Linked by Thom Holwerda on Tue 13th Apr 2010 18:17 UTC
Google Okay, this news hit my inbox and the OSNews queue this morning (and another ten million times during the day) but since I was doing more important things than OSNews today, I only now have the time to dive into this. A site I've never heard before claims that Google will open source the VP8 video codec next month, providing the world with a high-quality, royalty and patent-free codec, which will most likely cause the internet to spontaneously start farting unicorns.
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RE[2]: HTML5?
by Wes Felter on Wed 14th Apr 2010 00:22 UTC in reply to "RE: HTML5?"
Wes Felter
Member since:
2005-11-15

Apparently GPU shaders are terrible at video decoding; that's why we have PureVideo and such. Unfortunately, neither approach is helpful with a new codec.

Reply Parent Score: 2

RE[3]: HTML5?
by lemur2 on Wed 14th Apr 2010 00:43 in reply to "RE[2]: HTML5?"
lemur2 Member since:
2007-02-17

Apparently GPU shaders are terrible at video decoding; that's why we have PureVideo and such. Unfortunately, neither approach is helpful with a new codec.


Source?

GPU shaders are possibly not efficient at decoding H.264/avc, which is very complex and demanding of computational grunt, but Theora at least is considerably easier, and possibly the same is true of VP8.

My source for backup:
http://en.wikipedia.org/wiki/Theora#Playback_performance
However there are currently no Theora decoder chips in production, and iPods and similar devices with limited computing power rely on such chips to provide efficient playback. However since decoding Theora is less CPU intensive than decoding H.264, hardware acceleration may not be necessary in all devices.


By metioning only dedicated decoder chips and very low resource devices (iPods and similar devices with limited computing power), this text actually avoids mentioning the possibility of a GLSL or GPGPU based decoder in any device with a little more resources (i.e. a GPU), such as netbooks, smartbooks, tablets and "pads".

However, the text does mention that Theora is less demanding of resources to decode, and it also says that for small screen resolutions (i.e. iPods and similar devices with limited computing power), dedicated decoing hardware may not be necessary at all.

Reply Parent Score: 2

RE[4]: HTML5?
by smitty on Wed 14th Apr 2010 01:33 in reply to "RE[3]: HTML5?"
smitty Member since:
2005-10-13

There are a bunch of different steps to video decoding, and they all run with varying levels of suitability on shaders. Parts can't be run on shaders at all, others run mediocre, and some run very well.

In practice, the first type end up getting run on the CPU while the rest run in shaders, and it ends up being a lot better than running everything on the CPU. But there's still a significant bit there that can't be shoved over to the GPU, and the general purpose shaders tend to be a lot more power hungry than a small fixed function video decoder, which makes the specialized hardware very nice to have.

Reply Parent Score: 3

RE[4]: HTML5?
by Kuukunen on Wed 14th Apr 2010 15:08 in reply to "RE[3]: HTML5?"
Kuukunen Member since:
2010-03-28

GPU shaders are possibly not efficient at decoding H.264/avc, which is very complex and demanding of computational grunt, but Theora at least is considerably easier, and possibly the same is true of VP8.

My source for backup:
http://en.wikipedia.org/wiki/Theora#Playback_performance

Read again. That doesn't say anything about GPU.

And as smitty said, there's stuff you just can't do practically on shaders. Basically the idea with GPGPU is that you have loads and loads of threads. If you can't multi-thread some part of the decoder by massive amounts, it gets VERY slow. For one, I've never heard of any video format use an entropy coding that would run well on shaders. Of course I could be wrong here. (There might be dedicated hardware for some entropy coding on modern GPUs, but that's another story and depends on the video format.)

Reply Parent Score: 1

RE[3]: HTML5?
by twitterfire on Wed 14th Apr 2010 02:20 in reply to "RE[2]: HTML5?"
twitterfire Member since:
2008-09-11

Apparently GPU shaders are terrible at video decoding; that's why we have PureVideo and such. Unfortunately, neither approach is helpful with a new codec.


True, but all GPUs have either PureVideo or AVIVO.

Reply Parent Score: 2

RE[4]: HTML5?
by Wes Felter on Wed 14th Apr 2010 20:00 in reply to "RE[3]: HTML5?"
Wes Felter Member since:
2005-11-15

As I said, PureVideo and AVIVO don't help you with a new codec like VP8. So if you can't decode VP8 with PureVideo and you can't decode it with shaders, then you're going to be stuck using the CPU.

Reply Parent Score: 2