newbie needs help on MPEG-2

Dear all,

I'm new to MPEG-2 and would appreciate any input to the following
questions:
1. Where can I get some popular test sequences such as Flowergarden,
Jeep and the like?
2. The MPEG-2 encoder by MPEG Software Simulation Group provides a
routine to calculate the SNR which is invoked in module putseq.c:

      transform(predframe,neworg,mbinfo,blocks);
      putpict(neworg[0]);
      for (k=0; k<mb_height2*mb_width; k++)
      {
        if (mbinfo[k].mb_type & MB_INTRA)
          for (j=0; j<block_count; j++)
            iquant_intra(blocks[k*block_count+j],blocks[k*block_count+j],
                         dc_prec,intra_q,mbinfo[k].mquant);
        else
          for (j=0;j<block_count;j++)
            iquant_non_intra(blocks[k*block_count+j],blocks[k*block_count+j],
                             inter_q,mbinfo[k].mquant);
      }
      itransform(predframe,newref,mbinfo,blocks);
      calcSNR(neworg,newref);

>From the code it seems that the reconstructed frame is newref, which
is calculated by adding predframe and IDCT of blocks. However, the
blocks are already quantized after DCT transform. That is, to obtain
the reconstructed frame, DCT is inverted by IDCT, yet quantization
effect of blocks is not accounted for. Am I missing something here?

Regards,

Bill