Concating file A with A, first A is silent

So, I have a bunch of sound files, short pronunciation examples. Most of them are from forvo.com, but I have now downloaded some from another site, parol.martinrue.com.

Let's say that I have a mp3 file named dormo with the pronunciation of that word.

I also have a mp3 file with 4 seconds silence, named 4sek.

The basic idea is that I concat dormo + 4sek + dormo (again). The 4 seconds silence gives me time to say the word out load.

Those from parol acts strangely when concating. The first dormo is silent, the second one is not.

How is this even possible? The first and second dormo is the same file!

I guess you need more information about the file but don't know what information would be of interest.

If this is a problem concerning the payload part of a file, then MP3tag is not the tool to deal with it. MP3tag only deals with the metadata around the payload part.

I don't even know what payload part means, my best guess is that it would be the actual sound.

dormo as standalone is audible

dormo + 4sek + dormo The dormo first is not audible, the second one is.

Yes, that is what I meant - but as files that MP3tag can tag may also include videos, I thought that "audio" would not be accurate enough.

Anyway: MP3tag does not deal with the audio part. You would have to use dedicated audio editors and see what is wrong with the file.
And once the file is fixed, you can add metadata with MP3tag.

You can imagine that payload part like this:

Metadata/Tags <-> Sound/Video/Payload part <-> Metadata/Tags
Mp3tag does not touch the "middle" sound/video/payload part.

(By mistake, I have called the file dorma here, the actual name is dormi.)

What file do you mean could be wrong?

dormi.mp3 is OK, it has both sound and an image that I've added.

When concatenated, the very same dormi.mp3 has the image but not the sound in the first instance. In the second instance, it has both sound and image.

It's the same dormi.mp3 in all three cases.

You do the concatenating with an audio editor, I assume.
It is that process that causes the problems. I can only guess that your audio editor does not treat already existing tags correctly and the subsequently used player skips that invalid audio part until it finds something digestible.

Please check that the audio part is OK. And that is outside the scope of functions in MP3tag.

Have a look at the tools linked in this thread:

No, it's done in DOS with ffmpeg.

@echo off &setlocal
chcp 65001
for /f "delims=" %%i in ('dir /b /a-d *.mp3^|findstr /vc:"4sec"') do ffmpeg -i "concat:%%~i|4sec.mp3|%%~i" -acodec copy "%%~ni4sec%%~i"
PAUSE

I cannot say a lot about ffmpeg - that would be a question in the program's support facilities.

What did the check of the files reveal?

The actual files might help.
Maybe you can upload an archive containing the 2 files that cause the problem.

I'm not sure what you mean checking the files.

have you tried the tool mp3diags from the linked thread?
That checks your file and you get a report about any findings.
So using that tool on your concatenated file is what I mean by "check the file".

No I haven't, but I will, and you will be able too as I'm about to send a zip file with the 3 mp3 files

Here are the 3 files involved.

dormi — the original sound file with an image that I added myself.

4sec — the silent sound file that I created myself, it hasn't got any image.

dormi4secdormi — the resulting concatenated file where the first dormi is silent, but the second one is audible.

Again:
This is not a problem for Mp3tag.

If you look at Audacity as specialized Audio Tool you see:

There is a valid 4 second silent file.
There is a valid very short ~700ms dormi audio file.
The third one that you try to concat is not a valid mp3 file.

You should really use an Audio Tool for that, not a (overly) complicated FFMPEG command line.

Concat_Audacity
Of course you could also delete the no more necessary (empty) audio track before export it to MP3.

BTW:

If I try it with:
ffmpeg -i "concat:dormi.mp3|4sec.mp3|dormi.mp3" -acodec copy dormi4secdormi_created-with-ffmpeg.mp3

I get this file (remove the additional .txt before playing)
dormi4secdormi_created-with-ffmpeg.mp3.txt (67,3 KB)

Thanks for the very cool and informative Audacity gif, love it.

The third one that you try to concat is not a valid mp3 file.

I'm not trying to concat dormi4secdormi. This file is the result of concat dormi + 4sek + dormi

There are only a handful of audio files right now, but I expect the number to grow to over a thousand, so some sort of automation is needed.

Sorry, that was my fault.
The file you have concatenated (with the previously two valid mp3 file) is no more a valid mp3 file.
I don't know what exactly is wrong with your batch command, because if I manually do the same with your two valid mp3 files it seems to work as expected.

Please double check the above audio file dormi4secdormi_created-with-ffmpeg.mp3
(remove the .txt extension before playing it)

Please double check the above audio file dormi4secdormi_created-with-ffmpeg.mp3
(remove the .txt extension before playing it)

I can't see it above or below, is there supposed to be a download link somewhere?

Do you can't see this blue DL link (in the picture with a green border) in my answer above?

repeated directly here:
dormi4secdormi_created-with-ffmpeg.mp3.txt (67,3 KB)