mpegvideo_enc.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

    return best_b_count;
}

static void select_input_picture(MpegEncContext *s){
    int i;

    for(i=1; i<MAX_PICTURE_COUNT; i++)
        s->reordered_input_picture[i-1]= s->reordered_input_picture[i];
    s->reordered_input_picture[MAX_PICTURE_COUNT-1]= NULL;

    /* set next picture type & ordering */
    if(s->reordered_input_picture[0]==NULL && s->input_picture[0]){
        if(/*s->picture_in_gop_number >= s->gop_size ||*/ s->next_picture_ptr==NULL || s->intra_only){
            s->reordered_input_picture[0]= s->input_picture[0];
            s->reordered_input_picture[0]->pict_type= I_TYPE;
            s->reordered_input_picture[0]->coded_picture_number= s->coded_picture_number++;
        }else{
            int b_frames;

            if(s->avctx->frame_skip_threshold || s->avctx->frame_skip_factor){
                if(s->picture_in_gop_number < s->gop_size && skip_check(s, s->input_picture[0], s->next_picture_ptr)){
                //FIXME check that te gop check above is +-1 correct
//av_log(NULL, AV_LOG_DEBUG, "skip %p %"PRId64"\n", s->input_picture[0]->data[0], s->input_picture[0]->pts);

                    if(s->input_picture[0]->type == FF_BUFFER_TYPE_SHARED){
                        for(i=0; i<4; i++)
                            s->input_picture[0]->data[i]= NULL;
                        s->input_picture[0]->type= 0;
                    }else{
                        assert(   s->input_picture[0]->type==FF_BUFFER_TYPE_USER
                               || s->input_picture[0]->type==FF_BUFFER_TYPE_INTERNAL);

                        s->avctx->release_buffer(s->avctx, (AVFrame*)s->input_picture[0]);
                    }

                    emms_c();
                    ff_vbv_update(s, 0);

                    goto no_output_pic;
                }
            }

            if(s->flags&CODEC_FLAG_PASS2){
                for(i=0; i<s->max_b_frames+1; i++){
                    int pict_num= s->input_picture[0]->display_picture_number + i;

                    if(pict_num >= s->rc_context.num_entries)
                        break;
                    if(!s->input_picture[i]){
                        s->rc_context.entry[pict_num-1].new_pict_type = P_TYPE;
                        break;
                    }

                    s->input_picture[i]->pict_type=
                        s->rc_context.entry[pict_num].new_pict_type;
                }
            }

            if(s->avctx->b_frame_strategy==0){
                b_frames= s->max_b_frames;
                while(b_frames && !s->input_picture[b_frames]) b_frames--;
            }else if(s->avctx->b_frame_strategy==1){
                for(i=1; i<s->max_b_frames+1; i++){
                    if(s->input_picture[i] && s->input_picture[i]->b_frame_score==0){
                        s->input_picture[i]->b_frame_score=
                            get_intra_count(s, s->input_picture[i  ]->data[0],
                                               s->input_picture[i-1]->data[0], s->linesize) + 1;
                    }
                }
                for(i=0; i<s->max_b_frames+1; i++){
                    if(s->input_picture[i]==NULL || s->input_picture[i]->b_frame_score - 1 > s->mb_num/s->avctx->b_sensitivity) break;
                }

                b_frames= FFMAX(0, i-1);

                /* reset scores */
                for(i=0; i<b_frames+1; i++){
                    s->input_picture[i]->b_frame_score=0;
                }
            }else if(s->avctx->b_frame_strategy==2){
                b_frames= estimate_best_b_count(s);
            }else{
                av_log(s->avctx, AV_LOG_ERROR, "illegal b frame strategy\n");
                b_frames=0;
            }

            emms_c();
//static int b_count=0;
//b_count+= b_frames;
//av_log(s->avctx, AV_LOG_DEBUG, "b_frames: %d\n", b_count);

            for(i= b_frames - 1; i>=0; i--){
                int type= s->input_picture[i]->pict_type;
                if(type && type != B_TYPE)
                    b_frames= i;
            }
            if(s->input_picture[b_frames]->pict_type == B_TYPE && b_frames == s->max_b_frames){
                av_log(s->avctx, AV_LOG_ERROR, "warning, too many b frames in a row\n");
            }

            if(s->picture_in_gop_number + b_frames >= s->gop_size){
              if((s->flags2 & CODEC_FLAG2_STRICT_GOP) && s->gop_size > s->picture_in_gop_number){
                    b_frames= s->gop_size - s->picture_in_gop_number - 1;
              }else{
                if(s->flags & CODEC_FLAG_CLOSED_GOP)
                    b_frames=0;
                s->input_picture[b_frames]->pict_type= I_TYPE;
              }
            }

            if(   (s->flags & CODEC_FLAG_CLOSED_GOP)
               && b_frames
               && s->input_picture[b_frames]->pict_type== I_TYPE)
                b_frames--;

