How to hit a file size limit without shortening the video
Give Vizard Agent the size limit and say the length has to stay. It works backwards from the two to find the bitrate available, spends that budget where the picture actually needs it rather than evenly, and measures the finished file against the ceiling instead of assuming the encoder hit the number it was given.
What do you type into Vizard Agent?
Give both numbers together. A size limit on its own invites shortening the video, and a runtime on its own invites ignoring the limit. Stating both makes it clear which variable is left to move, which is the picture quality. Then say what must stay sharp, so Vizard Agent knows where to spend the budget.
Prompt
What does Vizard Agent actually do?
Size divided by length is a bitrate, and every other decision follows from that number: resolution, how much goes to audio, whether the fast sections can afford their detail. Looking at the footage first shows where detail is doing work and where a dark, slow shot can take less without anyone noticing. In the session behind this article it:
- Took the hard size limit and the runtime that had to stay, derived the available bitrate and checked whether it was workable at the requested resolution before encoding anything.
- Looked at the footage to see where detail actually mattered, such as captions, faces and a logo, and gave more of the budget to those sections.
- Set the audio at a deliberate share rather than the default, then encoded the file to the derived target.
- Measured the finished file against the limit, with a re-encode if it overshot, because an encoder given a target bitrate doesn't always deliver a file under it.
- Checked the captions and faces at full size in the result and confirmed the runtime was unchanged.
When does this not work well?
Sometimes the numbers simply don't allow it. A long video at a small limit leaves a bitrate that no allocation Vizard Agent makes can rescue, and then the honest options are a lower resolution, a shorter cut or a bigger limit. High-motion footage costs far more bitrate, fine detail throughout leaves nothing to sacrifice, and lossless requirements aren't compatible with a size cap.
Common questions
Can it keep the length? Yes. Vizard Agent moves picture quality rather than runtime.
What if the numbers do not work? Vizard Agent says so and offers a lower resolution instead.
Will it check the actual file? Yes. Vizard Agent measures it against the limit.