Soft subtitle pass-through (especially for m4v to m4v)

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Kem
Posts: 37
Joined: Tue Nov 10, 2009 2:55 pm

Soft subtitle pass-through (especially for m4v to m4v)

Post by Kem »

It would be great if Handbrake could support soft subtitle pass-through. Especially for m4v --> m4v.

Example:
You have a high quality m4v (SVN2907) file with soft subtitles (tx3g) for your HTPC. If you want to re-encode a file for you iPhone, the subtitle stream gets lost.

I know that there is no pass-through for video and audio (except AC3), but at least these you can easily re-encode via Handbrake. Demuxing and re-adding the subtitle file in Handbrake doesn't work either, because m4v uses tx3g subtitle streams (I think). I'm sure you can do it somehow with other tools, but even that is more difficult than with mkv's srt subtitles.

If m4v soft subtitle pass-through doesn't fit within Handbrake's philosophy, maybe you could just add support for tx3g import (like srt today). At least then you can more easily re-import your demuxed subtitles (although I'm still looking for a tool that can do this).
eddyg
Veteran User
Posts: 798
Joined: Mon Apr 23, 2007 3:34 am

Re: Soft subtitle pass-through (especially for m4v to m4v)

Post by eddyg »

Good idea - ideally we'd allow pass-through of any of the input video/audio/subtitle/metadata. It's just a matter of getting around to it.

The way subtitle pass-through would have to work is to read the input subs into HBs internal representation, and then reencode them using the desired output options (e.g. if the conversion is MP4 to MKV). Getting the text wouldn't be that hard, but parsing all the tx3g atoms and then adding the <i> tags would be a bit of a pain, not impossible.

The key thing is finding a developer interested in doing this, and having the time to do it. I have neither at the moment.

Cheers, Ed.
jbjoret
Regular User
Posts: 100
Joined: Sat Feb 16, 2008 12:08 pm

Re: Soft subtitle pass-through (especially for m4v to m4v)

Post by jbjoret »

If you are on a Mac, you can use Subler. In addition to add Tags, Artwork etc, Subler will allow you to add a subtitle track as well as chapters. Actually it is completing what you do with Handbrake. Having both separately is also not a bad thing. Subler will add your subtitle file as a track within seconds.
crestedpenguin
Posts: 2
Joined: Tue May 04, 2010 6:32 pm

Re: Soft subtitle pass-through (especially for m4v to m4v)

Post by crestedpenguin »

In addition to soft subtitle passtrough it would be nice to have an interface to convert vobsub to text subtitles. I've written a tool that converts an image with DVD subtitles to text. Today I'm using lots of scripting using the following tools:
- mkvextract
- tccat
- tcextract
- subtitle2pgm
- imagemagick
- subocr (my simple DVDSub OCR)
- subler

This works, but seems to be too complex for most users. Having an interface to integrate an "OCR" for image->text recognition could simplify this for many users.
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Rodeo
HandBrake Team
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Joined: Tue Mar 03, 2009 8:55 pm

Re: Soft subtitle pass-through (especially for m4v to m4v)

Post by Rodeo »

crestedpenguin wrote:This works, but seems to be too complex for most users. Having an interface to integrate an "OCR" for image->text recognition could simplify this for many users.
You mean in HandBrake? This is hardly feasible given HB's interface. IMO this is best left to other tools.
alehel
Regular User
Posts: 83
Joined: Wed Feb 14, 2007 11:08 am

Re: Soft subtitle pass-through (especially for m4v to m4v)

Post by alehel »

It sure would be great to have OCR, but not in handbrake. It would be hard to implement into the interface and also make it bloated. OCR tools for Mac certainly would be nice though, as there isn't really any good alternatives at the moment. I used to have windows installed on my Mac purely for doing PGS -> sub -> srt, but it was a major pain to do, so I gave up on it. Having a nice Mac GUI program would be great and would mean I'd start doing it again. I'm aware of places like opensubtitles.org, but I want Norwegian subtitles and the majority of the ones on the net are created using computer generated translations of the english srt files, and are absolutely terrible.
Norrin
Posts: 2
Joined: Mon May 10, 2010 3:23 am

Re: Soft subtitle pass-through (especially for m4v to m4v)

Post by Norrin »

From this discussion, I see that HB cannot convert DVD vobsubs to TX3G track on mp4 container.
But why does that seem to be exactly what is described in the HB wiki that was written 6 months ago?

