在mpegvideo.c中，
AVCodec mpeg4_encoder = {
???"mpeg4",
???CODEC_TYPE_VIDEO,
???CODEC_ID_MPEG4,
???sizeof(MpegEncContext),
???MPV_encode_init,
???MPV_encode_picture,
???MPV_encode_end,
??? .pix_fmts=(enum PixelFormat[]){PIX_FMT_YUV420P, -1},
???.capabilities= CODEC_CAP_DELAY,
};

MPV_encode_picture()
{
?encode_picture();
}

encode_picture()
{
?//對每個宏塊MB進行運動估計
?estimate_motion_thread();

?encode_thread();
}

encode_thread()
{
?encode_mb_hq();
}

encode_mb_hq()
{
?encode_mb();
}

encode_mb()
{
?encode_mb_internal();
}

encode_mb_internal()
{
?//對單一的宏塊進行運動補償
?MPV_motion();

?//DCT & quantize
?dct_quantize_c();

?//huffman encode
?mpeg4_encode_mb();
}

幀內和幀間的量化矩陣在mpeg4data.h中
const int16_t ff_mpeg4_default_intra_matrix[64] = {
? 8, 17, 18, 19, 21, 23, 25, 27,
?17, 18, 19, 21, 23, 25, 27, 28,
?20, 21, 22, 23, 24, 26, 28, 30,
?21, 22, 23, 24, 26, 28, 30, 32,
?22, 23, 24, 26, 28, 30, 32, 35,
?23, 24, 26, 28, 30, 32, 35, 38,
?25, 26, 28, 30, 32, 35, 38, 41,
?27, 28, 30, 32, 35, 38, 41, 45,
};

const int16_t ff_mpeg4_default_non_intra_matrix[64] = {
?16, 17, 18, 19, 20, 21, 22, 23,
?17, 18, 19, 20, 21, 22, 23, 24,
?18, 19, 20, 21, 22, 23, 24, 25,
?19, 20, 21, 22, 23, 24, 26, 27,
?20, 21, 22, 23, 25, 26, 27, 28,
?21, 22, 23, 24, 26, 27, 28, 30,
?22, 23, 24, 26, 27, 28, 30, 31,
?23, 24, 25, 27, 28, 30, 31, 33,
};

D、量化矩陣

mpeg中的量化是對8x8 YUV 信號圖塊進行DCT變換之后的系數的量化。通過對高頻分量使用比較大的量化階從而達到減小高頻分量的編碼空間，達到壓縮的目的。代價就是喪失圖像細節，邊緣模糊等。

1）幀內編碼量化矩陣：這是指對I幀使用的幀內編碼量化矩陣

2）幀間編碼量化矩陣：是指對非I幀的幀間預測誤差編碼所用的量化矩陣。威龍漢化版中叫外部矩陣