leo.bugzilla.gecko Reporter
	Description • 12 years ago

Start music application -> play any mp3 file -> home button -> start browser -> visit any url -> zooming while it loads web page

Then BGM is jittered.
If you visit the page that has lot of media, it can easily reproduced.

Build ID : 20130503155504
Gaia : 5cbb19e4bb78a7ad879fbe4b9a841e1c35714f5c
Gecko : 950b402b6188bb2f3ce3176e620ed5249719d720

	Lukas Blakk [:lsblakk] use ?needinfo
	Comment 1 • 12 years ago

Adding qawanted to add this to test plans - trying to listen to music while browsing the web on media-heavy sites.

	Deepa Subramanian
	Comment 2 • 12 years ago

There is jittering experienced when visiting any url and zoomed while the web page still loading. 
Also, the user is also unable to increase the volume when a headset is used for listening to songs. 

Reproduces 3/8 times on Leo 
Build ID: 20130510070207
Gecko: http://hg.mozilla.org/releases/mozilla-b2g18/rev/2aba3b5ac1c2
Gaia: fcaa90923894211c19b3544b5cb16eb0db5a6286

	David Flanagan [:djf]
	Comment 3 • 12 years ago

This is not related to the Video app so changing the component.

Deepa: you should probably report the headphone issue as a separate bug.

Leo: What does BGM mean?

	Deepa Subramanian
	Comment 4 • 12 years ago

> Deepa: you should probably report the headphone issue as a separate bug.
David there is a bug on it already. https://bugzilla.mozilla.org/show_bug.cgi?id=870894

	leo.bugzilla.gecko Reporter
	Comment 5 • 12 years ago

(In reply to David Flanagan [:djf] from comment #3)

> Leo: What does BGM mean?

Sorry, for confusing.
BGM means Back Ground Music.
(Start music application -> play any mp3 file -> home button)

	leo.bugzilla.gecko Reporter
	Comment 6 • 12 years ago

According to my investigation, audio flinger cannot receive any audio buffer to be rendered.
If you check the log, you can find log line like below.
05-09 17:10:05.050 V/AudioFlinger(  893): getNextBuffer() no more data for track 4097 on thread 0x191f248

At that point, CPU usage is over 80% (B2G + plugin container)

	Marco Chen [:mchen] Assignee
	Comment 7 • 12 years ago

Hi,

I found some info related to this issue.

  1. music app in background on playing will be on BACKGROUND_PERCEIVABLE priority.
  2. BACKGROUND_PERCEIVABLE priority will get nice value 10.
  3. B2G process and browser app is under foreground priority and nice value will be 0 & 1

It seems to that B2G process & browser are busy on rendering action and occupy much cpu slots, then the remaining cpu slot is not enough for music app even rendering may occupy 80% but their's high nice value take the cpu slot from music app when it trys to do decoding.

If I set music app to nice value 1 then this bug is gone.

	Justin Lebar (not reading bugmail)
	Comment 8 • 12 years ago

> If I set music app to nice value 1 then this bug is gone.

What's the highest niceness value you can set the music app to without causing this bug?

We're faced with some hard trade-offs here, because if we increase the priority of the music app, we're decreasing the smoothness of scrolling and other operations in the foreground app.  But I'd be up for giving the music app more CPU.

	Marco Chen [:mchen] Assignee
	Comment 9 • 12 years ago

(In reply to Justin Lebar [:jlebar] from comment #8)
> What's the highest niceness value you can set the music app to without
> causing this bug?
> 

After the testing, set background_perceivable to 7 can avoid this issue but 8.

Hi Leo,

May be you can have a test on your side? Thanks.

http://mxr.mozilla.org/mozilla-central/source/b2g/app/b2g.js#596

	leo.bugzilla.gecko Reporter
	Comment 10 • 12 years ago

(In reply to Marco Chen [:mchen] from comment #9)
> After the testing, set background_perceivable to 7 can avoid this issue but
> 8.
> 
> Hi Leo,
> 
> May be you can have a test on your side? Thanks.
> 

When it's 8, I got some jittering 1~2 times for 15 minutes web surfing.
However the jittering is for a moment. So it doesn't bother me.

	Marco Chen [:mchen] Assignee
	Comment 11 • 12 years ago

(In reply to leo.bugzilla.gecko from comment #10)
> (In reply to Marco Chen [:mchen] from comment #9)
> When it's 8, I got some jittering 1~2 times for 15 minutes web surfing.

Yes, the nice value 8 will still have jitter issue but 7 can avoid it at all on this test case.

	Marco Chen [:mchen] Assignee
	Comment 12 • 12 years ago

Based on comment 8, the nice value 7 can avoid this issue so have a patch on this change.

Could you review it or any other suggestion?
Thanks.

	Justin Lebar (not reading bugmail)
	Comment 13 • 12 years ago

Comment on attachment 749715 [details] [diff] [review]
Modify_Nice_To_7 v1

Okay, this sounds fine.

	Marco Chen [:mchen] Assignee
	Comment 14 • 12 years ago

https://tbpl.mozilla.org/?tree=Try&rev=c626b42ce39f

	Marco Chen [:mchen] Assignee
	Comment 15 • 12 years ago

Add reviewer and approval for leo.

	Ryan VanderMeulen [:RyanVM]
	Comment 16 • 12 years ago

https://hg.mozilla.org/projects/birch/rev/8e524063308f

	Ryan VanderMeulen [:RyanVM]
	Comment 17 • 12 years ago

https://hg.mozilla.org/mozilla-central/rev/8e524063308f

	Ryan VanderMeulen [:RyanVM]
	Comment 18 • 12 years ago

https://hg.mozilla.org/releases/mozilla-b2g18/rev/66f95939ca61

	Marco Chen [:mchen] Assignee
	Comment 19 • 12 years ago

Bug Description:
  When user scrolls the screen on a big page then user will hear audio is jitter.

User Impact:
  When this bug is happened, it degrades user experience on music playback.

Side Effect:
  To raise the nice of background perceivable process may affect the performance of foreground process. But currently foreground's nice value (1) is still more bigger then background perceivable (7).

	Jason Smith [:jsmith]
	Comment 20 • 12 years ago

This is currently a leo+. This still stands as a wontfix unless this gets a tef+. If you want consideration for tef, please nom.

If it's possible to reproduce this on 1.01, then set this to affected. If we don't know, then we need to nom and set to ?.

	Marco Chen [:mchen] Assignee
	Comment 21 • 12 years ago

Bug Description:
  When user scrolls the screen on a big page in the browser then user will hear audio played by music app in the background is jitter.

User Impact:
  When this bug is happened, it degrades user experience on music playback.

Side Effect:
  To raise the nice of background perceivable process may affect the performance of foreground process. But currently foreground's nice value (1) is still more bigger then background perceivable (7).

	Alex Keybl [:akeybl]
	Comment 22 • 12 years ago

Daniel - no strong opinion here, up to you.

	Daniel Coloma:dcoloma
	Comment 23 • 12 years ago

Not blocking, changing process priority at this stage seems to me very risky