[Webkit-unassigned] [Bug 147309] New: [Mac] canPlayType('audio/mpeg; codecs="mp3"') returns "maybe" instead of "probably" on AVFoundation

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=147309

            Bug ID: 147309
           Summary: [Mac] canPlayType('audio/mpeg; codecs="mp3"') returns
                    "maybe" instead of "probably" on AVFoundation
    Classification: Unclassified
           Product: WebKit
           Version: 528+ (Nightly build)
          Hardware: Macintosh
               URL: http://jsbin.com/vubukodepo/edit?js,output
                OS: Mac OS X 10.10
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: Media Elements
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: sajidanwar94 at gmail.com

I've reported part of this bug as <rdar://22000718>.

The Objective-C platform media player/source calls [AVFoundation isPlayableExtendedMIMEType:] to determine if a MIME type + codec string is supported. I've peeked inside with a debugger and found that it obtains the list of supported video/audio types and codecs from /System/Library/Frameworks/MediaToolbox.framework/Resources/MediaValidator.plist . Inside this plist is a list of supported "AudioCodecs", which contains strings like "aac " and ".mp3". However, "mp3" is nowhere to be found, despite the fact that virtually all examples, tutorials, and specifications online use canPlayType() to check the 'audio/mpeg; codecs="mp3"' MIME type.

Currently, canPlayType('audio/mpeg; codecs="mp3"') returns "maybe", but you can edit the plist and add the "mp3" entry, and then canPlayType will return "probably", which is expected since AV Foundation can obviously play MP3 audio.

On top of that, as I reported in the radar, there appears to be a bug in the implementation of [AVURLAsset isPlayableExtendedMIMEType:] that returns NO on the ".mp3" codec despite its existence in the plist, meaning even canPlayType('audio/mpeg; codecs=".mp3"') returns "maybe".

Should WebKit special-case the "mp3" audio codec to return "probably"? That might not be an elegant solution, but unless Apple adds the "mp3" entry to the "AudioCodecs" section of the plist, the call will always return "maybe" instead of "probably".

A little more information about the AV Foundation bug can be found at the radar, which I've duplicated on Open Radar: https://openradar.appspot.com/22000718

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