1574042 - Wistia video on Zapier.com doesn't play in Firefox (no support for H264 High 4:4:4 Predictive profiles)

Status: RESOLVED DUPLICATE of bug 1368063

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

Description

[Chris Pearce [:cpearce (Not reading bugmail)]]

STR:

1. Open https://zapier.com/apps/webhook in Firefox and ensure you're on the "overview" tab of that page. I'm using Firefox Release on latest MacOS.
2. Scroll down to the bottom and play the video in the "Webhooks by Zapier in Action" section.
3. Click on the video to play it..

Expected result: Video plays..
Observed result: Audio plays but video does not; only a black screen shows.

This works in Chrome.

From a MOZ_LOG I believe I found the cause:
[Child 4288: Main Thread]: D/MediaSource dom::MediaSource[0x11dcd36a0] ::AddSourceBuffer: AddSourceBuffer(aType=video/mp4;codecs=avc1.f4001f) [not supported]

It looks like Firefox rejects the profile level in that content type, and so video segments can't be appended:
https://searchfox.org/mozilla-central/rev/3366c3d24f1c3818df37ec0818833bf085e41a53/dom/media/mp4/MP4Decoder.cpp#37

That video is served by a service called Wistia. It's not clear to me whether this a config error on Zapier's part, or whether Wistia makes a habit of serving video with this content type. I'll ask around at Zapier to try to figure whether it's a config error on Zapier's part, but given this video works in Chrome but not Firefox, I thought you guys might like to hear about it...

Comment 1

[Andreas Pehrson [:pehrsons]]

Cheers Chris. I'm not really sure who'd know more about h264 profile support, Bryce would you know?

Since we're using platform decoders for h264 support this would be in their hands anyhow. Not sure how chrome does things.

Solving this would mean adding support for higher H264 profiles. Marking this as an enhancement.

FWIW I did note that videos on wistia.com play fine, so that indicates a Zapier config is resulting in this problem, rather than some general Wistia setting.

Comment 2

[Chris Pearce [:cpearce (Not reading bugmail)]]

Thanks I didn't realize 1F was a valid profile. I note the video also doesn't play in Safari on MacOS. So either the MacOS platform decoder can't play the video, or Safari rejects the content type in the addSourceBuffer() call like Firefox does. I haven't tried patching Firefox to report that it can actually play that content type. I suggest someone try that, just to be sure that the platform decoder can't actually play that profile, and the problem is actually that Firefox reports it can't play what it can play.

Comment 3

[Bryce Seager van Dyk [:bryce] (he/him) - Not reading bugmail]

I've tried hacking around this in a Windows build to no avail. I think this is a case of the platform decoders restricting what we can play, and unless those change we're not going to be able to support 4:4:4 subsampling and other such features.