Author
| PCM player using SCC
|
nikodr
msx addict
Posts: 453 |  Posted: April 14 2008, 16:39 |
Testing it right now.Well there are many files one called fifth_60hz.rom
fth01.bin
fth01.raw
triang_60.rom
which one is the correct?
UPDATE:Guys something strange happened!I closed my msx i rebooted it,and leila worked,just a few seconds of sound,then noise,and repeating the same sounds over and over probably it needs the reset switch.How can i know if the sound is good?
|
|
ARTRAG
msx master
Posts: 1592 | Posted: April 14 2008, 16:43 |
Quote:
| My guess is that its something with the SCC-I rom mapper. I did a quick test in bluemsx and switched SCC mode and Leila K works fine, but running it with the SCC-I mapper didn't work.
|
I tried to load leilaK with scrom in the emulated scc-i with 128K and it started (option -r)
but the sound was terrible and (but this is natural) lasted only few secs |
|
ARTRAG
msx master
Posts: 1592 | Posted: April 14 2008, 16:45 |
hmmm, fifth_60hz.rom
IIRC
|
|
dvik
msx master
Posts: 1302 | Posted: April 14 2008, 16:45 |
|
|
nikodr
msx addict
Posts: 453 | Posted: April 14 2008, 16:46 |
Just tested it.I closed my machine opened it after 1 second and leila was still in ram,sound was not good.
|
|
dvik
msx master
Posts: 1302 | Posted: April 14 2008, 16:47 |
|
|
ARTRAG
msx master
Posts: 1592 | Posted: April 14 2008, 16:47 |
Yes
it seems the good one
both fifth_60hz.rom and sccplay.rom are good
|
|
nikodr
msx addict
Posts: 453 | Posted: April 14 2008, 16:49 |
Right now i am going to load that rom file you said.Strangely enough the ram of scc+ would not clear even after 15 seconds,i opened up msx and msx crashed showing garbagge on screen.It took me 30 seconds of having machine off to clear ram.I loaded the 60hz rom all i could hear was sound of a frequency going down and after a while sounding like some zx spectrum effects from manic miner when you hit and loose.
A sound doing a glissando like effect from higher frequency to a lower one.It sounds like a spectrum
|
|
nikodr
msx addict
Posts: 453 | Posted: April 14 2008, 17:00 |
Artrag if this would help you with your current programming of player,i could send you my scc+ from snatcher so you can do all the tests you want -if you promise me that you will give it back in the future when you wouldnt need it anymore-.
Send me an email if you are interested.I think as an msx programmer it would do you much good to have an original scc+ card to do your tests
|
|
ARTRAG
msx master
Posts: 1592 | Posted: April 14 2008, 17:02 |
thanks a lot but I cannot accept
I appreciate really your kindness
but it is too much responsibility
We will find away to do tests do not worry
|
|
ARTRAG
msx master
Posts: 1592 | Posted: April 14 2008, 17:07 |
I think the problems are in the code that finds the period too
(this is what you have heard)
asap i'll try to send you something that avoids that part of
duties.
Thanks for the tests you did!
|
|
nikodr
msx addict
Posts: 453 | Posted: April 14 2008, 17:08 |
Actually since i am not a programmer i do not think that i can have much use for this card except for collective purposes.I trust you and i am sure that my card would have no problem with you
I want to help you as much as i can.
If you think that it would help you in any way please feel free to ask me.
And postage costs for sending you the card are mine |
|
ARTRAG
msx master
Posts: 1592 | Posted: April 14 2008, 17:15 |
|
|
ARTRAG
msx master
Posts: 1592 | Posted: August 14 2008, 10:42 |
Handy info, to be stored here
Quote:
|
Nominal NTSC carrier frequency is 3,579,545.454545... Hz. The precise
frequency is (455/2) * (525/2) * (60/1.001), or 5.000000... MHz * (63/88)(see
SMPTE 170M, the authoritative reference for NTSC). The latter formula is
what's usually used to synthesize subcarrier from a rubidium or cesium standard.
Historical note: The original intent of NTSC II, the committee working on
compatible color, was to maintain the frame rate at 60.00 Hz. However, in
order to minimize visibility of the audio carrier in the received picture, it
was necessary to shift its frequency to 4.5045 MHz above video carrier instead
of precisely 4.5 MHz. This would have caused problems with few existing B&W
receivers. However, there were some receiver manufacturers who, for reasons
of cost, had implemented simpler audio receiving circuits that would have been
adversely impacted by the 0.1% shift, and the FCC ruled that for the sake of
backward compatibility the video frequencies (subcarrier, vertical and
horizontal) were to be shifted down by 0.1% instead. Apparently nobody ever
considered that rolling hum bars would be far worse impairments than the audio
distortion caused by having the FM discriminator circuit run slightly off
center. We've been paying the price ever since.
|
|
|
ARTRAG
msx master
Posts: 1592 | Posted: August 14 2008, 11:19 |
|
|
|
|
|
