<p>Each line in the concat list must be either a comment (start line with #) or a keyword. To specify an input, start with <code>file</code>,</p>
<p>so <code>01.mp3</code> becomes <code>file 01.mp3</code>.</p>

CC BY-SA 4.0
2020-07-02T09:20:14.120Z
2020-07-02T09:20:14.120Z
Gyan
<p>Instructions from this site, <a href="https://video.stackexchange.com/questions/28120/can-ffmpeg-input-mp4-and-convert-it-to-m4b-or-m4a">Can ffmpeg input mp4 and convert it to m4b or m4a?</a>  fail to concatenate and convert multiple MP3 files into one M4A file.</p>
<p>I downloaded the ffmpeg static build for Windows 10 <strong>git-2020-06-26-7447045</strong> from <a href="http://ffmpeg.zeranoe.com/builds/" rel="nofollow noreferrer">http://ffmpeg.zeranoe.com/builds/</a></p>
<p>I generated a file <strong>list.txt</strong> containing the files to concatenate, numbered from 01.mp3 to 51.mp3 .</p>
<p>When I try to combine those MP3 files into 1 M4A file, the error happened as below. How do I resolve this?</p>
<p>I ran:</p>
<pre><code>ffmpeg -f concat -safe 0 -i list.txt -vn -y -b:a 64k -acodec aac -ac 2 result.m4a
</code></pre>
<p>and got</p>
<pre><code>[concat @ 000002652204c840] Line 1: unknown keyword '01.mp3'
list.txt: Invalid data found when processing input
</code></pre>
<p>Here's the content of list.txt:</p>
<pre><code>01.mp3
02.mp3
03.mp3
04.mp3
05.mp3
06.mp3
07.mp3
08.mp3
09.mp3
10.mp3
11.mp3
12.mp3
13.mp3
14.mp3
15.mp3
16.mp3
17.mp3
18.mp3
19.mp3
20.mp3
21.mp3
22.mp3
23.mp3
24.mp3
25.mp3
26.mp3
27.mp3
28.mp3
29.mp3
30.mp3
31.mp3
32.mp3
33.mp3
34.mp3
35.mp3
36.mp3
37.mp3
38.mp3
39.mp3
40.mp3
41.mp3
42.mp3
43.mp3
44.mp3
45.mp3
46.mp3
47.mp3
48.mp3
49.mp3
50.mp3
51.mp3
</code></pre>

<ffmpeg><windows>
ffmpeg concatenation of MP3 files to single M4A file fails
K7AAY
# ffmpeg concatenation of MP3 files to single M4A file fails

(Asked by: username_0 on 2020-07-01)

Instructions from this site, Can ffmpeg input mp4 and convert it to m4b or m4a?  fail to concatenate and convert multiple MP3 files into one M4A file.
I downloaded the ffmpeg static build for Windows 10 git-2020-06-26-7447045 from http://ffmpeg.zeranoe.com/builds/
I generated a file list.txt containing the files to concatenate, numbered from 01.mp3 to 51.mp3 .
When I try to combine those MP3 files into 1 M4A file, the error happened as below. How do I resolve this?
I ran:
ffmpeg -f concat -safe 0 -i list.txt -vn -y -b:a 64k -acodec aac -ac 2 result.m4a

and got
[concat @ 000002652204c840] Line 1: unknown keyword '01.mp3'
list.txt: Invalid data found when processing input

Here's the content of list.txt:
01.mp3
02.mp3
03.mp3
04.mp3
05.mp3
06.mp3
07.mp3
08.mp3
09.mp3
10.mp3
11.mp3
12.mp3
13.mp3
14.mp3
15.mp3
16.mp3
17.mp3
18.mp3
19.mp3
20.mp3
21.mp3
22.mp3
23.mp3
24.mp3
25.mp3
26.mp3
27.mp3
28.mp3
29.mp3
30.mp3
31.mp3
32.mp3
33.mp3
34.mp3
35.mp3
36.mp3
37.mp3
38.mp3
39.mp3
40.mp3
41.mp3
42.mp3
43.mp3
44.mp3
45.mp3
46.mp3
47.mp3
48.mp3
49.mp3
50.mp3
51.mp3

**Tags:** ffmpeg, windows


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## 1 answers

### Answer by username_1 on 2020-07-02. Score: 3 | Accepted answer

Each line in the concat list must be either a comment (start line with #) or a keyword. To specify an input, start with `file`,

so `01.mp3` becomes `file 01.mp3`.


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