best free option to edit (cut+join) and re-encode webinar video

[Alex1st]

Hi All!

I have webinar video in several mp4 files recorded by OBS studio,
sometimes it may be the case that those files have different bitrates.

What is the best free option to edit (cut+join) those files, preferrably without re-encoding?

If none - what is recommended settings for adobe premiere elements export?
tried mp4 5 mbps for 1280*720 picture and got result 5 times larger (in gigabytes) than source files!

Is there a more efficient way to keep webinars (i.e. VERY slowly changing on-screen presentation with voiceover) than h264?

Thanks!

[abolibibelot]

I don't think that the different bitrates are a problem when it comes to joining clips (and those are usually average bitrates so the actual bitrate varies constantly anyway). What would be problematic would be different resolutions, or framerates, potentially different encoding settings like the profile or the number of reference frames (but not sure about that).

Avidemux could work. If there are issues with Avidemux (audio / video synchronization for instance), mp4box or ffmpeg should work better, but those are command line tools, which means no preview, and the cuts would be less accurate (both accept trimming times in seconds, whereas Avidemux allows to cut losslessly on any key frame). A workaround would be to cut individual clips in Avidemux, export them in “copy” mode, then join them with a mp4box or ffmpeg command.

Of course is the source is 1mbps the output bitrate is set to 5mbps, the output will be 5 times larger. (And 5 times larger is 5 times larger regardless of the unit !) Better choose a quality based setting (if re-encoding is required). If no quality based setting is available in Adobe Premiere Elements (which would be suprising although not impossible), to get an efficient compression and reduce quality loss you woud have to do the export in a lossless format, then encode this with x264 (or anything that relies on x264 under the hood) with the CRF parameter set between 18 and 22 (the lower the number, the higher the quality, and the bitrate, and the file size, all else being equal).

I don't know how newer codecs like H.265 fare compared with H.264 when it comes to encoding mostly static contents. There are specific settings which could improve the compression efficiency (with the risk of reducing the compatibility with standalone devices), although I wouldn't feel confident enough on the subject to give precise recommendations.