mpeg12enc.c

ffmpeg的完整源代码和作者自己写的文档。不但有在Linux的工程哦

/*
 * MPEG1/2 encoder
 * Copyright (c) 2000,2001 Fabrice Bellard.
 * Copyright (c) 2002-2004 Michael Niedermayer <[e-mail]>
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file mpeg12enc.c
 * MPEG1/2 encoder
 */

#include "avcodec.h"
#include "dsputil.h"
#include "mpegvideo.h"

#include "mpeg12.h"
#include "mpeg12data.h"
#include "bytestream.h"


static const uint8_t inv_non_linear_qscale[13] = {
    0, 2, 4, 6, 8,
    9,10,11,12,13,14,15,16,
};

static const uint8_t svcd_scan_offset_placeholder[14] = {
    0x10, 0x0E,
    0x00, 0x80, 0x81,
    0x00, 0x80, 0x81,
    0xff, 0xff, 0xff,
    0xff, 0xff, 0xff,
};

static void mpeg1_encode_block(MpegEncContext *s,
                         DCTELEM *block,
                         int component);
static void mpeg1_encode_motion(MpegEncContext *s, int val, int f_or_b_code);    // RAL: f_code parameter added

static uint8_t mv_penalty[MAX_FCODE+1][MAX_MV*2+1];
static uint8_t fcode_tab[MAX_MV*2+1];

static uint8_t  uni_mpeg1_ac_vlc_len [64*64*2];
static uint8_t  uni_mpeg2_ac_vlc_len [64*64*2];

/* simple include everything table for dc, first byte is bits number next 3 are code*/
static uint32_t mpeg1_lum_dc_uni[512];
static uint32_t mpeg1_chr_dc_uni[512];

static uint8_t mpeg1_index_run[2][64];
static int8_t mpeg1_max_level[2][64];

static void init_uni_ac_vlc(RLTable *rl, uint8_t *uni_ac_vlc_len){
    int i;

    for(i=0; i<128; i++){
        int level= i-64;
        int run;
        for(run=0; run<64; run++){
            int len, bits, code;

            int alevel= FFABS(level);
            int sign= (level>>31)&1;

            if (alevel > rl->max_level[0][run])
                code= 111; /*rl->n*/
            else
                code= rl->index_run[0][run] + alevel - 1;

            if (code < 111 /* rl->n */) {
                /* store the vlc & sign at once */
                len=   rl->table_vlc[code][1]+1;
                bits= (rl->table_vlc[code][0]<<1) + sign;
            } else {
                len=  rl->table_vlc[111/*rl->n*/][1]+6;
                bits= rl->table_vlc[111/*rl->n*/][0]<<6;

                bits|= run;
                if (alevel < 128) {
                    bits<<=8; len+=8;
                    bits|= level & 0xff;
                } else {
                    bits<<=16; len+=16;
                    bits|= level & 0xff;
                    if (level < 0) {
                        bits|= 0x8001 + level + 255;
                    } else {
                        bits|= level & 0xffff;
                    }
                }
            }

            uni_ac_vlc_len [UNI_AC_ENC_INDEX(run, i)]= len;
        }
    }
}


static int find_frame_rate_index(MpegEncContext *s){
    int i;
    int64_t dmin= INT64_MAX;
    int64_t d;

    for(i=1;i<14;i++) {
        int64_t n0= 1001LL/ff_frame_rate_tab[i].den*ff_frame_rate_tab[i].num*s->avctx->time_base.num;
        int64_t n1= 1001LL*s->avctx->time_base.den;
        if(s->avctx->strict_std_compliance > FF_COMPLIANCE_INOFFICIAL && i>=9) break;

        d = FFABS(n0 - n1);
        if(d < dmin){
            dmin=d;
            s->frame_rate_index= i;
        }
    }
    if(dmin)
        return -1;
    else
        return 0;
}

static int encode_init(AVCodecContext *avctx)
{
    MpegEncContext *s = avctx->priv_data;

    if(MPV_encode_init(avctx) < 0)
        return -1;

