[webkit-gtk] Ogg media support questions / compiling with debug enabled

[Philippe Normand]

On 2012-06-14 21:42, Daniel Drake wrote:
> On Thu, Jun 14, 2012 at 10:19 AM, Philippe Normand <philn at igalia.com> 
> wrote:
>>> - Does WebKit's inbuilt ogg theora support use Xv for video 
>>> playback?
>>
>>
>> The MediaPlayerPrivateGStreamer backend has some support for 
>> autovideosink
>> (which internally may chose to use the Xv video-sink). This code 
>> path is
>> used for fullscreen video display. However the plan is to remove 
>> support for
>> this once we have a working Accelerated Compositing video layer 
>> working.
>> This will internally rely on OpenGL.
>
> Glad that it is using autovideosink - that should use Xv.
> Is this used in non-fullscreen mode too?
>

No.
For in-window playback we have a video-sink rendering the GstBuffers to 
Cairo surfaces.

> It's a little sad to hear about the move to OpenGL - this will punish
> systems (like all 3 generations of XO laptop) that have good Xv
> support but no OpenGL support. It would be great if the Xv codepath
> could be left in place in addition to OpenGL.
>

Well... Not sure what to do about this. The current GStreamerGWorld 
class using autovideosink is a maintenance burden IMHO.

>>> - How can the inbuilt theora support be made to fill the screen 
>>> when
>>> accessed from a <a type="application/ogg">foo</a> link? Right now 
>>> it
>>> renders small, leaving most of the screen unused.
>>
>>
>> An anchor tag? How can this work?
>> To play media you have 2 alternatives:
>> - the HTML5 way: <audio> and <video> tags
>> - the plugin way: some <object> black magic :)
>
> <a type='application/ogg' href='2970.ogg'>link</a> works just fine 
> here.
>

Ah I see. When you click on this link a HTMLMediaDocument is created 
and loads the href in a audio or video element.

>>> - Why don't the vorbis audio controls (play/stop/etc) appear on 
>>> OLPC
>>> XO laptops? (I think they appear, but 1 pixel in height)
>>
>> I'd be interested to see a screenshot. A bug report might be worth 
>> too
>> (please CC me).
>> What version of WebKitGTK are you using?
>
> WebKit-1.8.1 on Fedora 17.
> Filed https://bugs.webkit.org/show_bug.cgi?id=89121
>

I can reproduce this issue here.
But loading an <audio contols src=http://..... /> should work.

> Also forgot to mention another issue: the audio device is not closed
> after the sound finishes playing. Filed
> https://bugs.webkit.org/show_bug.cgi?id=89122
>

I commented on the bug.

>>> - Can the inbuilt ogg support be disabled, so that we fallback to 
>>> the
>>> browser plugin provided by totem which doesn't have any of these
>>> issues?
>>
>> You can disable video support at configure time if you like.
>
> What about audio, and what about at runtime through some kind of
> system configuration?

You reported the bugs under the "Web Audio" category, which is a 
different thing than the Media elements.
<audio> and <video> elements are backed by the same MediaPlayerPrivate 
implementation. So ./configure --disable-video will also disable the 
<audio> element. This is a bit confusing indeed.

You can read about WebAudio at 
https://dvcs.w3.org/hg/audio/raw-file/tip/webaudio/specification.html

Philippe