savonet

Hello everyone,

In the geek.liq example, on can see the form :

schedule([("0m & 0-5s",delay(5.,clock))])]) ;

Is delay a trick to play a single sound from the "clock" playlist
every hour? I am looking for the best way to extract a single sound
from a playlist, randomly or in sequence,  and play it entirely at
fixed times. In the above example, it seems that schedule would play
several sounds in a row if they last less than 5 seconds,

Thanks!
X.

Re: [Savonet-users] Scheduling a single sound out of a playlist From: David Baelde <david.baelde@gm...> - 2006-04-30 17:33 Hi Xavier, > schedule([("0m & 0-5s",delay(5.,clock))])]) ; > > Is delay a trick to play a single sound from the "clock" playlist > every hour? I am looking for the best way to extract a single sound > from a playlist, randomly or in sequence, and play it entirely at > fixed times. In the above example, it seems that schedule would play > several sounds in a row if they last less than 5 seconds, You've guessed right, that's really a trick, but it hasn't the problem you describe. At the beginning of every hour the schedule calls the delay, which calls the clock, which starts streaming back a jingle. At the end of the jingle, if the jingle is less than 5 seconds, the schedule asks the delay if it has something more to say, but the delay won't answer positively until 5. seconds are elapsed. At that time the schedule won't be asking anymore. So in theory that trick works well. Don't you observe the behaviour I describe ? Cheers. -- David

Re: [Savonet-users] Scheduling a single sound out of a playlist From: Xavier Cazin <xavier.cazin@gm...> - 2006-04-30 19:52 Thanks David for the explanation. I couldn't test it right now because the latest svn version doesn't seem to like operators with float parameters (at least on my Ubuntu boxes: I just filed a bug on sourceforge; I hope this was a real one:-). By the way, if I understand well, this trick wouldn't work if you have in your "clock" playlist both sounds lasting less and sounds lasting more than the delay you're asking for. For instance, I would like to be able to play announcements of our next live sessions, every two hours. Depending of the session, the ad would last anything between 10 seconds and 30 seconds. Also, some days, we want to air interviews of arbitrary people answering an arbitrary question. Here too, we don't want to constrain the duration in advance. Could you suggest another trick that would work in this cases? Cheers! X. On 4/30/06, David Baelde <david.baelde@...> wrote: > Hi Xavier, > > > schedule([("0m & 0-5s",delay(5.,clock))])]) ; > > > > Is delay a trick to play a single sound from the "clock" playlist > > every hour? I am looking for the best way to extract a single sound > > from a playlist, randomly or in sequence, and play it entirely at > > fixed times. In the above example, it seems that schedule would play > > several sounds in a row if they last less than 5 seconds, > > You've guessed right, that's really a trick, but it hasn't the problem > you describe. At the beginning of every hour the schedule calls the > delay, which calls the clock, which starts streaming back a jingle. At > the end of the jingle, if the jingle is less than 5 seconds, the > schedule asks the delay if it has something more to say, but the delay > won't answer positively until 5. seconds are elapsed. At that time the > schedule won't be asking anymore. So in theory that trick works well. > Don't you observe the behaviour I describe ? > > Cheers. > -- > David >

