Yes, audio is possible as well. I don't have plans to work on this myself
but happy to give guidelines if anyone else wants to.

- Alon



On Sun, Dec 29, 2013 at 4:54 PM, Richard Janicek <[email protected]> wrote:

> Hello,
>
> I am testing --proxy-to-worker with VICE.js. Looks like it's getting +10%
> performance boost on Chrome. Very nice.
>
> Would it be possible to also proxy SDL audio?
>
> Best regards,
> ~Richard Janicek
>
> On Saturday, September 14, 2013 12:37:21 AM UTC-4, azakai wrote:
>
>> Close to that, yes. SDL_Delay can be implemented as a busy-wait both on
>> the main thread and in workers, but on the main thread _it blocks
>> rendering_. On workers, it just blocks event handling; the worker can still
>> send out paint events.
>>
>> This actually happens in Doom, it does screen wipe effects synchronously.
>> Those are not shown when running on the main thread, because nothing
>> renders until the event loop is exited. But when running in a worker, they
>> are shown perfectly. Input events can't be handled during that time, but in
>> that case it doesn't matter - this might be a problem in other ones.
>>
>> I see it refresh the canvas very quickly, and this is without much
>> optimization (no typed array transfers, for example). No reason it can't be
>> 60fps.
>>
>> - Alon
>>
>>
>>
>>
>>
>> On Fri, Sep 13, 2013 at 6:34 PM, Richard Janicek <[email protected]> wrote:
>>
>>> Oh wow, I think this may work for my app. Does this mean it is possible
>>> to allow synchronous blocking flow control in the worker thread (SDL_Delay)
>>> ? How fast can it refresh the canvas, is 60 fps possible?
>>>
>>> Thank you very much for this!
>>>
>>> § Richard Janicek <http://janicek.co> ¦ mappur <http://mappur.com> ¦
>>> player <http://player.janicek.co/#player> ¦ clock2d<http://www.clock2d.com/>
>>>
>>>
>>> On Fri, Sep 13, 2013 at 8:47 PM, Alon Zakai <[email protected]> wrote:
>>>
>>>> If you use HTML canvas commands like lines, shapes, fills, etc., all
>>>> those need a 2D canvas context, and do not work in workers (yet). Right now
>>>> what works is if all you do is render pixels to a buffer and do
>>>> SDL_UnlockSurface to push them to the screen.
>>>>
>>>> But this is temporary, there is spec work going on to get canvas and
>>>> WebGL to workers, it will happen eventually, see e.g.
>>>>
>>>> https://bugzilla.mozilla.org/show_bug.cgi?id=801176
>>>>
>>>> - Alon
>>>>
>>>>
>>>>
>>>> On Fri, Sep 13, 2013 at 5:44 PM, Richard Janicek <[email protected]>wrote:
>>>>
>>>>> What do you mean by "software renderer" ? My app 
>>>>> (VICE.js<http://vice.janicek.co/>)
>>>>> renders frames to HTML canvas, does this mean I can't take advantage of
>>>>> this new technique?
>>>>>
>>>>> Thank you,
>>>>>
>>>>> § Richard Janicek <http://janicek.co> ¦ mappur <http://mappur.com> ¦
>>>>> clock2d <http://www.clock2d.com/>
>>>>>
>>>>>
>>>>> On Fri, Sep 13, 2013 at 7:49 PM, Alon Zakai <[email protected]> wrote:
>>>>>
>>>>>> 1. Proxing to/from a worker. With
>>>>>>
>>>>>> emcc --proxy-to-worker
>>>>>>
>>>>>> the compiler will generate html and js files, where the html is a
>>>>>> small shim that just proxies events to the js, which runs in a worker, 
>>>>>> and
>>>>>> the js sends back the SDL screen which the html then renders. So 
>>>>>> basically
>>>>>> this lets you run simple SDL apps in a worker, which is usually good for
>>>>>> performance (doing less on the main thread).
>>>>>>
>>>>>> This just supports code that does not use HTML canvas or WebGL,
>>>>>> because those don't run in workers in browsers (yet). So it will work 
>>>>>> right
>>>>>> now for a software renderer, for example. I've tested this on Doom.
>>>>>>
>>>>>> 2. emscripten_async_load_script (see emscripten.h)
>>>>>>
>>>>>> This loads a url into a newly-created HTML script element. This is
>>>>>> the most efficient way to load a new large amount of code into your app
>>>>>> (emscripten_run_script converts binary to text, then evals, which is
>>>>>> worse). It also integrates with the run dependencies system, which means
>>>>>> that you can generate code to preload some files using the file packager,
>>>>>> and emscripten_async_load_script of that will asynchronously load the
>>>>>> script as well as fetch the file data and prepare it; the callback will
>>>>>> happen when all the data is ready. This can be used e.g. to load the next
>>>>>> level in your game, at the right time, and in general it can make it 
>>>>>> easier
>>>>>> to avoid preloading everything at the beginning, which can cause a
>>>>>> noticeable pause.
>>>>>>
>>>>>> - Alon
>>>>>>
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