LCEVC如何运作

Learn more about emerging codecs and standards at 流媒体西部2020.

Read the complete transcript of this clip:

圭多Meardi: 经常, 当谈到LCEVC时, I hear words like "too good to be true", 或者“这怎么可能?,或者“这不可能。." So, my objective would be to make sure that you understand how it works and the fact that it's not magic. It's actually pretty simple also; that's why it's "low complexity."

本质上, the codec works by using another codec at the lower resolution, 当然, to make sure that the combined entity of leverage codec plus enhancement takes less power and less bandwidth One requirement is using the leverage codec at the lower resolution so that it can focus on fewer pixels. So, less processing, and it can be more efficient than cranking those pixels. 然后, 高频, so the additional data is encoded using a special encoder, 什么是LCEVC, that is aimed specifically at coding enhancement data.

I will show in a bit what enhancement data is, 但本质上, what LCEVC does is it codes the lower resolution 然后 the delta between the lower resolution and the top resolution, 高质量的, gets encoded with this special enhancement codec.

在解码端, the video stream is a master stream containing two elementary streams, 基本编解码器的正常流, and an enhancement stream which can be packaged as a separate PID or SICI metadata, or even sent as an independent stream--there are several options.

但是在解码方面, 有一个标准的解码器, even hardware that decodes the base codec, 然后, the enhancement is decoded separately and overlaid and merged with the base in order to obtain the final output. If you want to see it in a more visual way, this is kind of like how it works at a decoding site, where you would get a sort of thumbnail video or a lower-resolution video encoded with the traditional codec, 是否H.264, HEVC, AV1等等. There's a first layer of residual correction before an upsampling pass.

There can be also an upsampling pass here--it depends; it's parametric. There's a correction layer that corrects before the most important upsampling pass, 这就完全解决了问题, 然后, there's an additional sublayer of residuals that adds the details at the end. 另外，利用时间缓冲区.

重要的是, 如你所见, these sublayers of one LCVEC and codes are not pictures, 它们是残差, 这是非常重要的, because they are something like this: When you talk about details, this is an example of what LCEVC would encode of a 1080p of, 在这种情况下, it's pretty evidently a Formula One video. And you can see that there are a lot of details, a lot of dots, a lot of edges, a lot of text detail. This stuff, which would be high frequencies, is very costly for traditional codecs.

If you are using a DCT with big blocks, think about HEVC 64x64 coding units with DCT, 当你有一个点, it will be tens of coefficients to encode it. LCEVC is actually meant to encode this stuff, 它有很小的变换, aimed at high frequencies that are extremely efficient at compressing high detail.

免费的

合资格订户

现在就订阅最新一期过去的问题

Testing EVC, VVC, and LCEVC: How Do the Latest MPEG Codecs Stack Up?

Jan Ozer说EVC, VVC, 和LCEVC的步伐, checking each for not only encoding quality, 编码的复杂性, and playback efficiency but also power consumption. Each one has its pros and cons; read on to find out how they all performed.

2021年12月29日

LCEVC:准备好黄金时段了

The Low Complexity Enhancement Video Codec (LCEVC) is ready for primetime. V-Nova is the primary developer behind the codec, and we talked to CEO and co-founder Guido Meardi about where things stand, both in terms of the technology and licensing structure.

2021年6月29日