    if(find_frame_rate_index(s) < 0){
        if(s->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL){
            av_log(avctx, AV_LOG_ERROR, "MPEG1/2 does not support %d/%d fps\n", avctx->time_base.den, avctx->time_base.num);
            return -1;
        }else{
            av_log(avctx, AV_LOG_INFO, "MPEG1/2 does not support %d/%d fps, there may be AV sync issues\n", avctx->time_base.den, avctx->time_base.num);
        }
    }

    if(avctx->profile == FF_PROFILE_UNKNOWN){
        if(avctx->level != FF_LEVEL_UNKNOWN){
            av_log(avctx, AV_LOG_ERROR, "Set profile and level\n");
            return -1;
        }
        avctx->profile = s->chroma_format == CHROMA_420 ? 4 : 0; /* Main or 4:2:2 */
    }

    if(avctx->level == FF_LEVEL_UNKNOWN){
        if(avctx->profile == 0){ /* 4:2:2 */
            if(avctx->width <= 720 && avctx->height <= 608) avctx->level = 5; /* Main */
            else                                            avctx->level = 2; /* High */
        }else{
            if(avctx->profile != 1 && s->chroma_format != CHROMA_420){
                av_log(avctx, AV_LOG_ERROR, "Only High(1) and 4:2:2(0) profiles support 4:2:2 color sampling\n");
                return -1;
            }
            if(avctx->width <= 720 && avctx->height <= 576) avctx->level = 8; /* Main */
            else if(avctx->width <= 1440)                   avctx->level = 6; /* High 1440 */
            else                                            avctx->level = 4; /* High */
        }
    }

    if((avctx->flags2 & CODEC_FLAG2_DROP_FRAME_TIMECODE) && s->frame_rate_index != 4){
        av_log(avctx, AV_LOG_ERROR, "Drop frame time code only allowed with 1001/30000 fps\n");
        return -1;
    }

    return 0;
}

static void put_header(MpegEncContext *s, int header)
{
    align_put_bits(&s->pb);
    put_bits(&s->pb, 16, header>>16);
    put_bits(&s->pb, 16, header&0xFFFF);
}

/* put sequence header if needed */
static void mpeg1_encode_sequence_header(MpegEncContext *s)
{
        unsigned int vbv_buffer_size;
        unsigned int fps, v;
        int i;
        uint64_t time_code;
        float best_aspect_error= 1E10;
        float aspect_ratio= av_q2d(s->avctx->sample_aspect_ratio);
        int constraint_parameter_flag;

        if(aspect_ratio==0.0) aspect_ratio= 1.0; //pixel aspect 1:1 (VGA)

        if (s->current_picture.key_frame) {
            AVRational framerate= ff_frame_rate_tab[s->frame_rate_index];

            /* mpeg1 header repeated every gop */
            put_header(s, SEQ_START_CODE);

            put_bits(&s->pb, 12, s->width);
            put_bits(&s->pb, 12, s->height);

            for(i=1; i<15; i++){
                float error= aspect_ratio;
                if(s->codec_id == CODEC_ID_MPEG1VIDEO || i <=1)
                    error-= 1.0/ff_mpeg1_aspect[i];
                else
                    error-= av_q2d(ff_mpeg2_aspect[i])*s->height/s->width;

                error= FFABS(error);

                if(error < best_aspect_error){
                    best_aspect_error= error;
                    s->aspect_ratio_info= i;
                }
            }

            put_bits(&s->pb, 4, s->aspect_ratio_info);
            put_bits(&s->pb, 4, s->frame_rate_index);

            if(s->avctx->rc_max_rate){
                v = (s->avctx->rc_max_rate + 399) / 400;
                if (v > 0x3ffff && s->codec_id == CODEC_ID_MPEG1VIDEO)
                    v = 0x3ffff;
            }else{
                v= 0x3FFFF;
            }

            if(s->avctx->rc_buffer_size)
                vbv_buffer_size = s->avctx->rc_buffer_size;
            else
                /* VBV calculation: Scaled so that a VCD has the proper VBV size of 40 kilobytes */
                vbv_buffer_size = (( 20 * s->bit_rate) / (1151929 / 2)) * 8 * 1024;
            vbv_buffer_size= (vbv_buffer_size + 16383) / 16384;

