Thank you. I will look at it! Am 17.03.2016 19:03 schrieb "Francisco Albani" <francisco.alb...@gmail.com>:
> Hi Anselm. > > Go to http://lists.gnu.org/archive/html/discuss-gnuradio/ and search this > "Asynchronous source with zeros in between" > > You will find an email I wrote to this list asking a similar question. I'm > not pasting a link here because I couldn't find the starting message; the > thread is split in many parts (I don't know why). I hope you should be able > to find all the pieces in the search results. If not, please write to me > and I will find a way of send it to you. > > I think my problem was different that yours and my solution will not be > fit, but it may give you some ideas. The key was to bring the payload in a > PDU message and to have a block that manages the "padding" before entering > to the "stream domain". > > Bye! > > > 2016-03-17 5:50 GMT-03:00 Anselm Karl <anselmkarl.in...@googlemail.com>: > >> Hi, Nikos, >> >> adding a buffer / fifo and matching the mean video rate to the rate of my >> transmission system should work. >> >> But i don't really want to match the rates, because i'll have to do that >> every time i change something on the source. It can be quite an effort, >> too. (Like interpolation the base-band signal) Or consider a asynchronous >> source (something like a serial terminal) with large intervals with no data. >> >> With the "zero stuffing solution" you just have to make sure, that the >> transmission is fast enough for the source, "plug in" the source and >> everything should be fine. >> >> I've done some gnu radio blocks. But i don't now how to tell the work >> function how many samples the down stream block needs. In my understanding >> the work functions gets some input samples and calculates some output >> samples out of them. It's like the block gets actively written to and >> passively read from. And i would need it the other way. >> >> BR, >> Anselm >> >> >> >> 2016-03-17 9:17 GMT+01:00 Nikos Balkanas <nbalka...@gmail.com>: >> >>> Hi, >>> >>> Have you tried using a FIFO block in your flow? There a few around and >>> it seems to me it would normalize your flow. >>> >>> BR, >>> Nikos >>> >>> On Thu, Mar 17, 2016 at 10:01 AM, Anselm Karl < >>> anselmkarl.in...@googlemail.com> wrote: >>> >>>> Hi all, >>>> >>>> i want to transmitt a video stream with gnuradio and usrps. There are >>>> some examples on the web and i got it working with vlc. >>>> >>>> The problem is, that the playback is quite choppey. This is because the >>>> digital transmission over the usrps has a fixed rate but the encoded video >>>> has a variable rate. If i set the transmission rate higher than the (mean) >>>> rate of the video, i get a lot of underruns on the tranmitting usrp (= >>>> chopped of rf signal). Which is bad because the transmission designed to be >>>> continous (for example the clockloop, ...). >>>> >>>> The transmission is based on fixed size fec code blocks starting with >>>> an preambel. A possible solution could be to stuff zeros between two blocks >>>> while waiting on the (video) source. On the receiver this stuffed zeros >>>> would be trown away automatically. >>>> >>>> That "zero stuffing" could be realized with a block, that puts out N >>>> (N= payload size of one block) input samples (first sample marked with a >>>> tag) at one "piece" or (if it has no N input samples in some internal >>>> buffer) it puts out zeros). Based on the tag a downstream block could mux >>>> in the preambel and everything would be fine. >>>> >>>> But here is my question: >>>> I don´t know how to write a block, that always has output samples >>>> available. Is there i kind of a non-blocking block template? >>>> >>>> >>>> Best regards, >>>> >>>> *Anselm* >>>> >>>> >>>> >>>> _______________________________________________ >>>> Discuss-gnuradio mailing list >>>> Discuss-gnuradio@gnu.org >>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>>> >>>> >>> >> >> >> -- >> Mit freundlichen Grüßen >> >> *Anselm Karl* >> >> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> >
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