Time Text subtitles

[vega69-ux]

I have a .mp4 file that has about 15 soft-coded Time Text subtitles with different languages. I would like to just change the container from .mp4 to .mkv, (no reconversions) but keep the 15 soft-coded Time Text subtitles with different languages, but have the English subtitles to be forced on by default. I tried using MKVToolNix, but found out that it does not support Time Text subtitles. Any help would be appreciated.

[vega69-ux]

*Timed Text

[usually_quiet]

I have a .mp4 file that has about 15 soft-coded Time Text subtitles with different languages. I would like to just change the container from .mp4 to .mkv, (no reconversions) but keep the 15 soft-coded Time Text subtitles with different languages, but have the English subtitles to be forced on by default. I tried using MKVToolNix, but found out that it does not support Time Text subtitles. Any help would be appreciated.

What kind of timed text subtitles do you have? I have MKVToolNix GUI installed, and it appears that MKVToolNix supports several timed text formats, SRT, VTT, SSA/ASS, USF, XML.

[vega69-ux]

TTML1 format.

[jagabo]

ffmpeg will automatically convert MP4 Timed Text to Advanced Sub Station Alpha ASS subs.

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

[usually_quiet]

I haven't used TTML 1 but it seems to be XML-based. What happens if you change a file extension to XML and then try to mux the file? If muxing works, do you lose any features?

Never mind. Try what jagabo suggested.

[vega69-ux]

Thank you. However...

1. The subtitles are very big, looks like x48 font. Also, they're displaying on the bottom left of the video. How do I center the fonts and make them the normal size?

2. How do I include the metadata of the subtitles? It currently says "Track 1 - English" "Track 2 - Spanish" etc. The original file says "Italian - [Italian]" "English - English" etc.

[jagabo]

Try forcing the sub(s) to SRT. I think this will work but I don't have an mp4 video with multiple subtitles to test:

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

Converting to SRT will lose all formatting info so you should get normal sized subs, centered horizontally. I don't know if it will keep the language metadata.

[vega69-ux]

I figured out the subtitles are tx3g. Is there a way to keep the metadata of the subtitles in the mp4, and just change the container from .mp4 to .mkv? No conversions? Lossless?

[october262]

I figured out the subtitles are tx3g. Is there a way to keep the metadata of the subtitles in the mp4, and just change the container from .mp4 to .mkv? No conversions? Lossless?

to change mp4 to mkv just run ffmpeg -i input.mp4 output.mkv

[jagabo]

to change mp4 to mkv just run ffmpeg -i input.mp4 output.mkv

That will encode the video, the audio, and convert the subs to ASS. And it will only include one of each stream type.

As far as I know ffmpeg will not copy mp4 subs to mkv without converting them to ASS or SRT or other sub format.

[vega69-ux]

Any ideas, if ffmpeg will not work if there is another way to achieve this?

[october262]

Any ideas, if ffmpeg will not work if there is another way to achieve this?

there is another thread that deals with timed time text subtitles - https://forum.videohelp.com/threads/402515-Problem-with-extracting-tx3g-subtitles
see if it'll be any help.

[jagabo]

Even if you manage to get 3GPP subs (aka MP4 Timed Text as defined by MPEG-4 Part 17) into an MKV file you probably won't find any player that plays them.

[usually_quiet]

Do you know for certain that whatever you plan to use to play these files will even display 3GPP format subtitles inside an MKV container? You may need to convert the subs and make them external subtitles.

It looks like jagabo and I had the same idea.

[vega69-ux]

I was able to extract the Timed Texts with My MP4Box GUI to .srt files. However, it does not export the metadata. So I don't know which language is what. Ideas?

[jagabo]

SRT is plain text. Use NotePad or WordPad to look at the text.

[jagabo]

If your subtitle fonts are too large you can change them. ASS and SRT plain text that you can edit in NotePad or WordPad. Here the fontsize is set to 40 (right after Arial in the V4+ Styles section) near the start of the file:

[Script Info]
; Script generated by FFmpeg/Lavc58.134.100
ScriptType: v4.00+
PlayResX: 384
PlayResY: 288
ScaledBorderAndShadow: yes

[V4+ Styles]
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
Style: Default,Arial,40,&Hffffff,&Hffffff,&H0,&H0,0,0,0,0,100,100,0,0,1,1,0,2,10,10,10,0

[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:18:37.00,0:18:39.00,Default,,0,0,0,,Blow them up.
Dialogue: 0,0:18:41.58,0:18:42.58,Default,,0,0,0,,MOVE IT!

With SRT the font size is probably set on each line:

1
00:18:37,021 --> 00:18:39,020
<font size="40">Blow them up.</font>

2
00:18:41,604 --> 00:18:42,603
<font size="40">MOVE IT!</font>

You can perform a global replacement of <font size="40">.

[pcspeak]

As a follow on to jagabo.

For my 'video.avi' I created a 'video.srt' file and a 'video.srt.style' file.
i.e.
3 files in the folder
video.avi
video.srt
video.srt.style

.srt

1
00:00:54,421 --> 00:00:58,981
Which is San Jose and that's only 40 kilometers

2
00:01:01,461 --> 00:01:07,461
And well I'm going to the capital because I'm\hgonna go past the Honda dealer there to pick up\h\h

.srt.style

[V4+ Styles]
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
Style: Default,Arial,10,&H0000ff,&H0000ff,&H0,&H0,0,0,0,0,100,100,0,0,1,1,0,2,10,10,10,0

By changing the font size and color in the .style file, MPC-HC played quite happily with the new size & color chosen.
There was no need to burn in subtitles or add the stream to an mkv. I just had the 3 files in a folder and told MPC-HC to play the subtitles.
The hexadecimal color shown above is for bright red.

Not sure how all this helps. Not sure how it plays on anything other than a computer.
But I learned stuff, and it was fun to play with.

Cheers

[jagabo]

Don't count on style files working with all players, especially outside a computer.

[vega69-ux]

I have about 35-40 different multi-languages subtitles to a video.