[linux-dvb] Re: AW: VDR: first step towards AC3 sound

[Klaus Schmidinger <Klaus.Schmidinger@cadsoft.de>]

Guido Fiala wrote:
> 
> On Sunday, 24. June 2001 11:00, Klaus Schmidinger wrote:
> > Andreas Vitting wrote:
> > > I have tried it out, but i can get no data! The command -a works, the
> > > ac3play starts, but no data was send to it. I have also tried your
> > > command -a "cat > vdr.ac3" but the file keeps empty. I'm using the newest
> > > cvs dvb api and your patch was successful read in. The records are new
> > > and from different channels.
> > > With the dvdplayer and the dvb card my ac3 works ok.
> > > Also, what's wrong ??
> >
> > Please make sure that the channel you are recording has the "Dpid1"
> > parameter set in the channel setup, and also that the channel actually
> > broadcasts AC3 sound. So far the only FTA channel I know of that does this
> > is Pro7, and its Dpid1 is 257. This works for me (at least I get the data,
> > since I don't have any AC3 equipment I can't actually replay it).
> 
> Have exactly the same problem and the DPID1 is set (i took your
> channels.conf), /var/log/messages shows a couple of
> 
> Jun 24 11:06:17 wonderbox vdr[819]: ERROR: wrote 968 byte to dolby device
> instead of 1806
> Jun 24 11:06:17 wonderbox vdr[819]: ERROR: wrote 484 byte to dolby device
> instead of 1806

Looks like 'ac3play' doesn't accept the entire data packet at once.
I thought that the pipe would be opened in blocking mode, but maybe that
was a false assumption.

Please try the following patch to the dvbapi.c file:

--- dvbapi.c.003        Sat Jun 23 18:27:49 2001
+++ dvbapi.c    Sun Jun 24 11:41:30 2001
@@ -808,12 +808,17 @@
          switch (c) {
            case 0xBD: // dolby
                 if (Except && dolbyDev) {
-                   int w = fwrite(&b[i], 1, l, dolbyDev);
-                   if (w < 0) {
-                      LOG_ERROR;
-                      }
-                   else if (w != l)
-                      esyslog(LOG_ERR, "ERROR: wrote %d byte to dolby device instead of %d", w, l);
+                   int written = 0;
+                   int n = l;
+                   while (n > 0) {
+                         int w = fwrite(&b[i + written], 1, n, dolbyDev);
+                         if (w < 0) {
+                            LOG_ERROR;
+                            break;
+                            }
+                         n -= w;
+                         written += w;
+                         }
                    }
                 // continue with deleting the data - otherwise it disturbs DVB replay
            case 0xC0 ... 0xC1: // audio

> I assume Pro7 sends AC3-stream all the time? How can i know that they
> actually do?

They always send data on PID 257 (at least as far as I have observed).
You can use my little 'xlist.c' program to dump a recorded file and see
if it contains "dolby" packets (see ftp://ftp.cadsoft.de/pub/people/kls/vdr/xlist.c).

Klaus
-- 
_______________________________________________________________

Klaus Schmidinger                       Phone: +49-8635-6989-10
CadSoft Computer GmbH                   Fax:   +49-8635-6989-40
Hofmark 2                               Email:   kls@cadsoft.de
D-84568 Pleiskirchen, Germany           URL:     www.cadsoft.de
_______________________________________________________________


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