Bug 44519 – HTMLMediaElement.canPlayType gives wrong results on the iPhone

• Status: RESOLVED
• Resolution: INVALID
• Component: Media

[Niels Leenheer (HTML5test)]

The canPlayType() function gives back wrong information on the iPhone and iPad (tested with iOS 3.2 and 4).

Safari for iOS will report back "probably: for containers that it supports when only a MIME type is specified. This is something that is explicitly discouraged by the specification. When no codecs parameter is present, it should report "maybe" at best.

v=document.createElement('video');
v.canPlayType('video/mp4')
-> probably     // incorrect, should be maybe


When a codecs parameter is present, Safari will strangely report back "maybe" for all MIME types it recognized, regardless of the contents of the codecs parameter. The proper response would be to report back "probably" for supported codecs and an empty string for codecs it doesn’t recognize. 

v=document.createElement('video');
v.canPlayType('video/mp4; codecs="avc1.42E01E"')
-> maybe     // incorrect, should be probably

v=document.createElement('video');
v.canPlayType('video/mp4; codecs="foobar"')
-> maybe     // incorrect, should be ""


This bug makes codec detection impossible on the iPhone and needs to be fixed as soon as possible.

[Niels Leenheer (HTML5test)]

Html5test.com currently uses a workaround for codec detection on the iPhone. This workaround will probably be removed in an upcoming version of the test. The result is that Safari for the iPhone will no longer score bonus points for codecs.

The idea is that if you can't properly detect a codec, it is not properly supported. Especially on mobile devices canPlayType is essential, because you can't simply try to load the stream and see what happens.

[Alexey Proskuryakov]

Please file iOS specific bugs via http://bugreport.apple.com, because iOS WebKit isn't built directly from webkit.org sources.

[Niels Leenheer (HTML5test)]

Radar #8349691