If you want it to stay at 480p then that preset is not what you want.
The best way to do this is to first manually change the video mode to one of the SD 16:9 presets before you bring in the video you want to modify. So right after you start Shotcut, go to Video Mode > Non-Broadcast and choose between 854x480 NTSC 16:9 or DVD Widescreen NTSC. Experiment between the two to see which is more suited for you.
Then bring in your video 4:3 video and use the Crop: Source filter to eliminate the black bars and make it fit into the aspect ratio you chose. I know you said that you when used this filter it cut off more than you wanted but that could be because you weren’t setting up your project correct. Try again with my suggestion and see how it goes.
Start with the top and bottom parameters then if you need to do the left and right. Make sure to hover the mouse on where the numbers are in the Crop: Source filter and use the middle mouse button to scroll the numbers with more precision.
At the risk of answering too early, this looks to be doing what I wanted to do. THANK YOU!!! Especially for the clear steps.
I don’t see much difference between the two modes at this point (maybe there are some audio differences I didn’t investigate yet, but 44100kHz, stereo, 128k b/s is all I do anyway).
Crop filter: I was previously using this wrong. Too great of pixel cropping values makes it start reducing video content; it reacted normal with appropriate values. Actually, also previously, I couldn’t see the “Center” checkbox in the dark screen, and using “Center” seems to handle the cropping amount perfectly (manually, I was doing 60/62 on each border and left/right fell into place as expected). I also, now, have a handle on using the up/down keyboard cursor controls at the various areas in the adjustment bars, which has much better control than adjustments by mouse.
In case you were wondering how this video file scenario comes about, I occasionally record a TV show from a Hauppauge USB TV tuner, which receives signal from Dish satellite of a secondary analog output (set for a 4:3 TV and split to the computer USB tuner). This recording comes out on the computer as a .ts file, mpeg2video 720x480 [SAR 8:9 DAR 4:3], 29.97 fps.
Edit: BTW, it seems it is successful in switching the video mode afterward – My first run had all the commercials cut out and other adjustments made, so I gave it a try, and it seems AOK.
The 854x480 NTSC 16:9 preset has a slightly greater width than the DVD Widescreen NTSC preset (854 vs 720). Depending on the image, sometimes one width is better suited than the other. Maybe for this one you can use the DVD Widescreen NTSC preset since the resolution is the same as your source.
It’s still not a good practice to get into. If you switch video modes in the middle of a project, the differences between the aspect ratios, resolutions and frame rates can take the specific cuts and video filters you made and mess them up. In your case, hopefully the switch in Video Modes didn’t mess with the settings you put in Crop: Source.
It’s important to get into the habit of knowing what aspect ratio, resolution and frame rate you want before each project. When you have time, familiarize yourself a bit with all of the presets in Video Mode including the ones in Non-Broadcast just so you have them in mind ahead of time for future projects in case you need any of those presets. Of course, if the aspect ratio, resolution and frame rate you want in your project is already set in at least one of the videos you are going to use in your project then just leave the Video Mode in Automatic and make sure to bring that video in Shotcut first so Shotcut can grab the info and set the project’s Video Mode accordingly.