[FFmpeg-devel] {WIP} {HELP} Dvb Subtitles and Hard Subtitles

Wed Jun 8 06:15:20 CEST 2011

On Tue, Jun 07, 2011 at 11:56:44PM +0100, JULIAN GARDNER wrote:
> 
> 
> 
> >________________________________
> >From: JULIAN GARDNER <joolzg at btinternet.com>
> >To: FFmpeg development discussions and patches <ffmpeg-devel at ffmpeg.org>
> >Sent: Tuesday, 7 June 2011, 14:00
> >Subject: Re: [FFmpeg-devel] {WIP} {HELP} Dvb Subtitles and Hard Subtitles
> >
> >
> >
> >
> >
> >----- Original Message -----
> >> From: Michael Niedermayer <michaelni at gmx.at>
> >> To: FFmpeg development discussions and patches <ffmpeg-devel at ffmpeg.org>
> >> Cc: 
> >> Sent: Monday, 6 June 2011, 13:34
> >> Subject: Re: [FFmpeg-devel] {WIP} {HELP} Dvb Subtitles and Hard Subtitles
> >> 
> >> On Mon, Jun 06, 2011 at 11:15:32AM +0100, JULIAN GARDNER wrote:
> >>> 
> >>> 
> >>> 
> >>>  >________________________________
> >>>  >From: JULIAN GARDNER <joolzg at btinternet.com>
> >>>  >To: FFmpeg development discussions and patches 
> >> <ffmpeg-devel at ffmpeg.org>
> >>>  >Sent: Sunday, 5 June 2011, 14:58
> >>>  >Subject: [FFmpeg-devel] {WIP} {HELP} Dvb Subtitles and Hard Subtitles
> >>>  >
> >>>  >Ok needing a bit of help here, ive added my current diff in the hope of 
> >> some help from a more knowledgable ffmpeg developer.
> >>>  >
> >>>  >My problem is that i need to get the main output loop to eventually 
> >> call the do_subtitle_out for every frame of video that is produced.
> >>>  >
> >>>  >I have attempted to change the code where the subtitle is decoded, only 
> >> once in the case of dvbsubs, and to output it multiple times, but the output bit 
> >> is still only called once.
> >>>  >
> >>>  >Can anybody help me in getting the loop to make the multiple calls to 
> >> output the subtitles, im trying not to have to write this as a filter, but to 
> >> have the subs placed on the output video plane BEFORE resizing and ENCODING?
> >>>  >
> >>>  >If you think im going about it the wrong way then let me know, and if 
> >> the only way is to produce a filter i will spend my time on that instead.
> >>>  >
> >>>  >So just for clarity i need to get the subs to be copied to the video 
> >> before any resize or encoding is performed, if this works it should be possible 
> >> to take any subs and have them placed on the video.
> >>>  >
> >>>  >also one more problem is that the TS si still has the entry for 
> >> "dvb subs" in its pmt, this will need removing, as i cant see the 
> >> point of having hard subs and soft subs whch are the same.
> >>>  >
> >>>  >joolz
> >>>  >
> >>>  >_______________________________________________
> >>>  >ffmpeg-devel mailing list
> >>>  >ffmpeg-devel at ffmpeg.org
> >>>  >http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> >>>  >
> >>>  >
> >>>  >
> >>> 
> >>>  Ok boys i have the "hards subs" kind of working, but i need some 
> >> help in dumping the subtitles onto the screen in the correct format.
> >>> 
> >>>  I have modified ffmpeg.c and in the routine 
> >> "pre_process_video_frame" i aim to do the dump of the subs, im just 
> >> testing but if i do a memset on the memory pointed at by 
> >> picture->data[0]+x+y*picture->linesize[0] i get my boxes in the correct 
> >> place.
> >>> 
> >>>  What i need to do now is translate the subtitles pixel and clut map into 
> >> the correct format and add this to the plane, now the good point of this is that 
> >> scaling the video works after this.
> >>> 
> >>>  Any help please.
> >> 
> >> for format convert see swscale (maybe libavfilter/vf_scale.c is a
> >> useable example on its useage)
> >> 
> >> for blend/overlay of stuff see vf_overlay.c
> >>     
> >>     
> >> [...]
> >> 
> >> -- 
> >> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
> >> 
> >> The real ebay dictionary, page 2
> >> "100% positive feedback" - "All either got their money back or 
> >> didnt complain"
> >> "Best seller ever, very honest" - "Seller refunded buyer after 
> >> failed scam"
> >> 
> >> _______________________________________________
> >> ffmpeg-devel mailing list
> >> ffmpeg-devel at ffmpeg.org
> >> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> >>
> >
> >OK "Hard Subtitles" working now, test phase to continue but i have a few queries regarding what should be done with certain cases
> >
> >1. dvd-subtitle-problem.vob
> >  This file has a video size of 352x288 but the dvbsubs are being displayed out of this range so my options are
> >    a) Dont render out of visible screen area (current system)
> >    b) Swscale the video to fix the subtitle expected screen size, draw subs, recscale back to original size (lots of cpu)
> >    c) Rescale the subtitles themselves and also the position and then draw on screen (need a new rescaler)
> >
> >2. As i see it .SRT and .SUB decode the subs but dont render them, what would be good would be for all the subtitle engines to render to a bitmap buffer, with clut and regions. If this is the case then we could do things like Hard Subs, Ass->Dvb, Srt-Dvb etc Is this a feasable way forward?
> >
> >3. Xsub seems to work now except for the demo i have being a 720x408 screen and the subtitles are positioned at 174,464, so back to 1
> >
> >I need to do more testing but the problem streams i started with all work well and the subtitles appear where and in the correct colours as they should.
> >
> >I have some encoded files i will put up on my ftp if anyone want to see some examples or the hard subs
> >
> >
> >joolz
> >_______________________________________________
> >ffmpeg-devel mailing list
> >ffmpeg-devel at ffmpeg.org
> >http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> 
> 
> OK boys i have another small problem, which im having trouble finding the cause of?
> 
> 

> When i put "hard subtitles" on the screen i get nice subtitles, but i also get atrifacts around the subtitles which move around the subtitle.

sounds like you write into the reference frames.
theres no alternative than making a copy

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

While the State exists there can be no freedom; when there is freedom there
will be no State. -- Vladimir Lenin
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