View Bug Details
|ID||Project||Category||View Status||Date Submitted||Last Update|
|0000981||DCP-o-matic||[All Projects] Bugs||public||2016-10-24 21:36||2017-04-21 09:11|
|Target Version||2.11.0||Fixed in Version|
|Summary||0000981: Merge better-seek branch|
|Tags||No tags attached.|
|Estimated work required||Average|
||Can we then also get rid of the subtitle period stuff? We can ask the parent decoder where we are so only scan the bit we are asked for.|
||Merged in 97d39f46795af78b84d5f7bc9118a188f2864781; need to look at subtitle period code.|
Had some hacks at this in no-subtitle-scan. The first problem is that you no longer definitely know when a subtitle ends.
One can imagine the corner case of an image subtitle which lasts a long time and is being written as a PNG subtitle in the DCP.
You have to know the duration of the subtitle when you write it to the DCP, but if it's written to a FFmpeg file as separate start/end you have to go through all the way to the end of the subtitle to find the end. This would slow things down a lot, but should still work, especially as the scan should only happen once.
Even with short subs though you may have a problem;
subtitle start packet
pass() until end is found, producing maybe 100s of video frames which are (currently) discarded
Either you need to only write the sub when it finishes, or you need to store all these video frames.
Subtitle sources can be "start/end" or "period". Destinations can be time-critical (burn) or non-time-critical (XML).
Start/end burn -> just assume unknown end means "infinity"
Start/end XML -> write subtitle when end is seen
Period burn -> no problem
Period XML -> no problem
Calls by Transcoder to Player are interleaved video,audio,sub,video,audio,sub so the Player has to return a subtitle when it's start has been seen, but not necessarily it's end.
Only way around this would be to allow out-of-order subtitle write calls to Writer, which would in turn mean you have to store them all and sort at the end I think.
||Also, how do you know how far back to go when seeking to frame N, if the subtitle starts before then?|
||Things have changed significantly in this area since merging "back-to-pass" so I'll close this and it can be re-examined later if necessary.|
|2016-10-24 21:36||carl||New Bug|
|2016-10-24 21:37||carl||Priority||normal => high|
|2016-11-02 12:23||carl||Priority||high => immediate|
|2016-11-07 13:20||carl||Note Added: 0001523|
|2016-11-17 01:09||carl||Note Added: 0001548|
|2016-11-17 11:11||carl||Note Added: 0001551|
|2016-11-17 12:00||carl||Note Added: 0001552|
|2016-11-17 12:04||carl||Note Edited: 0001552||View Revisions|
|2016-11-17 20:37||carl||Note Added: 0001553|
|2017-04-21 09:11||carl||Assigned To||=> carl|
|2017-04-21 09:11||carl||Status||new => resolved|
|2017-04-21 09:11||carl||Resolution||open => fixed|
|2017-04-21 09:11||carl||Note Added: 0001634|