Keeping english subtitles only after ffmpeg conversion

[Nico Darko]

Hi.

I'm currently using this script to convert the audio of my mkv video files. What would I need to change so that only the subtitles flagged as english remain after the conversion?

for %%a in (*.mkv) do ffmpeg -y -i "%%a" -map 0 -c:v copy -c:a ac3 -b:a 640k -c:s copy "output_%%~na.mkv"

Thank you.

[jagabo]

I think this:

for %%a in (*.mkv) do ffmpeg -y -i "%%a" -map 0:v -map 0:a -map 0:m:language:eng -c:v copy -c:a ac3 -b:a 640k -c:s copy "output_%%~na.mkv"

but i don't have a a suitable source file handy. I expect it will only work if the subs are marked as english.

[Nico Darko]

It worked for the subs, but for some reason it duplicated both the video track and the audio track. So the new file is twice the size of the original.

[sekininsha]

try edit this: '-map 0:m:language:eng' --> change the 'm' by 's'

[Nico Darko]

It says '0: s:language:eng' matches no stream.

[Selur]

are you sure the source subtitle stream is flagged as 'eng'?
What does ffmpeg report when you call

ffmpeg -i "path to input"

(no further parameters)?

Cu Selur

[Nico Darko]

Both the audio and 2 subtitles tracks are flagged as 'English", I tried '0: s:language:english', it still says no match. It's odd because it works with "0:m:language:eng", only the english subtitles remained, but the audio and video duplicated.

The report says, path to input: No such file or directory.

[Selur]

without the whole output of ffmpeg this is wild guessing,...
you can also set a higher log level when using ffmpeg to see in more details what it is doing,...

[Nico Darko]

I don't know how to do that.

[Selur]

instead of calling ffmpeg (with proper paths not variables) through a batch file call it in a Windows Command Prompt, copy the output (right click, mark all, copy it by right click, and paste it here)

[Nico Darko]

First maybe I can try to select the subtitle track number instead of the language? What would it be in the script if the only track I need is number 4?

[jagabo]

I found a suitable MKV sample and tried the batch file I gave in post #2. The output video only had one copy of the video, one copy of the audio. The source had two English subtitles (vobsub, srt) -- both were copied to the output. Chapters too.

[Nico Darko]

@jagabo: Strange, but I figured it out! I removed the extra "-map 0:v" and "-map 0:a" and it worked perfectly, no duplicates!

So the script is:

for %%a in (*.mkv) do ffmpeg -y -i "%%a" -map 0:m:language:eng -c:v copy -c:a ac3 -b:a 640k -c:s copy "output_%%~na.mkv"

Thank you.

[jagabo]

Weird. When I run your batch file I get an output file with no video or audio. Only English subs and chapters.

I have ffmpeg version 4.2.2, about six months old.

[Nico Darko]

My version seems to be 4.1.4, so maybe that's why.

[Catw3lk]

Hmm, your code looks good

[Samangel]

Hi! you can modify the script like this:
Code: for %%a in (*.mkv) do ffmpeg -y -i ""%%a"" -map 0 -c:v copy -c:a ac3 -b:a 640k -map 0:0 -map 0:1 -c copy -metadata:0 language=eng -metadata:1 language=eng ""output_%%~na.mkv""
By specifying ""-map 0:0"" and ""-map 0:1"", you're selecting the first and second subtitle streams, respectively. I also id that to watch my series with subtitles, as I'm currently learning English and preparing for IELTS. I also use https://practicalielts.com/ielts/ultimate-ielts-guide/ to prepare better. Series is just another fun way to learn a new language.