我指的是这个

preset会影响画质

预设的参数是在默认的基础上覆盖一些设置，区别如下：
1、ultrafast
param->i_frame_reference = 1;
param->i_scenecut_threshold = 0;
param->b_deblocking_filter = 0;
param->b_cabac = 0;
param->i_bframe = 0;
param->analyse.intra = 0;
param->analyse.inter = 0;
param->analyse.b_transform_8x8 = 0;
param->analyse.i_me_method = X264_ME_DIA;
param->analyse.i_su
bp
el_refine = 0;
param->rc.i_aq_mode = 0;
param->analyse.b_mixed_references = 0;
param->analyse.i_trellis = 0;
param->i_bframe_adaptive = X264_B_ADAPT_NONE;
param->rc.b_mb_tree = 0;
param->analyse.i_weighted_pred = X264_WEIGHTP_NONE;
param->analyse.b_weighted_bipred = 0;
param->rc.i_lookahead = 0;
2、superfast
param->analyse.inter = X264_ANALYSE_I8x8|X264_ANALYSE_I4x4;
param->analyse.i_me_method = X264_ME_DIA;
param->analyse.i_subpel_refine = 1;
param->i_frame_reference = 1;
param->analyse.b_mixed_references = 0;
param->analyse.i_trellis = 0;
param->rc.b_mb_tree = 0;
param->analyse.i_weighted_pred = X264_WEIGHTP_SIMPLE;
param->rc.i_lookahead = 0;
3、veryfast
param->analyse.i_me_method = X264_ME_HEX;
param->analyse.i_subpel_refine = 2;
param->i_frame_reference = 1;
param->analyse.b_mixed_references = 0;
param->analyse.i_trellis = 0;
param->analyse.i_weighted_pred = X264_WEIGHTP_SIMPLE;
param->rc.i_lookahead = 10;
4、faster
param->analyse.b_mixed_references = 0;
param->i_frame_reference = 2;
param->analyse.i_subpel_refine = 4;
param->analyse.i_weighted_pred = X264_WEIGHTP_SIMPLE;
param->rc.i_lookahead = 20;
5、fast
param->i_frame_reference = 2;
param->analyse.i_subpel_refine = 6;
param->analyse.i_weighted_pred = X264_WEIGHTP_SIMPLE;
param->rc.i_lookahead = 30;
6、medium
默认
7、slow
param->analyse.i_me_method = X264_ME_UMH;
param->analyse.i_subpel_refine = 8;
param->i_frame_reference = 5;
param->i_bframe_adaptive = X264_B_ADAPT_TRELLIS;
param->analyse.i_direct_mv_pred = X264_DIRECT_PRED_AUTO;
param->rc.i_lookahead = 50;
8、slower
param->analyse.i_me_method = X264_ME_UMH;
param->analyse.i_subpel_refine = 9;
param->i_frame_reference = 8;
param->i_bframe_adaptive = X264_B_ADAPT_TRELLIS;
param->analyse.i_direct_mv_pred = X264_DIRECT_PRED_AUTO;
param->analyse.inter |= X264_ANALYSE_PSUB8x8;
param->analyse.i_trellis = 2;
param->rc.i_lookahead = 60;
9、veryslow
param->analyse.i_me_method = X264_ME_UMH;
param->analyse.i_subpel_refine = 10;
param->analyse.i_me_range = 24;
param->i_frame_reference = 16;
param->i_bframe_adaptive = X264_B_ADAPT_TRELLIS;
param->analyse.i_direct_mv_pred = X264_DIRECT_PRED_AUTO;
param->analyse.inter |= X264_ANALYSE_PSUB8x8;
param->analyse.i_trellis = 2;
param->i_bframe = 8;
param->rc.i_lookahead = 60;
10、placebo
param->analyse.i_me_method = X264_ME_TESA;
param->analyse.i_subpel_refine = 11;
param->analyse.i_me_range = 24;
param->i_frame_reference = 16;
param->i_bframe_adaptive = X264_B_ADAPT_TRELLIS;
param->analyse.i_direct_mv_pred = X264_DIRECT_PRED_AUTO;
param->analyse.inter |= X264_ANALYSE_PSUB8x8;
param->analyse.b_fast_pskip = 0;
param->analyse.i_trellis = 2;
param->i_bframe = 16;
param->rc.i_lookahead = 60;

这问的是模板present，而不仅仅是速度问题了。。。。