[mpeg2] MPEG-1 progress

[Lawrence Gold <gold@shell.aros.net>]

Hi, just wanted to report the progress I've made with encoding MPEG-1
movies.  There're still improvements to be made, but things are looking a
lot better.  Here's my big list of hints and questions:

* Although P->AspectRatio = VT_KFIR_ASPECT_4_3 movies play fine with
  Linux players, they look squashed when played by Quicktime on a Mac or
  when they're fullscreened in older Windows Media Players.  The solution
  is to change the line in kfir.c to

	P->AspectRatio			= VT_KFIR_ASPECT_SQUARE;

* mpeg_stat was complaining that the VBV buffer was too large to meet the
  constrained parameters requirement that some MPEG players have.  The
  solution is to change the relevant line in kfir.c to

	P->VBFBufferSize = mpeg1mode ? 20 : 112;

  This may solve the audio sync problems on Macs, but I haven't been able
  to test this yet.

* If you wish to make VCDs, I've read that you're best off using a vidrate
  of 1150000.  If you just want to stick to the constrained parameters
  set, you can go up to a maximum of 1862000.  

* Every movie I encoded had a bar on the left side.  I was able to get
  rid of it like so:

	P->Horiz	 = 10;

* From what I've read, MPEG-1 supports only progressive frame and
  progressive sequence.  Accordingly, I made the following change, but I
  haven't noticed any differences in playback:

        P->ProgressiveSequence  = mpeg1mode ? VT_KFIR_ON : VT_KFIR_OFF;
        P->ProgressiveFrame     = mpeg1mode ? VT_KFIR_ON : VT_KFIR_OFF;

* Does anyone have any ideas about how the 3/2 pulldown stuff should be
  set?  Right now, P->KF_Auto_3_2_PullDown is set to 0 and
  P->KF_3_2_PullDown is set to KFIR_AUTO.  (There's also a line that sets
  the auto pulldown to 1 if a KFIR_IPBB_PICT encoding is used, but it's
  overridden by the line that sets it to 0.)  Does this make sense for
  encoding MPEG-1 from a VHS source?

* mpeg_stat now complains of just one problem with my encodings:

	Motion vectors are larger than 8 (f_code>4)

  Any ideas how to fix this?  Other MPEG-1 files I've tested don't have
  this problem.

Thanks in advance!