When I submit my film to a distributor, the system gives an error that I am missing one black frame at the beginning and at the end of the film. I have tried to tpad and other options, which did not work but I thought for sure the concat would work

First I create a solid 3840x2160 black colored png file that had the same 4K UHD HDR format as my mp4 file and saved it as black-frame.png

Followed by using the following to convert it to match the video:
ffmpeg -framerate 23.976 -i black-frame.png -c:v libx265 -x265-params "crf=0:vbv-maxrate=50000:vbv-bufsize=250000:colorprim=bt2020:transfer=smpte2084:colormatrix=bt2020nc:master-display=G(13250,34500)B(7500,3000)R(34000,16000)WP(15635,16450)L(10000000,1):max-cll=475,385:ref=2" -pix_fmt yuv420p10le -vsync 1 -b:v 59.18M black-frame.mp4

In a text file called inputs.txt:
file 'black-frame.mp4'

file 'Not-if-ac3.mp4'

file 'black-frame.mp4'

Then I used the concat command to bring them together:
ffmpeg -f concat -safe 0 -i inputs.txt -c copy Not-if-aac-w-black-frames.mp4

But this reduces the video from an overall bit rate of 59.5 MB/s to 29.5 MB/s and the framerate changed as well from 23.976 to 11.976 - I thought the -c copy was supposed to not change anything in the video quality

I have also tried:
ffmpeg -i Not-if-aac.mp4 -filter_complex "[0:v]tpad=start=1:stop=1:color=black[v]" -map "[v]" -map 0:a? -c:v libx265 -crf 0 -c:a copy Not-if-aac-w-black-frames.mp4

But then it loses it's HDR format and it changes the audio from AC3 to AAC - see second screenshot

Why isn't the "copy" working?

Automated ffmpeg concat scripts fall apart fast when the main character morphs between consecutive five-seconds clips.I am wiring up a local assembly pipeline for a faceless storytelling channel and testing seedance 2.5 through dreamina for the character shots .

The $0.29 first month offer caught my attention, but the bigger issue for this workflow is how many rerolls I would need across twenty scenes before the clips are consistent enough to assemble automatically. To keep those rerolls down, is it better to feed a clean three- angle character sheet into the reference slots or pass the cropped final PNG frame from the previous clip ?

For those using FFmpeg in production, how much of your encoding is still software-based vs hardware-accelerated? We’re NETINT, and every year we run the State of Video Encoding survey. We’re collecting responses for the 2027 edition now, and one of the things we’re looking at is how teams are actually using CPUs, GPUs, VPUs, and other hardware acceleration in their encoding workflows. The survey also covers codecs, encoding ladders, AI in the workflow, and cost per channel. If you’re curious, the 2026 results are public here, no form required:
netint.com/2026-state-of-video-encoding-early-access

A couple of things that stood out last year: H.264 was still in production at 84% of teams, while AV1 was at 17%. We also found that budget and team capacity were reported much more often as barriers than technical issues.

The 2027 survey takes about 10 minutes, and everyone who completes it gets the full report before it’s publicly released. Would be interesting to hear what people here are using too, especially where hardware encoding has or hasn’t made sense in your FFmpeg setup.
netint.biz/encoding-survey