Re: auval and you
Re: auval and you
- Subject: Re: auval and you
- From: William Stewart <email@hidden>
- Date: Tue, 20 Mar 2007 15:05:55 -0700
Our customers do not give us the luxury of waiting for 2 to 3 years
to turn around critical bugs. I really am surprised that you consider
it reasonable to expect users to live with plugins that might be
scribbling over memory and causing random crashes and so forth for
such a period of time.
Regardless of this (and I think we'll have to agree to disagree
here), bare in mind that auval doesn't prohibit anything. For
instance, in Logic if an AU fails validation, the user can still
bypass this and use the AU; it still will behave exactly the same way
as it did before. We don't explicitly disable the AU completely (nor
do we have any plans to do that either). The difference is that the
user now knows that if they are experiencing instabilities in their
projects, then it could be due to problems with some of the audio
units they are using, rather than the host apps. Remember, all that
the user knows is that Logic crashed.
Finally, I would also reiterate that for many of these enhancements
we are giving you 2 to 3 years to fix them. As I said below, many of
the tests that now fail an audio unit in Leopard have been explicitly
bypassed for the 10.4.9 update for just the reason you ascribe (even
though some of these I consider to be quite serious problems). The
time difference between Tiger and Leopard is about 2 years. Ideally,
I would hope that the AUs themselves would be fixed before we
explicitly start failing them.
Bill
On 20/03/2007, at 12:54 PM, Angus F. Hewlett wrote:
Bill,
May I respectfully suggest that six months is NOWHERE NEAR LONG
ENOUGH when you're talking about breaking previously-'compatible'
software.
Yes, I realise you're keen to get new features rolled out, and have
host developers being in a position to take advantage of new
features with full confidence, but a six month window bears little
relation to a lot of devs' working cycles.
I'm sure we all have our own ideas as to what the cutoff period or
compatibility window should be, my £0.011 is that actual
compatibility should not be broken for perhaps 2 or 3 years after
full warning is given to developers.
There are a lot of AUs written in the last 2-3 years that are still
'current' from a user point of view, but may well be no longer
supported by their developer, or are just not at a phase in the dev
cycle where the dev is able to put out new releases at a few
months' notice. Are the gains from tightening the spec at this
point really big enough to cause end-users as much inconvenience as
this may do?
Best regards,
Angus.
William Stewart wrote:
As many of you know, audio units are plugins that run within the
process (address space) of a host application. They enhance the
capabilities of the host apps, providing many choices to users for
synthesis, sampling, audio processing and so forth.
From the perspective of a host app, there are two primary
conditions that must be met:
(1) The API as specified for the audio unit must be implemented
correctly
(2) The behaviour of the audio unit must be predictable and reliable.
If these two criteria are not met the user can experience
instabilities when using the audio unit within a host application
(such as Logic, Garage Band, Digital Performer, etc), including
catastrophic consequences such as crashing and the loss of unsaved
data.
auval is a tool that was designed to validate the basic behaviour
and operation of an audio unit. Its primary focus applies to two
areas:
(1) API conformance/correctness
- does the audio unit implement the semantics of the API
contract correctly?
(2) Behaviour
- does the audio unit have bugs that would cause random
crashes or other undesired consequences?
An audio unit passed through the validation process can have
several results:
(1) PASS
- the API is implemented correctly and no problems have been
detected
(2) PASS with warnings
- the audio unit may have some problems in some situations,
but in general it is behaving correctly
In the following two cases the audio unit should be considered to
be unreliable and problematic if used:
(3) FAIL with errors
- the audio unit exhibits some significant problems that would
impact its general usability
(4) Crashes
- in some cases the auval tool is not able to directly detect
a problem with the audio unit, but it can cause something bad to
happen in the audio unit through the testing that it does.
Regardless of any of these results, auval has no actual influence
or affect on the audio unit when it is used within a host app.
The primary API specification for audio units was described with
Mac OS X 10.2; it is known colloquially as "Audio Unit v2";
version two of the API. The API calls are expressed primarily in
the AudioUnit.framework, in the header files AUComponent.h and
AudioUnitProperties.h. Audio units have of course developed since
then, with new features added to accommodate different scenarios
and user requirements, however the basic API semantic and
compatibility has remained as defined at that time.
The auval tool has also developed since then; it has changed to
test and validate new features and is also able to detect problems
now that it previously wasn't able to. We regularly seed copies of
auval to all audio unit developers to ensure that the auval tool
is not itself introducing problems as well as to provide a chance
for feedback and other comments. We seed as often as we can;
providing builds months ahead of when we would expect these to be
released to the general public. We expect developers, just as our
users expect this of us, to incorporate fixes to these problems in
their updates, hopefully before a new version auval itself is
released.
As an example of this, the changes that were made to auval as
released in 10.4.9 were largely made and seeded to developers in
Sept/Oct 2006 (some of these changes even earlier than this). We
also disabled some of the tests as they would apply to a Tiger
based system because we didn't think they warranted a failure on
such a system. In these cases, they will however fail when running
against the auval installed with a Leopard system; this version
has also been seeded to developers.
If you are not on the auval seeding program and you are developing
audio units, then please contact me (William Stewart:
email@hidden).
We'll gladly answer any comments or concerns.
Thanks
Bill
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The current state of knowledge can be summarized thus:
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"Much human ingenuity has gone into finding the ultimate Before.
The current state of knowledge can be summarized thus:
In the beginning, there was nothing, which exploded" - Terry Pratchett
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