From 077f84ac1f89770faf8b8af7c0856ec765906a89 Mon Sep 17 00:00:00 2001 From: Jan Schmidt Date: Mon, 27 Aug 2007 14:33:59 +0000 Subject: dvdspu element donated by Fluendo. It implements a DVD Sub-Picture Original commit message from CVS: * configure.ac: * gst/dvdspu/.cvsignore: * gst/dvdspu/Notes.txt: * gst/dvdspu/gstdvdspu-render.c: (dvdspu_recalc_palette), (dvdspu_update_palettes), (dvdspu_clear_comp_buffers), (dvdspu_get_nibble), (dvdspu_get_rle_code), (dvdspu_draw_rle_run), (rle_end_x), (dvdspu_render_line), (dvdspu_update_chgcol), (dvdspu_render_line_with_chgcol), (dvdspu_blend_comp_buffers), (gstdvdspu_render_spu): * gst/dvdspu/gstdvdspu.c: (dvdspu_base_init), (dvdspu_class_init), (dvdspu_init), (dvdspu_clear), (dvdspu_dispose), (dvdspu_finalize), (dvdspu_flush_spu_info), (dvdspu_buffer_alloc), (dvdspu_src_event), (dvdspu_video_set_caps), (dvdspu_video_proxy_getcaps), (dvdspu_video_event), (dvdspu_video_chain), (dvspu_handle_vid_buffer), (dvdspu_redraw_still), (gstdvdspu_parse_chg_colcon), (dvdspu_exec_cmd_blk), (dvdspu_finish_spu_buf), (dvdspu_setup_cmd_blk), (dvdspu_handle_new_spu_buf), (dvdspu_handle_dvd_event), (dvdspu_dump_dcsq), (dvdspu_advance_spu), (dvdspu_check_still_updates), (dvdspu_subpic_chain), (dvdspu_subpic_event), (dvdspu_change_state), (gstdvdspu_plugin_init): * gst/dvdspu/gstdvdspu.h: dvdspu element donated by Fluendo. It implements a DVD Sub-Picture Unit, decoding and overlaying DVD subtitles and menu graphics. * gst/mpeg2sub/.cvsignore: * gst/mpeg2sub/Makefile.am: * gst/mpeg2sub/Notes.txt: * gst/mpeg2sub/gstmpeg2subt.c: * gst/mpeg2sub/gstmpeg2subt.h: * gst/mpeg2sub/mpeg2subt.vcproj: Delete old and broken mpeg2subt element that was never ported from 0.8 --- gst/mpeg2sub/Notes.txt | 324 ------------------------------------------------- 1 file changed, 324 deletions(-) delete mode 100644 gst/mpeg2sub/Notes.txt (limited to 'gst/mpeg2sub/Notes.txt') diff --git a/gst/mpeg2sub/Notes.txt b/gst/mpeg2sub/Notes.txt deleted file mode 100644 index a0e56e3c..00000000 --- a/gst/mpeg2sub/Notes.txt +++ /dev/null @@ -1,324 +0,0 @@ - - DVD subtitles - --------------- - - - 0. Introduction - 1. Basics - 2. The data structure - 3. Reading the control header - 4. Decoding the graphics - 5. What I do not know yet / What I need - 6. Thanks - 7. Changes - - - - - -The latest version of this document can be found here: -http://www.via.ecp.fr/~sam/doc/dvd/ - - - - - -0. Introduction - - One of the last things we missed in DVD decoding under my system was the -decoding of subtitles. I found no information on the web or Usenet about them, -apart from a few words on them being run-length encoded in the DVD FAQ. - - So we decided to reverse-engineer their format (it's completely legal in -France, since we did it on interoperability purposes), and managed to get -almost all of it. - - - - - -1. Basics - - DVD subtitles are hidden in private PS packets (0x000001ba), just like AC3 -streams are. - - Within the PS packet, there are PES packets, and like AC3, the header for the -ones containing subtitles have a 0x000001bd header. - As for AC3, where there's an ID like (0x80 + x), there's a subtitle ID equal -to (0x20 + x), where x is the subtitle ID. Thus there seems to be only -16 possible different subtitles on a DVD (my Taxi Driver copy has 16). - - I'll suppose you know how to extract AC3 from a DVD, and jump to the -interesting part of this documentation. Anyway you're unlikely to have -understood what I said without already being familiar with MPEG2. - - - - - -2. The data structure - -A subtitle packet, after its parts have been collected and appended, looks -like this : - - +----------------------------------------------------------+ - | | - | 0 2 size | - | +----+------------------------+-----------------+ | - | |size| data packet | control | | - | +----+------------------------+-----------------+ | - | | - | a subtitle packet | - | | - +----------------------------------------------------------+ - -size is a 2 bytes word, and data packet and control may have any size. - - -Here is the structure of the data packet : - - +----------------------------------------------------------+ - | | - | 2 4 S0+2 | - | +----+------------------------------------------+ | - | | S0 | data | | - | +----+------------------------------------------+ | - | | - | the data packet | - | | - +----------------------------------------------------------+ - -S0, the data packet size, is a 2 bytes word. - - -Finally, here's the structure of the control packet : - - +----------------------------------------------------------+ - | | - | S0+2 S0+4 S1 size | - | +----+---------+---------+--+---------+--+---------+ | - | | S1 |ctrl seq |ctrl seq |..