Hillsboro, OR
Yea. There's a lit more to sound quality than stereo vs mono.
(Topic ID: 79721)
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Quoted from Part_3:Well, is that because of crappy speakers? That could be upgraded, or piped out to a receiver.
Its due to crappy audio amps and craply sound samples limited by space in older roms. The data east speakers are actually slightly better.
Quoted from Crash:To compare, Jersey Jack uses straight-up 16-bit 44KHz PCM. Full CD quality. Actually it exceeds CD quality due to the absense of compression.
Cd quality is uncompressed as CDs are not compressed.
Quoted from Part_3:CD's are compressed, they're just not compressed to the extent that we think of today, like MP3 and AAC, etc.....
I'm the case of compression we are talking about is data compression. This is an entirely different and unrelated process vs dynamic range compression which yields a more constant , normalized, louder track. CDs are not data compressed.
Moving to stereo sound would require another tda2030 amp in the board set which might require beefing up the 12v section on the power board. But the biggest concern would be the size of game rom. The sounds in stern games are 24khz uncompressed. To add a second channel would double the size of the audio in the game.
Quoted from m00dawg:Technically, it's not compression but error correction. The audio itself is uncompressed, and, in fact, the error correction requires more space, not less though I think it's marginal.
To avoid confusion, I just think of CD audio as 16-bit/44kHz. Uncompressed it is about 10MB/min for stereo music. It's an aside, but modern lossless compression approaches, like FLAC and ALAC, can get it down to say 40-60% of the original. FLAC is also a very cheap codec in terms of CPU power (when compared to, say, MP3s) though requires a good deal more bandwidth obviously.
I'm sorry but error correction like ECC is not related to compression of audio *at all*. And in fact, audio is written to CD media without the standard error correction used on regular data cd because the thought is a bit here or there being off is no big deal in streaming playback. Modern CD audio is uncompressed audio data. It's the same as a 44khz 16 bit PCM data file without any codec.
The point above was that by making the audio tracks stereo, because they're uncompressed, it would double the size of the tracks for the pinball machine roms.
They would need another audio amp to do it right. The costs would be minimal. But they would need a board spin. They could do it using the two amps they have but it would require wiring the cabinet speaker in with the backbox. They could do it neatly with a dvc cabinet speaker but I've never seen a dvc speaker efficient enough to run on a shared 18 watt amp.
Quoted from m00dawg:Agreed in regards to stereo, but according to Wikipedia, I believe you are mistaken:
http://en.wikipedia.org/wiki/Compact_Disc_Digital_Audio
"This stream of audio frames, as a whole, is then subjected to CIRC encoding, which segments and rearranges the data and expands it with parity bits in a way that allows occasional read errors to be detected and corrected. CIRC encoding also interleaves the audio frames throughout the disc over several consecutive frames so that the information will be more resistant to burst errors. Therefore, a physical frame on the disc will actually contain information from multiple logical audio frames. This process adds 64 bits of error correction data to each frame. After this, 8 bits of subcode or subchannel data are added to each of these encoded frames, which is used for control and addressing when playing the CD."
All correct. But none of that is a form of compression. It's more a light form of parity. Its a weak form of error correction (not data compression) allowing for 2352 bytes per sector and nowhere near as aggressive as the standard data error correction used with say mode 1 data written at 2048 bytes per sector. I never said there was no error correction. I said it wasn't the same as the ECC used for data disks. Again, (while interesting) this has absolutely nothing to do with audio compression which is a way to shrink the audio file so it takes up less space on the media, requiring it to be decompressed on playback by a codec. Nor does any of this have to do with pinball.
Quoted from oga83:In fact, Stern pinballs that are based on SAM boards ARE stereo :
- The audio DAC is a PCM1755 and it supports stereo
- The SAM pcb has 2 channels on the J10 connector; each one is driving a different speaker
See schematics below.
So, I guess we could enable stereo... it's just a question of software.
Do you think it would be interesting to add this feature with Pinball Browser ?AudioPanel.png 45 KB
AudioSch.png 89 KB
Cool post. But the two channels, I believe, are separated for backbox and cabinet. There are only two amps on the board.
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