[FFmpeg-trac] #11464(avfilter:new): Subtitles extracted out of order 608 TS [out+subcc]

[FFmpeg]

#11464: Subtitles extracted out of order 608 TS [out+subcc]
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             Reporter:  Monquis       |                    Owner:  (none)
                 Type:  defect        |                   Status:  new
             Priority:  minor         |                Component:  avfilter
              Version:  7.1           |               Resolution:
             Keywords:  eia-608 atsc  |               Blocked By:
             Blocking:                |  Reproduced by developer:  0
Analyzed by developer:  0             |
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Description changed by Monquis:

Old description:

> Summary of the bug: Subtitle extraction either mis-orders or completely
> misses initial lines of specific broadcasts. I've noticed it on
> commercials during work on identification, but it may be revealing a
> subtle bug.  The same commercials, during different shows.  If one is
> affected, it seems always affected.  If not, it seems never affected.
> This happens on streams validated using  Cinegy / TsAnalyser (on github).
> This is not canonical validation, but nothing major seems incorrect.
>
> Minor output variation such as spelling can happen of course, but in
> either a clean capture or mildly corrupt the output is consistently out
> of order.
>
> Source: USA ATSC via Hauppauge, captured by (Hauppauge) WinTV or NextPVR
> latest versions.  WinTV retains the caption stream AFAICT, NextPVR muxes
> it into the MPEG. Same output.
>
> How to reproduce:
> ffmpeg.exe -report -n -f lavfi -i
> "movie='subtitles_out_of_order.ts'[out+subcc]" -map s -f SRT
> subtitles_out_of_order.srt

New description:

 Summary of the bug: Subtitle extraction either mis-orders or completely
 misses initial lines of specific broadcasts. I've noticed it on
 commercials during work on identification, but it may be revealing a
 subtle bug.  The same commercials, during different shows.  If one is
 affected, it seems always affected.  If not, it seems never affected.
 This happens on streams validated using  Cinegy / TsAnalyser (on github).
 This is not canonical validation, but nothing major seems incorrect.

 Minor output variation such as spelling can happen of course, but in
 either a clean capture or mildly corrupt the output is consistently out of
 order.  EX:
 According to selecting CC1 in VLC, this should be

 "Okay everyone, our mission is to provide complete, balanced nutrition for
 strength and energy Yay - Woo Hoo!".

 The result instead is:

 14
 00:00:38,672 --> 00:00:40,741
 <font face="Monospace">{\an7}\h\h\hbalanced nutrition
 for strength and energy.</font>

 15
 00:00:40,741 --> 00:00:42,176
 <font face="Monospace">{\an7}Okay everyone, our mission
 \h\h\h\h\h\hYay - Woo Hoo!</font>


 Source: USA ATSC via Hauppauge, captured by (Hauppauge) WinTV or NextPVR
 latest versions.  WinTV retains the caption stream AFAICT, NextPVR muxes
 it into the MPEG. Same output.

 How to reproduce:
 ffmpeg.exe -report -n -f lavfi -i
 "movie='subtitles_out_of_order.ts'[out+subcc]" -map s -f SRT
 subtitles_out_of_order.srt

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Ticket URL: <https://trac.ffmpeg.org/ticket/11464#comment:2>
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