Re: [Savonet-users] Scheduling a single sound out of a playlist From: David Baelde <david.baelde@gm...> - 2006-04-30 20:56 Hi, I hope we understand and fix that bug soon. For now, I can answer your other question. On 4/30/06, Xavier Cazin <xavier.cazin@...> wrote: > By the way, if I understand well, this trick wouldn't work if you have > in your "clock" playlist both sounds lasting less and sounds lasting > more than the delay you're asking for. Indeed, there would be a problem with long tracks, since the schedule node would declare itself as not being ready anymore when "0m & 0-5s" is false -- you might actually be lucky and avoid that problem if the operator on top of schedule keeps asking for frames without noticing the status change, it can happen, I don't know if I should tighten the policy here, but that's not the question. Another problem with that trick is when the delay between two scheduling periods is less than the duration of the period itself. But that's probably less frequently annoying. > For instance, I would like to > be able to play announcements of our next live sessions, every two > hours. Depending of the session, the ad would last anything between 10 > seconds and 30 seconds. Also, some days, we want to air interviews of > arbitrary people answering an arbitrary question. Here too, we don't > want to constrain the duration in advance. Could you suggest another > trick that would work in this cases? We should definitely find something better than this trick, for scripts using add(..clock) as well as needs like yours. I don't think you can do with the current set of operators. It is possible to write a function which takes a source S and returns a source playing only the first track of S: once =3D fun (s) -> sequence([s,fallback([])]). But once(clock) would have to be regenerated to be able to play another track, which schedule doesn't do. A possible extension would thus be to make a more dynamic operator, which would create its source child when selecting a branch: dynamic_select([("0m&0-5s", fun () -> once(clock))]). It could be done, but that's not very satisfying, and the implementation would imply code duplication. Another solution: add a not_twice parameter to schedule (I don't think other switch operators need it) which forbids the selection of the same branch twice. It sounds better. What do you think ? Other ideas ? -- David

Re: [Savonet-users] Scheduling a single sound out of a playlist From: David Baelde <david.baelde@gm...> - 2006-05-01 08:32 Good morning, Xavier Cazin wrote: > It would seem more natural to me to use a "pick" operator that would > pick one (by default) or more tracks in the scheduled source: > > schedule([("0m",pick(clock))]); The problem here is that pick doesn't know what's going on on top of him, thus cannot distinguish between * the situation where schedule just entered the "0m" period and asks for da= ta * the situation where schedule is still in "0m" and asks for (more) data Actually pick is the once() operator I had defined in the previous mail, and has the same problems: it would need to be reinitialized at some point. Moreover, in the current implementation, your schedule node in that example would declare itself as not being ready to stream as soon as "0m" is false, which could cause the interruption of the clock streaming. That's a minor problem, I can change the default behaviour, or add a parameter for modifying it. The architecture of liquidsoap is a strength, but imposes some constraints on the design of operators: everything has to be local, the same protocol is used everywhere between sources, etc. -- David

Re: [Savonet-users] Scheduling a single sound out of a playlist From: David Baelde <david.baelde@gm...> - 2006-05-01 17:47 Hi list, I implemented the two new parameters for the schedule operator: "strict" and "single". I will eventually write some detailed doc about them on the wiki, together with many examples.. for now here is a quick explanation on the following example: output.alsa(add([ schedule(strict=3Dtrue,[("0-1s", sine(440))]), schedule(single=3D[true],[("30-60s", single(".../jingle.mp3"))]), schedule(single=3D[true,false], [("0-10s", playlist("/tmp/jingles.m3u")), ("", playlist.safe("/home/dbaelde/lists/playlist.m3u"))])])) We output the sum of three schedule nodes. The first one has a single branch, valid during "0-1s", with a since() source. The since plays a continuous infinite track. A normal schedule node would play the entire track, even if it goes beyond "0-1s". The strict flag avoids that. Shouldn't be needed very often. The second child is another schedule with a single branch. That branch is in single mode, which means that it won't be selected twice in a row. However, it can be reselected as soon as one frame after the end of track. So basically the schedule() node loops on the jingle during all the interval, and the single flag doesn't change much for the user -- no one hears a delay of one frame. The third child is the interesting one for the problem raised in that thread. It's first branch is in single mode, on the interval "0-10s". The second one is a safe playlist, in normal mode, on the full interval. Everytime the schedule() reselects a child during "0-10s" it will move to the jingles playlist, but will never reselect it after one track, and will thus move to the normal playlist. If the normal playlist's track finishes within "0-10s" (another instance, or the same one) the schedule() goes back to the jingles again, and so on. Enjoy ! -- David

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