pass a command to cmd

Hi all,

I want to append several mp3 files using cmd. Files are under different folder, so I need to first swith to the path:

cd /b E:\Voice\Folder 01

Then need to exclude the following:

copy /b 1.mp3+2.mp3+3.mp3+4.mp3 All.mp3

To append all mp3 files to a single file.

Does anyone know how can I do that?

Thanks.

[DGM]

This isn't a MATLAB issue. That's not how you concatenate files, and no, just using cat on mp3 files won't necessarily produce a usable file either. Depending on the settings of the files and what's trying to read them, a directly concatenated file may only be readable up to the end of one of its segments. Metadata will be effectively obfuscated as well.

I don't know that windows has any system utilities for processing media files, so someone else will have to recommend a method if you want to do it outside of MATLAB.

If you want to do it in MATLAB, you can use audioread, resample if necessary, concatenate the vectors, and write it out with audiowrite.

[Sonima]

Thanks DGM for your comment.

I underestand your point. However, this method works for my perpose and most easiest and fast solution. The only issue I have is to how excude those commands to cmd.

[Walter Roberson]

The depths of my memory are saying that mp3 files were defined in a way that you can concatentate them. mp3 is a container format, and the music chunks are identified within the container, so the question becomes whether the reader will stop at the end of the "first" container. mp3 container does not assume that there is only one music chunk in a file.

[DGM]

I've done it before and it usually works when the files are similar, but as you said, it depends on the reader and it seems to depend on the files being concatenated. If I concatenate a file with itself, Totem plays both segments fine. If I pick two files with differing bitrate or other options, Totem may or may not pick up the second segment. Similar happens with Audacious, though sometimes it displays incorrect track times when it does succeed.

Answer 1

[Walter Roberson]

Use dir() to get the names of all of the mp3 files in the directory. Use natsortdir() from the File Exchange to sort them into numeric order -- most of the time dir() will tell you that the file after 1.bmp is 11.bmp and 2.bmp is not in the list until after 19.bmp and you need to rearrange the entries.

Then pull out the sorted names, and strjoin() them with '+' character. You can then use sprintf() to put together a command to pass to system()

[Stephen23]

Download NATSORTFILES() from here:

https://www.mathworks.com/matlabcentral/fileexchange/47434-natural-order-filename-sort