Quality counts

[LumenLux]

If I have good digital (mini dv) video that I want to combine in a presentation with good still photos (not from video camera), what is best way to do so and maintain visual quality of both?

The presentation will be shown on likely 8 to 12 foot screen. Is it best to use a video format that then includes a DVD output from PTE? Or is it best to include the video footage into a PTE sequence?

[MikeL117]

Hi

A lot depends on what budget you have. If, like most of us, your budget is severly limited you are going to have to compromise. For a slik presentation then combining both on a DVD is a good way. This will mean reducing the quality of both video and stills.

Another way would be to capture the video as an AVI or MOV file and use one of Granot's utilities to switch between them in the computer. This is probably the most cost effective method with little drop in quality of video and none of stills.

There are several pieces of software/hardware that will switch between sources some of them (the more expensive!) will do so smoothly even using a transition. The projector should be able to do this and the switch may be acceptable. Try it.

As a last ditch, desparate measure there is always PowerPoint . Crude, slow but effective.

Hope this is of some help.

[LumenLux]

Thank you Mike for your thoughts. It looks like I have been negligent in responding and further discussion. I have concluded for this particular situation, I am going to yield my love for PTE features and quality and let my video friend be the driver. We are going to do a video (for DVD) that will use the video editing software and just insert my still shots in the video editor.

With that apparent conclusion, my question is now - What is optimum size of each still photo file that will be used in the video. What dimensions 1024x768 or ? The dvd will be projected with a projector resolution of at least 1024x768 (maybe greater.) Is there any to worry at all about total file size (mb's.)? In a little trial run, using the video editing software on a Mac G5 with LCD screen, some of the stills had very bad quivering/twinkling effects. I don't know if it was worse when using the Ken Burns effect which video people seem so hooked on. But I am wondering if the still photo dimensions are bigger than needed, can that actually downgrade the visual quality. In other words, if 1024x 768 is the right size for the screen/projector, is it detrimental to use the original file at 2816x2112? Could such extra size be making the twinkling jiggles worse?

I've let this go too long so am now in urgent mode. So any thoughts will be very welcome.

[MikeL117]

Hi Again

These things do tend to creep up on one and suddenly turn into a panic.

There is a fairly comprehensive answer in the recent post started by Barry Beckham DVD quality http://www.picturestoexe.com/forums//index...&f=2&t=2819&hl=

A simple® answer:

Flickering is almost inevitable with sharp detailed stills because of the interlacing in normal video and the only way to avoid it is to soften any fine detail particularly horizontal (or near horizontal) lines or to use a format that is not interlaced.

I am not sure from whence you hail, but will assume from the time difference that you are using NTSC video.

That resolution of the projector is, to be frank, wasted if all you are doing is giving it video to eat. The best you will get from NTSC DVD is 720 x 480 pixels with the vertical information being displayed as two sequential 240 pixel interlaced fields. Regardless of the resolution of the projector you will not get any more information out than that.

Yes, giving the video editing software too big an image is rarely a good idea as it has to throw away the extra information and it may not do as good a job as Photoshop and its ilk AND it has to do it for every frame which is quite a burden on the processor. For incorporating the still into the video you are best to resize and crop it to the final size used in the video (make sure to allow for the pixel aspect ratio if you want to eliminate any distortions – Photoshop CS can do this for you{most people will not notice if you do not do this}). Take great care with sharpening as this can increase the flicker (it may be best to soften a little). For full screen stills the size should be 720x480 with a pixel aspect ratio of 0.9. For any zoom or pans make then the largest size that you need and hope the video editing software (never used the Mac versions) will use all the pixels you give it. It may be worth having the editor apply a little blur during the move to again reduce the flicker which is likely to be worse than when still. You will need to experiment somewhat to find the best degree of softening and positioning (sometimes nudging the image up or down by one pixel can reduce the apparent flicker).

As I mentioned in the other post if you can use a computer to drive the projector you could convert to a non-interlaced format and, depending on the power of the computer, up-scale it to better make use of the available resolution of the projector. In this case the video is not likely to be improved (if the de-interlacer used is not a good one it could make it look a little worse) but the quality of the stills would be enormously better with no flicker.

Final file size of the edited video is irrelevant as long as the total playing time is less than two hours it will be squashed onto a 4.7GB DVD.

