Visual C++实现JPEG-MPEG编解码技术书后附带的代码

mpeg2encode

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MPEG-2 Video Encoder, Version 1.1, June 1994

MPEG Software Simulation Group

(MPEG-L@netcom.com)

Contents:

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1. Overview

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This is the second public release of our MPEG-2 encoder. It converts an

ordered set of uncompressed input pictures into a compressed bitstream

compliant with ISO/IEC 13818-2 DIS [1] (MPEG-2).

This program will evolve to become: ISO/IEC 13818-5 Software Simulation

of MPEG-2 Systems, Video, and Audio.

2. Features and Limitations

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2.1 Features

- generates constant bit rate streams

2.2 Current limitations

The encoder currently does not support

- scalable extensions

- MPEG-1 integer pel vectors (half-pel is typically 1 dB better anyway)

and D frame sequences.

- checking for maximum number of generated bits per macroblock

- automatic 3:2 pulldown detection or irregular 3:2 pulldown signaling.

- intra refresh slices (e.g. low delay)

- concealment motion vectors

- special low delay mode rate control

The execution template for the encoder is:

mpeg2encode parameter_file output.m2v

Coding parameters can be modified by editing the parameter_file. Since the

parser expects the operating parameters to be on certain line numbers,

kindly do not insert or delete lines from the file.

We have provided a couple of sample parameter files in the par directory.

It is recommended to use the one closest to your application as a starting

point for customization.

The first line of the parameter file is a comment which is inserted near

/* name of source frame files */

contain exactly one numerical descriptor (%d, %x etc.):

Example: frame%02d

Then the encoder looks for files: frame00, frame01, frame02

The encoder adds an extension (.yuv, .ppm, etc.) which depends on the

input file format. Input files have to be in frame format, containing

two interleaved fields (for interlaced video).

/* name of reconstructed frame files */

This user parameter tells the encoder what name to give the reconstructed

frames. These frames are identical to frame reconstructions of decoders

following normative guidelines (except of course for differences caused by

different IDCT implementation). Specifying a name starting with - (or just

- by itself) disables output of reconstructed frames.

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

or newline), one corresponding to each of the 64 DCT coefficients. They

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)

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.

/* name of statistics file */

Statistics output is stored into the specified file. - directs statistics

---- ------------------------------------------------------------------

correspond to the selected chroma_format (4:2:0, 4:2:2, 4:4:4, see

is also used in the Stanford PVRG encoder.

1 similar to 0, but concatenated into one file (extension .yuv).

This is the format used by the Berkeley MPEG-1 encoder.

2 PPM, Portable PixMap, only the raw format (P6) is supported.

/* number of frames */

This defines the length of the sequence in integer units of frames.

/* number of first frame */

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

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).

0 selects frame picture coding, in which both fields of a frame are coded

simultaneously, 1 select field picture coding, where fields are coded

separately. The latter is permitted for interlaced video only.

/* horizontal_size */

Pixel width of the frames. It does not need to be a multiple of 16.

You have to provide a correct value even for PPM files (the PPM

file header is currently ignored).

/* vertical_size */

Pixel height of the frames. It does not need to be a multiple of 16.

Defines the display aspect ratio. Legal values are:

---- --------------

2 4:3 display

3 16:9 display

4 2.21:1 display

MPEG-1 uses a different coding of aspect ratios. In this cases codes

1 to 14 are valid.

/* frame_rate_code */

Defines the frame rate (for interlaced sequences: field rate is twice

the frame rate). Legal values are:

Code Frames/sec Meaning

---- ---------- -----------------------------------------------

7 60000/1001 double frame rate NTSC

8 60 double frame rate drop-frame NTSC

In units of bits/sec.

/* 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 112 for