Can I play two WAV files at the same time?

Tomlikesrocks · 2010-07-13 02:47

Hi everyone,

I've just starting working with the Propeller Chip and while i've managed to play a single WAV file fine and an MP3 file using the VS1002.
I'm wanting to know if there a way to play two .WAV files at the same time with the one SD card?

Thanks

Regards
Tom

Rayman · 2010-07-13 12:35

I bet you can... You just have to juggle access to the SD card, but I think it can be done. I'm pretty sure the FSRW driver in OBEX can read much faster than .wav players play...

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lonesock · 2010-07-13 14:10

Simply declare 2 FSRW objects, only initialize one of them, then you can open a different file with each copy of the FSRW object. You should probably call both copies of the object from the same cog, though. (It might work since you are doing read only, but I wouldn't chance it.) Make sure to use the latest FSRW 2.6 from the OBEX, since some earlier versions don't support multiple copies.

Jonathan

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lonesock
Piranha are people too.
(geek humor escalation => "There are 100 types of people: those who understand binary, and those who understand bit masks")

sssidney · 2010-07-13 20:24

lonesock - could you call the read routine from different cogs if you put spin lock loops around the calls?


  repeat until not lockset(SemID)
  retLen := fr[noparse][[/noparse]0].pread(buf, BUF_SIZE)
  lockclr(SemID)

lonesock · 2010-07-13 20:46

FSRW is only the upper layer, and each instance will get it's own copy of local variables. The underlying block driver that talks with the card only runs a single copy of itself, so you should not need to use any locks. For read-only operation, I believe you can call FSRW from multiple cogs...I just have never tried it. (The mildly more difficult task is modifying FSRW to use 2 different block-layer drivers, for e.g. if you have 2 SD card slots physically hooked up to the prop.)

Jonathan

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lonesock
Piranha are people too.
(geek humor escalation => "There are 100 types of people: those who understand binary, and those who understand bit masks")

sssidney · 2010-07-13 20:55

What happens in the block driver if it receives a new request while it is still handling the previous one?

lonesock · 2010-07-13 21:05

You know what, you're right. Looking at the code, there is a possibility that one of the FSRW objects will mistakenly think it's request has been handled, while it is really another FSRW's request that was being answered. So, yes, if calling from a different cog, we can get into trouble.

So, either set up a handler cog to do the reading from all files as necessary, or put some form of locking around the 'readblock' calls.

I should have some free time in about a week, if you need any support.

Jonathan

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lonesock
Piranha are people too.
(geek humor escalation => "There are 100 types of people: those who understand binary, and those who understand bit masks")

sssidney · 2010-07-13 21:13

Yeah, SPI_command variable would get out of sync. There would either have to be locking at that level or some form of queuing of requests.

Tomlikesrocks · 2010-07-14 01:15

Wow, thanks guys.

I went to bed with no replies, and wake up this morning with lots of helpful info.

I didn't think FSRW could handle multiple files so i'll have a play and see what i can come up with.
Looks like i have a challenge. (which is a good thing)

Cheers [noparse]:)[/noparse]

Can I play two WAV files at the same time?

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