How to concatenate two MP4 files using FFmpeg?

Question

I'm trying to concatenate two mp4 files using ffmpeg. I need this to be an automatic process hence why I chose ffmpeg. I'm converting the two files into .ts files and then concatenating them and then trying to encode that concated .ts file. The files are h264 and aac encoded and I'm hoping to keep the quality the same or as close to original as possible.

ffmpeg -i part1.mp4 -vcodec copy -vbsf h264_mp4toannexb -acodec copy part1.ts
ffmpeg -i part2.mp4 -vcodec copy -vbsf h264_mp4toannexb -acodec copy part2.ts
cat part1.ts part2.ts > parts.ts
ffmpeg -y -i parts.ts -acodec copy -ar 44100 -ab 96k -coder ac -vbsf h264_mp4toannexb parts.mp4

Unfortunately I'm getting the following error message coming back from ffmpeg during encoding:

[h264 @ 0x1012600]sps_id out of range
[h264 @ 0x1012600]non-existing SPS 0 referenced in buffering period
[h264 @ 0x1012600]sps_id out of range
[h264 @ 0x1012600]non-existing SPS 0 referenced in buffering period
[NULL @ 0x101d600]error, non monotone timestamps 13779431 >= 13779431kbits/s    
av_interleaved_write_frame(): Error while opening file

This happens about half way through encoding which makes me think that you can't concat two .ts files together and have it work.

Answer 1

FFmpeg has three concatenation methods.

1. concat video filter

ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv \
  -filter_complex "[0:v] [0:a] [1:v] [1:a] [2:v] [2:a] concat=n=3:v=1:a=1 [v] [a]" \
  -map "[v]" -map "[a]" output.mkv

Note that this method performs a re-encode.

2. concat demuxer

$ cat mylist.txt
file '/path/to/file1'
file '/path/to/file2'
file '/path/to/file3'

$ ffmpeg -f concat -i mylist.txt -c copy output

for Windows:

(echo file 'first file.mp4' & echo file 'second file.mp4' )>list.txt
ffmpeg -safe 0 -f concat -i list.txt -c copy output.mp4

3. concat protocol

ffmpeg -i "concat:input1|input2" -codec copy output

This method does not work for many formats, including MP4, due to the nature of these formats and the simplistic concatenation performed by this method.

Which one to use

• concat filter: Use if your inputs do not have the same parameters (width, height, etc), or are not the same formats/codecs, or if you want to perform any filtering. (You could re-encode just the inputs that don't match so they share the same codec and other parameters, then use the concat demuxer to avoid re-encoding the other inputs).

• concat demuxer: Use when you want to avoid a re-encode and your format does not support file level concatenation (most files used by general users do not support file level concatenation).

• concat protocol: Use with formats that support file level concatenation (MPEG-1, MPEG-2 PS, DV). Do not use with MP4.

If in doubt try the concat demuxer.

Also see

• FFmpeg FAQ: How can I join video files?
• FFmpeg Wiki: How to concatenate (join, merge) media files

Answer 2

Here's a fast (takes less than 1 minute) and lossless way to do this without needing intermediate files:-

ls Movie_Part_1.mp4 Movie_Part_2.mp4 | perl -ne 'print "file $_"' | ffmpeg -f concat -i - -c copy Movie_Joined.mp4

The "ls" contains the files to join The "perl" creates the concatenation file on-the-fly into a pipe The "-i -" part tells ffmpeg to read from the pipe

(note - my files had no spaces or weird stuff in them - you'll need appropriate shell-escaping if you want to do this idea with "hard" files).

Answer 3

I ended up using mpg as the intermediate format and it worked (NOTE this is a dangerous example, -qscale 0 will re-encode the video...)

ffmpeg -i 1.mp4 -qscale 0 1.mpg
ffmpeg -i 2.mp4 -qscale 0 2.mpg
cat 1.mpg 2.mpg | ffmpeg -f mpeg -i - -qscale 0 -vcodec mpeg4 output.mp4

Answer 4

for MP4 files:

If they are not exactly same (100% same codec, same resolution, same type) MP4 files, then you have to trans-code them into intermediate streams at first:

ffmpeg -i myfile1.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts temp1.ts
ffmpeg -i myfile2.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts temp2.ts
// now join
ffmpeg -i "concat:temp1.ts|temp2.ts" -c copy -bsf:a aac_adtstoasc output.mp4

Result: Output will behave like first file ( and not a second one)

Answer 5

I was trying to concatenate three .mp3 audio files into one .m4a file and this ffmpeg command works.

Input command:

ffmpeg -i input1.mp3 -i input2.mp3 -i input3.mp3 -filter_complex concat=n=3:v=0:a=1 -f MOV -vn -y input.m4a

Meanings of : " -filter_complex concat=n=3:v=0:a=1" :

concat means use the media concatenate (joining) function.
n means confirm total count of input files.
v means has video? use 0 = no video, 1 = contains video.
a means has audio? use 0 = no audio, 1 = contain audio.
-f means force set file format (to see all supported formats, use ffmpeg -formats)
-vn means disable video (and also -an would disable audio if not wanted)
-y means overwrite output files (if the output file already exists).

For more info: use ffmpeg -h full print all options (including all format and codec specific options, very long)

Answer 6

FOR MP4 FILES

For .mp4 files (which I obtained from DailyMotion.com: a 50 minute tv episode, downloadable only in three parts, as three .mp4 video files) the following was an effective solution for Windows 7, and does NOT involve re-encoding the files.

I renamed the files (as file1.mp4, file2.mp4, file3.mp4) such that the parts were in the correct order for viewing the complete tv episode.

