  The contents of this file were edited from the original MSSG
  ditribution. The parameter file is a subset of the MSSG version
  since avi2mpg1 only generates MPEG-1, and since many of the
  encoding parameters can be determined from the avi file format.
  The file "TEMPLATE.PAR" should be used as a template for any
  changes. TEMPLATE.PAR contains the same parameters that are used
  by default by avi2mpg1 if no parameter file is specified. The main
  use of a parameter file will probably be to experiment with different
  motion estimation search vectors.

  DO NOT ADD OR DELETE LINES FROM THE PARAMETER FILE, the input
  routines depend on the exact ordering of the parameter lines!
  Use the template.par provided and edit the given parameters.

  The first line of the parameter file is a comment which is inserted near
  the beginning of the MPEG bitstream as a user_data field, and can be 
  used for arbitrary purposes.

  The remaining lines are described below:

 /* name of intra quant matrix file     ("-": default matrix) */ 

  Setting this to a value other than  -  specifies a file containing
  a custom intra quantization matrix to be used instead of the default 
  matrix specified in ISO/IEC 13818-2 and 11172-2. This file has to contain 
  64 integer values (range 1...255) separated by white space (blank, tab, 
  or newline), one corresponding  to each of the 64 DCT coefficients. They 
  are ordered line by line, i.e. v-u frequency matrix order (not by the 
  zig-zag pattern used for transmission). The file intra.mat contains the 
  default matrix as a starting point for customization. It is neither 
  necessary or recommended to specify the default matrix explicitly.

  Large values correspond to coarse quantization and consequently more
  noise at that particular spatial frequency.

  For the intra quantization matrix, the first value in the file (DC value)
  is ignored. Use the parameter intra_dc_precision (see below) to define
  the quantization of the DC value.
    
 /* name of non intra quant matrix file ("-": default matrix) */

  This parameter field follows the same rules as described for the above 
  intra quant matrix parameter, but specifies the file for the NON-INTRA 
  coded (predicted / interpolated) blocks. In this case the first 
  coefficient of the matrix is NOT ignored.    

  The default matrix uses a constant value of 16 for all 64 coefficients.
  (a flat matrix is thought to statistically minimize mean square error). 
  The file inter.mat contains an alternate matrix, used in the MPEG-2 test
  model.

 /* timecode of first frame */

  This line is used to set the timecode encoded into the first 'Group of
  Pictures' header. The format is based on the SMPTE style:

  hh:mm:ss:ff (hh=hour, mm=minute, ss=second, ff=frame (0..picture_rate-1)

 /* N (# of frames in GOP) */

  This defines the distance between I frames (and 'Group of Pictures'
  headers). Common values are 15 for 30 Hz video and 12 for 25 Hz video.

 /* M (I/P frame distance) */

  Distance between consecutive I or P frames. Usually set to 3.
  N has to be a multiple of M.   M = 1 means no B frames in the sequence.
  (in a future edition of this program, M=0 will mean only I frames).

 /* aspect_ratio_information */

  Defines the display aspect ratio. Legal values are:

  Code    Meaning
  ----    --------------
  1       square pels
  2       4:3 display
  3       16:9 display
  4       2.21:1 display

  MPEG-1 uses a different coding of aspect ratios. In this case codes
  1 to 14 are valid.

 /* vbv_buffer_size (in multiples 16 kbit) */

  Specifies, according to the Video Buffering Verifier decoder model,  
  the size of the bitstream input buffer required in downstream 
  decoders in order for the sequence to be decoded without underflows or 
  or overflows.  You probably will wish to leave this value at
  20 for Constrained Parameters Bitstreams MPEG-1.

 /* constrained_parameters_flag */

  You may set this to 1 if you encode an MPEG-1 
  sequence which meets the parameter limits defined in ISO/IEC 11172-2 
  for constrained parameter bitstreams:

    horizontal_size <= 768
    vertical_size   <= 576
    picture_area    <= 396 macroblocks
    pixel_rate      <= 396x25 macroblocks per second
    vbv_buffer_size <= 20x16384 bit
    bitrate         <= 1856000 bits/second
    motion vector range <= -64...63.5

 /* Profile ID */

  Specifies the subset of the MPEG-2 syntax required for decoding the 
  sequence. All MPEG-2 sequences generated by the current version of 
  the encoder are either Main Profile or Simple Profile sequences.

