@john_dennis are you certain about #1? I'd read it was dependent on file type and mp4 wasn't in the list.

If you used the same render template for each of the three parts.

FFMPEG will join the files without re-encoding

@john_dennis just to confirm, would rendering in VP with Voukoder will really not re-encode those files? With same render template & settings which I've used in rendering all those three parts & apply to the new project for combining them.

@john_dennis are you certain about #1? I'd read it was dependent on file type and mp4 wasn't in the list.

yeah, that's what I know too but asking to be sure & to confirm also, to avoid unnecessary work.

@ram17 @michael-harrison

I'm not absolutely certain about FFMPEG command line joining of MP4. Except for the syntax of the commands, it wouldn't take longer than a file copy to find out.

https://stackoverflow.com/questions/49371422/how-to-merge-two-videos-without-re-encoding

VideoReDo TV Suite uses FFMPEG under the hood and it can join AVC and AAC in an MP4 wrapper without re-encoding every frame (it might encode a few frames at the file boundaries).

@john_dennis are you certain about #1? I'd read it was dependent on file type and mp4 wasn't in the list.

yeah, that's what I know too but asking to be sure & to confirm also, to avoid unnecessary work.

Ffmpeg wiki page for the "concat" demuxer and protocol filters is here. Demuxer requires matching codecs in all clips but the protocol filter apparently does not. They both require all the frame sizes to match. I usually use the protocol one and can verify it works for avc or hevc mp4, mxf, and mov files but I've always done this with the clips from the same camera so everything always matches up. The way I do it is to first create a clip-list of clips in a directory by running a script like this:

(for %%i in (*.mp4) do @echo file '%%i') | sort > mp4_list.txt

I sort them because my camera clips have sequence numbers in the file name but may not appear in that order in the raw windows directory. I often edit the mp4_list.txt output file with notepad if there are any files in the directory I don't want in the list. Then I run this ffmpeg command to join all the clips in the list.

ffmpeg -f concat -i mp4_list.txt -c:v copy -c:a copy -map 0:v:0 -map 0:a:0 mp4_cat.mp4

That command assumes there's one video stream and one audio stream. If there's 2 mono audio streams, you'd probably want to add an additional map command to copy both audio streams or other stuff if you want to join the 2 mono streams into one stereo stream. Mp4_cat.mp4 is the output file.

Thanks Howard.

Out of curiosity, have you checked audio at the places where the concatenations happened?

With all these audio offsets, this might cause some glitches.

Out of curiosity, have you checked audio at the places where the concatenations happened?

With all these audio offsets, this might cause some glitches.

Yup, its ok they're sub-divided neatly. Every parts are different topic so they're separated by titles/intro & fade outs.

You can use the feature Smart Trim of the Vegasaur or Video Redo to do this. See video bellow.

Here's another option--the Happy Otter MP4 File Joiner, a free tool I wrote a couple of years ago. It has four different options for joining files that make use of FFmpeg, MP4Box and Exiftool. The reason for 4 options is that not all footage will work correctly without glitches such as added frames, audio out-of-sync, variable frame rate output, etc. The audio sync issue was one reason for including the option to re-render the audio in Vegas. The user should always be very careful and test the results, regardless of the method used for joining. Here's a screen grab of the UI showing the different joining options.

It can be freely downloaded here. https://tools4vegas.com/library/

Another option to VideReDo is TMPGEnc's MPEG Smart Renderer https://tmpgenc.pegasys-inc.com/en/product/tmsr5.html which also supports joining and smart-rendering of MP4 formats.

I want to use the 3 split parts to join as one to sped up the render.

If that's the only reason, and you still have the original projects, I would combine or nest them and go that route instead.

Otherwise, VideoRedo will re-establish GOP integrity with new IDR frames and resync if necessary. But cocatenated files "usually" play OK.

cocatenated files "usually" play OK.

For paid work I always re-render the whole project in Vegas just to make sure the video does not have glitches at the joints... I guarantee my work, so I don't want to have to fix something on my own time because I trusted an app I am not familiar with... I charge clients a very reasonable "workstation use" fee when they want additional file types in addition to those listed in the original quote, which helps me maintain equipment... Even a lengthy 9 hour 4K project would render-out overnight on my current system & I don't have to waste time learning a new app or double-checking to make sure it didn't mess-up my video...

cocatenated files "usually" play OK.

For paid work I always re-render the whole project in Vegas just to make sure the video does not have glitches at the joints...

I've used a joiner, file had no glitches when played, played fine between joints when played in vegas, but when I uploaded it to youtube, it constantly got stuck, and never uploaded. Was not using a sophisticated joiner like video redo though.