Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.sys.sinclair > #2519

Re: Speccy video player in C?!!

Show all headers | View raw

On 10/02/2011 13:09, BitNaughty wrote:
> On Feb 9, 4:04 am, Matthew Westcott<gas...@raww.org>  wrote:
>> On 08/02/2011 14:20, BitNaughty wrote:
>>
>> 3) Compare that screen with the previous one*, making a list of all the
>> runs of continuous bytes that differ between them (but with some tricky
>> special cases: for example, if you've got two runs that are only a few
>> bytes apart, it's better to treat them as one long run rather than
>> having the extra overhead of reading two data chunks)
>
> OK, so this is something like LZW GIF compression, if I understand it
> correctly, am I right......?

It's a bit simpler than that... LZW is all about building up a 
dictionary of the strings you've encountered so far in the 
compression/decompression, so that if you find a repeating pattern you 
can just refer back to the last place it appeared, rather than storing 
it in full. Here there's nothing like that - the rule is just "only 
store the bits of screen that have changed".

>> keep a
>> rough count of how long it's going to take the Spectrum to process the
>> stuff you're generating, so that you can pick out the right sample from
>> the audio stream that will be played at that point.
>
> This sounds amazing! How do you do this?

Well, this is the point at which the cleverness ends and the tedious 
messy code begins :-) Best to just look at the code - the 
delta_compressor_pack_deltas function in
https://github.com/gasman/divideo/blob/master/c/delta_compressor.c
is where we keep count of timings (in the variable frame_time).

Back to comp.sys.sinclair | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Re: Speccy video player in C?!! Matthew Westcott <gasman@raww.org> - 2011-02-04 12:29 +0000
  Re: Speccy video player in C?!! "Paul E Collins" <find_my_real_address@CL4.org> - 2011-02-10 21:53 +0000
    Re: Speccy video player in C?!! "Daniel Mandic" <daniel_mandic@hotmail.com> - 2011-02-10 22:29 +0000
  Re: Speccy video player in C?!! Matthew Westcott <gasman@raww.org> - 2011-02-11 00:17 +0000
    Re: Speccy video player in C?!! Matthew Westcott <gasman@raww.org> - 2011-02-13 16:26 +0000
  Re: Speccy video player in C?!! Matthew Westcott <gasman@raww.org> - 2011-02-08 23:04 +0000
    Re: Speccy video player in C?!! BitNaughty <bit-naughty@hotmail.com> - 2011-02-10 05:09 -0800
  Re: Speccy video player in C?!! BitNaughty <bit-naughty@hotmail.com> - 2011-02-08 06:20 -0800

csiph-web