Subtitles running out of sync on Channel 4 channels

[notapom]

The past few months the subtitles on channel 4 channels have been out of sync. They start ok, it's just when there is a pause in dialogue, the subtitles seem to not hold a pause the same length as the pause in dialogue and begin to run early.

In order the get the subtitles back into sync, I have to rewind or forward, instant replay or skip forward doesn't sync the subs. The subs then again start falling behind at the next pause in dialogue.

It might be more than just the channel 4 group, definitely doesn't happen on BBC channels.

This is happens when watching live, time delayed or recorded.

Any idea on a cause?

 

[Black Hole]

If you plug keywords "subtitle" and "sync" into the forum search tool, you'll find this is a well-worn subject of complaint. The most relevant discussion appears to be this one: https://hummy.tv/forum/threads/subtitle-sync-problem.9479/, and the most useful work-around:

If you have a Firestick 4k you can resolve the problem by watching via the Firestick as DLNA. (No need to decrypt)

Install 'Archos Video Player' (which is free) on the Firestick and set the default player within Archos to 'MX Player' (also free). Also set within MX Player to always use SW decoder because if you use HW decoder it will just freeze. (Use the 'Legacy Mode' within Archos, you will see what I mean if you decide to try this route)

I have been using the above method for yonks and the subs do not go out of sync and you do not lose ffwd/rw functions.

As that particular thread only dates back to 2019, it occurs to me that if this is a relatively recent phenomenon (no guarantees - do your own reading of the archive via search as suggested above) it might have been some incompatibility the broadcasters have introduced, or a defect introduced by a Humax firmware revision.

 

[MartinLiddle]

As that particular thread only dates back to 2019, it occurs to me that if this is a relatively recent phenomenon (no guarantees.

As someone who has become increasingly reliant on subtitles, I think there have always been issues with subtitles on the HDR-FOX T2 (and the HDR-2000T) with the BBC channels not as badly affected as the commercial channels. My own experience is that subtitles remain perfectly in synch on the FVP-5000T and the Aura and I am told that is also true on the Humax Youview boxes.

 

[MikeSh]

It's a problem with our HDR-FOXs and Freesat 1010, and has been as long as I can remember.
As Martin says BBC not quite as bad, but not immune.

 

[/df]

I last looked at this (see linked thread above) before I'd spent some time trying to get two imported movies working with subtitles. I found that a separate .srt file could be made to work well. In principle it might be possible to extract the broadcast subtitles as .srt but, if (as I recall) they are actually sent as a video overlay, even in the other forum we don't have the wherewithal of either ffmpeg codecs or CPU power to do this.

 

[Black Hole]

if (as I recall) they are actually sent as a video overlay

That is my recollection too.

 

[EEPhil]

That is also my recollection. Along with my inability to extract subtitles from the overlay. Every OCR based extraction has failed spectacularly (for me - maybe I’m just inept ).

 

[fenlander]

Freeview subtitles are transmitted as a DVB stream which is preserved within the .ts file. Assuming you have the .ts file decrypted and downloaded to a pc, the best way I've found to extract the subs and save them as a .srt file is by using 2 free pieces of software - tesseract ocr and Subtitle Edit. Both are free, but the latter is Windows only. Subtitle Edit requires the presence of tesseract in order to perform ocr. Drop the .ts file into Subtitle Edit: it will detect the DVB stream and read it into a fully synchronised editable file that can be saved in a variety of formats.

Obviously, setting the system up to provide the result you want is a little more complicated, but once you've got it sorted, it's quicker to do that it is to explain. The most time-consuming part of the whole process is then doing the decryption and export from the Hummy.

I should also mention Videoredo. It's commercial software and not cheap, but it performs flawless edits allowing invisible removal of ads, lead-ins and lead-outs. It also correctly preserves the DVB subtitle stream while editing (unlike the free alternative, AVIDemux, which discards it). I routinely edit files from ITV/C4 and other commercial channels, first removing the unwanted material from the .ts file and saving the result as .mp4 or .mkv, from which I can then extract an .srt subtitle. I also edit the .srt file to remove stuff I don't want like [DOOR SLAMS] and song lyrics. It's worth mentioning that I've had no synchronisation issues with subtitles extracted in this way, so whatever is causing the glitches in subtitle use on the hummy, I doubt that the programme source is responsible.

On BBC channels, get_iplayer is quicker and simpler. Instead of a DVB stream, subtitles are downloaded as a separate .srt file.

 

[EEPhil]

Assuming you have the .ts file decrypted and downloaded to a pc, the best way I've found to extract the subs and save them as a .srt file is by using 2 free pieces of software - tesseract ocr and Subtitle Edit.

I must be inept. Those are the programs I've tried. I either get complete garbage out or nothing at all. I've given up trying.

 

[/df]

... I've had no synchronisation issues with subtitles extracted in this way, so whatever is causing the glitches in subtitle use on the hummy, I doubt that the programme source is responsible. ...

Indeed, so unless all the broadcasters are sending incorrect streams that every other product has worked around, there's some problem with the Humax player that doesn't correctly render the STTL stream.

...
On BBC channels, get_iplayer is quicker and simpler. Instead of a DVB stream, subtitles are downloaded as a separate .srt file.

Youtube-DL should also be able to do that, which would be within the capability of the CFW platform. Possible issues:

• do the embedded subtitles override the .srt?
• how to identify the iPlayer URL or programme ID corresponding to a recording?

And for ITV too, possibly.

 

[bottletop]

As far as I know the HDR recordings are fine, it's a HDR playback issue.
Eg a work around is to transfer/stream from HDR to secondary device using VLC to view (with synced subtitles).
I've only tried it on laptop, tablet & mobile but it should work for other devices/viewers.

 

[sine24]

As far as I know the HDR recordings are fine, it's a HDR playback issue.
Eg a work around is to transfer/stream from HDR to secondary device using VLC to view (with synced subtitles).
I've only tried it on laptop, tablet & mobile but it should work for other devices/viewers.

The easiest workaround is to skip back 7 seconds when the subtitles unsync and they play fine for a while.

 

[MartinLiddle]

The easiest workaround is to skip back 7 seconds when the subtitles unsync and they play fine for a while.

In my experience that is a reasonable solution for BBC channels but gets very tedious on ITV channels where the problem is more severe and really irritates SWMBO who doesn't need the subtitles.

 

[RichFX]

Since 25th Sept last year much of TV broadcast in UK has been cobbled together from backup locations following the smoke detector incident in the Red Bee play-out centre. Subtitles and audio-description were the main casualties. I'm not sure when full normal service will resume.

Apparently the (possibly not fit for purpose?) shock-wave from the rapid-fill event of the inert-gas fire extinguisher system shattered all the hard disk platters. You can imagine the political and financial blame-game wrangling between insurers, landlord, Red Bee and the broadcasters.

 

[sine24]

Since 25th Sept last year much of TV broadcast in UK has been cobbled together from backup locations following the smoke detector incident in the Red Bee play-out centre. Subtitles and audio-description were the main casualties. I'm not sure when full normal service will resume.

That has already happened. Abt a month ago