  Code  Meaning                       Typical use
  ----  --------------------------    ------------------------
  1     High Profile                  production equipment requiring 4:2:2
  2     Spatially Scalable Profile    Simulcasting 
  3     SNR Scalable Profile          Simulcasting
  4     Main Profile                  95 % of TVs, VCRs, cable applications
  5     Simple Profile                Low cost memory, e.g. no B pictures

 /* Level ID */

  Specifies coded parameter constraints, such as bitrate, sample rate, and 
  maximum allowed motion vector range.

  Code  Meaning         Typical use
  ----  --------------- -----------------------------------------------
  4     High Level      HDTV production rates: e.g. 1920 x 1080 x 30 Hz
  6     High 1440 Level HDTV consumer rates: e.g. 1440 x 960 x 30 Hz
  8     Main Level      CCIR 601 rates: e.g. 720 x 480 x 30 Hz
  10    Low Level       SIF video rate: e.g. 352 x 240 x 30 Hz

 /* video_format: 0=comp., 1=PAL, 2=NTSC, 3=SECAM, 4=MAC, 5=unspec. */
 
 /* color_primaries */

  Specifies the x, y chromaticity coordinates of the source primaries.

  Code   Meaning
  ----   -------
  1      ITU-R Rec. 709 (1990)
  2      unspecified
  4      ITU-R Rec. 624-4 System M
  5      ITU-R Rec. 624-4 System B, G
  6      SMPTE 170M
  7      SMPTE 240M (1987)

 /* transfer_characteristics */

  Specifies the opto-electronic transfer characteristic of the source picture.

  Code   Meaning
  ----   -------
  1      ITU-R Rec. 709 (1990)
  2      unspecified
  4      ITU-R Rec. 624-4 System M
  5      ITU-R Rec. 624-4 System B, G
  6      SMPTE 170M
  7      SMPTE 240M (1987)
  8      linear transfer characteristics

 /* matrix_coefficients */

  Specifies the matrix coefficients used in deriving luminance and chrominance
  signals from the green, blue, and red primaries.

  Code   Meaning
  ----   -------
  1      ITU-R Rec. 709 (1990)
  2      unspecified
  4      FCC
  5      ITU-R Rec. 624-4 System B, G
  6      SMPTE 170M
  7      SMPTE 240M (1987)

 /* intra_dc_precision */

  Specifies the effective precision of the DC coefficient in MPEG-2 
  intra coded macroblocks. 10-bits usually achieves quality saturation.

  Code    Meaning
  ----    -----------------
  0       8 bit
  1       9 bit
  2       10 bit
  3       11 bit

 /* frame_pred_frame_dct (I P B) */

  Setting this parameter to 1 restricts motion compensation to frame 
  prediction and DCT to frame DCT. You have to specify this separately for 
  I, P and B picture types.

 /* q_scale_type (I P B) */
  
  These flag sets linear (0) or non-linear (1) quantization scale type 
  for the three respective picture types.

 /* intra_vlc_format (I P B) */

  Selects one of the two variable length coding tables for intra coded blocks.
  Table 1 is considered to be statistically optimized for Intra coded 
  pictures coded within the sweet spot range (e.g. 0.3 to 0.6 bit/pixel)
  of MPEG-2.
  
  Code  Meaning
  ----  -----------------
  0     table 0 (= MPEG-1) 
  1     table 1

 /* alternate_scan (I P B) */

  Selects one of two entropy scanning patterns defining the order in 
  which quantized DCT coefficients are run-length coded.  The alternate 
  scanning pattern is considered to be better suited for interlaced video 
  where the encoder does not employ sophisticated forward quantization 
  (as is the case in our current encoder).
  
  Code  Meaning
  ----  -----------------
  0     Zig-Zag scan (= MPEG-1)
  1     Alternate scan 

 /* repeat_first_field */

  If set to one, the first field of a frame is repeated after the second by
  the display process. The exact function depends on progressive_sequence
  and top_field_first.  repeat_first_field is mainly intended to serve as 
  a signal for the Decoder's Display Process to perform 3:2 pulldown.
 
