Doom?

[dudleysoft71]

The speech chip has an eight bit data bus and some address pins and is connected to the slow data bus, so it is best programmed from software on the beeb's 6502, or possibly via the OS (I don't know the OS route).

Putting analogue audio in via the PiCoPro is cheating even more than sending the samples back, but not too much to not have the option

The reason I suggested the speech audio pin is that my 1MHz bus is already in use with Pi1MHz adaptor, plus if you're using a game like Doom then you'll need a HDD, so the 1MHz bus is already in use for that.

If you're looking for an audio feed direct from the Pi, then the speech chip is less likely to be in use and probably isn't any more cheating than using the 1MHz bus anyway. One major advantage is that we wouldn't have to deal with 4bit samples.

I did toy with the idea of creating a simple sample player for the Pi1MHz, it would use 4 addresses in FRED (2 for frequency, 1 for volume and 1 for a sample FIFO), but it still requires transmitting the data back over the tube, given the limited bandwidth there I feel it would be better spent on transmitting video data.

There are two potential issues.

1. The Speech audio in is apparently filtered to remove frequences higher than 7Khz.
2. The audio pins on the PiTubeDirect may already be being used which would rule out using a Pi Zero.

[dominicbeesley]

I usually tap into the top end of R172 on my beeb to feed in sound.

D

[tricky]

...
The reason I suggested the speech audio pin is that my 1MHz bus is already in use with Pi1MHz adaptor,
...

This is why I keep asking on 1mhz threads to have the audio brought out to a pin.

[RobC]

This is why I keep asking on 1mhz threads to have the audio brought out to a pin.

I've not tried it but I guess there's also the modem input internally on the Master?

I did toy with the idea of creating a simple sample player for the Pi1MHz, it would use 4 addresses in FRED (2 for frequency, 1 for volume and 1 for a sample FIFO), but it still requires transmitting the data back over the tube, given the limited bandwidth there I feel it would be better spent on transmitting video data.

I had a similar idea but was going to load the samples up to the 1MHz Pi at the start and then get it to do the mixing etc. to save on the Tube bandwidth.

I think I should bite the bullet for Doom and either go with tricky's suggestion of interleaving samples with the video stream or use the Pi audio.

[tricky]

The samples will be cheaper if you can fill the gap, but that might get more complicated.
Do you know if there is a suitable IO pin on the PI?
I think I asked a long time ago, but can't remember.
If one hasn't been used for this before - but I guess it has on the 1MHz PI, is there one that can be used an still be compatible with the SpectrumNext:beeb+PiCoPro?
IIRC, when connecting to the audio, you have a cap in series, does this allow multiple connections to the same audio in pin, or do they interfere too much?

[RobC]

Do you know if there is a suitable IO pin on the PI?

I think this is only an issue on the Zero? It looks like you can use GPIO 13 or GPIO 19 which aren't used by PiTubeDirect.