Question 1 - Yes the filesize is based on the output frames making up the 1080 video not the input
Question 2. Makes no difference - the output is based on the chosen output size and framerate
Question 3. Video filesize is based on pixel size in each frame, the amount of change in each frame (i.e. how much compression can be applied, the type of compression applied and the number of frames per second so the same number of slides each played for twice as long will roughly double the size)
Thank you Dave, that is most informative.
May I press the point and ask 2 more?
My slides are static photos, not moving videos. Does Lightroom automatically reduce the frame rate to the duration of the slides (1 every 6 seconds) or does it run on 30 fps or some such thing?
Does either Lightroom or Premier Pro allow be to make a 34-photo slide show at 1080 but at a much reduced file size than my reported 930Meg or is that about par for the course?
Just for you I exported a 34 slide video slideshow from Lightroom.
I used 6 secs per slide and a 1 second crossfade. I used "standard" quality. I did not add any music. I exported at 1080p and opened the file in Premiere Pro to check the format.
The file was at a constant framerate of 29.97 fps and lasted 4 minutes 0 seconds and 22 frames which included a fadeout to black at the end
The size on disk was 417MB.
I repeated the above using a set of slides with more fine detail (lots of trees very little sky) with the same settings as above.
This time the file size was 502MB which was not as big an increase as I expected.
Finally I repeated the last set but changed quality to high. This made no difference at all. The file size was still 502MB. It may make a difference when encoding to say jpeg rather than video - but to video no difference.
You could use Premiere/Adobe Media encoder to encode the file differently but with Lightroom you are limited in the settings you can adjust.
I hope that helps you
Dave, your a star!
Your experiment is much appreciated. It gives me a sense of proportion and saves me from having to do the same thing.
It is a big leaning curve. My 960 Meg mp4 looks great on my 34 Inch monitor running locally from my Surface Pro 2. I uploaded it to my web site, using HTML 5 <Video> as the means of displaying it. Unfortunately it only runs for about every 10 seconds before stopping whilst the data flow catches up. Mozart's "Elvira Madigan" loses is impact when played like that! I am now investigating whether it is my ISP, or the file itself, or my over expectation of HTML <video> or whether the hosting of such a file can only practically done on a specialist site like Vimeo or YouTube.
Just a thought:
If you have access to Premiere Pro - you could export the stills from Lightroom and import then assemble them on the Premiere timeline. You will get a lot more control over the rendering options that way. Given that the stills have been captured at a higher resolution than the required output, you could also add interest by panning and zooming over the stills as the timeline progresses
I did prepare a video in Premier Pro , my one and only attempt so far . I blindly followed through the myriads of setup options of exporting to YouTube without really understanding why the author made is various choices. I shall follow your suggestion and hopefully gain some further insight. I tried Lightroom this time to see if was easy and effective.
I have now uploaded my Adobe Lightroom Slide Show .mp4 file both to my website and to YouTube.
On my web site , the code which places it is (Tags omitted) :-
video width="100%" autoplay
source src= "images/corfu/corfu_VillaGeorge.mp4"
On youtube the video works flawlessly.
On my web site the video hangs every 15 seconds when played on my computer usIng Chrome, and the same happens on my neighbour's using Chrome and with his Firefox, does not get beyond the intro screen. When the tech support of my ISP run it, it works fine on their computers.
I say all this because the moral, for a newbie like me, it seems, is to have faith that your video will work when prepared in Lightroom (which incidentally auto adds pan and zoom very effectively if you wish, and it auto times it to coincide with the length your sound track if you wish) proving you upload it to YouTube.
It would none-the-less be interesting to know why the HTML video code does not work in this instance.