|ctrl seq |ff| end seq | | - | +----+---------+---------+--+---------+--+---------+ | - | | - | the control packet | - | | - +----------------------------------------------------------+ - -To summarize : - - - S1, at offset S0+2, the position of the end sequence - - several control sequences - - the 'ff' byte - - the end sequence - - - - - -3. Reading the control header - -The first thing to read is the control sequences. There are several -types of them, and each type is determined by its first byte. As far -as I know, each type has a fixed length. - - * type 0x01 : '01' - 1 byte - it seems to be an empty control sequence. - - * type 0x03 : '03wxyz' - 3 bytes - this one has the palette information ; it basically says 'encoded color 0 - is the wth color of the palette, encoded color 1 is the xth color, aso. - - * type 0x04 : '04wxyz' - 3 bytes - I *think* this is the alpha channel information ; I only saw values of 0 or f - for those nibbles, so I can't really be sure, but it seems plausable. - - * type 0x05 : '05xxxXXXyyyYYY' - 7 bytes - the coordinates of the subtitle on the screen : - xxx is the first column of the subtitle - XXX is the last column of the subtitle - yyy is the first line of the subtitle - YYY is the last line of the subtitle - thus the subtitle's size is (XXX-xxx+1) x (YYY-yyy+1) - - * type 0x06 : '06xxxxyyyy' - 5 bytes - xxxx is the position of the first graphic line, and yyyy is the position of - the second one (the graphics are interlaced, so it helps a lot :p) - -The end sequence has this structure: - - xxxx yyyy 02 ff (ff) - - it ends with 'ff' or 'ffff', to make the whole packet have an even length. - -FIXME: I absolutely don't know what xxxx is. I suppose it may be some date -information since I found it nowhere else, but I can't be sure. - - yyyy is equal to S1 (see picture). - - -Example of a control header : ----- -0A 0C 01 03 02 31 04 0F F0 05 00 02 CF 00 22 3E 06 00 06 04 E9 FF 00 93 0A 0C 02 FF ----- -Let's decode it. First of all, S1 = 0x0a0c. - -The control sequences are : - 01 - Nothing to say about this one - 03 02 31 - Color 0 is 0, color 1 is 2, color 2 is 3, and color 3 is 1. - 04 0F F0 - Colors 0 and 3 are transparent, and colors 2 and 3 are opaque (not sure of this one) - 05 00 02 CF 00 22 3E - The first column is 0x000, the last one is 0x2cf, the first line is 0x002, and - the last line is 0x23e. Thus the subtitle's size is 0x2d0 x 0x23d. - 06 00 06 04 E9 - The first encoded image starts at offset 0x006, and the second one starts at 0x04e9. - -And the end sequence is : - 00 93 0A 0C 02 FF - Which means... well, not many things now. We can at least verify that S1 (0x0a0c) is - there. - - - - - -4. Decoding the graphics - - The graphics are rather easy to decode (at least, when you know how to do it - it - took us one whole week to figure out what the encoding was :p). - - The picture is interlaced, for instance for a 40 lines picture : - - line 0 ---------------#---------- - line 2 ------#------------------- - ... - line 38 ------------#------------- - line 1 ------------------#------- - line 3 --------#----------------- - ... - line 39 -------------#------------ - - When decoding you should get: - - line 0 ---------------#---------- - line 1 ------------------#------- - line 2 ------#------------------- - line 3 --------#----------------- - ... - line 38 ------------#------------- - line 39 -------------#------------ - - Computers with weak processors could choose only to decode even lines - in order to gain some time, for instance. - - - The encoding is run-length encoded, with the following alphabet: - - 0xf - 0xe - 0xd - 0xc - 0xb - 0xa - 0x9 - 0x8 - 0x7 - 0x6 - 0x5 - 0x4 - 0x3- - 0x2- - 0x1- - 0x0f- - 0x0e- - 0x0d- - 0x0c- - 0x0b- - 0x0a- - 0x09- - 0x08- - 0x07- - 0x06- - 0x05- - 0x04- - 0x03-- - 0x02-- - 0x01-- - 0x0000 - - '-' stands for any other nibble. Once a sequence X of this alphabet has - been read, the pixels can be displayed : (X >> 2) is the number of pixels - to display, and (X & 0x3) is the color of the pixel. - - For instance, 0x23 means "8 pixels of color 3". - - "0000" has a special meaning : it's a carriage return. The decoder should - do a carriage return when reaching the end of the line, or when encountering - this "0000" sequence. When doing a carriage return, the parser should be - reset to the next even position (it cannot be nibble-aligned at the start - of a line). - - After a carriage return, the parser should read a line on the other - interlaced picture, and swap like this after each carriage return. - - Perhaps I don't explain this very well, so you'd better have a look at - the enclosed source. - - - - - -5. What I do not know yet / What I need - -I don't know what's in the end sequence yet. - -Also, I don't know exactly when to display subtitles, and when to remove them. - -I don't know if there are other types of control sequences (in my programs I consider -0xff as a control sequence type, as well as 0x02. I don't know if it's correct or not, -so please comment on this). - -I don't know what the "official" color palette is. - -I don't know how to handle transparency information. - -I don't know if this document is generic enough. - -So what I need is you : - - - if you can, patch this document or my programs to fix strange behaviour with your subtitles. - - - send me your subtitles (there's a program to extract them enclosed) ; the first 10 KB - of subtitles in a VOB should be enough, but it would be cool if you sent me one subtitle - file per language. - - - - - -6. Thanks - - Thanks to Michel Lespinasse for his great help on understanding -the RLE stuff, and for all the ideas he had. - - Thanks to mass (David Waite) and taaz (David I. Lehn) from irc at -openprojects.net for sending me their subtitles. - - - - - -7. Changes - - 20000116: added the 'changes' section. - 20000116: added David Waite's and David I. Lehn's name. - 20000116: changed "x0" and "x1" to "S0" and "S1" to make it less confusing. - - - - --- -Paris, January 16th 2000 -Samuel Hocevar -- cgit v1.2.1