Re: [ecasound] What is the purpose of AUDIO_IO_DEVICE::io_mode == io_readwrite?

[Lorenz M. <lm...@gm...>]

Hi Kai,

Thanks for your explanations, they are very much appreciated!  The
message I take home from this is that is that devices (unlike file
backends) ought to not implement io_readwrite, since there is no proper
analogy.

As a note aside, "r+" (with creation of a new file if no such already
exists) would be the better analogy below, since "w+" discards the
contents of the previous file, which apppears not to be what is intended
here.  

Best,
--Lorenz

Kai Vehmanen wrote:
> >I have a question regarding the io_mode for an audio device:  What is
> >the purpose of the io_readwrite mode?  I was assuming that devices
> 
> it's analogous to "w+" mode of fopen. Quoting fopen man page:
> ""w+: Open for reading and writing.  The file is created if it does
> not exist, otherwise it is truncated.  The stream is positioned at
> the beginning'of the file.""
> 
> Simiarly io_write is similar to "w" mode, i.e. the output is always
> truncated.
> 
> >So what is the purpose if io_readwrite in that context, and how is a
> >device supposed to handle that?
> 
> The main use case for io_readwrite is the ability to open file
> outputs in update mode (e.g. to replace only portions of a
> recording, or continue recording at the end of an existing file).