High Profile w/o 8x8DCT

[Balthazar2k4]

I am trying to assist the XBMC development team with their DXVA implementation. Currently it only works with files using 8x8DCT, but we would like to confirm that. Is it possible to encode a movie to High Profile w/o using 8x8DCT?

[Blue_MiSfit]

You could make a video that looks like Main Profile aside from its bitrate.

For example, MP@3.1 means you can have a max of 14mbps. HP@3.1 allows for 17.5mbps. So you would encode a stream like this (for 17.5mbps CBR):

x264.exe input.avs --level 31 --profile high --no-8x8dct --bitrate 17500 --vbv-bufsize 17500 --preset fast --output "17500kbps.mp4"

... or something along those lines. I'd suggest a 720p version, to make the high bitrates remotely interesting. I think CBR would be the appropriate choice for a testing scenario like this.

The way I read it, 8x8dct is an optional component of high profile. I'm not sure if this is technically correct, but it seems logical enough.

~MiSfit

[Balthazar2k4]

You could make a video that looks like Main Profile aside from its bitrate.

For example, MP@3.1 means you can have a max of 14mbps. HP@3.1 allows for 17.5mbps. So you would encode a stream like this (for 17.5mbps CBR):

x264.exe input.avs --level 31 --profile high --no-8x8dct --bitrate 17500 --vbv-bufsize 17500 --preset fast --output "17500kbps.mp4"

... or something along those lines. I'd suggest a 720p version, to make the high bitrates remotely interesting. I think CBR would be the appropriate choice for a testing scenario like this.

The way I read it, 8x8dct is an optional component of high profile. I'm not sure if this is technically correct, but it seems logical enough.

~MiSfit

Thanks, I'll give that a try.

[Dark Shikari]

Won't work. x264 always uses the lowest common denominator profile.

What you could do is use a CQM (requires high profile).

[Blue_MiSfit]

Ah-Hah!

That makes sense.

Shouldn't over 12mbps (in the case of specifying level 3.1) bump up the level, or the profile?

~MiSfit

[Balthazar2k4]

Won't work. x264 always uses the lowest common denominator profile.

What you could do is use a CQM (requires high profile).

Yeah, I tried the above suggestion and could not get a HP video. I apologize in advance, but what is a CQM?

[nurbs]

A custom quantization matrix. You can find some here:
http://forum.doom9.org/showthread.php?t=96298
http://forum.doom9.org/showthread.php?t=117041

[J_Darnley]

For testing, you don't even have to bother with an external one, just use: --cqm jvt

[Balthazar2k4]

Thanks everyone! I'll work on this first thing tomorrow and let everyone know what I found.

[nurbs]

IIRC the JVT matrix doesn't count as a custom matrix, but I might be mistaken.

[J_Darnley]

IIRC the JVT matrix doesn't count as a custom matrix, but I might be mistaken.
It must be because using --no-8x8dct --cqm jvt produces high profile output.

[Balthazar2k4]

Thanks again everyone. The --cqm jvt option worked beautifully!