[directmusic] Re: question
- From: "Todor Fay" <todor@xxxxxxxxxxxxx>
- To: <directmusic@xxxxxxxxxxxxx>
- Date: Fri, 28 Feb 2003 09:37:12 -0800
Josh,
You can use DirectMusic for sound effects in DX8, but low latency
"twitch" sound effects that need to respond quickly to user input will,
by default, delay up to 85ms. You can use the code below in DX8 to drop
that delay down to as low as 20 ms on some machines with DX8. But, it
isn't as low as DX9 and isn't self calibrating to be glitch free, so you
would need to provide a UI element so the user could dial it down until
it start breaking up.
However, if you are about to ship a game now, you probably are running
on DX9, even if you didn't code to it. In DirectX Audio, there are no
API changes between DX8 and DX9, just performance enhancements. Once the
DX9 release is installed on a user's machine, be it by your game or
another, all calls to DirectX Audio will go through the new, improved
bits. Actually, I expect your game will ship with the latest DirectX
install, and not the older one. I wouldn't be surprised if Microsoft
will not allow you to ship the older bits.
So, even though you've developed with DX8, you've got the DX9
enhancements for free.
Todor
-----Original Message-----
From: directmusic-bounce@xxxxxxxxxxxxx
[mailto:directmusic-bounce@xxxxxxxxxxxxx] On Behalf Of Joshua P. Jung
Sent: Friday, February 28, 2003 8:19 AM
To: directmusic@xxxxxxxxxxxxx
Subject: [directmusic] Re: question
So, what your saying is that DirectMusic 8 should NOT be used for games=
sound effects... which is what I was planning on doing.
I am finishing up a game, and was getting ready to implement sound
(basic=
stuff). Is there any way I could get directmusic 8 to have low
latency,=
like you showed DirectMusic 9 could do?
Josh <><
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Orignal Message
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On 2/27/2003 at 6:29 PM Todor Fay wrote:
>With DX8, using DirectMusic for sound effects had a problem: you
>couldn't get low latency for sudden sound effects, in particular any
>sounds that are in reaction to user input (like gun shots, etc.)
>
>In DX9, you get really low latency. I've measured 4ms latency on the
>Creative Audigy card, for example, so it's a totally different story.
>
>By default, however, the latency is not low. This was done to handle
>worse case scenarios of really lousy cards on old slow computers.
>
>But, you can overwrite the latency and write period. Note that the
>latency is added to whatever hardware / software latency is introduced
>by the drivers, so results will vary depending on the card. The
>following code drops the latency to 1ms and the period to 3ms. This
>results in about 4-6 ms latency on an Audigy card:
>
>IDirectMusicAudioPath *pPath;
>if (m_pPerformance &&
>SUCCEEDED(m_pPerformance->GetDefaultAudioPath(&pPath)))
>{
> IKsControl *pControl =3D NULL;
>
>pPath->GetObjectInPath(0,DMUS_PATH_PORT,0,GUID_All_Objects,0,IID_IKsCon
t
>rol,(void **)&pControl);
> pPath->Release();
> if (pControl)
> {
> KSPROPERTY ksp;
> DWORD dwData;
> ULONG cb;
> dwData =3D 3;
> ksp.Set =3D GUID_DMUS_PROP_WritePeriod ;
> ksp.Id =3D 0;
> ksp.Flags =3D KSPROPERTY_TYPE_SET;
> pControl->KsProperty(&ksp, sizeof(ksp),
> &dwData, sizeof(dwData), &cb);
> dwData =3D 1;
> ksp.Set =3D GUID_DMUS_PROP_WriteLatency ;
> ksp.Id =3D 1;
> ksp.Flags =3D KSPROPERTY_TYPE_SET;
> pControl->KsProperty(&ksp, sizeof(ksp),
> &dwData, sizeof(dwData), &cb);
> pControl->Release();
> }
>}
>
>BTW, A bunch of us are contributing to a book called DirectX Audio
>Exposed that will ship in a few months. In it, I have written a chapter
>on programming with sound effects that covers this and most other
>questions and issues.
>
>Todor
>
>
>-----Original Message-----
>From: directmusic-bounce@xxxxxxxxxxxxx
>[mailto:directmusic-bounce@xxxxxxxxxxxxx] On Behalf Of justin
>Sent: Thursday, February 27, 2003 11:59 AM
>To: directmusic@xxxxxxxxxxxxx
>Subject: [directmusic] question
>
>
>Hi everyone,
>
>I am working on creating adaptive audio for a DX game and I am using
>direct music to handle all of the aa. I was wondering if it was ok to
>use direct music for all the sounds in the game i.e gunshots or if I
>should use direct sound to deal with the small one off stuff...
>
>Justin Love
>University of Victoria
>
>-----Original Message-----
>From: directmusic-bounce@xxxxxxxxxxxxx
>[mailto:directmusic-bounce@xxxxxxxxxxxxx] On Behalf Of Scott Morgan
>Sent: February 27, 2003 8:47 AM
>To: directmusic@xxxxxxxxxxxxx
>Subject: [directmusic] Re: Ciaran - you mentioned...
