1192694 - mp4 playback can't leave dormant on gonk

Status: RESOLVED FIXED

(Core :: Audio/Video: Playback, defect)

Description

[Alfredo Yang (:alfredo)]

When decoder enters dormant state before decoding first frame. It can't leave dormant state even set SetDormant(false) because mQueuedSeek is always there without transiting to mPendingSeek.

It's reproduced on gonk but I think the same problem may also exist on other platforms.

[1] https://dxr.mozilla.org/mozilla-central/rev/d6ea652c579992daa9041cc9718bb7c6abefbc91/dom/media/MediaDecoderStateMachine.cpp#1327

Comment 1

[Jean-Yves Avenard [:jya]]

You can't enter dormant before decoding the first frame.

so how could you "decoder enters dormant state before decoding first frame" ?

Comment 2

[Alfredo Yang (:alfredo)]

Attachment: dispath_task_if_decoding_first_frame

The DispatchDecodeTasksIfNeeded() should not return when decoding first frame.

Comment 3

[Alfredo Yang (:alfredo)]

There must be a mochitest for dormant in gonk, somehow it doesn't work. checking...

Comment 4

[Jean-Yves Avenard [:jya]]

Comment on attachment 8645592 [details] [diff] [review]
dispath_task_if_decoding_first_frame

Review of attachment 8645592 [details] [diff] [review]:
-----------------------------------------------------------------

::: dom/media/MediaDecoderStateMachine.cpp
@@ +1507,5 @@
>        mState != DECODER_STATE_SEEKING) {
>      return;
>    }
>  
> +  if (mState == DECODER_STATE_DECODING && !IsDecodingFirstFrame() && mDecodingFrozenAtStateDecoding) {

80 columns formatting

Comment 5

[JW Wang [:jwwang] [:jw_wang]]

Comment on attachment 8645592 [details] [diff] [review]
dispath_task_if_decoding_first_frame

Review of attachment 8645592 [details] [diff] [review]:
-----------------------------------------------------------------

https://hg.mozilla.org/mozilla-central/file/d6ea652c5799/dom/media/MediaDecoderStateMachine.cpp#l1261
I think we can just remove mDecodingFrozenAtStateDecoding which is an optimization to halt decoding when MDSM expect seek will happen immediately.

https://hg.mozilla.org/mozilla-central/file/d6ea652c5799/dom/media/MediaDecoderStateMachine.cpp#l1327
Since jya has kinda changed the timing to start seeking, MDSM now checks if there is a pending seek in StartDecoding(). This is exactly what mDecodingFrozenAtStateDecoding tries to optimize! Thanks to jya!

Comment 6

[Alfredo Yang (:alfredo)]

Bug 1192733 for test case.

Comment 7

[Alfredo Yang (:alfredo)]

Attachment: remove_mDecodingFrozenAtStateDecoding_in_MDSM

Comment 8

[JW Wang [:jwwang] [:jw_wang]]

Comment on attachment 8645623 [details] [diff] [review]
remove_mDecodingFrozenAtStateDecoding_in_MDSM

Review of attachment 8645623 [details] [diff] [review]:
-----------------------------------------------------------------

Thanks.

Comment 9

[Alfredo Yang (:alfredo)]

Attachment: remove_mDecodingFrozenAtStateDecoding_in_MDSM

Comment 10

[Alfredo Yang (:alfredo)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=3218707d873a

Comment 11

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/633fb9a5405e

Comment 12

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/633fb9a5405e