FFmpeg - Concatenate MP4 Files - Revision history

Dex at 14:36, 14 March 2026

2026-03-14T14:36:55Z

← Older revision		Revision as of 14:36, 14 March 2026
Line 1:		Line 1:
	[[Category:FFmpeg]]		[[Category:FFmpeg]]
	[[Category:MP4]]		[[Category:MP4]]
	Concatenating ~~video~~ files in FFmpeg can be ~~achieved in several ways, depending on your input formats~~, ~~codecs~~, and ~~whether you want to avoid re‑encoding~~. This article explains ~~the three official FFmpeg concatenation methods,~~ when to use each ~~one~~, and common pitfalls.		Concatenating MP4 files in FFmpeg can be done using three official methods. Each method behaves differently, has different requirements, and supports different levels of compatibility. This article explains when to use each method, how they work, and common pitfalls to avoid—especially when working with MP4, which is strict about matching codecs and container metadata.

	== 1. concat Video Filter ==		== 1. concat Video Filter ==
	~~Use this method when:~~		The concat filter works at the decoded‑frame level. FFmpeg fully decodes each input, merges the streams, and then re‑encodes the result.
	* Your inputs do not share the ~~same properties (resolution, frame rate, codec)~~.
	* You want to apply filters, ~~scaling~~, ~~or other transformations.~~
	* You are comfortable with a full re‑encode of all inputs.

	Because the filter merges ~~decoded streams~~, ~~FFmpeg must re‑encode everything~~.		=== Use this method when: ===
			* Your input files do not match (resolution, codec, bitrate, frame rate, audio layout).
			* You need to apply filters, scaling, overlays, trimming, or processing.
			* A full re‑encode is acceptable or required.

			Because the filter merges raw audio and video frames, re‑encoding is mandatory.

	=== Example: Concatenating Three Clips ===		=== Example: Concatenating Three Clips ===
	~~<pre>~~		```
	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		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
	~~</pre>~~		```

	== Notes ==		=== Notes ===
	* ~~Ideal for complicated workflows~~ or ~~mismatched~~ sources.		* Most flexible method; works with mismatched or problematic sources.
	* If you want to avoid ~~full~~ re‑encode, ~~pre‑normalise~~ the ~~odd~~ inputs first, then use the concat demuxer.		* If you want to avoid re‑encode, normalise the inputs first, then use the concat demuxer.

	== 2. concat Demuxer ==		== 2. concat Demuxer ==
	~~Use this method when you want to avoid re‑encoding and your formats support stream copying. This~~ is the recommended method ~~for MP4 as long as the~~ files are perfectly matching (~~same~~ codec, profile, level, frame rate, resolution, audio layout).		The concat demuxer is the recommended MP4 method when files are perfectly matching. It concatenates at the container level while rewriting metadata, allowing stream copying (-c copy) for a lossless, fast result.

			=== Use this method when: ===
			* All inputs are identical in codec, profile, level, frame rate, resolution, pixel format, audio codec, and channel layout.
			* You want to avoid re‑encoding.
			* You're joining MP4 files exported from the same device or encoder.

	=== Create a List File ===		=== Create a List File ===
	~~<pre>~~		```
	file '/path/to/file1'		file '/path/to/file1.mp4'
	file '/path/to/file2'		file '/path/to/file2.mp4'
	file '/path/to/file3'		file '/path/to/file3.mp4'
	~~</pre>~~		```

	=== Concatenate Without Re‑Encoding ===		=== Concatenate Without Re‑Encoding ===
	~~<code>~~		```
	ffmpeg -f concat -i mylist.txt -c copy output.mp4		ffmpeg -f concat -i mylist.txt -c copy output.mp4
	~~</code>~~		```

	=== Windows Examples ===		=== Windows Examples ===

	==== Manual list: ====		==== Manual list: ====
	~~<pre>~~		```
	(echo file 'first file.mp4' & echo file 'second file.mp4') > list.txt		(echo file 'first file.mp4' & echo file 'second file.mp4') > list.txt
	ffmpeg -safe 0 -f concat -i list.txt -c copy output.mp4		ffmpeg -safe 0 -f concat -i list.txt -c copy output.mp4
	~~</pre>~~		```

	==== Automatically list all MP4 files: ====		==== Automatically list all MP4 files: ====
	~~<pre>~~		```
	(for %i in (*.mp4) do @echo file '%i') > list.txt		(for %i in (*.mp4) do @echo file '%i') > list.txt
	ffmpeg -safe 0 -f concat -i list.txt -c copy output.mp4		ffmpeg -safe 0 -f concat -i list.txt -c copy output.mp4
	~~</pre>~~		```

	== Notes ==		=== Notes ===
	* All parameters must match~~. Even slight differences can break~~ stream copy.		* All technical parameters must match, or FFmpeg cannot stream copy.
	* Safest method for MP4 ~~when conditions are met~~.		* Safest method for MP4.
			* -safe 0 allows absolute or unusual paths.
			* Use UTF‑8 list files for international filenames.

