View Bug Details

IDProjectCategoryView StatusLast Update
0001581DCP-o-maticBugspublic2021-10-08 00:06
Reportercarl Assigned To 
Status closedResolutionopen 
Target Version2.16.0 
Summary0001581: Burnt-in subtitles sometimes missing from DCP

Content is a MKV and a SRT. MKV has subtitles but they are not being used.

MKV's subtitles finish about 16s before the end of the MKV (let's say at time t). After this point the MKV's decoder reports its position as t forever, since t is found by Decoder::position after it asks the TextDecoder where it is.

This means that the MKV is pass()ed instead of the SRT, so eventually there is a frame of video for which a sub from the SRT has not yet been received.

Additional Information

TagsNo tags attached.
Estimated weeks required
Estimated work requiredUndecided



2019-07-07 22:47

administrator   ~0003381

Can the TextDecoder know that it is "finished" i.e. no more subs will be emitted? I don't think so; here the problematic TextDecoder is being fed by subs muxed into a MKV.


2019-07-07 22:50

administrator   ~0003382

Could FFmpegDecoder ignore subtitles when doing Decoder::position() in the hope that they will be "swept along" by the emissions from video/audio?


2019-07-07 22:51

administrator   ~0003383

We could ignore unused subtitle streams in MKVs but this would just be a sticking plaster and it doesn't solve the underlying problem (and wouldn't solve the case when the MKV's subs were being used).

Bug History

Date Modified Username Field Change
2019-07-07 22:45 carl New Bug
2019-07-07 22:46 carl Description Updated
2019-07-07 22:47 carl Note Added: 0003381
2019-07-07 22:50 carl Note Added: 0003382
2019-07-07 22:51 carl Note Added: 0003383
2019-07-08 00:19 carl Status new => resolved
2019-07-08 00:19 carl Target Version 2.14.x => 2.16.0
2021-10-08 00:06 carl Status resolved => closed