            put_bits(&s->pb, 18, v & 0x3FFFF);
            put_bits(&s->pb, 1, 1); /* marker */
            put_bits(&s->pb, 10, vbv_buffer_size & 0x3FF);

            constraint_parameter_flag=
                s->width <= 768 && s->height <= 576 &&
                s->mb_width * s->mb_height <= 396 &&
                s->mb_width * s->mb_height * framerate.num <= framerate.den*396*25 &&
                framerate.num <= framerate.den*30 &&
                s->avctx->me_range && s->avctx->me_range < 128 &&
                vbv_buffer_size <= 20 &&
                v <= 1856000/400 &&
                s->codec_id == CODEC_ID_MPEG1VIDEO;

            put_bits(&s->pb, 1, constraint_parameter_flag);

            ff_write_quant_matrix(&s->pb, s->avctx->intra_matrix);
            ff_write_quant_matrix(&s->pb, s->avctx->inter_matrix);

            if(s->codec_id == CODEC_ID_MPEG2VIDEO){
                put_header(s, EXT_START_CODE);
                put_bits(&s->pb, 4, 1); //seq ext

                put_bits(&s->pb, 1, s->avctx->profile == 0); //escx 1 for 4:2:2 profile */

                put_bits(&s->pb, 3, s->avctx->profile); //profile
                put_bits(&s->pb, 4, s->avctx->level); //level

                put_bits(&s->pb, 1, s->progressive_sequence);
                put_bits(&s->pb, 2, s->chroma_format);
                put_bits(&s->pb, 2, 0); //horizontal size ext
                put_bits(&s->pb, 2, 0); //vertical size ext
                put_bits(&s->pb, 12, v>>18); //bitrate ext
                put_bits(&s->pb, 1, 1); //marker
                put_bits(&s->pb, 8, vbv_buffer_size >>10); //vbv buffer ext
                put_bits(&s->pb, 1, s->low_delay);
                put_bits(&s->pb, 2, 0); // frame_rate_ext_n
                put_bits(&s->pb, 5, 0); // frame_rate_ext_d
            }

            put_header(s, GOP_START_CODE);
            put_bits(&s->pb, 1, !!(s->avctx->flags2 & CODEC_FLAG2_DROP_FRAME_TIMECODE)); /* drop frame flag */
            /* time code : we must convert from the real frame rate to a
               fake mpeg frame rate in case of low frame rate */
            fps = (framerate.num + framerate.den/2)/ framerate.den;
            time_code = s->current_picture_ptr->coded_picture_number + s->avctx->timecode_frame_start;

            s->gop_picture_number = s->current_picture_ptr->coded_picture_number;
            if (s->avctx->flags2 & CODEC_FLAG2_DROP_FRAME_TIMECODE) {
                /* only works for NTSC 29.97 */
                int d = time_code / 17982;
                int m = time_code % 17982;
                //if (m < 2) m += 2; /* not needed since -2,-1 / 1798 in C returns 0 */
                time_code += 18 * d + 2 * ((m - 2) / 1798);
            }
            put_bits(&s->pb, 5, (uint32_t)((time_code / (fps * 3600)) % 24));
            put_bits(&s->pb, 6, (uint32_t)((time_code / (fps * 60)) % 60));
            put_bits(&s->pb, 1, 1);
            put_bits(&s->pb, 6, (uint32_t)((time_code / fps) % 60));
            put_bits(&s->pb, 6, (uint32_t)((time_code % fps)));
            put_bits(&s->pb, 1, !!(s->flags & CODEC_FLAG_CLOSED_GOP));
            put_bits(&s->pb, 1, 0); /* broken link */
        }
}

static inline void encode_mb_skip_run(MpegEncContext *s, int run){
    while (run >= 33) {
        put_bits(&s->pb, 11, 0x008);
        run -= 33;
    }
    put_bits(&s->pb, ff_mpeg12_mbAddrIncrTable[run][1],
             ff_mpeg12_mbAddrIncrTable[run][0]);
}

static av_always_inline void put_qscale(MpegEncContext *s)