Technical Overview of AV1 Spec
github.com
Technical Overview of AV1 Spec
1–10 of 22 posts
Re: Technical Overview of AV1 Spec
#2Are there any FPGA implementations of the AV1 codec, and if so, how do the resource requirements compare to HEVC?
Re: Technical Overview of AV1 Spec
#3For those of you who are new to movie codecs, here is some info that might be useful:
roughly, videos are not streams of images, one after the other (well motion jpeg is, but ignore that) They are "key frames" ie full images, then a set of blocks with some vectors that move those blocks around to make a moving image. So you'll see something like b, i and p frames, each have a different role for making either a full image from which the next frames re-constructed, or the blocks that make the in-between frames.
Re: Technical Overview of AV1 Spec
#4For those of you who are new to movie codecs, here is some info that might be useful: roughly, videos are not streams of images, one after the other (well motion jpeg is, but ignore that) They are "key frames" ie full images, then a set of blocks with some vectors that move those blocks around to make a moving image. So you'll see something like b, i and p frames, each have a different role for making either a full i…
There's a great introduction to video tech, including codecs, at https://github.com/leandromoreira/digital_video_introduction
Re: Technical Overview of AV1 Spec
#5For those of you who are new to movie codecs, here is some info that might be useful: roughly, videos are not streams of images, one after the other (well motion jpeg is, but ignore that) They are "key frames" ie full images, then a set of blocks with some vectors that move those blocks around to make a moving image. So you'll see something like b, i and p frames, each have a different role for making either a full i…
Modern codecs can smear the information over multiple P frames and have no iframes at all.
Re: Technical Overview of AV1 Spec
#6For those of you who are new to movie codecs, here is some info that might be useful: roughly, videos are not streams of images, one after the other (well motion jpeg is, but ignore that) They are "key frames" ie full images, then a set of blocks with some vectors that move those blocks around to make a moving image. So you'll see something like b, i and p frames, each have a different role for making either a full i…
I created a tutorial that covers some of these basic video codec concepts here: https://github.com/kevmo314/codec-from-scratch
Re: Technical Overview of AV1 Spec
#7Are there any FPGA implementations of the AV1 codec, and if so, how do the resource requirements compare to HEVC?
Yes, I believe the folks at BlueDot have an FPGA implementation.
Re: Technical Overview of AV1 Spec
#8For those of you who are new to movie codecs, here is some info that might be useful: roughly, videos are not streams of images, one after the other (well motion jpeg is, but ignore that) They are "key frames" ie full images, then a set of blocks with some vectors that move those blocks around to make a moving image. So you'll see something like b, i and p frames, each have a different role for making either a full i…
Modern codecs can smear the information over multiple P frames and have no iframes at all.
I liked this explanation: https://web.archive.org/web/20141101184307/http://x264dev.mu...
Re: Technical Overview of AV1 Spec
#9For those of you who are new to movie codecs, here is some info that might be useful: roughly, videos are not streams of images, one after the other (well motion jpeg is, but ignore that) They are "key frames" ie full images, then a set of blocks with some vectors that move those blocks around to make a moving image. So you'll see something like b, i and p frames, each have a different role for making either a full i…
Another key piece is the discrete cosine transform.
Most image and video codecs (JPEG and MPEG and AV1 too) use DCT or a related technique. It's a very simple idea at its core. The algorithm looks for an equation that, when plotted, somewhat looks like the original bitmap. The set of possible equations are picked so they can produce a lot of complex different patterns, and be compactly represented.
In more detail, the sum of a set of sine waves, can describe discrete data, or vice versa. It is related to how the sum of square waves produced by a digital to analog converter, are exactly the same as the original analog waveform, within the sampling rate and bit depth limits. Once the data is transformed into a set of sine waves added up, you can drop the minor terms with relatively little effect on the output. The more terms you drop, the higher the compression, and the more blobby and repetitive the pattern, and the blurrier and less detailed the result.
This technique is also used in lossy audio compression.
Re: Technical Overview of AV1 Spec
#10For those of you who are new to movie codecs, here is some info that might be useful: roughly, videos are not streams of images, one after the other (well motion jpeg is, but ignore that) They are "key frames" ie full images, then a set of blocks with some vectors that move those blocks around to make a moving image. So you'll see something like b, i and p frames, each have a different role for making either a full i…
Another key piece is the discrete cosine transform. Most image and video codecs (JPEG and MPEG and AV1 too) use DCT or a related technique. It's a very simple idea at its core. The algorithm looks for an equation that, when plotted, somewhat looks like the original bitmap. The set of possible equations are picked so they can produce a lot of complex different patterns, and be compactly represented. In more detail, th…
Can you dumb this down to ELI16 for me? I'm intrigued but am not following.