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Extremely small ASS/SSA subtitle appearance on android


nishwahareesh
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nishwahareesh

InkedScreenshot_20210109-204415_Emby_LI.thumb.jpg.045a053ef178df75b9a41979b1295e3a.jpg

and no i doubt its the subtitle itself since it appears perfectly sized in other players

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pwhodges

What version are you running?  There were subtitle size issues with a beta a little while back (when they first changed to using Exoplayer), but they got resolved.

Paul

Edited by pwhodges
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nishwahareesh
21 minutes ago, pwhodges said:

What version are you running?  There were subtitle size issues with a beta a little while back (when they first changed to using Exoplayer), but they got resolved.

Paul

Emby for android 3.1.73

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pwhodges

Hmm.  I have the same version.  My subs are much bigger than yours (though considerably smaller than the correct font would show).

It is transcoding for me, because my Android device can't handle 10-bit HEVC, and the server is set to extract subs and pass them separately.  If I disable extraction, making the server burn the subs in, then the subs are the right size although the font remains wrong (the server can't do ASS properly either).

Emby isn't capable of passing the ASS fonts to the client (which are correctly attached in the video file), or using them in the Exo player, at least.

Paul

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nishwahareesh
2 hours ago, pwhodges said:

Hmm.  I have the same version.  My subs are much bigger than yours (though considerably smaller than the correct font would show).

It is transcoding for me, because my Android device can't handle 10-bit HEVC, and the server is set to extract subs and pass them separately.  If I disable extraction, making the server burn the subs in, then the subs are the right size although the font remains wrong (the server can't do ASS properly either).

Emby isn't capable of passing the ASS fonts to the client (which are correctly attached in the video file), or using them in the Exo player, at least.

Paul

yeah transcoding increases the sub size but i gotta sacrifice video quality for that 

any fix for the small appearance?

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pwhodges

Well, not from me - I'm just another user like you.

But I'm seeing that other videos with ASS subs are displaying them substantially larger than this one does.

As I do a fair amount of work adapting subtitles for my own use (I'm just converting PGS subs for 83 episodes to ASS for one series), I'll try to find what's different for your subs from the others I've got.  If I find anything, maybe it will help the devs fix it - but I can't guarantee to see the crucial thing, of course...

Paul

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pwhodges

Right, I've found the reason - but I don't know the SSA/ASS spec to know what's actually specified.

What's actually happening is this: The subtitles file contains a line specifying the resolution that the subtitles are defined for, and the other dimensions - margins, font size, etc are related to this.  Now consider the three cases I have looked at...

(1) My own subtitles for a series which is 1520x1080 resolution (actually1420x1080 with slight pillarboxing for a good reason).  The file specifies the resolution 1520x1080 with the lines:
     PlayResX: 1520
     PlayResY: 1080
and my default text size is 65 (pt, presumably though the program doesn't say). This gives good size subs, similar to your Netflix clip in a standalone player (it's the same font even!).

(2) The provided subs in a random video I downloaded.  The video is 1920x1080, but the subtitles file gives the PlayRes values as 640x360.  The font size is 26, and the subs are a decent size, similar to the previous.  

(3) Your Netflix clip.  In this, the video size is actually 1440x1080 - but the resolution is not specified in the file - there are no PlayRexX or PlayRexY values.  The font size is 21.  These subs show as expected in standalone players, and when burned in by the Emby server, but the Emby Android client (only) gets them wrong.

The proportions of the error in the last case make me propose the following mechanism: The font size and PlayRes values need to be in proportion for the subs to appear the same size on the screen regardless of the actual source or screen resolution - so case cases (1) and (2) have PlayRes values which are different in the ratio 3:1 and the font sizes are also in the ratio 3:1 (roughly, but the fonts are different).  In case (3) there is no PlayRes specified, so the subtitle renderer needs to assume a value to do its calculations.  Given the font size specified and the fact that other players are happy with it, they must be assuming PlayRes values similar to my case (2) as default values to be used if not specified - but it seems that the Emby Android client is assuming the source or screen resolution as the values that are missing, which being three times bigger is making the subtitles appear a third of the desired size.  (I conjecture that your screen is probably a higher resolution than mine, which is why the error is even worse on yours than mine.)

@Luke I hope this is helpful! (along with the OP's sample clip)

Paul

Edited by pwhodges
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pwhodges

I modified the clip to have four sets of subtitles, with the names showing the values used (the 0x0 subs have no Playres specified, as the original).  It seems to me that the sub size when 480x360 is assumed are the most likely to be correct, and the size with no values is too big (when played in VLC).  But they demonstrate the errors which occur when the PlayRes and font size are not correctly in proportion - and that assuming 480x360 when no values are present is likely to give the right answer.

As I said, I don't know if this is specified anywhere, nor do I know how common it is for this value to be missing in the source file for the subs.

Paul

One Piece - S01E001 - I`m Luffy! The Man Who`s Gonna Be King of the Pirates! .mkv

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