NAB news: Silverlight 1080p24 playback and taste of new VC-1

[benwaggoner]

I've got my big blog post up about what's happening with Silverlight at NAB:

http://on10.net/blogs/benwagg/NAB-Da...VC-1-and-more/

A few things of particular notice:

• Silverlight 3 can do 1080p24 on a Core 2 Duo 2.4 GHz
• We've got lots of tool vendors and CDNs announcing support for Smooth Streaming
• We've got a new VC-1 implementation coming tuned for Smooth Streaming

I thought the latter might whet folks appitite. It's a new 2-pass mode tuned for Smooth Streaming's multiple bitrate approach, so it offers the aligned Closed GOPs we need for seamless bitrate switching. And it offers a big improvement for 2-pass CBR in VC-1 in general due to a bunch of rate control and other improvements. We've got a number of partners working on incorporating it into their products.

Here's a taste of it with Big Buck Bunny at 1920x1080 24 fps @ 4 Mbps.

http://silverlight.services.live.com...ming/video.wmv

There will be a lot more info about it in coming months. I can show some other samples here at NAB; they're also demoing at the Inlet booth.

[Blue_MiSfit]

Looks pretty good, Ben!

Almost flawless, except for some pretty bad banding in the fades. Quite good for 1080p24 at 4mbps CBR. I didn't think VC-1 was capable of this.

Still - you have to admit, Big Buck Bunny is pretty darned compressible

I wonder how things would look at ~6mbps for a live action movie. x264's CBR surprises me with its visual quality, but its VBV model seems to choke at higher bitrates when you ask for CBR.

-Derek

[benwaggoner]

Originally Posted by Blue_MiSfit

Looks pretty good, Ben!

Almost flawless, except for some pretty bad banding in the fades. Quite good for 1080p24 at 4mbps CBR. I didn't think VC-1 was capable of this.

Yeah, we could be doing better at fades and black areas in general. This isn't the final version, but a good indication of the progress since VC-1 Encoder SDK.

We get a little hit by the Smooth Streaming requirement, as we're doing Closed GOPs every 2-ish seconds in order to provide easy switching points.

Still - you have to admit, Big Buck Bunny is pretty darned compressible

For VBR, yes, but it's got some very high motion high detail parts as well that can really stress CBR. Plus all that grass is a great place to show detail. Noise can help mask higher QPs as well.

I wonder how things would look at ~6mbps for a live action movie. x264's CBR surprises me with its visual quality, but its VBV model seems to choke at higher bitrates when you ask for CBR.

Actually I've got some film source that looks pretty darn good at 4 Mbps too. I'll see what I've got here in Vegas and try to get something uploaded later.

[Blue_MiSfit]

Actually I've got some film source that looks pretty darn good at 4 Mbps too. I'll see what I've got here in Vegas and try to get something uploaded later.

Awesome! I look forward to it!

We get a little hit by the Smooth Streaming requirement, as we're doing Closed GOPs every 2-ish seconds in order to provide easy switching points.

Indeed - so Smooth Streaming is basically shorter GOP CBR, so you can easily adapt to volatile bandwidth conditions? Smart

Thanks for posting info in doom9 as always!

-Derek

[turbojet]

benwaggoner: As you work for microsoft could you inquire about their decoder having the ability to decode all interlaced VC-1 streams?

I posted a sample here

Also as VC-1 directshow playback is very iffy on even current hardware do you know if they are planning on multithreaded decoding in the near future?

[zambelli]

Speaking of x264... At our Microsoft booth at NAB we were also showing a 720p24 H.264 version of "Big Buck Bunny" (to demonstrate Silverlight 3's support for H.264/AAC/MP4). I encoded it using x264, of course.

[Dark Shikari]

Big Buck Bunny is really great for demonstrating how good a crappy encoder is

[benwaggoner]

Originally Posted by turbojet

benwaggoner: As you work for microsoft could you inquire about their decoder having the ability to decode all interlaced VC-1 streams?

I posted a sample here

I think the decoder is generally in good shape. It's just getting the end-to-end pipeline do a proper Bob without tweaking registry keys that's a challenge .

Also as VC-1 directshow playback is very iffy on even current hardware do you know if they are planning on multithreaded decoding in the near future?

