Is it possible to join 2 mp4 files without re-encoding?

[Alberto78]

I want to insert at the beginning of my 4K MP4 movies, is an introductory video (netflix style) possible without re-encoding the whole film?

I've already tried it with mp4 joiner, but it tells me that it takes 4 hours for the operation, which seems absurd ...

thanks to anyone who wants to help me

[smrpix]

Make sure your "Netflix Style" (whatever that means) file has the same parameters as the file you're joing it to.

If it is the files you posted the info in the other day, you have different frame rates and different audio configurations, for starters.

[George53]

I think that's not possible to join 2 mp4 files without re-encoding.You have to first encode.

[jagabo]

It's possible to append the contents of two mp4 videos if the codecs and other properties are the same.

[Budman1]

What you are up against is a difficult process, asked many times with the same answers, in one form or another.

Most times if both videos are re-coded, they probably have the same format and can be joined without much effort and by several different methods/programs.. The problem is they will both lose some quality, depending on how the were encoded, what program did the encoding, and what specifications were used.

The other options is to find the specification of the main film and re-encode the leading(shorter) with those specs. Unfortunately that would require a CLI command line program such as FFMpeg and a sequence which is extremely difficult to create unless you have an automated process such as below. I use the method below and it has worked seamlessly for me so far, at least MP4/AVC (264 codec):

ffmpeg -i "C:\Users\Bud\Documents\Applian\Replay Media Catcher\video.mp4" -vf scale=w=854:h=480:force_original_aspect_ratio=1,pad=854:480:(ow-iw)/2:(oh-ih)/2 -vcodec libx264 -crf 20 -b:v 400K -bufsize:v 400K -r 29.97 -acodec aac -ab 128k -ar 48k -x264-params "ref=1:me=umh:subme=8:psy=1:mixed-refs=0:me-range=16:chroma-me=1:trellis=1:8x8dct=0:cqpfile=0:fast-pskip=1:chroma-qp-offset=-1:threads=12:lookahead-threads=1:sliced-threads=0:nr=0:interlaced=0:bluray-compat=0:stitchable=1:constrained-intra=0:bframes=0:weightp=0:keyint=50:min-keyint=5:scenecut=40:intra-refresh=0:rc-lookahead=50:rc=2pass:mbtree=1:bitrate=400:ratetol=1.0:qcomp=0.60:qpmin=0:qpmax=69:qpstep=4:vbv-maxrate=800:vbv-bufsize=800:nal-hrd=none:filler=0" -max_muxing_queue_size 9999  "C:\Users\Bud\Documents\Applian\Replay Media Catcher\Altered_video.mp4"