[vdr] Re: How to use 5.1 with VDR?

["Jan Rieger" <jan@ricomp.de>]

Hi Stefan,

since I have no Premiere, I can't maintain the patch in this
way. If you want, you can take the control over this...

Jan



> -----Original Message-----
> From: vdr-bounce@linuxtv.org [mailto:vdr-bounce@linuxtv.org] 
> On Behalf Of Stefan Huelswitt
> Sent: Saturday, January 18, 2003 7:42 PM
> To: vdr@linuxtv.org
> Subject: [vdr] Re: How to use 5.1 with VDR?
> 
> 
> On 18 Jan 2003 s.huelswitt@gmx.de (Stefan Huelswitt) wrote:
> 
> > My problem with the one strange recording is related to the 
> > substreamtype detection (the old code doesn't had such thing). If I 
> > hardcode the type to 0x8 the recording is played fine. May 
> be channels 
> > away from Pro7 use other encoding. I'll have to dig into this.
> 
> OK, I got some results on this ...
> 
> Pakets from Pro7 start with (as assumed):
> 00 00 01 bd 07 08 81 80 05 23 f9 ff 2a 61 0b 77 fb ae 1e 40 e1 dc 
> 00 00 01 bd 07 08 81 80 05 23 f9 ff 40 e1 0b 77 57 25 1e 40 e1 dc 
> 00 00 01 bd 07 08 81 80 05 23 f9 ff 57 61 0b 77 64 06 1e 40 e1 dc 
> 00 00 01 bd 07 08 81 80 05 23 f9 ff 6d e1 0b 77 ea 30 1e 40 e1 dc 
> 
> While the one other recording:
> 
> 00 00 01 bd 07 fa 87 80 05 2f 7f 1b 02 33 0b 77 1a 35 1e 40 e1 dc 
> 00 00 01 bd 07 fa 80 00 00 99 fa 57 4f 9c d5 af 5d 
> 00 00 01 bd 07 fa 80 00 00 7a 93 37 89 95 4c 21 3c 
> 00 00 01 bd 07 fa 80 00 00 84 bb 58 d7 51 88 85 f8 
> 00 00 01 bd 03 2c 80 00 00 22 a4 a4 e6 91 55 50 43 
> 00 00 01 bd 07 fa 87 80 05 2f 7f 1b 72 b3 0b 77 f2 9d 1e 40 e1 dc 
> 00 00 01 bd 07 fa 80 00 00 4d 53 a6 b1 a9 a9 7c fd 
> 00 00 01 bd 07 fa 80 00 00 7a ee eb ac 1f 00 20 08 
> 00 00 01 bd 07 fa 80 00 00 29 fd b8 38 58 3e 00 00 
> 00 00 01 bd 03 2c 80 00 00 d5 bb b6 6b 7a 4d b6 73 
> 
> As you can see, in the second case not every PES pakets has 
> the begining of an AC3 paket. The AC3 pakets cross the PES 
> paket boundaries. So we have to make some more effort to 
> detect the substream type.
> 
> Here my patch (against Jan's second patch. I guess we need 
> version numbering here) :
> 
> --- multichannelaudio.c	2003-01-18 19:31:04.000000000 +0100
> +++ 
> /usr/local/source/VDR/vdr-1.1.x-current/multichannelaudio.c	
> 2003-01-18 19:32:56.000000000 +0100
> @@ -9,6 +9,7 @@
>  //#define DEBUG(x...) fprintf(stderr, x );
>  #endif
>  
> +//#define DEBUG_BUFF
>  
>  #ifndef uchar
>  typedef unsigned char uchar;
> @@ -84,7 +85,8 @@
>  void cAudioEncapsulator::MakeFrame(const uchar *ac3data, int 
> size, uint8_t PTSflags, const uint8_t *PTSdata)  {
>  
> -#define MAXSIZE 1024
> +#define MAXSIZE 1536 //1024 // don't create more pakets than 
> necessary
> +                            // 1536=6144/4
>  
>    int offset = 0;
>    while (size > 0) {
> @@ -181,6 +183,9 @@
>  
>    //do we enter with an empty buffer
>    bool sendPTS = (bufptr - buf) < 40;
> +#ifdef DEBUG_BUFF
> +  printf("enter: c=%d t=%d ",bufptr-buf,end-start);
> +#endif
>  
>    for (;;) {
>  
> @@ -206,11 +211,17 @@
>                }
>  
>             bufpos = buf + length;
> +#ifdef DEBUG_BUFF
> +           printf("l=%d ",length);
> +#endif
>             }
>  
>          else {
>  
>             SendIEC60958(buf, bufpos - buf, sendPTS ? 
> PTSflags : 0, PTSdata);
> +#ifdef DEBUG_BUFF
> +           printf("s=%d ",bufpos-buf);
> +#endif
>  
>             sendPTS = false;
>             bufptr = buf;
> @@ -218,6 +229,9 @@
>             }
>          }
>       }
> +#ifdef DEBUG_BUFF
> +   printf("rest=%d\n",bufptr-buf);
> +#endif
>  }
>  
>  
> @@ -309,6 +323,8 @@
>       burst[7] = (length * 8) & 0xFF;                      // Pd2
>  
>       memcpy(burst + 8, buf, length);
> +     // is there any reason to send 6144 bytes every time, 
> even if the
> +     // normal ac3 paket size is only 1792 bytes???