	== 3. concat Protocol ==		== 3. concat Protocol ==
	Use this only ~~when formats support raw file‑level concatenation (~~MPEG‑1, MPEG‑2 ~~PS,~~ DV~~). Do not use this for MP4.~~		This is a raw byte-level concatenation method used only for formats that can be joined without adjusting metadata.

			=== Use this only for: ===
			* MPEG‑1
			* MPEG‑2 Program Streams
			* DV

	=== Example ===		=== Example ===
	~~<code>~~		```
	ffmpeg -i "concat:input1\|input2" -codec copy output.mkv		ffmpeg -i "concat:input1\|input2" -codec copy output.mkv
	~~</code>~~		```

	== Why This Fails for MP4 ==		== Why This Fails for MP4 ==
	The concat protocol ~~performs raw joining without rewriting~~ container metadata. MP4 ~~requires regenerated~~ moov atoms and ~~indices, so raw~~ concatenation corrupts ~~the container~~.		The concat protocol does not rewrite container metadata. MP4 containers require updated moov atoms, index tables, durations, and sample tables. Raw concatenation usually corrupts playback, causes wrong durations, broken seeking, or player failures.

	== Summary ==		== Summary ==
	{\| class="wikitable"		{\| class="wikitable"
	! Method !! ~~Re-Encode~~? !! MP4 Support !! Best Use Case		! Method !! Re‑Encode? !! MP4 Support !! Best Use Case
	\|-		\|-
	\| concat filter \|\| Yes \|\| Yes \|\| Mismatched sources, filtering		\| concat filter \|\| Yes \|\| Yes \|\| Mismatched sources, filtering, full control
	\|-		\|-
	\| concat demuxer \|\| No \|\| Yes (if identical) \|\| Safe MP4 joining		\| concat demuxer \|\| No \|\| Yes (if identical) \|\| Safe MP4 joining with stream copy
	\|-		\|-
	\| concat protocol \|\| No \|\| No \|\| MPEG‑1 / MPEG‑2 PS / DV		\| concat protocol \|\| No \|\| No \|\| MPEG‑1 / MPEG‑2 PS / DV only
	\|}		\|}

	== Reference ==		== Reference ==
	* https://stackoverflow.com/questions/7333232/how-to-concatenate-two-mp4-files-using-ffmpeg		* https://stackoverflow.com/questions/7333232/how-to-concatenate-two-mp4-files-using-ffmpeg

Dex at 13:53, 14 March 2026

2026-03-14T13:53:11Z

@@ Line 1: / Line 1: @@
 [[Category:FFmpeg]]
 [[Category:MP4]]
-== 1. concat video filter ==
+Concatenating video files in FFmpeg can be achieved in several ways, depending on your input formats, codecs, and whether you want to avoid re‑encoding. This article explains the three official FFmpeg concatenation methods, when to use each one, and common pitfalls.
-Note that this method performs a re-encode of all inputs. If you want to avoid the re-encode, 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 everything.<br/>
+== 1. concat Video Filter ==
 <pre>
-ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv \
+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
 </pre>
 <pre>
 file '/path/to/file1'
 file '/path/to/file2'
 file '/path/to/file3'
 </pre>
 <pre>
-(echo file 'first file.mp4' & echo file 'second file.mp4' )>list.txt
+(echo file 'first file.mp4' & echo file 'second file.mp4') > list.txt
 ffmpeg -safe 0 -f concat -i list.txt -c copy output.mp4
 </pre>
 <pre>
 (for %i in (*.mp4) do @echo file '%i') > list.txt
@@ Line 36: / Line 49: @@
 </pre>
-== 3. concat protocol ==
+== Notes ==
-Use this method with formats that support file-level concatenation (MPEG-1, MPEG-2 PS, DV). Do not use with MP4.<br/>
+* All parameters must match. Even slight differences can break stream copy.
-<code>ffmpeg -i "concat:input1|input2" -codec copy output.mkv</code><br/>
+== Reference ==
-This method does not work for many formats, including MP4, due to the nature of these formats and the simplistic physical concatenation performed by this method. It's the equivalent of just raw joining the files.<br/>
+* https://stackoverflow.com/questions/7333232/how-to-concatenate-two-mp4-files-using-ffmpeg

Knowledgebaseadmin at 12:36, 6 March 2025

2025-03-06T12:36:09Z

← Older revision		Revision as of 12:36, 6 March 2025
Line 1:		Line 1:
	[[Category:FFmpeg]]		[[Category:FFmpeg]]
			[[Category:MP4]]
	== 1. concat video filter ==		== 1. concat video filter ==
	Use this method 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.<br/>		Use this method 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.<br/>

Knowledgebaseadmin at 11:50, 6 March 2025

2025-03-06T11:50:51Z

← Older revision		Revision as of 11:50, 6 March 2025
Line 1:		Line 1:
			[[Category:FFmpeg]]
	== 1. concat video filter ==		== 1. concat video filter ==
	Use this method 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.<br/>		Use this method 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.<br/>

Knowledgebaseadmin: Knowledgebaseadmin moved page FFMpeg - Concatenate MP4 Files to FFmpeg - Concatenate MP4 Files

