Is HQX more efficient than HQ? (e.g. smaller file sizes)

[Kris]

I'm surprised to see that projects exported to HQX are coming in significantly smaller than exports to HQ with the same settings (Q and Max/Min). HQX Fine is only a teensy bit larger than HQ standard, and is MUCH smaller than HQ Fine.

Is HQX tweaked for efficiency this way, or might I be missing something...other than experience? (My gear's only 8-bit, so maybe it's dumbing it down accordingly. Still, any reason not to go with HQX Fine?) Thanks.

[antonsvideo]

I use HQ Fine, it gives a cleaner result than HQX fine, can be easily verified with difference keyer

HQX super fine gives a better result than HQ fine, but file size will be double

http://www.videoproductions.com.au/edius6/HQ-fine-quality.png

http://www.videoproductions.com.au/edius6/HQX-fine-quality.png

http://www.videoproductions.com.au/edius6/HQX-superfine-quality.png

[antonsvideo]

and then there is Canopus Lossless, where there is 0.0000% quality loss, much better than HQX super fine

http://www.videoproductions.com.au/edius6/Lossless-quality.png

[Red Union Films]

I was under the impression that in certain situations the HQX codec dropped down to 8Bit. Like when feeding it an 8Bit source, or when the settings go below a certain amount. This was something that was said to me last year, maybe Steve or someone from GV would know.

Cheers.

Dave.

[Andrzej]

HQX and HQ have about the same efficiency, with HQX being a bit better.

There is one main difference- HQX presets do not translate 1:1 to HQ presets.

If you use Fine and Normal than HQ is better, but not because it's more efficient, but because HQX files will be smaller. If you chose custom setting for HQX and match files size for HQ and HQX than HQX is bit better.

Super Fine for HQX is almost lossless and works faster than lossless codec.
Difference is tiny, not like Anton said- big, but in the same time size is just a bit smaller- no magic again.

I still have not done test, but HQX Super Fine should be above HDCAM-SR quality, so it's very high quality mode and can be used instead of uncompressed or lossless.
None of the other intermediate codecs has such a mode (except Cineform)- all stops at 5:1 compression ratio, which is about HQ Fine quality. Already very good, but for some specific cases someone could wish for bit more and that's why HQX is great.

GV has white paper about HQX:

http://www.grassvalley.com/docs/WhitePapers/professional/GV-4097M_HQX_Whitepaper.pdf

[Andrzej]

I was under the impression that in certain situations the HQX codec dropped down to 8Bit. Like when feeding it an 8Bit source, or when the settings go below a certain amount. This was something that was said to me last year, maybe Steve or someone from GV would know.

Cheers.

Dave.

If source is 8bit than last 2 bits in HQX will filled with 0.
I don't believe it upscales/rescales 8bit signals to 10bit.
Cineform has such a feature as an option.

There is no need to go to 8bit for lower modes as 10bit signlas compress better than 8bit ones.

I wish HQX has an option for good dithering (Ordered or Floyd-Steinberg one) when output from codec is 8bit- eg. when used outside Edius.

[Andrzej]

I use HQ Fine, it gives a cleaner result than HQX fine, can be easily verified with difference keyer

HQX super fine gives a better result than HQ fine, but file size will be double

http://www.videoproductions.com.au/edius6/HQ-fine-quality.png

http://www.videoproductions.com.au/edius6/HQX-fine-quality.png

http://www.videoproductions.com.au/e...ne-quality.png

This what you see in vectroscope is just a some "interpretation" of the difference- look at the picture, to see what is exactly different. You need to zoom a lot for Super Fine to see this difference- it's very high quality mode (almost lossless).

One difference- Lossless works in both RGB and 4:2:2 mode- HQX is always 4:2:2.

HQX Super Fine should not really take more time than eg. HQX Fine. For me export times are about the same. It also looks like Edius 6 works better on 12/24 cores machines compared to Edius 5.

[Andrzej]

Is HQX tweaked for efficiency this way, or might I be missing something...other than experience? (My gear's only 8-bit, so maybe it's dumbing it down accordingly. Still, any reason not to go with HQX Fine?) Thanks.

If you need: 10bit than go HQX- not your case.
If you need more quality than HQ Fine (eg for keying etc) than use HQX with custom setting, eg. Q=0, Size=30 to get 3:1 compression and very high quality with still 3-4x smaller file size compared to uncompressed.
HQX is an extension to HQ and offers (except 10bit) more quality if you need it.

Another difference- HQ frame size is limited to broadcast standards- HQX is not- can be almost any size.

[GrassValley_SL]

HQX and HQ have about the same efficiency, with HQX being a bit better.

There is one main difference- HQX presets do not translate 1:1 to HQ presets.

I

This is correct.
Since this is confusing for a lot if users I have discussed this with the Product manager.
It could be that at some point in the future we will adjust the "default preset" parameters for HQX.
But you can do it manually because the parameters can be adjusted to ones need.

[Andrzej]

Good idea- I think these settings are bit to low- quality is not good enough.

Could you mention 10bit output/input pins (also maybe 10bit in AE) for directshow decoder/encoder and optional dithering setting for 8bit output. This would made HQX best codec out there :)

[Kris]

There is one main difference- HQX presets do not translate 1:1 to HQ presets.

That explains everything. (It never occurred to me that they wouldn't correspond.)

Thanks.