"HandBrake can use subtitles tracks as INPUT from the following sources:
• From DVD’s – Either VOBSUB or CC tracks.
• User supplied SRT files. "

"HandBrake has two methods of subtitle OUTPUT:
• Hard Burn: This means the subtitles are written on top of the image permanently. They cannot be turned on or off like on the DVD.
• Soft Subtitles: This means the subtitles will appear as separate selectable tracks in your output file. With the correct playback software, you’ll be able to enable / disable these subtitles as required."

http://trac.handbrake.fr/wiki/Subtitles

It's written there, however I used it and I have YET to get the subtitles to appear using vlc or divx player. Either I haven't found the right player yet, or they're not actually there.

In short, I'm seeing contradictions. Can HB 0.9.4 convert vobsubs to track-based (not hard burn-in) mp4 (TX3G?)? If so, what player is needed in order to play them?
TedJ
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Re: Soft subtitle pass-through (especially for m4v to m4v)

Post by TedJ »

Norrin wrote:In short, I'm seeing contradictions. Can HB 0.9.4 convert vobsubs to track-based (not hard burn-in) mp4 (TX3G?)? If so, what player is needed in order to play them?
One would argue that the entry on the wiki is ambiguous and you're choosing to read it as such, but that it beside the point.

HB cannot turn DVD vobsubs into a text subtitle track as this would require OCR (optical character recognition) - vobsubs are are stored as images in the MPEG program stream, hence their alternative title subpics. OCR for this application is notoriously flaky and always requires human supervision and/or post rip editing and corrections.

By the same token, HB cannot take a text based subtitle source (CC from DVD, SRT, etc.) and hardsub them into the encoded video, because this would require a resolution independent font rendering engine.
Bling2Ming
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Posts: 104
Joined: Mon Dec 29, 2008 10:03 pm

Re: Soft subtitle pass-through (especially for m4v to m4v)

Post by Bling2Ming »

@ Norrin

Are you aware that DVD sourced vobsubs are indeed, supported as soft subs by HB, as long as the container you are encoding to is MKV?


Which IMO makes the wiki entry substantially correct.
Norrin
Posts: 2
Joined: Mon May 10, 2010 3:23 am

Re: Soft subtitle pass-through (especially for m4v to m4v)

Post by Norrin »

Thank you so much for your replies.
I spent basically all of yesterday trying to figure out why I could not view these subtitles. media player classic is detecting that there is a subtitle track. Then I found this tutorial and followed it (the part about using UltraEdit to replace "text" with "sbtl"), afterwards the video player on the iPad detected the subtitle stream as well. Except for when enabled, there were still no subtitles.

At first I thought the subtitle functionality in HB was broken, due to this part of the wiki (seemingly) explicitly saying subs could be put in a mp4 container, I kept trying at it.

"Subtitle Outputs
. . . .
Bitmap (VOBSUB)
o With MP4, you can burn ONLY 1 subtitle track into the video.
o With MP4, you can not pass-through VOBSUB tracks.
o With MKV, you can pass-through multiple VOBSUB tracks. These are not burned into the video unless you choose to do so however you can only burn 1 subtitle track into the file. The rest must be passed through."

This is confusing at best, misleading at worst. VOBSUB is listed under Outputs. MP4 is listed under VOBSUB. It says it cannot be passed-through, which did confuse me. But I had no reason to believe that HB would not convert into this MP4 that it says it "CAN burn only 1 subtitle track [into the video]"

Bad day for me. Anyways thanks. Maybe MKV would be better for backing-up DVDs....
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