2025-03-06T11:31:01Z

Knowledgebaseadmin moved page FFMpeg - Concatenate MP4 Files to FFmpeg - Concatenate MP4 Files

← Older revision		Revision as of 11:31, 6 March 2025
(No difference)

Knowledgebaseadmin: /* 3. concat protocol */

2025-03-05T15:51:49Z

3. concat protocol

← Older revision		Revision as of 15:51, 5 March 2025
Line 37:		Line 37:
	Use this method with formats that support file-level concatenation (MPEG-1, MPEG-2 PS, DV). Do not use with MP4.<br/>		Use this method with formats that support file-level concatenation (MPEG-1, MPEG-2 PS, DV). Do not use with MP4.<br/>

	<code>ffmpeg -i "concat:input1\|input2" -codec copy output.mkv</code>		<code>ffmpeg -i "concat:input1\|input2" -codec copy output.mkv</code><br/>
	This method does not work for many formats, including MP4, due to the nature of these formats and the simplistic physical concatenation performed by this method. It's the equivalent of just raw joining the files.<br/>		This method does not work for many formats, including MP4, due to the nature of these formats and the simplistic physical concatenation performed by this method. It's the equivalent of just raw joining the files.<br/>
	Reference: [[https://stackoverflow.com/questions/7333232/how-to-concatenate-two-mp4-files-using-ffmpeg stackoverflow: How to concatenate two MP4 files using FFmpeg?]]		Reference: [[https://stackoverflow.com/questions/7333232/how-to-concatenate-two-mp4-files-using-ffmpeg stackoverflow: How to concatenate two MP4 files using FFmpeg?]]

Knowledgebaseadmin at 15:51, 5 March 2025

2025-03-05T15:51:04Z

← Older revision		Revision as of 15:51, 5 March 2025
Line 25:		Line 25:
	<pre>		<pre>
	(echo file 'first file.mp4' & echo file 'second file.mp4' )>list.txt		(echo file 'first file.mp4' & echo file 'second file.mp4' )>list.txt
	~~<code>~~ffmpeg -safe 0 -f concat -i list.txt -c copy output.mp4~~</code>~~		ffmpeg -safe 0 -f concat -i list.txt -c copy output.mp4
	</pre>		</pre>
	or<br/>		or<br/>

Knowledgebaseadmin at 15:50, 5 March 2025

2025-03-05T15:50:30Z

← Older revision		Revision as of 15:50, 5 March 2025
Line 23:		Line 23:
	For Windows:<br/>		For Windows:<br/>

	(echo file 'first file.mp4' & echo file 'second file.mp4' )>list.txt~~<br/>~~		<pre>
	<code>ffmpeg -safe 0 -f concat -i list.txt -c copy output.mp4</code><br/>		(echo file 'first file.mp4' & echo file 'second file.mp4' )>list.txt
			<code>ffmpeg -safe 0 -f concat -i list.txt -c copy output.mp4</code>
			</pre>
	or<br/>		or<br/>

Knowledgebaseadmin at 15:49, 5 March 2025

2025-03-05T15:49:44Z

← Older revision		Revision as of 15:49, 5 March 2025
Line 20:		Line 20:
	</pre>		</pre>

	<code>$ ffmpeg -f concat -i mylist.txt -c copy output.mp4</code>		<code>$ ffmpeg -f concat -i mylist.txt -c copy output.mp4</code><br/>
	For Windows:<br/>		For Windows:<br/>

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

Knowledgebaseadmin: Created page with "== 1. concat video filter == Use this method 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.
Note that this method performs a re-encode of all inputs. If you want to avoid the re-encode, 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 everything.

 ffmpeg..."

2025-03-05T15:49:02Z

Created page with "== 1. concat video filter == Use this method 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. Note that this method performs a re-encode of all inputs. If you want to avoid the re-encode, 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 everything. <pre> ffmpeg..."

New page

== 1. concat video filter ==
Use this method 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. 

Note that this method performs a re-encode of all inputs. If you want to avoid the re-encode, 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 everything. 

<pre>
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
</pre>
== 2. concat demuxer ==
Use this method 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).

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

<code>$ ffmpeg -f concat -i mylist.txt -c copy output.mp4</code>
For Windows: 

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

<pre>
(for %i in (*.mp4) do @echo file '%i') > list.txt
ffmpeg -safe 0 -f concat -i list.txt -c copy output.mp4
</pre>

== 3. concat protocol ==
Use this method with formats that support file-level concatenation (MPEG-1, MPEG-2 PS, DV). Do not use with MP4. 

<code>ffmpeg -i "concat:input1|input2" -codec copy output.mkv</code>
This method does not work for many formats, including MP4, due to the nature of these formats and the simplistic physical concatenation performed by this method. It's the equivalent of just raw joining the files. 
Reference: [[https://stackoverflow.com/questions/7333232/how-to-concatenate-two-mp4-files-using-ffmpeg stackoverflow: How to concatenate two MP4 files using FFmpeg?]]