Hope these pointers are of use. Getting the best out of video is still a black art. When it works it can be very effective, when it goes wrong…

If I can help further, don't hesitate

[LumenLux]

Mike - Thank you for an excellent, well written answer. The information is very helpful.

On the thought of using the computer to drive the projector -

At this point I am sure we want the "slides" to be interspersed periodically throughout the video. We could certainly have a laptop send the show to the projector instead of a DVD player to the projector. But is there a way to directly use the final edited video (including slides) without the show being put first onto DVD? And if there is, would it show better quality slides, or is the damage totally done once the slides are inserted into the video editor and thus become "video" themselves?

Another option? Would we get any better quality for the final video if we saved it back to mini dv camera tape instead of onto DVD? (Using always the same projector.)

Thank you for your timely help. Yes, time stamp is correct if it is -7. I am in Salt Lake City, Utah amid the desert and the mountains.

[MikeL117]

Yes, you are correct, the quality will be better if you save back to DV rather than transcoding to DVD. That is going to be the best quality you can get from the video (as it should not be re-compressed except for the modified parts). Unfortunately this will not give a significant improvement in the quality of the stills and offers no improvement to the flicker.

As for permanent damage to the slides, a lot depends on the capabilities of the video editing software. I believe that Final Cut Pro, which is one of the standard video packages for a Mac, is quite advanced and capable. So I suspect that you should be able to generate a non-interlaced and, posssibly, higher resolution version without the flicker and a good compromise between video and stills.

There are video packages that are restricted to editing DV and if this is what you have to use you may not be able to better the quality. If not try to render a short sequence with video and stills at various sizes and with different codecs and see what the laptop is capable of showing reliably. I would suggest you try MPEG2, Quicktime MPEG4 and Sorensen. This part may require several attempts before you get a suitable solution(if you are resizing up remember to keep the pixel resolution divizable by 16). You want a file that is not too compressed to show the compression artifacts but not so big that it can't be retrieved from the hard disk fast enough (laptops have slow hard disks). The higher the resolution the better the stills but this means bigger files or more compression. Another thing to juggle with is the MPEG codecs are very complex at decompression time so they also require a lot of computer power. If all you manage to do is to de-interlace the final movie you will have removed the flicker which means you do not have to soften the stills to make them watchable. I tend to use MPEG4 a lot for non-standard size video and even at highest quality it seems to play very well on computer as long as the image size is not too great (I am working on a presentation that is 2048x1024 and I haven't got that to play smoothly yet ).

Good Luck and let me know if I can shed any more light. When is the presentation?

I am amidst the rain (but not today) and the Pennine Hills .

[LumenLux]

Once again Mike, you are great.

The presentation is Saturday 2/26. Bid proposals provide either 2 screens 10.5ft x 14.0 ft or one screen 12 x 16 ft. Projectors two @ 3700 lumen, or for single screen, one 6500 lumen.

Right now I must devote further time to presentation content, so I likely won't be barraging you with more tech questions tonight.

Indeed thank you.

[MikeL117]

Same time scale as myself.

Two 4500 SXGA projectors 5.5m x 2.5m screen, back projection. Live performance on stage in front of it.

Good Luck it is going to be a long week .

I shall check in each day, let me know how you go on, if you have time. If I can be of further help... email me if it is urgent.

[ronwil]

Mike

I notice you refer to back projection. I have had the occasion to do this for an AV Festival and had to advise the authors of each sequence to bulk flip the images at the *.pte stage by using Irfanview.

Ron [uK]

[MikeL117]

Hi Ron

Most modern projectors will now flip (and/or invert) the image to allow back projection (and ceiling mounting) without changing the presentation content. Any projector that was not capable of this feature I would consider inadequate for general presentation use.

[ronwil]

Mike

If what you are saying is that you can horizontally flip the whole of a *.exe presentation with most modern digital projectors, can someone tell me please if and how you can do this on a Plus U3-1080 Digital Projector. Thanks.

Ron [uK]

[Ian]

Hi Ron

If you call up the on-screen menu, there is an option in the "View" setup to change from the default "normal" setting to either vertical flip, horizontal flip or both.

Its on page 21 of the manual item B-29

Ian

[ronwil]

Thanks Ian

To think of all the trouble I went to last year doing all the digital projection for South London AV Championships. I must get some fresh batteries for the remote control unit. For my normal presentations I use a radio controlled keyboard and mouse.

Regards

Ron [uK]