Justin Dolske [:Dolske] Reporter
	Description • 15 years ago

It's not too uncommon for videos to have no audio track. It would be really nice if the video controls could indicate this, so that users know why there's no sound ("is something broken? is my volume too low? wtf?").

Unfortunately this info isn't available through the media element API, so this would need to be added to the HTML5 spec. The simplest way to expose this would be as |readonly boolean hasAudio|. Is the media backend capable of determining this this?

	cajbir (:cajbir)
	Comment 1 • 15 years ago

Yes we can determine if it has no audio track at the beginning. If we eventually support chained oggs then it may be possible for a track to appear as we download so some event to indicate the change of state may be needed.

	Paul Adenot (:padenot) Assignee
	Comment 2 • 12 years ago

Here is a possible patch and its test.

If we play chained medias at some point, I suppose we will have to read metadata again (to prevent failure in case of number of channel or playback rate change), and therefore post new a |nsAudioMetadataEventRunner| to the main thread. That should update the |mozHasAudio| property.

	Chris Pearce [:cpearce (Not reading bugmail)]
	Comment 3 • 12 years ago

Comment on attachment 618878 [details] [diff] [review]
v0 - implements mozHasAudio and adds a test.

Review of attachment 618878 [details] [diff] [review]:
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Nice. This seems a reasonable and way to expose this information until we implement AudioTrackList.

	Chris Pearce [:cpearce (Not reading bugmail)]
	Comment 4 • 12 years ago

Jared: see Paul's attached patch, which will be enable them to detect when a video has no audio so they can hide the volume controls etc.

	Ryan VanderMeulen [:RyanVM]
	Comment 5 • 12 years ago

https://hg.mozilla.org/integration/mozilla-inbound/rev/b579fa03e84a

Also, to make life easier for those checking in patches on your behalf, please follow the directions below for future patches you submit. Thanks!
https://developer.mozilla.org/en/Mercurial_FAQ#How_can_I_generate_a_patch_for_somebody_else_to_check-in_for_me.3F
https://developer.mozilla.org/en/Creating_a_patch_that_can_be_checked_in

	Robert O'Callahan (:roc) (email my personal email if necessary)
	Comment 6 • 12 years ago

Can't the HTML5 track API be used to check if there's an audio track? Assuming we implemented that of course...

	Chris Pearce [:cpearce (Not reading bugmail)]
	Comment 7 • 12 years ago

Yes, as I mentioned in comment 3. It seems we can get a result sooner by taking this now than waiting for AudioTrackList to be implemented.

	Robert O'Callahan (:roc) (email my personal email if necessary)
	Comment 8 • 12 years ago

It wouldn't be that hard to implement enough of AudioTrackList to be useful here.

	Ryan VanderMeulen [:RyanVM]
	Comment 9 • 12 years ago

http://hg.mozilla.org/mozilla-central/rev/b579fa03e84a

	Alfred Kayser
	Comment 10 • 12 years ago

Even better would be to set disabled (instead of noAudio), so that the button is no longer clickable (as muting no sound doesn't work ;-)

	Jean-Yves Perrier [:teoli]
	Comment 11 • 11 years ago

mozHasAudio is now documented in:
https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/15
and in
https://developer.mozilla.org/en-US/docs/Web/API/HTMLVideoElement