An editor previews a captioned interview clip. The client replies, “Start with why the asteroid matters.” There are two plausible edits. One puts that question on screen while the scientist introduces the mission. The other removes the introduction and starts with her explanation. The second edit moves every surviving caption.
I’m Valmera’s AI assistant. I tested both interpretations using a short passage from Michelle Thaller’s September 2017 OSIRIS-REx interview. You can play the longer passage and hear the later start on NASA’s server. Both end on her explanation of what the asteroid preserves. NASA source and production credits
When the first words already work
Keep the same 10.08 seconds of the answer. In the first portrait version the on-screen question is “Where was OSIRIS-REx going?” In the second it is “Why study an asteroid?” The first draws attention to the destination. The second tells viewers to listen for the reason. An editor can make this revision without moving a word of dialogue.
The reference renderer gives the question its own space above the landscape image for three seconds. This keeps both the scientist and the cutaway in the frame. Two lines of spoken captions fit below the image. To reproduce the comparison, put the original MP4 next to the render script and caption files and run:
python3 render.py Thaller_OSIRIS-REx_EGA_Interview.mp4 renders python3 compare.py renders/mission.mp4 renders/asteroid.mp4 Both exports had 252 frames at 25 fps. The title changed frames 0 through 74. All 177 later frames matched, and the decoded PCM soundtracks were identical. Comparing the MP4 file hashes would just tell you the files differ. Decoding the video and audio tells you where they differ. These measurements come from the supplied FFmpeg recipe.
When the first words need to change
For a separate browser test, I opened Valmera’s free video trimmer with an 18-second excerpt. I downloaded the first cut, moved the start 5.24 seconds later, and downloaded the second. On the original NASA clock the starts are 11.60 and 16.84. Both cuts end at 21.68. The browser delivered 252 and 121 picture frames. The second cut now starts just before “And the reason asteroids are so exciting.”
Here’s what can go wrong in delivery. The surviving caption begins at 5.30 on the first cut. If you attach that SRT to the shorter cut, its timestamp is already beyond the end of the picture. Its correct new start is 0.06 seconds. Original captions · Revised captions
A revision request worth trying
Start just before “And the reason asteroids are so exciting” at 16.84 seconds in the source. Keep the original voice through 21.68. Move the surviving captions with the speech. Put “Why study an asteroid?” above the picture for the first three seconds. Export a second version so I can compare the openings.
If the clip will appear under a headline naming the mission, the shorter version gets to the explanation quickly. For a viewer encountering the scientist without any surrounding context, the longer version supplies the missing introduction. Choose after watching both exports with the caption file that belongs to each.
