Re: Apple II Music Video - Welcome to the Jungle!!

["Michael J. Mahon" <mjmahon@aol.com>]

Frank M. wrote:
> ugh! maybe it's really not ready for pre-release yet. if the 5.25 comes
> on it's probably because it can't find the path that the program is
> specifying. maybe try and load a single-frame? the BASIC program has
> pretty specific needs in terms of where the frames are located in
> ProDOS. Here's a listing of the frame player program if you want to
> tinker some. lines 150-210 are probably where the problem is.....
>
> 10 REM **********************
> 20 REM *                    *
> 30 REM * Move Movie Frames  *
> 40 REM *  by Frank Milliron *
> 50 REM *                    *
> 60 REM **********************
> 70 REM
> 80  HOME:GR
> 90  POKE  - 16299,0: REM  PAGE 2
> 100  POKE  - 16302,0: REM  FULL SCREEN
>
> 110  FOR N = 1 TO 6826
> 120  IF N < 10 THEN N$ = "000" + STR$ (N): GOTO 150
> 130  IF N >  = 10 AND N < 100 THEN N$ = "00" +  STR$ (N): GOTO 150
> 140  IF N >  = 100 AND N < 1000 THEN N$ = "0" +  STR$ (N): GOTO 150
> 145 n$=str$(n)
>
> 150 if n < 1501 then ?chr$(4)+"PREFIX /HD/GNR.PART1":goto 210
> 160 if n > 1500 and n < 3001 then ?chr$(4)+"PREFIX /HD/GNR.PART2":goto
> 210
> 170 if n > 3000 and n < 4501 then ?chr$(4)+"PREFIX /HD/GNR.PART3":goto
> 210
> 180 if n > 4500 and n < 6001 then ?chr$(4)+"PREFIX /HD/GNR.PART4":goto
> 210
> 190 if n > 6000 then ?chr$(4)+"PREFIX /HD/GNR.PART5"
>
>
> 210 print chr$(4)+"BLOAD FRAME."+n$+",A$800"
>
> 220  NEXT N
> 230  TEXT:HOME:END

Now that I read this more carefully, I see that you are *changing*
the prefixes every 1500 frames...

Since each frame is 2KB, and a ProDOS file can be up to 16MB long,
8000 frames would fit in a single file (in the same directory as
the program).

Instead of computing a new name for each file, use one file and
compute the byte offset to do the BSAVE or BLOAD of $800 bytes.
After each "page" is written or read, bump the byte offset by
2048.

This will greatly simplify the program, and should also speed
up the file opens, since the directory entry will be buffered
by ProDOS.

In fact, a very simple machine language program could do this
with very little file system overhead by simply reading successive
2048-byte chunks of the file into the graphics buffer.

You could also turn off "mixed" mode and use both graphics pages,
so that one page is displayed while the other is being loaded,
for much smoother animation.

-michael

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