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Request for TTML subtitle support (STPP) #7573

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teb opened this issue Mar 31, 2020 · 8 comments
Closed

Request for TTML subtitle support (STPP) #7573

teb opened this issue Mar 31, 2020 · 8 comments
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down-upstream:ffmpeg meta:feature-request

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@teb
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teb commented Mar 31, 2020

I just tested a mp4 file with STPP (TTML) subs and mpv shows it as 0 subs.
Output from mp4box under:

Track # 4 Info - TrackID 4 - TimeScale 1000
Media Duration 02:09:02.400 - Indicated Duration 02:09:02.400
Media Info: Language "Norwegian (nor)" - Type "subt:stpp" - 1825 samples
XML Subtitle Stream - namespace http://www.w3.org/ns/ttml
 Size 0 x 0 - Translation X=0 Y=0 - Layer 0
        RFC6381 Codec Parameters: stpp
        All samples are sync
@jeeb
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jeeb commented Mar 31, 2020

This should be a request towards FFmpeg.

Demuxing these is simple (as long as you remember stpp is "times are offsets from PTS=0, not the sample", and dfxp is "times the sane way, offsets from the sample"), too bad the format is XML and all. Thus I am noting that it is highly unlikely that someone will attempt to make a decoder for this.

@CounterPillow
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Already reported upstream https://trac.ffmpeg.org/ticket/4859

@teb
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teb commented Mar 31, 2020

Well, ffmpeg closed this case years ago, not willing to move it with a cryptic response ;).
TTML is the defacto standard for CMAF in the form of the IMSC1 format which is common for Apple as well as android cmaf. @jeeb Not sure why the resentment for xml ?

@CounterPillow
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Well, ffmpeg closed this case years ago

No they didn't, the ticket is still open.

not willing to move it

because presumably, nobody who isn't getting paid to wants to touch this trash fire of a standard.

@ghost
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ghost commented Apr 1, 2020

Not sure why the resentment for xml ?

Because it's one of the worst pieces of shits ever invented?

@teb
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teb commented Apr 1, 2020

@CounterPillow Ure right! Its still open for business, just got put of on the discussion at the end!
@wm4 that can be

@ghost
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ghost commented Apr 1, 2020

It certainly is. Because XML is so surprisingly complex and messy, and because there's no sane light-weight XML parser, ffmpeg does not well with XML based stuff. On top of this, TTML seems to have its own misdesigned mess on top of it.

@DaDirnbocher DaDirnbocher mentioned this issue Jul 14, 2022
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@3052
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3052 commented Mar 15, 2024 •
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looking at sample from Mubi, it seems easy enough to parse:

<?xml version="1.0" encoding="utf-8"?>
<tt xmlns="http://www.w3.org/ns/ttml"
xmlns:ttm="http://www.w3.org/ns/ttml#metadata"
xmlns:ttp="http://www.w3.org/ns/ttml#parameter"
xmlns:tts="http://www.w3.org/ns/ttml#styling" xml:lang="en"
ttp:profile="http://www.w3.org/ns/ttml/profile/imsc1/text">
  <head>
    <metadata>
      <ttm:title/>
      <ttm:desc/>
      <ttm:copyright/>
    </metadata>
    <styling>
      <style xml:id="basic" tts:backgroundColor="transparent" tts:color="white" tts:fontFamily="proportionalSansSerif" tts:fontSize="16px" tts:textAlign="center"/>
    </styling>
    <layout>
      <region style="basic" xml:id="speaker" tts:displayAlign="center" tts:extent="80% 10%" tts:origin="10% 85%"/>
    </layout>
  </head>
  <body>
    <div xml:lang="en">
      <p begin="00:01:08.000" end="00:01:09.642" region="speaker">Sorry to interrupt your dinner.</p>
      <p begin="00:01:09.666" end="00:01:10.000" region="speaker">Never mind, let's sit over there.</p>
    </div>
  </body>
</tt>

@Sneakpeakcss Sneakpeakcss mentioned this issue Jul 16, 2024
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@VimWei VimWei mentioned this issue Oct 8, 2024
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@jeeb @CounterPillow @teb @3052