Convert MKV to MP4 with subtitles hardcoded

[tomasrage]

Hello guys, I have mkv file with subtitles merged on it, I need to convert to MP4 with subtitles hardcoded or burned into the mp4, I did this command "ffmpeg -i file.mkv -vf subtitles=file.mkv file.mp4" and works great but takes about 25 minutes for each file, then i try to add "-preset ultrafast -crf 0" but converts files from 250Mb to 8.8Gb.. any way to do this fast and losseless quality??

[johns0]

Get a faster computer and add a 2 to crf so it reads as -crf 20.

[jagabo]

the veryfast preset is about twice as fast as the medium preset (the default). If you have a graphics card with hardware encoding you can get even faster encoding, with about the same quality as the veryfast preset.

[tomasrage]

preset veryfast is faster than ultrafast? i try ultrafast and crf 0

[johns0]

Dont use crf 0,use crf 20 or you will still get a big file.What kind of computer do you have?

[tomasrage]

i7, 16ram, ssd, not video card yet...

i do this command

ffmpeg -i file.mkv -vf subtitles=file.srt -preset veryfast -crf 24 file.mp4 and works GREAT! file size less than 50% of the original size, quality not loss, now facing the subtitle size is very small, is there a way to change the size ?

[jagabo]

preset veryfast is faster than ultrafast? i try ultrafast and crf 0

No, it's faster than medium. In your first command line (ffmpeg -i file.mkv -vf subtitles=file.mkv file.mp4) you didn't specify a preset so the default, medium, was used.

ffmpeg -i file.mkv -vf subtitles=file.srt -preset veryfast -crf 24 file.mp4 and works GREAT! file size less than 50% of the original size, quality not loss...

The quality is less than the original. You just haven't looked closely enough.

now facing the subtitle size is very small, is there a way to change the size ?

Add the Fontsize spec:

-vf "subtitles=file.srt:force_style='Fontsize=24'"

[abolibibelot]

Quote from video.baba :

What's important to you? Speed, quality? or size? (pick two!)

You can't have all three qualities, unless you're God or Chuck Norris.
The setting suggested above, -crf 20, is a good compromise as the quality loss will be barely noticeable and the file size will stay manageable. Depending on the purpose of the MP4 file(s), if using a fast preset, you may want to select a lower CRF value (= higher quality) to compensate.

To preview the size / style of subtitles, create a simple Avisynth script and open it with either VirtualDub2 or AVSPMod. To get almost total control over the aspect of the subtitles, use ASS format instead of SRT.
https://forum.videohelp.com/threads/394091-SRT-change-vertical-margin-but-keep-1-line-...cally-centered

[tomasrage]

Thank you guys for all your replies, I'm doing with this command finally, I have a list of mp4 and srt and run this on terminal, just need to had the same File Name for both files(mp4 and srt).

for f in *.mp4; do ffmpeg -i $f -vf subtitles=""${f/.mp4}".srt":force_style=FontSize=24 -preset veryfast -crf 24 /hardcoded/$f ; mv $f ""${f/.mp4}".srt" /tmp/ ; done

This works great for my needs, thanks again!!