AVC-Intra 100 profile

[Atak_Snajpera]

I'm trying to create something similar to AVC-Intra 100 (http://en.wikipedia.org/wiki/AVC-Intra#Technical_details)

At the moment I use following settings
--crf 16 --preset superfast --min-keyint 1 --keyint 1 --no-cabac --no-deblock --scenecut 0 --slices 10

Any sugestions?

BTW. I chose --crf 16 because I wanted to have average bitrate at around 100mbps for 1920x1080@50fps

[J_Darnley]

Perhaps --tune fastdecode instead of --no-cabac --no-deblock This is effectively the same. Also --keyint 1 makes --min-keyint 1 redundant which also makes --scenecut ineffective. Also "size of each frame is fixed" makes it sound like you should be forcing the size of each frame with stupid VBV constraints. 10 slices also seems somewhat odd...

Basically I mean: --crf 16 --preset superfast --tune fastdecode --keyint 1 --slices 10

Offtopic but, why on earth does "AVC-Intra 50" demand CABAC and AVC-Intra 100" demand CAVLC?

[Dark Shikari]

Perhaps --tune fastdecode instead of --no-cabac --no-deblock This is effectively the same. Also --keyint 1 makes --min-keyint 1 redundant which also makes --scenecut ineffective. Also "size of each frame is fixed" makes it sound like you should be forcing the size of each frame with stupid VBV constraints.Which would mean something like (for 25fps):

--vbv-maxrate 100000 --vbv-bufsize 4000 --nal-hrd cbr

Since AVC-Intra requires filler for the constant framesize, AFAIK.

[Blue_MiSfit]

CAVLC for 100mbps will make things easier to decode. I guess the AVC Intra standard assumes decoders are fast enough for 50mbps 1080p with CABAC, but not 100mbps 1080p with CABAC.

Constant frame size makes things quite predictable, which is nice for acquisition formats.

This also implies --bitrate 100000 instead of --crf 16.

~MiSfit

[Atak_Snajpera]

# AVC-Intra 50:

* nominally 50 Mbit/s, size of each frame is fixed
* CABAC entropy coding only.
* 1920x1080 formats are High 10 Intra Profile, Level 4
* 1280x720 formats are High 10 Intra Profile, Level 3.2
* 4:2:0 chrominance sampling
* frames are horizontally scaled by 3/4 (1920x1080 is scaled to 1440x1080. 1280x720 is scaled to 960x720)



1440x1080 = 1555200 pixels
1280x720 = 921600 pixels

why they force scaling to 960x720 if both can use 50mbps???

[Blue_MiSfit]

presumably 50mbps CBR is not enough for full raster 10 bit 4:2:2

especially when not using x264 :devil:

[Atak_Snajpera]

Which would mean something like (for 25fps):

--vbv-maxrate 100000 --vbv-bufsize 4000 --nal-hrd cbr

Does this mean that I should use --vbv-bufsize 8000 for 50fps? What's the correct bufsize for AVC-Intra 100?

[kieranrk]

What's the correct bufsize for AVC-Intra 100?

vbv-maxrate divided by fps.

[Atak_Snajpera]

Thanks!

[Gser]

I thought x264 only supports YV12 and AVC-Intra 100 demands 4:2:2 chrominance sampling.

[Atak_Snajpera]

That's why I wrote "something similar" not the same :)

[Gser]

That's why I wrote "something similar" not the same :)

So I'm guessing no intra-frame only compression either :(

[Gser]

That's why I wrote "something similar" not the same :)

So I'm guessing no intra-frame only compression either :( My hopes were set up too high.

[Blue_MiSfit]

Of course x264 supports intra-only coding. This is a trivial thing to enable. Simply add the following to your command line:

--keyint 1

And you will produce an H.264 stream with only I(DR?) frames.

~MiSfit