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SCC PCM replayer

Small updates on the PCM replayer documented here : http://www.msx.org/forumtopic7875p210.html

I tuned the filtering and re-sampling in my M file that does the conversion of the wav files to the phases data.
I fixed also some errors in the due to overflow in the integer representation of samples and added a small heuristic able to improve the SNR when there is overflow.
 
I fixed the asm replayer in order to be slightly more efficient.

No solution jet to the problem that affect the real SCC HW.
On emulators it sounds excellent, on the real thing just sufficient.

The results are in attach.

Use the SCC Flash Rom from Manuel Pasos or just an emulator and a NTSC machine (on PAL machines all will be distorted, samples and replayer need to be tuned to work at 50Hz).

Keys from C to Z are active.

Key Y will play a sawtooth waveform at 480Hz.

All the original audio samples are in the WAV subdirectory.

Compile using the SJASM version included in the RAR file typing on command line:

sjasm new_sccpoliplayer.asm

Comments from anyone willing to investigate the differences between the real thing and emulators are welcome.

[EDIT]
The second version adapted to sjasm 042c should use the first SCC found in the system. If you want to hear a chip different from the one on the flash cartridge, put the flash cartridge in slot 2 and the SCC chip to be tested in slot 1.

The third version is based on ascii 8 mapper and works only with an external SCC in the other slot.

[EDIT2]
The last scc_player_isr.rar now works also with SCC+ 

[EDIT3]
in scc_player_isr_3c_4c.rar  there is a new player using ONLY channels 1 2 and 3 that is immune to any SCC glitch 
Sadly it works at 60*3*32 = 5760Hz, so only sounds at low frequencies are properly reproduced


Credits to dvik who did the major coding work on the player
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scc_player_isr.rar
(2430k)
arturo ragozini,
Nov 29, 2015, 2:37 PM
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scc_player_isr42c_ascii8.zip
(3799k)
arturo ragozini,
Nov 25, 2015, 3:15 PM
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scc_player_isr_0.39g6.rar
(3122k)
arturo ragozini,
Nov 24, 2015, 11:29 PM
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scc_player_isr_0.42c.rar
(3489k)
arturo ragozini,
Nov 25, 2015, 2:10 PM
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scc_player_isr_3c_4c.rar
(12837k)
arturo ragozini,
Dec 8, 2015, 3:30 PM
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sccplay3c_bas.rom
(1024k)
arturo ragozini,
Dec 13, 2015, 12:47 PM
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