            s->reordered_input_picture[0]= s->input_picture[b_frames];
            if(s->reordered_input_picture[0]->pict_type != I_TYPE)
                s->reordered_input_picture[0]->pict_type= P_TYPE;
            s->reordered_input_picture[0]->coded_picture_number= s->coded_picture_number++;
            for(i=0; i<b_frames; i++){
                s->reordered_input_picture[i+1]= s->input_picture[i];
                s->reordered_input_picture[i+1]->pict_type= B_TYPE;
                s->reordered_input_picture[i+1]->coded_picture_number= s->coded_picture_number++;
            }
        }
    }
no_output_pic:
    if(s->reordered_input_picture[0]){
        s->reordered_input_picture[0]->reference= s->reordered_input_picture[0]->pict_type!=B_TYPE ? 3 : 0;

        copy_picture(&s->new_picture, s->reordered_input_picture[0]);

        if(s->reordered_input_picture[0]->type == FF_BUFFER_TYPE_SHARED || s->avctx->rc_buffer_size){
            // input is a shared pix, so we can't modifiy it -> alloc a new one & ensure that the shared one is reuseable

            int i= ff_find_unused_picture(s, 0);
            Picture *pic= &s->picture[i];

            pic->reference              = s->reordered_input_picture[0]->reference;
            alloc_picture(s, pic, 0);

            /* mark us unused / free shared pic */
            if(s->reordered_input_picture[0]->type == FF_BUFFER_TYPE_INTERNAL)
                s->avctx->release_buffer(s->avctx, (AVFrame*)s->reordered_input_picture[0]);
            for(i=0; i<4; i++)
                s->reordered_input_picture[0]->data[i]= NULL;
            s->reordered_input_picture[0]->type= 0;

            copy_picture_attributes(s, (AVFrame*)pic, (AVFrame*)s->reordered_input_picture[0]);

            s->current_picture_ptr= pic;
        }else{
            // input is not a shared pix -> reuse buffer for current_pix

            assert(   s->reordered_input_picture[0]->type==FF_BUFFER_TYPE_USER
                   || s->reordered_input_picture[0]->type==FF_BUFFER_TYPE_INTERNAL);

            s->current_picture_ptr= s->reordered_input_picture[0];
            for(i=0; i<4; i++){
                s->new_picture.data[i]+= INPLACE_OFFSET;
            }
        }
        copy_picture(&s->current_picture, s->current_picture_ptr);

        s->picture_number= s->new_picture.display_picture_number;
//printf("dpn:%d\n", s->picture_number);
    }else{
       memset(&s->new_picture, 0, sizeof(Picture));
    }
}

int MPV_encode_picture(AVCodecContext *avctx,
                       unsigned char *buf, int buf_size, void *data)
{
    MpegEncContext *s = avctx->priv_data;
    AVFrame *pic_arg = data;
    int i, stuffing_count;

    for(i=0; i<avctx->thread_count; i++){
        int start_y= s->thread_context[i]->start_mb_y;
        int   end_y= s->thread_context[i]->  end_mb_y;
        int h= s->mb_height;
        uint8_t *start= buf + (size_t)(((int64_t) buf_size)*start_y/h);
        uint8_t *end  = buf + (size_t)(((int64_t) buf_size)*  end_y/h);

        init_put_bits(&s->thread_context[i]->pb, start, end - start);
    }

    s->picture_in_gop_number++;

    if(load_input_picture(s, pic_arg) < 0)
        return -1;

    select_input_picture(s);

    /* output? */
    if(s->new_picture.data[0]){
        s->pict_type= s->new_picture.pict_type;
//emms_c();
//printf("qs:%f %f %d\n", s->new_picture.quality, s->current_picture.quality, s->qscale);
        MPV_frame_start(s, avctx);
vbv_retry:
        if (encode_picture(s, s->picture_number) < 0)
            return -1;

        avctx->real_pict_num  = s->picture_number;
        avctx->header_bits = s->header_bits;
        avctx->mv_bits     = s->mv_bits;
        avctx->misc_bits   = s->misc_bits;
        avctx->i_tex_bits  = s->i_tex_bits;
        avctx->p_tex_bits  = s->p_tex_bits;
        avctx->i_count     = s->i_count;
        avctx->p_count     = s->mb_num - s->i_count - s->skip_count; //FIXME f/b_count in avctx
        avctx->skip_count  = s->skip_count;

