╔═--------------------- -- -- -- | Video on Spectrum. | -- -- -- -----------------------═╝ (c)Lynx/Infotek Continuation of the story about the video. Beginning in Plutonium#9 Interlaced video and a little video compression theory MPEG. In the above issue of our newspaper we discussed the highest quality video output on the Spectrum screen - video output in high- com permission. Yes, it's high qualityoutput video to screen, but it is not acceptable for long ro- faces Another widespread best interlaced video - video, the frames of which are displayed on the screen through line. Accordingly, both in memory and on disk image data takes up two times smaller than the screen - 3O72 bytes (#COO). How to 'create' this image on Spectrum? Of course, first you need have the source - frames of the converted video deo. Next you need to thin them out through the line - Interlace. Those. take an image from the screen through a line. This can be done easily make in my Firestarter program. Next you need to read these files into the page memory and then upload it to disk images of these pages. The following table will help you with your calculations: ╔═══════+════════════+════════╗ ║ Frame | Page | address ║ +-------+-----------+--------+ ║ 1. | O(#1O) | #COOO ║ ║ 2. | | #CCOO ║ ║ 3. | | #D9OO ║ ║ 4. | | #EbOO ║ ║ 5. | | #F2OO ║ ║ 6. | 1 (#11) | #COOO ║ ║ 7. | | #CCOO ║ ║ 8. | | #D9OO ║║ 9. | | #EbOO ║ ║ 1O. | | #F2OO ║ ║ 11. | 3 (#13) | #COOO ║ ║ 12. | | #CCOO ║ ║ 13. | | #D9OO ║ ║ 14. | | #EbOO ║ ║ 15. | | #F2OO ║ ║ 16. | 4 (#14) | #COOO ║ ║ 17. | | #CCOO ║ ║ 18. | | #D9OO ║ ║ 19. | | #EbOO ║ ║ 2O. | | #F2OO ║ ║ 21. | 6 (#16) | #COOO ║ ║ 22. | | #CCOO ║ ║ 23. | | #D9OO ║ ║ 24. | | #EbOO ║ ║ 25. | | #F2OO ║ ║ 26. | 7 (#17) | #COOO ║ ║ 27. | | #CCOO ║ ║ 28. | | #D9OO ║ ║ 29. | | #EbOO ║ ║ 3O. | | #F2OO ║ ╚══════════════════════════ Next, based on this data we need draw up a table by which the ori- ent your video output routine. It is necessary to do it sl. thus: db frame address, page number,... For example: db #COOO,#13,#CCOO,#13,#D9OO,#13...After the construction of the table is completed of course we need to create an algorithm that similar to the one in number 9 of ours newspapers. But the procedure for outputting the inter- leysen frame of video onto the screen (data must be sprite sized 32*12). :Interlaced screen print :(c)Infotek INTSCR LD L,ХOOOO LD DE,#ЧOO1 LD VS,6144 LD(HL),L LDIR LD HL,#DBOO :Buffer in memory LD DE,#ХОOO :Where to withdraw LD B,#6O INT1 PUSH BC,DE LD Sun,#2O LDIR POP DE INC D INC D LD A,D AND 7 JR NZ,INT2 LD A,D SUB8 LD D,A LD A,E ADD A,32 LD E,A JR NC,INT2 LD A,D ADD A,8 LD D,A INT2 POP Sun DJNZ INT1 RET Here. Now let's talk about where this The video has already been used. Dems to list quite difficult, but the most striking ob- The video size in this format has Deme Power Up. There's a pretty good video there. Occupies it is there the entire disk and is read directly by the one with VG93. And it's quite readable quickly. This is one option. Other, also inter- I saw this video in the Refresh demo - there the video is removed from memory, and then I, as it is displayed, loads itself dema. Other interlaced video options - this is scaling the sprites twice via pixel. This video is awesome but not enough (1248 bytes per frame). This time it's all about the video.In the next but- At least the video will be reviewed in chunks (pixels 4*4). ╔╗ ╔╗ ═══════════════╝║╔═╗║╚═════════════════ ╚╝ ╚╝ Just a little compression theory comparison method (MPEG) TheMPEGmethod is a method compression of information by recording only changed bytes. For a certain video this is very A useful and effective compression method. The method is as follows: Two frames are taken. First frame in the video is taken as the basis for the entire video. He broke is divided into sectors (for example, 64 bytes). Next, these two frames are compared and recorded only the differences between the second frame and first. This then happens with every frame. You may ask: why split the frame into sections? For what's changing byte was not three bytes (2 bytes - address, 3 - the byte itself), and only two (1 byte - but- measures the sector and the byte in it, 2 - the byte itself). This method allowspack vi- deo in decent volumes. For example - ro- face at the beginning of the game Kobuhoba MegaBoom in ZOO frames (or so) takes 3O kilo- byte (!!!). By the way Kovinov is the first to invent and I used this format on Specky!!! So don't let your mouth water!!! Well, finally everything...
Video on the Spectrum - Continuation of the story about the video. Start in Plutonium #9 Interlaced video and a little theory of MPEG video compression.
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