Windows – Find all MKV files and remove all subtitles

batch filematroskasubtitleswindows

I'm currently looking at a Windows program called mkvmerge. I would like to create a batch file to find all MKV files recursively from a specified path, and remove all subtitles from the MKV files found (if the MKV found contains subtitles), finally deleting all the original MKV files that had the subtitles removed.

I've done about 2 hours of googling, and I'm finding that you have to be able to write things like this:

FOR /F "delims=*" %%A IN ('dir /b *.MKV') DO "C:\mkvmerge.exe" -o "fixed_%%A" -a 4 -s 7 --compression -1:none "%%A"

I'm still trying, but if someone can give me a bit of help, I'd really appreciate it.

Best Answer

Save the following as something like DelMKVSubs.bat in the same directory mkvmerge.exe is in, edit the rootfolder variable as per your requirements and run the batch file:

@echo off
cls
set rootfolder=C:\
echo Enumerating all MKVs under %rootfolder%
echo.
for /r %rootfolder% %%a in (*.mkv) do (
    for /f %%b in ('mkvmerge -i "%%a" ^| find /c /i "subtitles"') do (
        if [%%b]==[0] (
            echo "%%a" has no subtitles
        ) else (
            echo.
            echo "%%a" has subtitles
            mkvmerge -q -o "%%~dpna (No Subs)%%~xa" -S "%%a"
            if errorlevel 1 (
                echo Warnings/errors generated during remuxing, original file not deleted
            ) else (
                del /f "%%a"
                echo Successfully remuxed to "%%~dpna (No Subs)%%~xa", original file deleted
            )
            echo.
        )
    )
)

The batch file should be easy enough to understand, but here's an overview nevertheless:

It uses for /r to recursively search %rootfolder% for all MKVs
It then runs mkvmerge -i on each MKV to check whether a subtitle track exists
If the MKV does contain subtitle tracks, it runs mkvmerge -S to remux the file while skipping all such tracks
Finally it checks the exit code of mkvmerge and if this (i.e. errorlevel) is 0 indicating success with no warnings/errors, it deletes the original file

For more see the mkvmerge documentation and also for /?, if /? etc. at the command prompt.

`mkvtomp4`

Looks like mkvtomp4 is what you want?

Uses mpeg4ip or GPAC's MP4Box, mkvtoolnix and ffmpeg to convert troublesome mkv files to mp4. The conversion does not re-encode the video and only re-encodes the audio if it doesn't use AAC codec (one can override this behaviour using --audio-codec).

You can download Windows and Linux versions on the Google Code page. You will need additional software though.

Check the sites for downloads for either Windows or Linux. On OS X, you only need to brew install mkvtoolnix mp4box if you have Homebrew.

This will not copy your subtitles though. You'll need an additional step.

FFmpeg batch

If mkvtomp4 does not work for you, a simple FFmpeg batch file could also do.

Install ffmpeg (e.g. via Homebrew or options from https://ffmpeg.org/download.html). Then, just call:

ffmpeg -i input.mkv -c:v copy -c:a copy output.mp4

This will create a valid MP4 container without re-encoding. Loop over the files as needed and available by your operating system. This batch won't, however, copy subtitles.

In *nix, you could do the following. Just create a file convert.sh:

#!/bin/bash
find /path/to/input/folder -iname '*.mkv' -print0 | while read -d '' -r file; do
    ffmpeg -i "$file" -c:v copy -c:a copy ${file%%.mkv}.mp4
done

Replace the path to your video folder here. Make it executable with chmod +x convert.sh, then run it with ./convert.sh.

In Windows, you probably need two Batch files (shameless plug from here), one being startconvert.bat:

for %%i IN (*.mkv) DO (convert-to-mp4.bat "%%i") 
pause

And one that performs the conversion:

IF EXIST "%1.mp4" GOTO exit

@echo Conversion for %1 started on %DATE% %TIME% 
ffmpeg -i %1 -c:v copy -c:a copy %1.mp4

:exit 
@echo %1.mp4 already exists

Save both in the video folder. Simply run startconvert.bat from the folder you want to start the conversion from.

Subtitles

If you want to add the subtitles, you might need a manual procedure if the following doesn't work for you:

ffmpeg -i input.mkv -c:a copy -c:v copy -map 0 output.mp4

To extract subtitles, use:

mkvextract tracks input.mkv 3:subtitles.srt

This is assuming that your file really contains the subtitles at track ID number 3 and they can be exported to the SRT format. To check whether a file really contains subtitles at track 3, use mkvmerge -i input.mkv.

Then, use MP4Box to re-add the subtitles to the MP4 file.

mp4box -add input.mp4 -add subtitles.srt -new output.mp4

Best Answer

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