[Ivan Myles]

For this project I was right clicking on the clips in the timeline and changing the “Speed/Duration…”. Is there better way to do this…

There are a few different methods depending on what you are trying to accomplish:

Interpret Footage – always play a source file at a specified frame rate; all clips from the file will play at the new frame rate (unless modified as outlined below)
Speed/Duration – specify a unique frame rate for a clip on a timeline; does not affect other clips from the same source file
Time Remapping – Use keyframes to vary speed at different points within a clip; does not affect other clips from the same source file

…so that I can say like 24fps…

Slowing a clip to 24fps on a 30fps timeline will result in every 5th frame being a repeat:

ABCDDEFGHHIJKLLMNOPP…

This won’t be noticeable in static shots, but high motion and panning shots might appear to stutter. Take a look at creating interpolated frames in After Effects.

…and it will play all the frames at that speed?

Interpret Footage or Speed/Duration will work.

[Ivan Myles]

It is not a playback issue; the choppiness is caused by repeated frames encoded into the export file.

I went through the first ~1000 frames and only noticed an issue with the clip starting at f226. Because the other clips look fine, it does not appear to be an encoder issue. To check, import the H.264 output file into your project and insert it onto the timeline. Compare the repeated frames (e.g. f228-229, f230-231, f233-234) in the H.264 file to the source clip on the timeline. Are the same frames repeated in the original clip on the timeline?

The clip starting at f226 repeats in the following pattern:

ABCCDDEFFGHHIJJKLLMNNOPPQRRSTTU

One out of every three frames is a repeat frame. It looks like Premiere is trying to play a 20fps clip on a 30fps timeline. You said you slowed down the original footage. I think this clip went too far. Verify the source frame rate and make sure the you don’t slow it below 30fps. Otherwise, try using After Effects to create interpolated frames.

[Ivan Myles]

1920 is 47% of 4096, but 1080 is 50% of 2160. So is it 47% or 50% that I should be scaling down to?

– Choose the larger percentage to fill the screen without black bars.
– Use the smaller percentage to maintain the entire clip with black bars.

The best choice will depend on the source footage and the nature of the content. Unless there is vital information along both edges of the 4k footage, I recommend scaling at 50%.

If the 480 footage is not 16:9, the scaling factor will depend on image quality. Enlarging a high bitrate 720×480 anamorphic widescreen clip to 1280×720 will probably be OK, but upscaling compressed 640×480 footage by 200% might be too much.

[Ivan Myles]

First, check whether Frame Blending is turned on/off. Also, does source frame rate = sequence frame rate = exported frame rate?

To determine whether the issue is with the encoder, effects, or other, try exporting a 2-3 second long section of the source file without any effects applied. Import the exported file and compare it to the source clip (a difference matte can be helpful). If everything looks OK, start applying effects to the source clip and exporting new versions as you go. Import the new clips and compare (stack the clips on top of each other in a sequence).

[Ivan Myles]

Right-click the source file in the project panel. Depending on which release of Premiere you are using, look for either “Interpret Footage” or “Modify” as an option in the right-click pop-up menu.

[Ivan Myles]

Which codec(s) did you use? Try exporting QuickTime H.264 with a key frame every 1 frame. QT will have an easier time playing the movie if it is encoded with all I-frames.

[Ivan Myles]

It is not clear to what you are referring. Would you please post a screen grab?

[Ivan Myles]

“I was trying to do the same process but interpret that section on the clip to 25fps.”

If you prefer to Interpret Footage, import a second instance of the source file and change the frame rate to 25fps.

“Does time remapping change the speeds or the framerates??”

The parameter for Time Remapping is “Speed” expressed as a percentage. Premiere Pro multiplies the Speed setting by frame rate to determine how the clip will play.

[Ivan Myles]

Use time remapping to have one clip play at different speeds. The Speed/Duration… function adjusts the speed of an entire clip.

tv.adobe.com: Time remapping
help.adobe.com: Duration and speed

[Ivan Myles]

What is the aspect ratio for the file as shown under “Interpret Footage”? What is the aspect ratio of the sequence?