There certainly have been mulithreaded VC-1 decoders built in the past. The Silverlight 3 one is currently single-threaded, as single-core machines are the biggest performance challenge, and we typically have plenty to do on a second core with the other parts of Silverlight (which itself is heavily multithreaded).

[benwaggoner]

Originally Posted by Dark Shikari

Big Buck Bunny is really great for demonstrating how good a crappy encoder is

Perhaps you ought to see more than one output from an encoder before determining its quality .

[turbojet]

Originally Posted by benwaggoner

I think the decoder is generally in good shape. It's just getting the end-to-end pipeline do a proper Bob without tweaking registry keys that's a challenge .


There certainly have been mulithreaded VC-1 decoders built in the past. The Silverlight 3 one is currently single-threaded, as single-core machines are the biggest performance challenge, and we typically have plenty to do on a second core with the other parts of Silverlight (which itself is heavily multithreaded).

I should have mentioned that I was referring to WMVideo directshow decoder.

While WMVideo decodes more than the only other free directshow decoder I know of, libavcodec from ffdshow. It still doesn't handle what has to be 30-40 retail BD streams reported so far.

Hopefully you can help out as I don't see anyone else working on an alternative decoder. I don't know how to contact libavcodec devs outside of ffdshow thread/bug tracker where it's already been posted for months with no reply other than libavcodec doesn't decode interlaced streams, which wasn't helpful. I've also tried contacting microsoft a few months ago without any reply.

Where do you see multithreaded VC-1 decoders?

[benwaggoner]

Originally Posted by turbojet

IWhile WMVideo decodes more than the only other free directshow decoder I know of, libavcodec from ffdshow. It still doesn't handle what has to be 30-40 retail BD streams reported so far.

In software? Normally we'd assume DXVA would be used for those kinds of bitrates. Generally any machine otherwise capable of BD playback would have a DXVA capable GPU anyway.

Hopefully you can help out as I don't see anyone else working on an alternative decoder. I don't know how to contact libavcodec devs outside of ffdshow thread/bug tracker where it's already been posted for months with no reply other than libavcodec doesn't decode interlaced streams, which wasn't helpful. I've also tried contacting microsoft a few months ago without any reply.

Who did you try to contact at Microsoft, and what was the request?

Where do you see multithreaded VC-1 decoders?

The HD DVD VC-1 and H.264 decoders were both multithreaded, for obvious reasons. Since VC-1 doesn't have CABAC, it's pretty easy to parallelize. However, as it doesn't have CABAC, there's less need to .

It's possible that the Win 7 software VC-1 decoder may also be multithreaded - haven't tried it myself on a machine that wouldn't have defaulted to the GPU.

[turbojet]

Originally Posted by benwaggoner

In software? Normally we'd assume DXVA would be used for those kinds of bitrates. Generally any machine otherwise capable of BD playback would have a DXVA capable GPU anyway.

I understand your point but the microsoft decoder from windows media player 11 isn't capable of DXVA as far as I know. Plus I'm one of numerous people that has a computer capable of playing 1080p seamlessly but it doesn't have a DXVA supported video card.

Who did you try to contact at Microsoft, and what was the request?

It was a few months ago now but I'm pretty sure I used this. If you can put me in contact with someone that works with the WMVideo decoder and I can send that clip to I'd appreciate it. Even easier would be for you to mention the clip to them and with any luck at all they'll fix it so it can decode a larger range of interlaced streams.

The HD DVD VC-1 and H.264 decoders were both multithreaded, for obvious reasons. Since VC-1 doesn't have CABAC, it's pretty easy to parallelize. However, as it doesn't have CABAC, there's less need to .

It's possible that the Win 7 software VC-1 decoder may also be multithreaded - haven't tried it myself on a machine that wouldn't have defaulted to the GPU.

What I said about multithreading of the WMV9 decoder is inaccurate as I seem to get 60-70% cpu usage on a dual core box with 1080p in MPC-HC. More efficient would be the correct term I guess as there still seems to be many frame drops with microsoft's decoder while cyberlink v7 and 8 plays seamlessly on the same computer without DXVA. I haven't tried windows 7 yet.

If you want to see how widspread the problem is a large majority of these 50 bug reports can be narrowed down to lack of a VC-1 directshow decoder that can decode all interlaced streams.

