mp4 subtitle font size too small

[trott]

Hi all,

I would like to use mp4 as a container format due to (any time now) standalone player support. However, when generating files (either through yamb or with command-line mp4box) containing subtitle text streams (ttxt) the resulting subtitles are always too small to read on-screen.
This is strange, since I explicitly tell mp4box to use sans-serif, 24-point as font (I understand the default is serif 18 pt).
Still, the resulting subtitles are much too small to read...difficult on pc, impossible on TV. I have verified this by extracting the ttxt file and checking with Notepad: indeed the font size is 24 points but no way is this what I see on-screen...
Is this normal? I get this result both with Haali's and Gabest's splitters...Does anybody know whether it's possible to embed the font in the mp4 file? According to the FAQ this should be possible but I haven't found how to.

[Eviltape]

Does your standalone have SSA or any other subtitle format support?

[trott]

I am still playing back on PC...

[bond]

are the subtitles always the same size on your tv, no matter what font size you set in the mp4 file?

if yes, ask your standalone player producer to fix this

[trott]

A misunderstanding...I'm playing back on my TV using directshow playback with my PC as source. The subs are too small when playing back on either PC or TV, they're just still barely readable on PC and practically unreadable on TV due to the lower resolution.
I did some tests; to get the equivalent of a 24 point font using vsfilter with an srt file I need to give the font 48 points when using timed text in mp4 (and even then even though it's big enough to be readable, it's still smaller than a 24 pt srt file).
Here is a screenshot:

This is a subtitle which looks okay except this was embedded in the mp4 container as Sans-Serif, 48-point. Surely this looks more like a 24 than a 48-point font?

This is wat a 24 point sans-serif font in mp4 looks like:


And this is what a 24-point font looks like when using an srt file:


Surely the last one not only looks better (shaded, smooth) but is the only one of the right size?

[bond]

i think that the haali mp4 splitter might ignore the font size (the haali splitter internally transforms ttxt to srt and gives it as srt to vsfilter)

to get the subtitle shown as you set it in ttxt, you need to use the gabest mp4 splitter together with vsfilter, as vsfilter can decode ttxt directly (but needs ttxt input of course, and thats what gabests mp4 splitter provides)