Re: [linux-audio-dev] Simple Plugin API: In/Out Ports

New Message Reply About this list Date view Thread view Subject view Author view Other groups

Subject: Re: [linux-audio-dev] Simple Plugin API: In/Out Ports
From: Paul Barton-Davis (pbd_AT_Op.Net)
Date: ma maalis 06 2000 - 20:51:53 EST


Bill writes:
>All existing digital audio wire formats (s/pdif, aes/ebu, TDIF, ADAT,
>others?) are based on integer sample values. All digital recording

yes and just today, i was have a conversation with a cabling/connector
wizard who runs another (mostly analog+protools) studio, and he was
commenting that he has come across several studio folk who have run
into problems mixing (digital) multiple hot channels down to a bus for
output, because the *mixed* signal exceeds the dynamic range of the
wire protocol. its this phenomenon (additive processing) that more or
less requires, IMHO, the use of (at least) 32 bit float even for
simple mixing.

that said, i took bill's advice in ardour, and read/write int32
from/to disk. its a happy concidence that the number of bits in the
mantissa of a IEEE float is 24, but given that the program can
actually handle 32 bit input data, using a float to represent that
would instantly break the in-bit-stream == out-bit-stream requirement.

if (or rather when ...) ardour ends up accepting plugins, this may
need to change.

Bill also noted:

>inputs and outputs that will be within a 24-bit range for the
>foreseeable future, I'd much rather have a fixed-point representation
>than floating point.

The creamware pulsar, using the off-the-shelf AD SHARC DSP, offers 32
bit sample values. How long is that "foreseeable future" foreseeable
for ?

Note also that CoolEdit Pro already advertises its "32/192"
capabilities.

--p

ps. does anyone on this list have any info or pointers to info about
TOSLINK patch bay components ? we are building one, and it seems less
than trivial to find the stuff. the cable wizard is going to talk to
markertech, but their catalog, despite featuring more cable connectors
than you could remember, doesn't include anything but pre-built
ADAT/TOSLINK cables.


New Message Reply About this list Date view Thread view Subject view Author view Other groups

This archive was generated by hypermail 2b28 : pe maalis 10 2000 - 07:23:28 EST