[FFmpeg-trac] #2024(undetermined:new): Reencoding dvbsub fails

FFmpeg trac at avcodec.org
Thu Dec 19 15:34:14 CET 2013

#2024: Reencoding dvbsub fails
             Reporter:  cehoyos      |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
              Version:  git-master   |  undetermined
             Keywords:  dvbsub       |               Resolution:
  av_interleaved_write_frame         |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |

Comment (by joolzg):

 Can I add something in so people will understand how DVBSUBS work.

 Dvb subs works on an idea of regions and objects, there are NO CLEAR SUBS
 commands, what is sent is a new region list with 0 regions, there should
 be no code to explicitly send clear screen or anything like this.

 What will happen is this

 New region with 2 objects
 New region with 1 object
 New region with 0 objects
 New region with 1 object

 Now all these new regions have a "timeout" which says that if NO NEW DATA
 arrives then clear the screen as sonething has gone wrong, stream
 corrupted, out of sync etc.

 The current ffmpeg fails in this as it does as posted above and tries to
 create a "clear screen" packet when it SHOULD NOT.

 What should happen is that once encoding it should check the timeout
 perion and if expired send a "New region with 0 objects", this means we
 can remove the hack in ffmpeg which makes up 2 packets when it should not.

Ticket URL: <https://trac.ffmpeg.org/ticket/2024#comment:8>
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