Like RF says, it is the total time of the video that will fit on a DVD or not, the number of photos do not really matter.
I have created slideshows for people of up to 2.5 hours standard definition on a single DVD without too much quality loss, but I do not recommend that. Anything over an hour is going to bore people to death, actually about 20 minutes is best.
You need to keep the photos on screen for at least 6 seconds for people to be able to process them, longer if you want them to actually see the images and even longer if you want to do any pan and zoom. My usual display time for images is at least 8 seconds, if the audience will be older people then I will use 12 seconds or more.
3700 photos times 6 seconds is equal to 370 minutes or almost 31 hours, you can't fit that on a DVD slideshow movie.
If the photos are 1mb each you can barely fit the images on a DVD as just photo files/data as that would be about 3.7 GB of data alone.
100 photos is plenty for any slideshow, just my opinion
Most DVD players will do a slideshow automatically if you put a data disc in the player that has photos on the disc.
The DVD player will display the photos for a length of time and then transition to the next, no need to create a slideshow with software if that is all you want to do. Most DVD players have menu options to set the length of time each photo is displayed among other options.
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