diff --git a/Av1an/concat.py b/Av1an/concat.py
new file mode 100644
index 0000000..464c87d
--- /dev/null
+++ b/Av1an/concat.py
@@ -0,0 +1,87 @@
+import subprocess
+import sys
+from subprocess import PIPE, STDOUT
+from pathlib import Path
+
+from Av1an.arg_parse import Args
+from Av1an.logger import log
+from Av1an.utils import terminate
+
+
+def concat_routine(args: Args):
+    """
+    Runs the concatenation routine with args
+
+    :param args: the Args
+    :return: None
+    """
+    try:
+        if args.encoder == 'vvc':
+            vvc_concat(args.temp, args.output_file.with_suffix('.h266'))
+        else:
+            concatenate_video(args.temp, args.output_file, args.encoder)
+    except Exception as e:
+        _, _, exc_tb = sys.exc_info()
+        print(f'Concatenation failed, FFmpeg error\nAt line: {exc_tb.tb_lineno}\nError:{str(e)}')
+        log(f'Concatenation failed, aborting, error: {e}\n')
+        terminate()
+
+
+def vvc_concat(temp: Path, output: Path):
+    """
+    Concatenates vvc files
+
+    :param temp: the temp directory
+    :param output: the output video
+    :return: None
+    """
+    encode_files = sorted((temp / 'encode').iterdir())
+    bitstreams = [x.as_posix() for x in encode_files]
+    bitstreams = ' '.join(bitstreams)
+    cmd = f'vvc_concat  {bitstreams} {output.as_posix()}'
+
+    output = subprocess.run(cmd, shell=True)
+
+
+def concatenate_video(temp: Path, output, encoder: str):
+    """
+    Uses ffmpeg to concatenate encoded segments into the final file
+
+    :param temp: the temp directory
+    :param output: the final output file
+    :param encoder: the encoder
+    :return: None
+    """
+    """With FFMPEG concatenate encoded segments into final file."""
+
+    log('Concatenating\n')
+
+    with open(f'{temp / "concat" }', 'w') as f:
+
+        encode_files = sorted((temp / 'encode').iterdir())
+        # Replace all the ' with '/'' so ffmpeg can read the path correctly
+        f.writelines("file '" + str(file.absolute()).replace('\'','\'\\\'\'') + "'\n" for file in encode_files)
+
+    # Add the audio file if one was extracted from the input
+    audio_file = temp / "audio.mkv"
+    if audio_file.exists():
+        audio = f'-i {audio_file} -c:a copy -map 1'
+    else:
+        audio = ''
+
+    if encoder == 'x265':
+
+        cmd = f' ffmpeg -y -fflags +genpts  -hide_banner -loglevel error -f concat -safe 0 -i {temp / "concat"} ' \
+            f'{audio} -c copy -movflags frag_keyframe+empty_moov -map 0  -f mp4 - | ffmpeg -y -hide_banner -loglevel error -i - -c copy {output} '
+        concat = subprocess.run(cmd, shell=True, stdout=PIPE, stderr=STDOUT).stdout
+
+    else:
+        cmd = f' ffmpeg -y -hide_banner -loglevel error -f concat -safe 0 -i {temp / "concat"} ' \
+            f'{audio} -c copy -map 0  -y "{output}"'
+
+        concat = subprocess.run(cmd, shell=True, stdout=PIPE, stderr=STDOUT).stdout
+
+    if len(concat) > 0:
+        log(concat.decode())
+        print(concat.decode())
+        raise Exception