Then I created a simple batch file (concat.bat), with the following contents:

:: Create File List
echo file file1.mp4 >  mylist.txt 
echo file file2.mp4 >> mylist.txt
echo file file3.mp4 >> mylist.txt

:: Concatenate Files
ffmpeg -f concat -i mylist.txt -c copy output.mp4

The batch file, and ffmpeg.exe, must both be put in the same folder as the .mp4 files to be joined. Then run the batch file. It will typically take less than ten seconds to run.

Answer 7

Detailed documentation on various ways of concatenation in ffmpeg can be found here.

You can use 'Concat filter' for quick concatenation.

It performs a re-encode. This option is best when inputs have different video/audio formats.

For Concatenating 2 files:

ffmpeg -i input1.mp4 -i input2.webm \
-filter_complex "[0:v:0] [0:a:0] [1:v:0] [1:a:0] concat=n=2:v=1:a=1 [v] [a]" \
-map "[v]" -map "[a]" output.mp4

---

For Concatenating 3 files:

ffmpeg -i input1.mp4 -i input2.webm -i input3.mp4 \
-filter_complex "[0:v:0] [0:a:0] [1:v:0] [1:a:0] [2:v:0] [2:a:0] concat=n=3:v=1:a=1 [v] [a]" \
-map "[v]" -map "[a]" output.mp4

This works for same as well as multiple input file types.

Answer 8

Here is a script I made to concatenate several GoPro mp4's into a 720p mp4. Hope it's of help.

#!/bin/sh
cmd="( "
for i; do
    cmd="${cmd}ffmpeg -i $i -ab 256000 -vb 10000000 -mbd rd -trellis 2 -cmp 2 -subcmp 2 -g 100 -f mpeg -; "
done
cmd="${cmd} ) | ffmpeg -i - -vb 10000000 -ab 256000 -s 1280x720 -y out-`date +%F-%H%M.%S`.mp4"
echo "${cmd}"
eval ${cmd}

Answer 9

based on rogerdpack's and Ed999's responses, I've created my .sh version

#!/bin/bash

[ -e list.txt ] && rm list.txt
for f in *.mp4
do
   echo "file $f" >> list.txt
done

ffmpeg -f concat -i list.txt -c copy joined-out.mp4 && rm list.txt

it joins all the *.mp4 files in current folder into joined-out.mp4

tested on mac.

resulting filesize is exact sum of my 60 tested files. Should not be any loss. Just what I needed

Answer 10

ffmpeg \
  -i input_1.mp4 \
  -i input_2.mp4 \
  -filter_complex '[0:v]pad=iw*2:ih[int];[int][1:v]overlay=W/2:0[vid]' \
  -map [vid] \
  -c:v libx264 \
  -crf 23 \
  -preset veryfast \
  output.mp4

Answer 11

Merging all mp4 files from current directory

I personnaly like not creating external file that I have to delete afterwards, so my solution was following which includes files numbering listing (like file_1_name, file_2_name, file_10_name, file_20_name, file_100_name, ...)

#!/bin/bash
filesList=""
for file in $(ls -1v *.mp4);do #lists even numbered file
    filesList="${filesList}${file}|"
done
filesList=${filesList%?} # removes trailing pipe
ffmpeg -i "concat:$filesList" -c copy $(date +%Y%m%d_%H%M%S)_merged.mp4

Answer 12

this worked for me (on windows)

ffmpeg -i "concat:input1|input2" -codec copy output

in particular

ffmpeg -i "concat:01.mp4|02.mp4" -codec copy output.mp4

Python

Using some python code to do it with as many mp4 there are in a folder import glob import os

stringa = ""
for f in glob.glob("*.mp4"):
    stringa += f + "|"

os.system("ffmpeg -i \"concat:" + stringa + "\" -codec copy output.mp4")

Answer 13

From the documentation here: https://trac.ffmpeg.org/wiki/Concatenate

If you have MP4 files, these could be losslessly concatenated by first transcoding them to MPEG-2 transport streams. With H.264 video and AAC audio, the following can be used:

ffmpeg -i input1.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts intermediate1.ts
ffmpeg -i input2.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts intermediate2.ts
ffmpeg -i "concat:intermediate1.ts|intermediate2.ts" -c copy -bsf:a aac_adtstoasc output.mp4

This approach works on all platforms.

I needed the ability to encapsulate this in a cross platform script, so I used fluent-ffmpeg and came up with the following solution:

const unlink = path =>
  new Promise((resolve, reject) =>
    fs.unlink(path, err => (err ? reject(err) : resolve()))
  )

const createIntermediate = file =>
  new Promise((resolve, reject) => {
    const out = `${Math.random()
      .toString(13)
      .slice(2)}.ts`

    ffmpeg(file)
      .outputOptions('-c', 'copy', '-bsf:v', 'h264_mp4toannexb', '-f', 'mpegts')
      .output(out)
      .on('end', () => resolve(out))
      .on('error', reject)
      .run()
  })

const concat = async (files, output) => {
  const names = await Promise.all(files.map(createIntermediate))
  const namesString = names.join('|')

  await new Promise((resolve, reject) =>
    ffmpeg(`concat:${namesString}`)
      .outputOptions('-c', 'copy', '-bsf:a', 'aac_adtstoasc')
      .output(output)
      .on('end', resolve)
      .on('error', reject)
      .run()
  )

  names.map(unlink)
}

concat(['file1.mp4', 'file2.mp4', 'file3.mp4'], 'output.mp4').then(() =>
  console.log('done!')
)