I just finished up a major project that mixed HDV and SD onto a SD timeline for DVD production. And I was very unhappy with the downconvert from HD to SD from within Liquid. I didn't have the time to play around with it, so I had to use the default settings. I'm now seriously considering re-doing the entire project.

What's happening is that when downcoverting from HD to SD, you end up with a rather pixelated result. This is very obvious when looking at colors that tend to bleed (e.g. birhgt red). This is a combination of CODEC, bitrate, and color space. Sometimes it's not obvious at all, and sometime it's extremely distracting. I'll post comparison shots tomorrow so you can see a clear example. This has been reported by several other users recently as well.

There's an easy solution for this. Use the DVCPro50 CODEC instead of DV for the SD timeline. This eliminates the pixelation at the expense that the final video is twice the size of DV video.

Hope this helps.

How about downconverting in the camera or player? I use the Sony HVR-M25 and it seems to me to get better results than with downconverting in Liquid. 

I have done all my multicams, mixed Sd and HD, as HD projects, in this case, you have a choice of doing either Dvd or BD in the end and letting Liquid create a dvd disc from an HD timeline gives very good results.

Roland, sometimes you can't downconvert fron the camera. For example, when you want to reframe the shots in post using pan-and-scan. In my case, I don't even have the camera from which to downconvert; it was a rental and all I have are the HDV clips.

Tomas, this all has to do with the CODEC and rendering. The pixelation only shows up using the DV CODEC after it's been rendered. When editing in HD and downconverting to MPEG-2 (and not DV) it doesn't show up. Unfortunately, my systems are older and don't edit HD all that well.

The really annoying part of the problem is if you simply take the HD and put it on a DV timeline and look at it before it renders, it looks really good. It's only after the downconvert renders that it looks pixelated. So if you edit on a DV timeline while viewing the yellow slices, you don't see any problems.

Using DVCPro50 is a good stopgap solution. It takes up twice as much space as DV, but considerably less than uncompressed, and needs less system resources to process than HD/HDV while editing.

Welcome to the joy of 4:1:1 color.  Our PAL friends may not notice this as much as we do Dave.

DVCPRO50 is a great solution is you plan on going to DVD or some other web based format.  The reason is because all mpeg2 and web based video uses 4:2:0 color.  Converting 4:1:1 to 4:2:0 is less then optimal and should be avoided as much as possible.  Of course I'm not saying it has to look bad since many NTSC users are used to making DVD's from 4:1:1 material.  All I'm saying is that your DVD's will look even better if you can start with a 4:2:2 source.

 Another codec option is the IMX based mpeg2 50 mbit I frame only codec in Liquid.  You will notice that DVCPRO50 only works for normal interlaced SD video.  If you want to work with progressive you will have to choose the mpeg2 based IMX codec.  Quality wise they are pretty much the same.  50 mbits, DCT based Intraframe compression with 4:2:2 color.

 Dave I think the reason why you noticed the blocky artifacts more then you would have from a 4:1:1 based SD camera is because down converting HD to 4:1:1 is just too good.  Most SD cameras are not capable of that level of precision and detail.  The more detailed a image is the easier it is to see chroma sub sampling artifacts.  Thats why computer generated color titles always kind of look like poopoo with 4:1:1 compression.  If you shot a cardboard cutout of a white title against a solid color piece of paper you wouldn't get the artifacts as bad.

DStone:

Tomas, this all has to do with the CODEC and rendering. The pixelation only shows up using the DV CODEC after it's been rendered. When editing in HD and downconverting to MPEG-2 (and not DV) it doesn't show up. Unfortunately, my systems are older and don't edit HD all that well.

Yes, Dave, time for you to update now, price are falling on all old good things when new things shows up on the market, you could propably build a machine like mine for less than a tenth of the price I paid when all these stuff was new.

Smetvid:

...  Thats why computer generated color titles always kind of look like poopoo with 4:1:1 compression. ...

I gotta make a note of that technical term, "poopoo"!

 

While there's noticeable artifacting with the HDV to DV rendering, it's really not too bad until it hits the color best labelled as Bright Red. I haven't gotten to the editing system yet today, but the comparison shots are forthcoming. I've made the decision to redo the entire project (OMG, am I out of my mind??) in DVCPro50.

