[FFmpeg-devel] [PATCH] movtextdec: MPEG4 Part 17 Timed Text Decoder.
philipl at overt.org
Thu Jul 5 18:50:54 CEST 2012
On 05.07.2012 08:06, Yusuke Nakamura wrote:
> I don't recommend you use MPEG4 Part17 as the "short" form.
> MPEG-4 Part17 defines structure of __streaming__ timed text format.
> MPEG-4 Part17 refers to 3GPP TS 26.245 as one example to fragment
> text sample into TTUs.
> (Streaming timed text access unit consists of concatenation of TTUs,
> simple text string + text modifiers.)
> Therefore, if you use MPEG-4 Part17, the decoder should extract text
> (text string + text modifiers) and sample description from TTUs and
> them, or just extract them.
> As long as this decoder decodes only 3GPP or QuickTime form timed
> stream, it is not an MPEG-4 Part17 decoder.
Yes, you make a very valid point. Man, this stuff makes my head hurt. I
stick to "3GPP Timed Text" as the description. Do you have access to
that actually use TTUs? I've never seen one or tools that will write
an mp4 container.
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