[vdr] Re: How to determine the APID languages?

["Sebastian Zechlin" <S.Zechlin@gmx.de>]

----- Original Message ----- 
From: "Klaus Schmidinger" <Klaus.Schmidinger@cadsoft.de>
To: <vdr@linuxtv.org>
Sent: Friday, January 23, 2004 5:32 PM
Subject: [vdr] How to determine the APID languages?


> I'm currently implementing a way to determine which APID broadcasts
> which language. To do so I parse the ISO639LanguageDescriptor that
> comes in the PMT together with the APIDs (see the attached patch
> if you'd like to test this).
>
> This appears to work on many channels, but for instance for the
> "Premiere 1" channel both APIDs always report "deu" (or "ger" for
> that matter). I wonder how I can detect that the second APID on
> this channel actually broadcasts the English version.
>
> Any ideas?
>
> Klaus


----------------------------------------------------------------------------
----


> --- ./libsi/descriptor.c 2004/01/12 16:17:20 1.3
> +++ ./libsi/descriptor.c 2004/01/23 14:31:14
> @@ -514,6 +514,14 @@
>     return (LinkageType)s->linkage_type;
>  }
>
> +void ISO639LanguageDescriptor::Parse() {
> +   unsigned int offset=0;
> +   data.setPointerAndOffset<const descr_iso_639_language>(s, offset);
> +   languageCode[0]=s->lang_code1;
> +   languageCode[1]=s->lang_code2;
> +   languageCode[2]=s->lang_code3;
> +}
> +
>  void ApplicationSignallingDescriptor::Parse() {
>     entryLoop.setData(data+sizeof(descr_application_signalling),
getLength()-sizeof(descr_application_signalling));
>  }
> --- ./libsi/descriptor.h 2004/01/12 16:17:47 1.3
> +++ ./libsi/descriptor.h 2004/01/23 14:29:55
> @@ -374,6 +374,15 @@
>     const descr_linkage *s;
>  };
>
> +class ISO639LanguageDescriptor : public Descriptor {
> +public:
> +   char languageCode[3];
> +protected:
> +   virtual void Parse();
> +private:
> +   const descr_iso_639_language *s;
> +};
> +
>  //a descriptor currently unimplemented in this library
>  class UnimplementedDescriptor : public Descriptor {
>  protected:
> --- ./libsi/si.c 2004/01/12 22:19:34 1.5
> +++ ./libsi/si.c 2004/01/23 14:27:45
> @@ -323,6 +323,9 @@
>           case LinkageDescriptorTag:
>              d=new LinkageDescriptor();
>              break;
> +         case ISO639LanguageDescriptorTag:
> +            d=new ISO639LanguageDescriptor();
> +            break;
>
>           //note that it is no problem to implement one
>           //of the unimplemented descriptors.
> @@ -335,7 +338,6 @@
>           case DataStreamAlignmentDescriptorTag:
>           case TargetBackgroundGridDescriptorTag:
>           case VideoWindowDescriptorTag:
> -         case ISO639LanguageDescriptorTag:
>           case SystemClockDescriptorTag:
>           case MultiplexBufferUtilizationDescriptorTag:
>           case CopyrightDescriptorTag:
> --- ./pat.c 2004/01/16 15:43:34 1.5
> +++ ./pat.c 2004/01/23 16:06:18
> @@ -337,8 +337,24 @@
>                case 3: // STREAMTYPE_11172_AUDIO
>                case 4: // STREAMTYPE_13818_AUDIO
>                        {
> -                      if (NumApids < MAXAPIDS)
> +                      if (NumApids < MAXAPIDS) {
>                           Apids[NumApids++] = stream.getPid();
> +                         }//XXX
> +                         else NumApids++;//XXX
> +                         SI::Descriptor *d;
> +                         for (SI::Loop::Iterator it; (d =
stream.streamDescriptors.getNext(it)); ) {
> +                             switch (d->getDescriptorTag()) {
> +                               case SI::ISO639LanguageDescriptorTag: {
> +                                    SI::ISO639LanguageDescriptor *ld =
(SI::ISO639LanguageDescriptor *)d;
> +                                    printf("language APID %d %5d %3d
%c%c%c\n", NumApids, stream.getPid(), d->getLength(), ld->languageCode[0],
ld->languageCode[1], ld->languageCode[2]);//XXX
> +                                    }
> +                                    break;
> +                               default: ;
> +                               printf("PAT: %02X %3d\n",
d->getDescriptorTag(), d->getLength());//XXX
> +                               }
> +                             delete d;
> +                             }
> +                         //XXX }
>                        }
>                        break;
>                case 5: // STREAMTYPE_13818_PRIVATE
>

There is a linkage descriptor which can be found in EIT referecing these
APIDs. This was done to allow such describtions as stadium, commentary etc.
You will find a similar technique used when implementing Premiere mutifeed.

Best Regards
Sebastian



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