batch adding logo without reencoding the whole frame area

[dudinka]

Hi!

I have hundreds of (720p) mp4s waiting to get a small logo watermarked at the far corner, for the first 10 secs of each file.
I really want to do it in a batch and most importantly - only reencode the area where the watermark would appear.
Also - reencode only the period where the logo is shown (not that important).
As a note, I'd really like to keep the audio track untouched in the process.

What would be the best way to do it?

thanks for the help!

[poisondeathray]

Not possible ; a permanent logo requires re-encoding the entire video dimensions (width and height) .

But if it's only the 1st 10 seconds, you can split the files at the 10 second mark, re-encode that section (for 10 seconds) and append it back to the main video . However it's often tricky to get the joins working properly... Sometimes there are glitches , or it will not append properly , or the split is not at the exact location (at the nearest keyframe)

But it is possible to retain (copy) the original audio

You might be able to do this with a ffmpeg batch script

[dudinka]

I know I'll have to reencode but I've read somewhere that you can encode only a specific area of a frame.
Isn't it so?

[poisondeathray]

I know I'll have to reencode but I've read somewhere that you can encode only a specific area of a frame.
Isn't it so?

No; you can encode specific entire frames (e.g. from 0 -10 seconds) , but NOT parts of individual frames (like the bottom corner).

[dudinka]

thanks for the help BTW

so to encode only the first 10 secs will require a split?
as for the appending risks, will it be wiser to split at a certain keyframe? (close to the 10 secs period)

[poisondeathray]

thanks for the help BTW

so to encode only the first 10 secs will require a split?
as for the appending risks, will it be wiser to split at a certain keyframe? (close to the 10 secs period)

That's the only way to split and append - at a keyframe. The 1st frame of the "main" section must start with a keyframe. But with many codecs, the keyframe distance might be 0-250 frames apart . (Might be 0-10 seconds accurate for a 25 FPS video)