ffmpeg -f h264 -i input.trec -c copy output.mp4 Some older .TREC files are actually renamed .mov or .mp4 . Try:
ffmpeg -f h264 -framerate 30 -i input.trec -c:v libx264 -pix_fmt yuv420p output.mp4 If it's Motion JPEG: .trec video
ffmpeg -i input.trec -c copy output.mp4 If that fails, try forcing demuxer: ffmpeg -f h264 -i input