How to concatenate 2 MP4 videos to output of certain bitrate? I've already read the other articles about concatenating but couldn't find any that discuss specifying the output bitrate.

I have 2 MP4 videos. 

What I want to do is speed up the first video to 110% speed (without changing audio pitch) and then concatenate it with the second video (which will remain at normal speed), and I want the resulting video to have a bitrate of 2.5 Mbps (since that's what Wistia told me should be the minimum for my upload).

Currently, my first attempt results in a video where the 2nd part is all mangled and shows bright green, etc. My second attempt (of Step 4) results in a video that has a total bitrate of only 1645kbps.

Step 1:

In Adobe Premiere Pro CC 2017, I've exported 2 videos, each using these settings:

Frame Rate: 30
Field Order: Progressive
Aspect: Square Pixels (1.0)
Profile: Main
Bitrate Encoding: CBR
Target Bitrate [Mbps]: 2.5
Audio Format: AAC
Audio Codec: AAC
Sample Rate: 48000 Hz
Bitrate [kbps]: 320


Step 2.

ffmpeg -i video1.mp4 -filter_complex "setpts=PTS/1.1;atempo=1.1" -c:v libx264 -x264-params "nal-hrd=cbr" -b:v 2.5M -minrate 2.5M -maxrate 2.5M -bufsize 5M video1_faster.mp4


Step 3.
Create a text file of this content:

file 'video1_faster.mp4'
file 'video2.mp4'


Step 4 (first attempt).

ffmpeg -f concat -safe 0 -i ffmpeg_concat_list.txt -c copy final.mp4


Step 4 (second attempt) (with re-encoding).

ffmpeg -i video1_faster.mp4 -i video2.mp4 -filter_complex "[0:v] [0:a] [1:v] [1:a] concat=n=2:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" -b:v 2.5M -minrate 2.5M -maxrate 2.5M -bufsize 5M final.mp4


What am I doing wrong? Thanks.
Step 4 (first attempt) will work if you re-encode the 2nd video like the first (without the filters).

What's happening is that besides the timescale difference between CC's output and ffmpeg's (which will only result in timing errors), x264 is producing a High profile stream with a different parameter set than CC's encoder. Re-encode the 2nd video with ffmpeg and your files should be matching. Alternatively, you can speed up in CC and export the 1st video.