Dafydd B, thanks for your response and help. For the benefit of others who may run into this, here is what I have found.
I have had two problems using PD14: this speed issue, and the seemingly random loss of the sound track, as described in a previous post here:
http://forum.cyberlink.com/forum/posts/list/48662.page#254882
Now I am blaming my camera rather than PD14. I use the camera built into my Samsung Galaxy S6 phone. By all reviews I've read it is a surprisingly good quality camera. However, I first encountered the sound issue right after an update to the phone's Android software. I posted about it on an Android forum but got no responses.
PD has regularly warned me, "Timeline Frame Rate Conflict: The frame rate of the clip you just added to the workspace (29.86 FPS) does not match the project's timeline frame rate set in General preferences (29.97 FPS)." The FPS of the videos coming from my camera are all over the place in those fractions after 29. When I check PD's Preferences Timeline frame rate, it says, "30 FPS (NTSC)". At first I ignored this, because it didn't seem to have any bad effect on the finished product. But when I researched why the setting would say 30 FPS when the program is expecting 29.97, I found a lot of detail that a noob couldn't know without being told. It's more than I can recount here, but if you don't know about it, it's worth researching. A search string like "30 FPS vs 29.97" should get you going.
So my S6 camera is producing videos with a frame rate that varies all over the milliseconds between 29 and 30, and PD14 objects to them. I wondered if this could be the source of my issues. After learning that 29.97 is a standard industry value, I found a program called Handbrake (free open source) which is a video converter. I set it up so that it converts the mp4 videos from my camera to the same thing, mp4's, but sets the FPS to 29.97. Given the choice of Constant Framerate or Peak Framerate, I have always chosen Constant.
I don't know how Handbrake works. I assume it is by duplicating frames to fill the missing slots. Whatever, when I process the mp4's this way and then load the result into PD14 I don't have either of the problems that were plaguing me before.
Is it possible that I'm the only person using an S6 with PD14? That seems so unlikely, but as Dafydd B pointed out, the problems seem to be unique to me. I don't know what to think. I'm just happy that the videos are working in PD14 now.
This message was edited 1 time. Last update was at Aug 01. 2016 14:39