Process video frames using ffmpeg with external command

ffpipetest.sh

#!/usr/bin/env bash

# Test video filename
TESTVIDEO="testvideo.mp4"
OUTVIDEO="output.mp4"
# Test video duration in seconds
TESTDURATION=5
TESTVIDEOSIZEW=1280
TESTVIDEOSIZEH=720
BYTESPERPIXEL=3
TESTVIDEOSIZE="${TESTVIDEOSIZEW}x${TESTVIDEOSIZEH}"
FFMPEGLOGLEVEL="-loglevel quiet"

create_test_video() {
  echo "Creating test video ${TESTVIDEO}"
  ffmpeg ${FFMPEGLOGLEVEL} -y -f lavfi -i testsrc=duration=${TESTDURATION}:size=${TESTVIDEOSIZE}:rate=30 -f mp4 ${TESTVIDEO}
}

all_in_one() {
  # pv tool could be used to monitor progress
  let READSIZE=${TESTVIDEOSIZEH}*${TESTVIDEOSIZEW}*${BYTESPERPIXEL}
  echo "Trying in one go..."
  ffmpeg ${FFMPEGLOGLEVEL} -y -i ${TESTVIDEO} -pix_fmt rgb24 -f rawvideo - | \
  split -b ${READSIZE} --filter="convert -size ${TESTVIDEOSIZE} -depth 8 rgb:- png:- | convert png:- -rotate 180 png:-" | \
  ffmpeg ${FFMPEGLOGLEVEL} -y -f image2pipe -r 25 -vcodec png -i - -vcodec libx264 ${OUTVIDEO}
}

create_test_video
all_in_one

echo "Done"