Simple FFMPEG command recently fails most of the time. (yes i know this is not good for repeatability)

[jernhenrik0809]

Hello Rendi

Having a bit of an issue that i hope you can help with

Using below setup in Make, FFMPEG have been able to cut off the first 0.3 seconds off the begining of a video many times.

Without any seeming change, the return from FFMPEG lost the visuals completely and returns a much smaller filesize. (as seen on the second screenshot with 11,2 MB of file transfer).

inspecting the storageURLs in the browser displays a black image, with only the audio remaining.

As mentioned, no changes that i know of have been made to the workflow prior or after it worked.

Your support is much appriciated :)

[yuyuvvall]

Hi 👋

This is a very common and subtle FFmpeg issue when using -ss with -c copy.
That usually works — but only if the seek point falls exactly on a keyframe. If it doesn’t, FFmpeg can’t start decoding from a partial frame

If you need to trim exactly 0.3 seconds from your video i would recommend decode and re-encode the video.
ffmpeg -i \{\{in_1\}\} -ss 3 -c:v libx264 -c:a aac \{\{out_1\}\}

This one will decode from the beginning, ensuring the cut starts exactly at 3.0s and no corrupted frames are created — though it’s slower and re-encodes the video.

You can also check out Rendi’s FFmpeg Cheat Sheet and specifically trim by time section.

— Yuval, Rendi Team 💜

[jernhenrik0809]

Thanks Yuval!

cutting at an exact frame is not a requirement in my case, plus/minus a few handful of frames is unimportant (for this use case).

And maybe reencoding comes with drawbacks?

Could you please recommend a perfered method when precision cutting is not required?

[yuyuvvall]

There are some drawbacks to re-encoding — mainly the extra processing time it adds.

I think the best solution in your case is to use:

ffmpeg -i {{in_1}} -ss 00:00:00.3 -to 10:00:00 {{out_1}}

Notice that I set the end time (-to) to a large value (10 hours) just to ensure it includes the entire remainder of the video after trimming.