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A JavaScript H.264 decoder

github.com

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Re: A JavaScript H.264 decoder

#3

Post by ck2 »

hmottestad wrote: post #2

Running on a macbook pro with i5 dual core 2.4 ghz, it uses 1 core at 100% in firefox and manages: 1.7 fps It's cool, but I don't see any real world applications. Anyone got any ideas?

I think it's more of an (impressive) mental exercise - if the code can be made straightforward enough to run on javascript, the future applications can only grow from there.

Re: A JavaScript H.264 decoder

#4

Post by robert-boehnke »

ck2 wrote: post #3
hmottestad wrote: post #2

Running on a macbook pro with i5 dual core 2.4 ghz, it uses 1 core at 100% in firefox and manages: 1.7 fps It's cool, but I don't see any real world applications. Anyone got any ideas?

I think it's more of an (impressive) mental exercise - if the code can be made straightforward enough to run on javascript, the future applications can only grow from there.

It's the Android encoder written in c++ cross compiled to JavaScript, not much of a mental exercise. Not to say it's not cool :)

Re: A JavaScript H.264 decoder

#6

Post by hmottestad »

salmanapk wrote: post #5
hmottestad wrote: post #2

Running on a macbook pro with i5 dual core 2.4 ghz, it uses 1 core at 100% in firefox and manages: 1.7 fps It's cool, but I don't see any real world applications. Anyone got any ideas?

Strange.. It was running at 4 fps on my Pentium 4 lol

hmmm....

What browser, OS and what Pentium 4 processor? And for how long did you run the video?

Mine drops to 1.7 after a few seconds, the first few frames are dark so in the beginning I get 6 fps.

Re: A JavaScript H.264 decoder

#7

Post by __alexs »

Apparently this can actually get decent frame rates. Although I suspect they are using the patched version of the JS interpreter mentioned on github.

http://yfrog.com/nmng0z

Still not sure how this is meant to actually be useful though. The problem with H.264 isn't availability of implementations, it's being non-free and heavily patented.

I can kind of see a use for this if you are a big content provider with a bunch of cash and want to distribute video to Firefox users without transcoding but it still seems pretty derpy.

Re: A JavaScript H.264 decoder

#8

Post by salmanapk »

hmottestad wrote: post #6
salmanapk wrote: post #5

Earlier quoted context omitted.

Strange.. It was running at 4 fps on my Pentium 4 lol

hmmm.... What browser, OS and what Pentium 4 processor? And for how long did you run the video? Mine drops to 1.7 after a few seconds, the first few frames are dark so in the beginning I get 6 fps.

Nightly, XP, 2.4 Ghz. Nearly 5 Minutes.. Here it starts at like 0.6 fps, and then runs at 4-7 fps onwards.

Re: A JavaScript H.264 decoder

#10

Post by shaver »

hmottestad wrote: post #2

Running on a macbook pro with i5 dual core 2.4 ghz, it uses 1 core at 100% in firefox and manages: 1.7 fps It's cool, but I don't see any real world applications. Anyone got any ideas?

You need Firefox nightly for it to run well, because it depends on the hybrid static/dynamic type inference work and some other optimizations. I believe that Brendan was demoing it from a Mac laptop of some kind.

As far as applications, it will let content providers who want to ship H.264 and pay the license fees do so without requiring all browser developers to pay such fees. (For Firefox it would be a meaningful portion of Mozilla's engineering budget.)

And it's a pretty compelling demo, IMO, of the fact that we're not done with JS performance yet, and that people don't need to be running to Dart or NaCl or other rip-and-replace technologies in order to get great perf. There's a lot of opportunity for even better performance on the engine side as well as the library side: they started a week ago with emscripten, Closure and the libstagefright C sources...

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