>
>
>Oh FYI, the point of the C++ Autodownload is to make life easier on the
>programmer. It means he doesn't have to load and unload every segment
>he
>calls play on. It's all handled automatically.
>-Scott Morgan
>http://Morganstudios.com
>
>
>----- Original Message -----
>From: "Scott Morgan" <scott@xxxxxxxxxxxxxxxxx>
>To: <directmusic@xxxxxxxxxxxxx>
>Sent: Thursday, February 27, 2003 8:31 AM
>Subject: [directmusic] Re: Ciaran - you mentioned...
>
>
>>
>> The Autodownload feature Todor is referring to is a C++ method that
>has
>> nothing to do with the download checkbox in scripts. The programmer
>would
>> be the person who decides to use AutoDownload, not the composer.
Just
>so
>> you know DMDemo does not use Autodownload. Typically if you are
using
>> scripting there is absolutely no need to use AutoDownload since the
>script
>> handles everything either through manual script commands or by
loading
>what
>> it needs at start (only once).
>>
>> There are periodic CPU spikes in DMusic playback, but my
understanding
>is
>> that it is the playback engine waking up every so often and writing
>new
>data
>> to the sound buffer.
>>
>> -Scott Morgan
>> http://Morganstudios.com
>>
>>
>> ----- Original Message -----
>> From: "Ciaran Walsh" <ciaran@xxxxxxxxxxxxxx>
>> To: <directmusic@xxxxxxxxxxxxx>
>> Sent: Thursday, February 27, 2003 7:34 AM
>> Subject: [directmusic] Re: Ciaran - you mentioned...
>>
>>
>> >
>> > that would definitely explain it - does it really download the
>instruments
>> > again every time you play a band? that seems like a really weird
way
>for
>> it
>> > to work...
>> >
>> > I thought the point of AutoDownload was so that all content
>referenced
>by
>> > the script was downloaded when the script loaded.
>> >
>> > -----Original Message-----
>> > From: directmusic-bounce@xxxxxxxxxxxxx
>> > [mailto:directmusic-bounce@xxxxxxxxxxxxx]On Behalf Of Todor Fay
>> > Sent: 27 February 2003 15:18
>> > To: directmusic@xxxxxxxxxxxxx
>> > Subject: [directmusic] Re: Ciaran - you mentioned...
>> >
>> >
>> >
>> > Is there any chance you had the AutoDownload command turned on?
It's
>a
>> > feature that would cause each band to automatically cause a
download
>of
>> > its instruments when it played. Playback of a band should normally
>not
>> > cause any spike because all it does is send program change events
to
>the
>> > synth which just stores them, so nothing active occurs.
>> >
>> > Todor
>> >
>> > -----Original Message-----
>> > From: directmusic-bounce@xxxxxxxxxxxxx
>> > [mailto:directmusic-bounce@xxxxxxxxxxxxx] On Behalf Of Ciaran Walsh
>> > Sent: Thursday, February 27, 2003 5:32 AM
>> > To: directmusic@xxxxxxxxxxxxx
>> > Subject: [directmusic] Re: Ciaran - you mentioned...
>> >
>> >
>> > The problem we were having was never pinned down 100% to one
>particular
>> > thing, but band events certainly seemed to be contributing
>> > significantly.
>> > Our performance tests showed big CPU spikes each time a segment was
>> > triggered with a new band event, and somehow there was a cumulative
>> > effect
>> > which had a big impact on the overall frame rate.
>> >
>> > When we removed band events from the segments the spikes
>disappeared.
>> >
>> > We defined the band globally by having a segment play right at the
>start
>> > containing just a band event and triggering the first Primary
>Segment.
>> > As
>> > long as you don't recreate the audiopath or change any band
settings
>you
>> > don't need to create the band again after that. I guess it's only a
>> > problem
>> > if you are re-assigning pchannels as you go along, but I've never
>needed
>> > to
>> > do that.
>> >
>> > Hope that helps,
>> > Ciaran
>> >
>> > -----Original Message-----
>> > From: directmusic-bounce@xxxxxxxxxxxxx
>> > [mailto:directmusic-bounce@xxxxxxxxxxxxx]On Behalf Of Paul Stroud
>> > Sent: 27 February 2003 10:59
>> > To: directmusic@xxxxxxxxxxxxx
>> > Subject: [directmusic] Ciaran - you mentioned...
>> >
>> >
>> >
>> > ..that band tracks were giving you and your dev team a few problems
>-
>> > causing some glitch?
>> >
>> > If you don't mind going over the same subject again; what was the
>> > problem?
>> > And how did you sort it?
>> >
>> > I seem to remember that you globally declared a band instead of use
>band
>> > tracks on each segment. Is this right? Did you need to play a
Band
>> > track
>> > at least once? Is this how you globally declare a band?
>> >
>> > Anyone else had problems with this sort of thing?
>> >
>> >
>> >
>> >
>> >
>> >
>>
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