LAV Filters - DirectShow Media Splitter and Decoders

[LigH]

Well, in my experience, Pro-Logic downmixes should be quite compatible to common stereo playback systems. You may not have a really distinct front/back separation, but the phase shifted weighted mix of surround channels into left and right channels still gives an impression of a less clearly located source.

A heavy weight on only one channel is certainly not the expected result, especially not when the source is mostly centered with only little surround impact; the center channel should be mixed equally to left and right if your downmix matrix is correct. Only surround channels should have a chance to get mixed with unequal weights.

[har3inger]

That's what I thought expected behavior to be. I'd assume that there is a bug with the way the matrix is being encoded currently? I have tried several samples where the audio clearly shifts to the right (even visible in the LAV sound channel volume tab) when switching from "none" to "pro logic II". Can anyone else reproduce to ensure it's not a config problem on my end?

I'm using matrix encoding for when I plug my computer into my TV with its 5.1 speaker setup, but leave it on for computer-only because of laziness.

[VictorLS]

Originally Posted by Nintendo Maniac 64

I did some quick-and-dirty testing and I think "None" actually doesn't hit my CPU anywhere near as hard as I thought it would

You want to say: despite of "None" in LAV Video decoder some hardware acceleration are active? I think this is impossible.

[ryrynz]

Originally Posted by VictorLS

You want to say: despite of "None" in LAV Video decoder some hardware acceleration are active? I think this is impossible.

He means to say that it's well optimized, as Nev has said earlier in the thread software decoding is preferred for most systems.. less issues and performance is very good.

[LigH]

To say it very generally:

Hardware chipset support speeds up the decoding process only if the decoder chip is faster than the CPU. Which is not anymore the default case. The current fast multi-core CPUs with SIMD instruction set extensions are equal or even superior to GPU decoders in many cases. Using hardware support is not generally an "acceleration".

[NikosD]

This is totally wrong.

I mean it is dead wrong.

Even from 2011, Intel's Sandybridge iGPU using QuickSync - a dedicated ASIC inside the GPU - was a lot faster than Core i7 CPU in all three codecs supported - H.264, MPEG2, VC-1/WMV3.

And the hardware decoder was present even in Core i3.

Nowadays, Intel's Skylake/Kabylake iGPU and Nvidia's Maxwell GM206/ Pascal have only increased the performance difference from the fastest Core i7 CPUs.

And the hardware decoders of Intel are present and activated even in Celerons/Pentiums since Haswell.

The latest variations of hardware decoders have added HEVC (8bit/10bit) and VP9 (mostly 8bit and Kabylake 8bit/10bit) with resolutions supported up to 8K.

Hardware dedoders are no match even for the fastest CPUs nowadays.

[VictorLS]

ryrynz, LigH, NikosD
I investigate hardware acceleration by videocards inserted in PCs with very weak CPUs since MPEG2 appeared and I agree with NikosD. On old lap top I'm sure it's must be more visible. It's a pity Nintendo Maniac 64 not answered my questions: Can you provide hardware (model of laptop, CPU, GPU if present) and software (OS and player with renderer you use or tried) configuration?
So I can't tell him what happens.

[LigH]

Okay, my scope in the previous reply was probably wrong. I remembered early Nvidia PureVideo generations being limited to common display framerates, they were an excecption to the generalized opinion that GPU decoding is "always" faster. And just displaying is also a different purpose than converting, where the result of the GPU decoding has to be transferred back to the RAM.

[nevcairiel]

It makes no difference how fast a decoder is for realtime playback if all options can play all your videos fast enough, however.

The key point is that even CPUs these days are plenty fast for FullHD H264 playback without any serious CPU usage, without requiring some i7 high-end CPU, so software decoding is a valid and viable option for a lot of people. Only if you go 4k or exorbitantly high bitrates it may no longer work - but thats far from what the majority actually plays.

[Aleksoid1978]

Latest NV CUvid with 375.xx drivers support P016 output and HEVC 12 bit decoding(not tested yet).

[nevcairiel]

Originally Posted by Aleksoid1978

Latest NV CUvid with 375.xx drivers support P016 output and HEVC 12 bit decoding(not tested yet).

They would need to release an updated SDK to make that properly available. We'll see if/when they do that.

