Re: [ecasound] preparing for release: 2.4.7pre1_2.5.0

From: Kai Vehmanen <kvehmanen@email-addr-hidden>
Date: Thu Jul 03 2008 - 18:58:19 EEST


thanks all for the quick feedback!

On Thu, 3 Jul 2008, Linux Media wrote:

> I've tested all the features in "Manipulating objects - looping,
> reversing, ..." section. I've even done some pretty amazing things (like
> using the 'loop device' to get the same audio file to play different
> segments at different times) and haven't found a bug.

Now that's reassuring to hear! The code for 'audioloop', 'select' et all
is now fully shared with the (new) EWF implementation, so this release
actually has less code and more releases.

> In the following...
> -i:select,start-time,duration,file.ext,params
> What 'params' are you referring to? Can you give me an example?

That can be any params given to 'file.ext'. For instance if you want to
use libsndfile to open a RIFF WAVE file (use libsndfile instead ecasound's
own implementation), you'd use "-i:sndfile,foo.wav".

So with 'select' this would look like:


... basicly you can freely "stack" the audio ops one after another.
Probably biggest bottleneck is readability. ;)

I've also added a lot more sanity checks to warn (or sometimes, even raise
an error) about cases where the result might not be what the user
initially excepted. One example is trying to loop a 'null' object. This
won't simply work as 'null' has no finite length:

ecasound -i audioloop,null -o alsa

... will now raise an error. I'm planning to add more of these.
For instance the following should raise an error, but doesn't do
it yet:

ecasound -i select,10,20,foo.m4a -o alsa

Seeking is not supported with AAC/MPEG4 inputs, so selecting a range is
not possible. Unfortunately ecasound just silently accepts the above and
plays out 'foo.m4a'.

One problem with adding these checks is that it is really difficult to
think of all possible use-scenarios and there's a big risk that you
prevent some valid use-case by adding sanitiy checks. Thus I prefer to add
warnings, and only in clear case raise an actual error.

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Received on Thu Jul 3 20:15:02 2008

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