 /* intra_slice refresh picture period (P factor) */
   
   This value indicates the number of successive P pictures in which  
   all slices (macroblock rows in our encoder model) are refreshed 
   with intra coded macroblocks.  This feature assists low delay mode
   coding.  It is currently not implemented.

 /* rate control: r (reaction parameter) */
 /* rate control: avg_act (initial average activity) */
 /* rate control: Xi (initial I frame global complexity measure) */
 /* rate control: Xp (initial P frame global complexity measure) */
 /* rate control: Xb (initial B frame global complexity measure) */
 /* rate control: d0i (initial I frame virtual buffer fullness) */
 /* rate control: d0p (initial P frame virtual buffer fullness) */
 /* rate control: d0b (initial B frame virtual buffer fullness) */

  These parameters modify the behavior of the rate control scheme. Usually
  set them to 0, in which case default values are computed by the encoder.

 /* P:  forw_hor_f_code forw_vert_f_code search_width/height */
 /* B1: forw_hor_f_code forw_vert_f_code search_width/height */
 /* B1: back_hor_f_code back_vert_f_code search_width/height */
 /* B2: forw_hor_f_code forw_vert_f_code search_width/height */
 /* B2: back_hor_f_code back_vert_f_code search_width/height */

  This set of parameters specifies the maximum length of the motion
  vectors. If this length is set smaller than the actual movement
  of objects in the picture, motion compensation becomes ineffective
  and picture quality drops. If it is set too large, an excessive
  number of bits is allocated for motion vector transmission, indirectly
  reducing picture quality, too.

  All f_code values have to be in the range 1 to 9 (1 to 7 for MPEG-1),
  which translate into maximum motion vector lengths as follows:

  code  range (inclusive)  max search width/height
  ================================================
  1        -8 ...    +7.5       7
  2       -16 ...   +15.5      15
  3       -32 ...   +31.5      31
  4       -64 ...   +63.5      63
  5      -128 ...  +127.5     127
  6      -256 ...  +255.5     255
  7      -512 ...  +511.5     511
  8     -1024 ... +1023.5    1023
  9     -2048 ... +2047.5    2047

  f_code is specified individually for each picture type (P,Bn), direction
  (forward prediction, backward prediction) and component (horizontal,
  vertical). Bn is the n'th B frame surrounded by I or P frames
  (e.g.: I B1 B2 B3 P B1 B2 B3 P ...).

  For MPEG-1 sequences, horizontal and vertical f_code have to be
  identical and the range is restricted to 1...7.

  P frame values have to be specified if N (N = # of frames in GOP) is
  greater than 1 (otherwise the sequences contains only I frames).

  M - 1 (M = distance between I/P frames) sets (two lines each) of values
  have to specified for B frames. The first line of each set defines
  values for forward prediction (i.e. from a past frame), the second
  line those for backward prediction (from a future frame).

  search_width and search_height set the (half) width of the window used
  for motion estimation. The encoder currently employs exhaustive
  integer vector block matching. Execution time for this algorithm depends
  on the product of search_width and search_height and, too a large extent,
  determines the speed of the encoder. Therefore these values have to be
  chosen carefully.

  Here is an example of how to set these values, assuming a maximum
  motion of 10 pels per frame in horizontal and 5 pels per frame in
  vertical direction and M=3 (I B1 B2 P):

  search width / height:

  forward  hor.  vert.     backward  hor.  vert.
  I -> B1  10     5        B1 <- P   20    10
  I -> B2  20    10        B2 <- P   10     5
  I -> P   30    15

  f_code values are then selected as the smallest ones resulting in a range
  larger than the search widths / heights:

  3 2  30 15 /* P:  forw_hor_f_code forw_vert_f_code search_width/height */
  2 1  10  5 /* B1: forw_hor_f_code forw_vert_f_code search_width/height */
  3 2  20 10 /* B1: back_hor_f_code back_vert_f_code search_width/height */
  3 2  20 10 /* B2: forw_hor_f_code forw_vert_f_code search_width/height */
  2 1  10  5 /* B2: back_hor_f_code back_vert_f_code search_width/height */


