Introduction
Have you ever tried to concatenate multiple MP3 files using a tool like ffmpeg, only to find that the resulting file stops playing after 15 seconds, even though the total duration is 12 minutes? This can be a frustrating problem, but it's one that has a simple explanation and solution.
Understanding the Problem
When you concatenate multiple MP3 files using a tool like ffmpeg, the resulting file will contain all of the audio data from the input files. However, each MP3 file also contains metadata, such as the duration of the file, the bitrate, and the format of the audio. If the metadata from the different files is not consistent, then the resulting file may not play correctly.
In particular, if the input files have different bitrates or formats, then the resulting file may contain inconsistencies that cause playback to stop after 15 seconds. This is because the player may encounter a section of the file that has different formatting or encoding, and it may not be able to handle the inconsistency.
Example Scenario
Let's say you have two MP3 files, file1.mp3 and file2.mp3. File1 has a bitrate of 128 kbps and is encoded in stereo, while file2 has a bitrate of 192 kbps and is encoded in mono.
If you concatenate these files using ffmpeg, the resulting file will contain both audio streams, but the metadata will not be consistent. In particular, the bitrate and encoding format will be different for different parts of the file.
Solution
To avoid this problem, you should make sure that the input files have consistent metadata before concatenating them. This can be done using a tool like mp3info or eyeD3, which allow you to modify the metadata of MP3 files.
In the example scenario above, you would need to modify the metadata of file2 to match that of file1. This would involve changing the bitrate to 128 kbps and changing the encoding format to stereo.
Modifying Metadata with mp3info
Here's an example of how to modify the metadata of an MP3 file using mp3info:
mp3info -a "Artist Name" -t "Song Title" -b 128 -f s file2.mp3
In this example, the -a option sets the artist name, the -t option sets the song title, the -b option sets the bitrate, and the -f option sets the encoding format.
Modifying Metadata with eyeD3
Here's an example of how to modify the metadata of an MP3 file using eyeD3:
eyeD3 --artist="Artist Name" --title="Song Title" --bitrate=128 --format=stereo file2.mp3
In this example, the --artist option sets the artist name, the --title option sets the song title, the --bitrate option sets the bitrate, and the --format option sets the encoding format.
Inconsistent metadata can cause concatenated MP3 files to stop playing after 15 seconds, even though the total duration is much longer. To avoid this problem, you should make sure that the input files have consistent metadata before concatenating them. This can be done using a tool like mp3info or eyeD3 to modify the metadata of the input files.