openstack
/
deb-spice-html5
Code Issues Proposed changes

Use modern browser information to detect underrun. 

We previously had a fairly crude 'gap detection', but browsers
are largely supporting the modern buffer semantics, and we can
now rely on them to detect under runs for us.

This improves audio in Chrome while playing large videos.
This commit is contained in:
Jeremy White 2016-09-26 15:29:14 -05:00
parent 1f4959e3c2
commit 245a476bd9
1 changed files with 8 additions and 22 deletions
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30
playback.js
View File

@ -29,8 +29,6 @@ function SpicePlaybackConn()
this.queue = new Array();
this.append_okay = false;
this.start_time = 0;
this.skip_until = 0;
this.gap_time = 0;
}
SpicePlaybackConn.prototype = Object.create(SpiceConn.prototype);
@ -103,19 +101,13 @@ SpicePlaybackConn.prototype.process_channel_message = function(msg)
if (! this.source_buffer)
return true;
/* Gap detection: If there has been a delay since our last packet, then audio must
have paused. Handling that gets tricky. In Chrome, you can seek forward,
but you cannot in Firefox. And seeking forward in Chrome is nice, as it keeps
Chrome from being overly cautious in it's buffer strategy.
So we do two things. First, we seek forward. Second, we compute how much of a gap
there would have been, and essentially eliminate it.
*/
if (this.last_data_time && data.time >= (this.last_data_time + GAP_DETECTION_THRESHOLD))
if (this.audio.readyState >= 3 && this.audio.buffered.length > 1 &&
this.audio.currentTime == this.audio.buffered.end(0) &&
this.audio.currentTime < this.audio.buffered.start(this.audio.buffered.length - 1))
{
this.skip_until = data.time;
this.gap_time = (data.time - this.start_time) -
(this.source_buffer.buffered.end(this.source_buffer.buffered.end.length - 1) * 1000.0).toFixed(0);
console.log("Audio underrun: we appear to have fallen behind; advancing to " +
this.audio.buffered.start(this.audio.buffered.length - 1));
this.audio.currentTime = this.audio.buffered.start(this.audio.buffered.length - 1);
}
this.last_data_time = data.time;
@ -126,18 +118,12 @@ SpicePlaybackConn.prototype.process_channel_message = function(msg)
if (this.start_time == 0)
this.start_playback(data);
else if (data.time - this.cluster_time >= MAX_CLUSTER_TIME || this.skip_until > 0)
else if (data.time - this.cluster_time >= MAX_CLUSTER_TIME)
this.new_cluster(data);
else
this.simple_block(data, false);
if (this.skip_until > 0)
{
this.audio.currentTime = (this.skip_until - this.start_time - this.gap_time) / 1000.0;
this.skip_until = 0;
}
if (this.audio.paused)
this.audio.play();
@ -205,7 +191,7 @@ SpicePlaybackConn.prototype.new_cluster = function(data)
{
this.cluster_time = data.time;
var c = new webm_Cluster(data.time - this.start_time - this.gap_time);
var c = new webm_Cluster(data.time - this.start_time);
var mb = new ArrayBuffer(c.buffer_size());
this.bytes_written += c.to_buffer(mb);