>       memset(burst + 8 + length, 0, 6144 - 8 - length);
>       MakeFrame(burst, 6144, PTSflags, PTSdata);
>       }
> @@ -475,19 +491,46 @@
>    for (int i=0; i < length - 6; ++i) {
>       if (b[i] == 0x00 && b[i + 1] == 0x00 && b[i + 2] == 0x01) {
>  
> -        uchar c = b[i + 3];
> -        int l = b[i + 4] * 256 + b[i + 5] + 6; // total 
> length of PES unit
> +        uchar *bi=&b[i];
> +        int l = bi[4] * 256 + bi[5] + 6; // total length of PES unit
>  
> -        switch (c) {
> +        switch (bi[3]) {
>          case 0xBD:    //private stream 1
>          case 0xBF:    //private stream 2 ???
>          {
>  
> +           const int ptsdata = 9;            // start of PTSdata
> +           int ptslen    = bi[ptsdata - 1];  // length of PTSdata
> +           int headerlen = ptsdata + ptslen; // total length 
> of PES header
> +           int offset    = 0;
> +
>             // check substream type
> -           int header = b[i + 8] + 9;
> -           int offset = 0;
> +           uchar subStreamType = bi[headerlen] & 0xF8;
>  
> -           uchar subStreamType = b[i + header] & 0xF8;
> +           // The simple assumption that the start of the 
> PES payload is also
> +           // the start of an audio paket is not true for 
> all broadcasts.
> +           // Audio pakets may very well cross PES paket boundaries.
> +           // To detect the correct substream type, we have 
> to wait for a PES
> +           // paket which actualy has the begining of an audio paket.
> +           // The trick is based on actual stream data and 
> may fail on other
> +           // broadcasts. Currently it seems that 
> "continuation" pakets doesn't
> +           // have PTS data.
> +           if(!(bi[6]&1) && !ptslen) { 
> +             // If we already have a encapsulator, we 
> continue with him,
> +             // if not, we have to wait until the next full 
> paket to identify
> +             // the substreamtype
> +             if(encapsulator) 
> subStreamType=encapsulator->StreamType();
> +             else subStreamType=0xFF;
> +             }
> +
> +#ifdef DEBUG_BUFF
> +           //printf("header=%d ptsdata=%d ptslen=%d 
> type=%x\n",headerlen,ptsdata,ptslen,subStreamType);
> +           int n=headerlen+8;
> +           for(int j=0 ; j<n ; j+=24) {
> +             for(int k=0 ; k<24 && j+k<n ; k++) printf("%02x 
> ",bi[j+k]);
> +             printf("\n");
> +             }
> +#endif
>  
>             switch (subStreamType) {
>             case aDTS:
> @@ -524,22 +567,17 @@
>                      }
>                   }
>  
> -              // extract if PTS info
> -              uchar PTSflags = (subStreamType == 0x8) ? 2 : 
> b[i + 7] >> 6;  // For PES we use fixed flags ??
> -              const uchar *PTSdata = b + i + 9;
> -              int PTSlength = b[i + 8];
> -
>                //skip to raw AC3 data
> -              offset += PTSlength + 9;
> +              offset += headerlen;
>                int n = min(l - offset, length - i);
>  
> -              encapsulator->Decode(b + offset + i, b + 
> offset + i + n, PTSflags, PTSdata);
> -
> +              encapsulator->Decode(bi + offset, bi + offset 
> + n, bi[ptsdata-2] >> 6, bi + ptsdata);
> +              }
> +              // fall through
> +           case 0xFF: // dummy to skip paket
>                // Cancel this stream
> -              memset(b + i, 0, l);
> -
> +              memset(bi, 0, min(l,length-i)); // check for buffer 
> + boundary
>                break;
> -              }
>             case aLPCM: // leave this untouched
>                break;
>             default:
> 
> 
> -- 
> Stefan Huelswitt
> huels@iname.com  | http://home.pages.de/~nathan
> 
> 
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