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Bug 1540573 - P6. Use frugal preloading of media data when on cellular, otherwise aggressive. r=jya

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We're allowed to take some liberties as to what the default value and behaviour
we assume for the 'preload' attribute on HTMLMediaElement by the spec. On
desktop we assumed preload="metadata", while on mobile we assumed the default
of preload="none" to save data. On mobile we also assumed that preload="auto"
meant preload="metadata".

I think it makes sense to instead of always assuming that data on Android is
always expensive, we can instead detect if we're running on a cellular connection,
and preload frugally then, otherwise aggressively.

Differential Revision: https://phabricator.services.mozilla.com/D26235
This commit is contained in:
Chris Pearce
2019-05-03 02:44:49 +00:00
parent f4772d90d2
commit 17057bfe78
3 changed files with 26 additions and 10 deletions
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30
dom/html/HTMLMediaElement.cpp
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@@ -2455,6 +2455,27 @@ bool HTMLMediaElement::AllowedToPlay() const {
return AutoplayPolicy::IsAllowedToPlay(*this);
}
uint32_t HTMLMediaElement::GetPreloadDefault() const {
if (mMediaSource) {
return HTMLMediaElement::PRELOAD_ATTR_METADATA;
}
if (OnCellularConnection()) {
return Preferences::GetInt("media.preload.default.cellular",
HTMLMediaElement::PRELOAD_ATTR_NONE);
}
return Preferences::GetInt("media.preload.default",
HTMLMediaElement::PRELOAD_ATTR_METADATA);
}
uint32_t HTMLMediaElement::GetPreloadDefaultAuto() const {
if (OnCellularConnection()) {
return Preferences::GetInt("media.preload.auto.cellular",
HTMLMediaElement::PRELOAD_ATTR_METADATA);
}
return Preferences::GetInt("media.preload.auto",
HTMLMediaElement::PRELOAD_ENOUGH);
}
void HTMLMediaElement::UpdatePreloadAction() {
PreloadAction nextAction = PRELOAD_UNDEFINED;
// If autoplay is set, or we're playing, we should always preload data,
@@ -2469,13 +2490,8 @@ void HTMLMediaElement::UpdatePreloadAction() {
mAttrs.GetAttr(nsGkAtoms::preload, kNameSpaceID_None);
// MSE doesn't work if preload is none, so it ignores the pref when src is
// from MSE.
uint32_t preloadDefault =
mMediaSource
? HTMLMediaElement::PRELOAD_ATTR_METADATA
: Preferences::GetInt("media.preload.default",
HTMLMediaElement::PRELOAD_ATTR_METADATA);
uint32_t preloadAuto = Preferences::GetInt(
"media.preload.auto", HTMLMediaElement::PRELOAD_ENOUGH);
uint32_t preloadDefault = GetPreloadDefault();
uint32_t preloadAuto = GetPreloadDefaultAuto();
if (!val) {
// Attribute is not set. Use the preload action specified by the
// media.preload.default pref, or just preload metadata if not present.