        MPV_frame_end(s);

        if (ENABLE_MJPEG_ENCODER && s->out_format == FMT_MJPEG)
            ff_mjpeg_encode_picture_trailer(s);

        if(avctx->rc_buffer_size){
            RateControlContext *rcc= &s->rc_context;
            int max_size= rcc->buffer_index/3;

            if(put_bits_count(&s->pb) > max_size && s->lambda < s->avctx->lmax){
                s->next_lambda= FFMAX(s->lambda+1, s->lambda*(s->qscale+1) / s->qscale);
                if(s->adaptive_quant){
                    int i;
                    for(i=0; i<s->mb_height*s->mb_stride; i++)
                        s->lambda_table[i]= FFMAX(s->lambda_table[i]+1, s->lambda_table[i]*(s->qscale+1) / s->qscale);
                }
                s->mb_skipped = 0;        //done in MPV_frame_start()
                if(s->pict_type==P_TYPE){ //done in encode_picture() so we must undo it
                    if(s->flipflop_rounding || s->codec_id == CODEC_ID_H263P || s->codec_id == CODEC_ID_MPEG4)
                        s->no_rounding ^= 1;
                }
                if(s->pict_type!=B_TYPE){
                    s->time_base= s->last_time_base;
                    s->last_non_b_time= s->time - s->pp_time;
                }
//                av_log(NULL, AV_LOG_ERROR, "R:%d ", s->next_lambda);
                for(i=0; i<avctx->thread_count; i++){
                    PutBitContext *pb= &s->thread_context[i]->pb;
                    init_put_bits(pb, pb->buf, pb->buf_end - pb->buf);
                }
                goto vbv_retry;
            }

            assert(s->avctx->rc_max_rate);
        }

        if(s->flags&CODEC_FLAG_PASS1)
            ff_write_pass1_stats(s);

        for(i=0; i<4; i++){
            s->current_picture_ptr->error[i]= s->current_picture.error[i];
            avctx->error[i] += s->current_picture_ptr->error[i];
        }

        if(s->flags&CODEC_FLAG_PASS1)
            assert(avctx->header_bits + avctx->mv_bits + avctx->misc_bits + avctx->i_tex_bits + avctx->p_tex_bits == put_bits_count(&s->pb));
        flush_put_bits(&s->pb);
        s->frame_bits  = put_bits_count(&s->pb);

        stuffing_count= ff_vbv_update(s, s->frame_bits);
        if(stuffing_count){
            if(s->pb.buf_end - s->pb.buf - (put_bits_count(&s->pb)>>3) < stuffing_count + 50){
                av_log(s->avctx, AV_LOG_ERROR, "stuffing too large\n");
                return -1;
            }

            switch(s->codec_id){
            case CODEC_ID_MPEG1VIDEO:
            case CODEC_ID_MPEG2VIDEO:
                while(stuffing_count--){
                    put_bits(&s->pb, 8, 0);
                }
            break;
            case CODEC_ID_MPEG4:
                put_bits(&s->pb, 16, 0);
                put_bits(&s->pb, 16, 0x1C3);
                stuffing_count -= 4;
                while(stuffing_count--){
                    put_bits(&s->pb, 8, 0xFF);
                }
            break;
            default:
                av_log(s->avctx, AV_LOG_ERROR, "vbv buffer overflow\n");
            }
            flush_put_bits(&s->pb);
            s->frame_bits  = put_bits_count(&s->pb);
        }

        /* update mpeg1/2 vbv_delay for CBR */
        if(s->avctx->rc_max_rate && s->avctx->rc_min_rate == s->avctx->rc_max_rate && s->out_format == FMT_MPEG1
           && 90000LL * (avctx->rc_buffer_size-1) <= s->avctx->rc_max_rate*0xFFFFLL){
            int vbv_delay;

            assert(s->repeat_first_field==0);

            vbv_delay= lrintf(90000 * s->rc_context.buffer_index / s->avctx->rc_max_rate);
            assert(vbv_delay < 0xFFFF);

            s->vbv_delay_ptr[0] &= 0xF8;
            s->vbv_delay_ptr[0] |= vbv_delay>>13;
            s->vbv_delay_ptr[1]  = vbv_delay>>5;
            s->vbv_delay_ptr[2] &= 0x07;
            s->vbv_delay_ptr[2] |= vbv_delay<<3;
        }
        s->total_bits += s->frame_bits;
        avctx->frame_bits  = s->frame_bits;
    }else{
        assert((pbBufPtr(&s->pb) == s->pb.buf));
        s->frame_bits=0;
    }
    assert((s->frame_bits&7)==0);

    return s->frame_bits/8;
}

static inline void dct_single_coeff_elimination(MpegEncContext *s, int n, int threshold)
{
    static const char tab[64]=
        {3,2,2,1,1,1,1,1,
         1,1,1,1,1,1,1,1,
         1,1,1,1,1,1,1,1,
         0,0,0,0,0,0,0,0,
         0,0,0,0,0,0,0,0,
         0,0,0,0,0,0,0,0,
         0,0,0,0,0,0,0,0,
         0,0,0,0,0,0,0,0};
    int score=0;
    int run=0;
    int i;
    DCTELEM *block= s->block[n];
    const int last_index= s->block_last_index[n];
    int skip_dc;

    if(threshold<0){
        skip_dc=0;