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

JULIAN GARDNER joolzg at btinternet.com
Wed Jun 8 09:29:47 CEST 2011 



>________________________________
>From: Michael Niedermayer <michaelni at gmx.at>
>To: FFmpeg development discussions and patches <ffmpeg-devel at ffmpeg.org>
>Sent: Wednesday, 8 June 2011, 5:15
>Subject: Re: [FFmpeg-devel] {WIP} {HELP} Dvb Subtitles and Hard Subtitles
>
>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 
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>> >> 
>> >> _______________________________________________
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>> >>
>> >
>> >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
>
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Thanks for that, will modify the code and test again.

Now another question. This test is being done on LIVE streams.

Iissue the ffmpeg line without the "-scodec" line everything works as it should.

Issue with the "-scodec dvbsub" AND THERE ARE dvbsubs in the stream again we work, not perfectly.

Issue with the "-scodec dvbsub" AND THERE ARE NO SUBS BEING TRANSMITTED, but the si contains the correct si saying they are there we get a problem.

What seems to be happening is that the new encoded data is being buffered and is waiting for the dvbsub title stream to pass data into the stream, what i see is the status line does not change so we get "time=00:00:00.00 bitrate=0.0kbits/s" and after a while ffmpeg just drops out without an error

joolz

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