[Libav-user] Encoding in MPEG2 XDCAM 50Mbit problem

[francesco at bltitalia.com]

Hi to all
I am attempting to encode in MPEG2 XDCAM long gop 50Mbit using libavcodec,
but I think that some settings are wrong and I can't setup values correctly.
Here is the code that generates first 20 blocks of data in separate files:

    /* find the video encoder */
 pcodec_xd = avcodec_find_encoder(CODEC_ID_MPEG2VIDEO);  
 if (pcodec_xd==NULL) { Memo1->Lines->Add("Unable to find codec "); goto
_Encod1Frame_err;}

 pCodecCtx_xd = avcodec_alloc_context3(pcodec_xd);
 if(pCodecCtx_xd==NULL) { Memo1->Lines->Add("Unable to alloc codec
context");goto _Encod1Frame_err;}
 pFrame_xd = avcodec_alloc_frame();
 if(pFrame_xd==NULL) { Memo1->Lines->Add("Unable to alloc frame");goto
_Encod1Frame_err;}

 vform.num = 16;    vform.den = 9;
 pCodecCtx_xd->sample_aspect_ratio = vform; // Set 16:9 aspect ratio

 pCodecCtx_xd->rc_max_rate = pCodecCtx_xd->rc_min_rate
=pCodecCtx_xd->bit_rate = 50000000;

 pCodecCtx_xd->flags =   CODEC_FLAG_INTERLACED_DCT |
CODEC_FLAG_INTERLACED_ME ;//| CODEC_FLAG_CLOSED_GOP ;  

 pCodecCtx_xd->qmin = 1;  //  pCodecCtx_xd->qmax = 3;
 pCodecCtx_xd->rc_buffer_size = 2000000;
 pCodecCtx_xd->rc_initial_buffer_occupancy = 2000000;
 pCodecCtx_xd->time_base.num = 1;        
 pCodecCtx_xd->time_base.den = 25;       

 pCodecCtx_xd->gop_size =  12;     pCodecCtx_xd->max_b_frames= 1;

 pCodecCtx_xd->pix_fmt = PIX_FMT_YUV422P;    
 pCodecCtx_xd->thread_count = Thread_Count;  // Thread_Count = Number of
available processors

 /* resolution must be a multiple of two */
 pCodecCtx_xd->width = Hsize;         // Hsize = 1920
 pCodecCtx_xd->height = (Vsize<<1) ;  // Vsize = 540

 /* the image can be allocated by any means and av_image_alloc() is
  * just the most convenient way if av_malloc() is to be used */
 rtv = av_image_alloc(pFrame_xd->data, pFrame_xd->linesize,
                   pCodecCtx_xd->width, pCodecCtx_xd->height,
pCodecCtx_xd->pix_fmt, 1);

 pFrame_xd->qscale_type = 1;
 pFrame_xd->top_field_first = 1;
 pFrame_xd->interlaced_frame = 1;

 if (avcodec_open2(pCodecCtx_xd, pcodec_xd,NULL) < 0) {rtv = -6; goto
_Encod1Frame_err; }

 for(fldXDCamCnt=0;fldXDCamCnt<nuFlds;fldXDCamCnt+=2)   
 {

   < Code for read two fields, decompress and interlace  them inserting data
in pFrame_xd->data[] >

   out_size = avcodec_encode_video(pCodecCtx_xd, tempBuffer,encBufSize ,
pFrame_xd); // encBufSize = 0x500000;

   if(out_size>0)
   {
    str1 = ExtractFilePath(Application->ExeName) + "\\RecompDir\\compressed_";
    str1.cat_printf("f%d_b%d.m2v",xd_frmNum,blk_cnt);
    PutBufferIntoFile (str1.c_str(), tempBuffer, frameSz);
    str1.printf("Saved block %d",blk_cnt); Memo1->Lines->Add(str1);
    blk_cnt++;
    if(blk_cnt>20) break;
   }

 }

Some questions:

Data out is analyzed using MPEG2-Video ES utils, and has a sample aspect
ratio of 1:2.21 not 16:9. Why ?

If I set the CODEC_FLAG_CLOSED_GOP in the pCodecCtx_xd->flags then the
avcodec_open2 routine fails
(returns -1).  Why he fails ?

I have a block output for every frame in input. Shouldn't I have a block
about  every 12 frames ?

Did someone have an idea ?