Closed Bug 875385 Opened 9 years ago Closed 9 years ago

canPlayType returns "" for video/mp4 even though playback is supported.


(Core :: Audio/Video, defect)

21 Branch
Not set





(Reporter: chandler.prall, Unassigned)



(1 file)

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_2) AppleWebKit/537.31 (KHTML, like Gecko) Chrome/26.0.1410.65 Safari/537.31

Steps to reproduce:

var elem = document.createElement('video'),
    response_1 = elem.canPlayType( 'video/mp4' ),
    response_2 = elem.canPlayType( 'video/mp4; codecs="avc1.42E01E"' )

Actual results:

response_1 === ""
response_2 === ""

Expected results:

response_1 === "maybe"
response_2 === "(maybe|probably)"

Both Firefox for desktop and Android can play mp4 videos such as but both browsers return empty strings for calls to canPlayType.
Component: Untriaged → Video/Audio
Product: Firefox → Core
Chandler: Does this also happen with a nightly build? See
Frank: I get the same results with the nightly. I tried with the Windows Standard build; Funnelcake Jul 2012 mozilla12 - 1.0
Just tried running the test case again in the nightly build and it is working as expected, with canPlayType returning "maybe" and "probably" for response_1 and response_2 respectively.
Sounds like we've fixed the bug here then?
Closed: 9 years ago
Resolution: --- → WORKSFORME
The testcase fails for me now on OSX 10.8.4 using:
* Firefox Nightly 26.0a1 (2013-09-17)
* Firefox Aurora 25.0a2 (2013-09-16)
* Firefox 24.0

It also returns empty string for the audio element when testing for mp4 support using .canPlayType('audio/mp4').
We can't play back MP4 on OSX yet, which is why canPlayType() is not reporting that Firefox can play MP4.
What do you mean you can't play it back? The MP4 video example at plays fine for me on OSX 10.8.4 with Firefox 24.0
I think what happens when following a link to an MP4 file directly (not embedded using a video tag) is that the file is opened using the Quicktime plugin.
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