Answers.Body: <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>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-07-02T09:20:14.120Z
Answers.LastActivityDate: 2020-07-02T09:20:14.120Z
Answers.UserDisplayName: Gyan
Body: <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>
  
Tags: <ffmpeg><windows>
Title: ffmpeg concatenation of MP3 files to single M4A file fails
UserDisplayName: K7AAY
ThreadText: # 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?](https://video.stackexchange.com/questions/28120/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
  
  
  ---
  
  ## 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`.
  
  
  ---
  
  