconds) is used to distinguish whether the seek request was
/// initiated by a script or by the user agent itself, rather than by the media engine and to
/// abort other running instance of the `seek` algorithm.
current_seek_position: Cell<f64>,
/// <https://html.spec.whatwg.org/multipage/#dom-media-muted>
muted: Cell<bool>,
/// Loading state from source, if any.
@@ -651,6 +655,7 @@ impl HTMLMediaElement {
default_playback_start_position: Cell::new(0.),
volume: Cell::new(1.0),
seeking: Cell::new(false),
current_seek_position: Cell::new(f64::NAN),
resource_url: DomRefCell::new(None),
blob_url: DomRefCell::new(None),
played: DomRefCell::new(TimeRangesContainer::default()),
@@ -1732,6 +1737,8 @@ impl HTMLMediaElement {
// Step 7.7. If seeking is true, set it to false.
self.seeking.set(false);
self.current_seek_position.set(f64::NAN);
// Step 7.8. Set the current playback position to 0.
// Set the official playback position to 0.
// If this changed the official playback position, then queue a media element task given
@@ -1933,9 +1940,10 @@ impl HTMLMediaElement {
return;
}
// TODO Step 3. If the element's seeking IDL attribute is true, then another instance of
// this algorithm is already running. Abort that other instance of the algorithm without
// waiting for the step that it is running to complete.
// Step 3. If the element's seeking IDL attribute is true, then another instance of this
// algorithm is already running. Abort that other instance of the algorithm without waiting
// for the step that it is running to complete.
self.current_seek_position.set(f64::NAN);
// Step 4. Set the seeking IDL attribute to true.
self.seeking.set(true);
@@ -2009,11 +2017,13 @@ impl HTMLMediaElement {
self.current_playback_position.set(time);
if let Some(ref player) = *self.player.borrow() {
if let Err(e) = player.lock().unwrap().seek(time) {
error!("Seek error {:?}", e);
if let Err(error) = player.lock().unwrap().seek(time) {
error!("Could not seek player: {error:?}");
}
}
self.current_seek_position.set(time);
// Step 12. Wait until the user agent has established whether or not the media data for the
// new playback position is available, and, if it is, until it has decoded enough data to
// play back that position.
@@ -2031,6 +2041,8 @@ impl HTMLMediaElement {
// Step 14. Set the seeking IDL attribute to false.
self.seeking.set(false);
self.current_seek_position.set(f64::NAN);
// Step 15. Run the time marches on steps.
self.time_marches_on();
@@ -2277,6 +2289,11 @@ impl HTMLMediaElement {
}
fn playback_end(&self) {
// Abort the following steps of the end of playback if seeking is in progress.
if self.seeking.get() {
return;
}
match self.direction_of_playback() {
PlaybackDirection::Forwards => self.end_of_playback_in_forwards_direction(),
PlaybackDirection::Backwards => self.end_of_playback_in_backwards_direction(),
@@ -2546,22 +2563,27 @@ impl HTMLMediaElement {
}
fn playback_duration_changed(&self, duration: Option<Duration>) {
// <https://html.spec.whatwg.org/multipage/#media-data-processing-steps-list>
// => "Once enough of the media data has been fetched to determine the duration..."
// Step 4. Update the duration attribute with the time of the last frame of the resource, if
// known, on the media timeline established above. If it is not known (e.g. a stream that is
// in principle infinite), update the duration attribute to the value positive Infinity.
// Note: The user agent will queue a media element task given the media element to fire an
// event named durationchange at the element at this point.
let duration = duration.map_or(f64::INFINITY, |duration| duration.as_secs_f64());
if duration == self.duration.get() {
if self.duration.get() == duration {
return;
}
self.duration.set(duration);
// When the length of the media resource changes to a known value (e.g. from being unknown
// to known, or from a previously established length to a new length), the user agent must
// queue a media element task given the media element to fire an event named durationchange
// at the media element.
// <https://html.spec.whatwg.org/multipage/#offsets-into-the-media-resource:media-resource-22>
self.queue_media_element_task_to_fire_event(atom!("durationchange"));
// If the duration is changed such that the current playback position ends up being greater
// than the time of the end of the media resource, then the user agent must also seek to the
// time of the end of the media resource.
if self.current_playback_position.get() > duration {
self.seek(duration, /* approximate_for_speed */ false);
}
}
fn playback_video_frame_updated(&self) {
@@ -2645,6 +2667,11 @@ impl HTMLMediaElement {
}
fn playback_position_changed(&self, position: f64) {
// Abort the following steps of the current time update if seeking is in progress.
if self.seeking.get() {
return;
}
let _ = self
.played
.borrow_mut()
@@ -2662,7 +2689,13 @@ impl HTMLMediaElement {
self.send_media_session_event(MediaSessionEvent::SetPositionState(media_position_state));
}
fn playback_seek_done(&self) {
fn playback_seek_done(&self, position: f64) {
// If the seek was initiated by script or by the user agent itself continue with the
// following steps, otherwise abort.
if !self.seeking.get() || position != self.current_seek_position.get() {
return;
}
// <https://html.spec.whatwg.org/multipage/#dom-media-seek>
// Step 13. Await a stable state.
let task = MediaElementMicrotask::Seeked {
@@ -2730,7 +2763,7 @@ impl HTMLMediaElement {
PlayerEvent::SeekData(p, ref seek_lock) => {
self.fetch_request(Some(p), Some(seek_lock.clone()))
},
PlayerEvent::SeekDone(_) => self.playback_seek_done(),
PlayerEvent::SeekDone(position) => self.playback_seek_done(position),
PlayerEvent::StateChanged(ref state) => self.playback_state_changed(state),
}
}
@@ -3167,16 +3200,11 @@ impl HTMLMediaElementMethods<crate::DomTypeHolder> for HTMLMediaElement {
Finite::wrap(if self.default_playback_start_position.get() != 0. {
self.default_playback_start_position.get()
} else if self.seeking.get() {
// Following the specification, any time the user agent provides a stable state, the
// official playback position must be set to the current playback position, and
// the `await a stable state` for `seek` (step 13) will be reached on receiving the
// `seek completion` signal from media engine, so the current playback position should
// be returned until the official playback position will be updated in `seek_end`.
// <https://html.spec.whatwg.org/multipage/#playing-the-media-resource:official-playback-position-2>
// <https://html.spec.whatwg.org/multipage/#dom-media-seek>
// Note that the other browsers do the similar (by checking `seeking` value or make no
// difference between `current` and `official` playback positions).
self.current_playback_position.get()
// Note that the other browsers do the similar (by checking `seeking` value or clamp the
// `official` position to the earliest possible position, the duration, and the seekable
// ranges.
// <https://github.com/whatwg/html/issues/11773>
self.current_seek_position.get()
} else {
self.official_playback_position.get()
})