So then after you are done editing you fuse out to the DVCPro50 codec then create the dvd from that fuse?

Dave, Thomas S mentioned the 50Mb MPEG-2 I-frame codec in Liquid that you can select as the render codec... It really is good - even going back to the original FAST Studio, the 50Mb codec kicked a$$... We still use it when doing anything SD from DigiBeta etc or when - like you - down-converting from HD sources that is destined for DV or DVD ... Like Thomas said "4:2:0 into 4:1:1 just won't go...well..."

R

smithe1:

So then after you are done editing you fuse out to the DVCPro50 codec then create the dvd from that fuse?

Yes. I use an external 3rd party MPEG-2 encoder for making DVDs, so this is a better workflow.

Just for grins, I decided to do a comparison of using the DVCPro50 CODEC and the I-Frame only MPEG-2 4:2:2 CODEC. Technically, there shouldn't be much different in size of the resulting files as I-Frame only means there's no inter-frame compression. And I presumed that the quality of the clips would be about the same. In doing the comparison, I think that the I-Frame MPEG-2 CODEC looks better than the DVCPro50.

Can anyone take a quick look at this and confirm?

Yes I agree.  I would go so far as to say these types of m2v files are better then DnxHD, Mjpeg and even Apple Prores.  m2v is one of the most universal but sadly misunderstood formats in the world.  Currently m2v is more or less the perfect video format.  The Matrox hardware products use Intraframe mpeg2 compression wrapped in a AVI file and those codecs are known to be rock solid.  IMX is known as a very highend solid format that either holds its own or is better then most other tape SD formats.

Of course Mjpeg gets a bad name as well since it is so old and many times it is used badly.  Products use such a watered down hacked form of mjpeg that it ends up looking bad.  If it is used correctly it can be a great format equal to most highend codecs.  One of my favorite formats to use is Quicktime photojpeg at 94% or 100%.  These files are visually lossless to uncompressed at a fraction of the size.

Sadly everyone thinks mpeg2 is an old format which it is but it has many years of life left in it.  There is so much hype over AVC-Intra but in all reality it isn't much different then M2v-Intra.  The name AVC is thrown in to make people think it is a better AVC format.  Once you go Intra based compression all of these formats mostly act like a regular DCT based compression format give or take a few minor differences.  Perhaps AVC-Intra is a smidge better then a M2v_intra format but it isn't worth the extra cost and decompression power needed.  Mpeg2 never got the recognition that it should have.  Pinnacle had enough vision to see how good of a format it really is.  To this day Liquid is still the best m2v based edit system out there.  If you can somehow work in a solid m2v based workflow then Liquid is one heck of a system.  Sadly we never really got any decent options for getting that sort of material into Liquid.  Liquid can edit, render and fuse every form of m2v you can think of but it cannot capture.  Oh well.

For the fun of it Dave compare m2v Intra based at 25 mbits to a DV compressed file and see how much better m2v is.  m2v at 4:2:2 Intra 25 mbits totally blows away DV 4:1:1.  This is the way DV should have been.

The more I look at this, the more I'm thinking I should re-title this thread to "... use I-Frame 4:2:2 MPEG-2". Plus the MPEG-2 does compress to slightly smaller than the DVCPro50.

I did make a 25Mbit CODEC profile but I haven't had a chance to check it out yet.

Dave have you tried my m2v HD presets for Liquid?  They offer the same level of quality for HD material.  300 mbits is the max with mpeg2 and offers the same quality as 50 mbits for SD material.  With HD however the sweet spot hovers around 150 to 200 mbits/s.  300 mbits is a little large even though it is much smaller then uncompressed HD.

 Now if I could only figure out a way to capture into this format.  Liquid would then have a solid intermediate workflow.

 

Of course the only down side to m2v Intra formats is that they are still limited to 8 bit color.  That is not a big deal for Liquid but in the professional world it is looked at as a negative.  Personally I don't think it is a big deal especially if you are already coming from a tape format which all of them are 8 bit including HDCAM.

I've not looked at the presets you made. Like I said, my system is not really good for HD/HDV, and would absolutely choke on HD @ 150+ mbits. I really need to upgrade.