[huhn]

even a 39 mbit BD doesn't need more than 22 % CPU usages on an old I3 4130 and the i3 isn't even using it highest clock speed.

[Aleksoid1978]

Originally Posted by nevcairiel

They would need to release an updated SDK to make that properly available. We'll see if/when they do that.

I tested(do modify LAVVideo) - perfect working P016(decoding HEVC 10 bit) output with MadVR using CUVID.

[NikosD]

H.264 codec is going to an end.

It has been replaced by VP9 in Youtube, which means that probably 80% of Internet's video traffic uses that codec now.

Also, FullHD is the minimum nowadays for almost everything.

Bluray UHD is obviously UHD (2160p) and it uses H.265 10bit and YouTube along with other online services use 4K and even has started testing 8K (!)

Generally speaking, we shouldn't talk so much about H.264 but H.265 and VP9 and a little more of UHD than FullHD.

VP9 and HEVC are a lot more demanding than H.264

We are on late 2016 afterall.

All of these cases are handled a lot better by hardware decoders which are necessary (probably a requirement) when we talk about laptops.

[huhn]

the number of UHD screen and the number of UBD players on the market is still super low.

UHD is not important yet!

and about youtube and VP9 80% traffic just no: http://appleinsider.com/articles/16/...-apples-itunes

[NikosD]

You are really unlucky because Netflix is moving to 4K and HEVC 10bit of course:

http://arstechnica.com/gadgets/2016/...-edge-browser/

I have to repeat myself and I hate that.

The world is moving to VP9/HEVC and to larger than 1080p resolutions.

[huhn]

no they are going back to mpeg2...

UHD will be important sometime in the future.
just read your own link and they got the specs wrong too...

And then there's the browser: 4K streaming only works in Microsoft Edge, because it's the only browser that supports PlayReady DRM. Basically, streaming 4K Netflix on a PC requires a CPU that's in barely any devices right now (desktop chips aren't expected until sometime in 2017), the latest version of Windows 10, and using an unpopular browser, making it a largely useless feature.

[NikosD]

I'm not trying to convince anyone that he clearly doesn't want to.

I'm just saying that hardware decoding is a lot faster than CPU decoding and it is necessary for codecs like VP9 and HEVC that are more and more used everyday, especially for resolutions above 1080p.

Just facts.

[Aleksoid1978]

nevcairiel
Bug in YUV 12bit 444 ->RGB conversion.

yuv2rgb.cpp -> yuv2rgb_convert_pixels() finction.

    // Shift to 12 bit
    if (shift > 4) {
      xmm1 = _mm_srli_epi16(xmm0, shift-4);
      xmm3 = _mm_srli_epi16(xmm2, shift-4);
    } else if (shift < 4) {
      xmm1 = _mm_slli_epi16(xmm0, 4-shift);
      xmm3 = _mm_slli_epi16(xmm2, 4-shift);
    }

forgot about shift == 4.
fix:

    else {
      xmm1 = xmm0;
      xmm3 = xmm2;
    }

Short sample - https://yadi.sk/i/u8pggKFqzJLcR

[CruNcher]

Originally Posted by NikosD

I'm not trying to convince anyone that he clearly doesn't want to.

I'm just saying that hardware decoding is a lot faster than CPU decoding and it is necessary for codecs like VP9 and HEVC that are more and more used everyday, especially for resolutions above 1080p.

Just facts.

an I5 (2nd Generation) is still very capable of playing back HEVC 10 Bit 4K at lower complexity (WEB VOD) without any Hardware support even at 60 FPS if done right.

And it becomes really interesting to see how close H.265 and VP9 get then at this merging point of complexity

The only area where CPU is not enough anymore is very High IPTV requirements and Higher Complexity Broadcast and partly 360 Video, especially when you have all the DRM overhead coming into play additionally.

And VP9 is a little less complex in decoding requirements overall.

From a Content Provider view it would be rather dumb not to catchup this wider reach possibility

Though obviously you more energy efficient on Nvidias or AMDs current IP even on the complete card overhead side to around 11-15W then pushing 4 cores to around 95W/65W, and try to get that stable with magic draining the batteries in no time
And then there is Hybrid which can be usefull depending on the Scenario supporting and lowering the overall drain a little further