[benwaggoner]

Originally Posted by turbojet

I understand your point but the microsoft decoder from windows media player 11 isn't capable of DXVA as far as I know. Plus I'm one of numerous people that has a computer capable of playing 1080p seamlessly but it doesn't have a DXVA supported video card.

What GPU do you have? Pretty much all the mainsteam cards have had at least some DXVA for years.

And WMP 11 definitely supports DXVA. I use it all the time.

It was a few months ago now but I'm pretty sure I used this. If you can put me in contact with someone that works with the WMVideo decoder and I can send that clip to I'd appreciate it. Even easier would be for you to mention the clip to them and with any luck at all they'll fix it so it can decode a larger range of interlaced streams.

Is this is a perf issue or a compliance issue. If you get a bug playing back, it's more likely you'd get a fix. Can you describe what happens when it doesn't work?

Win 7 has gotten a huge amount of media performance tuning as part of the general adoption of MediaFoundation. However, since that has lots of OS dependencies you shouldn't expect much of that to get backported to older versions of Windows.

What I said about multithreading of the WMV9 decoder is inaccurate as I seem to get 60-70% cpu usage on a dual core box with 1080p in MPC-HC. More efficient would be the correct term I guess as there still seems to be many frame drops with microsoft's decoder while cyberlink v7 and 8 plays seamlessly on the same computer without DXVA. I haven't tried windows 7 yet.

Is this XP or Vista? Vista can be quite a bit more performant for media playback; I can get 1080i30 @ 35 Mbps to playback smoothly on my laptop in WMP 11 on Vista 32-bit with DXVA. With quite nice bobbing to 1080p60.

[mariner]

Originally Posted by benwaggoner

What GPU do you have? Pretty much all the mainsteam cards have had at least some DXVA for years.

And WMP 11 definitely supports DXVA. I use it all the time.

Greetings Ben.

1. WMVideo decoder only offer up to VC1_IDCT DXVA decoding (mode A,B and C). So DXVA does not work with ATI GPU that only support VC1_VLD (mode D).

You can us DXVA Checker to determine the capabilities of GPU and decoders.

http://bluesky23.hp.infoseek.co.jp/i...ml#DXVAChecker

2. So far I have not had any success getting WMVideo decoder to work with interlaced contents.

Thanks and best regards.

[benwaggoner]

@mariner,
Right. I'm not familiar with the backstory, but Mode D isn't ever going to be supported for XP/Vista AFAIK. ATI was informed about that ages ago, so it's really up to them to enable A, B, or C.

My machines that do interlaced playback all have NVidia cards...

[mariner]

Thanks of the kind reply, Ben.

I had no success with interlaced contents on NV based system. Did you use software decoding?

[benwaggoner]

DXVA, on Vista. I did turn on the DXVA and Interlaced Decode reg keys with WMV9 PowerToy.

I haven't tried on XP.

[mariner]

Thanks. Will try again.

Would appreciate you could tell me the registry keys location.

[Comatose]

Originally Posted by benwaggoner

with WMV9 PowerToy

http://lmgtfy.com/?q=WMV9+PowerToy

[turbojet]

Originally Posted by benwaggoner

What GPU do you have? Pretty much all the mainsteam cards have had at least some DXVA for years.

And WMP 11 definitely supports DXVA. I use it all the time.

Geforce 6600GT.

Is this is a perf issue or a compliance issue. If you get a bug playing back, it's more likely you'd get a fix. Can you describe what happens when it doesn't work?

Decoding issue, it's from retail BD's which I guess could be non-compliant but cuda decodes them fine. Freezes, blocky and green screen are some of the things I've seen. Check out the sample I posted last week in this thread.

Win 7 has gotten a huge amount of media performance tuning as part of the general adoption of MediaFoundation. However, since that has lots of OS dependencies you shouldn't expect much of that to get backported to older versions of Windows.


Is this XP or Vista? Vista can be quite a bit more performant for media playback; I can get 1080i30 @ 35 Mbps to playback smoothly on my laptop in WMP 11 on Vista 32-bit with DXVA. With quite nice bobbing to 1080p60.

Vista 64 bit but still same issue with xp 64 bit on the same box, I dual boot on an X2 3800+. VC-1 software decoding performance is about 60% compared to tuned H.264 decoders. Should this be the case?