1468796 - 100% cpu usage when playing h264 videos with media.hardware-video-decoding.failed set to true

Status: RESOLVED INVALID

(Core :: Audio/Video, defect)

Description

[1]

Attachment: about_support.txt

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:60.0) Gecko/20100101 Firefox/60.0
Build ID: 20180605171542

Steps to reproduce:

1. set media.hardware-video-decoding.failed to true
2. play h264 video like YT livestream or this:
http://distribution.bbb3d.renderfarming.net/video/mp4/bbb_sunflower_1080p_60fps_normal.mp4


Actual results:

Observed cpu usage when playing 1080p60 bbb:

- WMP (local) h264 : 1% average 

- ff (not failed) h264 : 10-20% after initial spike
https://perfht.ml/2JJyD91

- ff (YT) vp9 : 40-60% average
https://perfht.ml/2JLNq3c

- ff (failed) h264 : 100% cpu usage without visible frame drops (also not counted by YT player)
https://perfht.ml/2ybHxel


Expected results:

Even if this flag was set for a reason, software h264 decoder should not waste that much of cpu.

Comment 1

[Jean-Yves Avenard [:jya]]

Don't set that flag. This indicates that your drivers caused crashes.

Comment 2

[1]

I didn't touch this flag untill I recently saw 100% cpu usage while playing such content.

In about:crashes I have found a long list of similiar crashes like [1] back to 23.06.2017 (probably OS reinstall), and had no cpu usage problem so far. Those crashes have to be manually submitted by the way.

I understand that it had to fallback to software decoder, but 100% cpu usage when software vp9 uses about 50% is not normal and I'm afraid that might also affect hardware without hardware decoder.

[1] https://crash-stats.mozilla.com/report/index/f67238f6-4b8e-40bb-b25f-284e80180614#tab-details

Comment 3

[Jean-Yves Avenard [:jya]]

This flag is set after repetitive crashes occurred with your GPU. This is often due to out of date drivers.
We unfortunately have no control over the H264 decoder as it's part of Windows.
However, when hardware decoding is disabled, it enables the vp9 decoder, so at least with YouTube you'll now use vp9

You can force the use of the hardware decoder if needed.