Re: Enhanced PLAY.CMD with play list support

From: Michael Baldwin Bruce (mbbruce_at_mighty.co.za)
Date: 11/03/04 

Date: 3 Nov 2004 01:46:13 -0800

bruce aka tholen@antispam.ham wrote in message news:<35Lhd.56735$Kl3.52139@twister.socal.rr.com>...
> Marty writes:
>
> >>> Peter Weilbacher wrote:
>
> >>>> Michael DeBusk wrote:
>
> >>>>> Marty wrote:
>
> >>>>>> Hi folks. I've been doing some REXX hacking lately and made some
> >>>>>> modifications to the standard PLAY.CMD script that IBM ships with
> >>>>>> MMOS/2.
>
> >>>>> Looks good from here.
>
> >>>> Yes, nicely done!
>
> >>> Thanks!
>
> >>>>> If I could make a wish, I'd wish that it didn't require the "FILE="
> >>>>> parameter. For some reason, I want to invoke it as "play foo.wav".
>
> >>>> Second that. Additionally, instead of the list= parameter, how about
> >>>> calling it like "play *.wav" and it automatically expands... OK, just
> >>>> dreaming. :-)
>
> >>> I could easily make another version to do this, but my intent with this
> >>> script was to be a drop-in replacement for IBM's PLAY.CMD (with complete
> >>> backwards compatibility).
> >>>
> >>> The most important aspect of the script for me was the resource leak
> >>> fix. Something inside of Timidity_MCD does not get cleaned up correctly
> >>> without the call to mciRxExit(). Strangely, missing this call doesn't
> >>> seem to cause a problem with any other codecs that I've found, just
> >>> Timidity. I guess the other codecs are smarter about cleaning up after
> >>> sloppy processes.
>
> >> I've probably encountered that problem. There have been times when
> >> PLAY.CMD would fail, while other audio file playing utilities would
> >> continue to work, including some Windows-based ones. But I have also
> >> encountered one instance in which PLAY.CMD worked from inside my editing
> >> program but failed as a standalone utility in another windowed command
> >> prompt session. Haven't been able to figure that one out.
>
> > Did you get any messages from PLAY about a "REXX Alias" or something to
> > that effect?
>
> Unfortunately, I cannot reproduce the problem on demand, so I have to
> rely on memory for the error message, but it was something like
> "mciRxInit routine not found".
>
> > Instead of maintaining handles with binary data and the
> > like, in REXX you create a name or "alias" to associate with your MCI
> > device. Every multimedia operation you do in REXX is done against this
> > alias so that the state is maintained by the MMPM libraries, but your
> > context is maintained.
> >
> > Unfortunately, PLAY.CMD hard-codes a REXX alias name, so that if you
> > attempt to run two of them at the same time, the same alias is used and
> > the context is applied from your original running PLAY.CMD. Likewise,
> > if you fail to close out and free the REXX alias (due to killing the CMD
> > process, for example), its state continues to be maintained by the
> > system. The alias is global. You have to free up the REXX alias before
> > it can be used again.
>
> Well, that seems consistent with one occasion in which I was repeatedly
> playing a very short audio clip, pressing the key to repeat the play
> very rapidly, such that it seems possible the system started up the next
> PLAY before completely cleaning up after the previous PLAY.
>
> > My version of PLAY checks for this condition and performs the free if
> > needed.
>
> I'm not sure under what conditions my audio subsystem supports the
> simultaneous playing of two audio streams. I'm using the SoundMax
> audio built in to the Intel 850 motherboard (ADI 1885). I know that
> if I'm playing a .wav file, then fire up Mahjongg, it complains about
> the device being busy, even though I've disabled sounds in Mahjongg.

maybe its complaining becuse you added it to one of your lits to
teach it a lesson, kook.

>
> On the other hand, the driver came with WarpMix, so it looks like it
> should be able to mix at least a few audio sources.

you mean like Barnes, kook?

>
> >> And I've
> >> also seen cases where the first invocation of PLAY.CMD would return an
> >> error message but a second invocation would cause the entire windowed
> >> command prompt session to die.
>
> > This one sounds like the MM libraries ran out of resources somewhere or
> > were left in an unstable state. This can be caused by not cleaning up
> > properly. I've seen this happen on my own system but haven't been able
> > to nail down the exact spark that triggered it. Since modifying
> > PLAY.CMD, I haven't seen this happen, but I'm not convinced that the
> > problem is gone yet.
>
> >> I'm curious as to how much digging others did to try and find the
> >> kinds of TIMEFMT supported by PLAY.CMD. I know it supports "samples"
> >> and "ms" (for milliseconds), but the default units are something like
> >> 15 samples (for 44.1 kHz audio). Haven't dug enough to understand
> >> the origin of that choice. Any other time formats supported?
>
> > 15 samples / 44100 samples/sec = .00034 secs of audio
> >
> > Seems like a strange choice indeed. It is approximately 1/100th of a
> > normal process time slice (32ms). That's a bit of a stretch, though.
>
> Sufficiently odd that I never use the default (other than to
> investigate it), which means I always have to use the TIMEFMT keyword,
> which is a bit annoying. On the other hand, my editing program works
> with the audio samples in memory, so to play an edited clip using
> PLAY.CMD, I need to write it to disk, so as long as I write just the
> clip I want to hear, I don't have to bother with the FROM, TO, and
> TIMEFMT keywords. Would be nicer to simply play a clip of audio
> samples directly from memory and thus avoid hitting the disk every
> time I want to repeat a short clip, but then I'd have to learn an
> entirely new part of the multimedia system. One of the editing
> tools plays a short clip whose end points I can move in 0.01 sec
> increments using the cursor keys; it has to write a new .wav file
> every time I press the key so as to utilize PLAY.CMD.

wow! you are a kook, bruce.

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