ffmpeg中CBR（固定码率控制）的设置：

c->bit_rate = br; 
c->rc_min_rate =br; 
c->rc_max_rate = br; 
c->bit_rate_tolerance = br; 
c->rc_buffer_size=br; 
c->rc_initial_buffer_occupancy = c->rc_buffer_size*3/4; 
c->rc_buffer_aggressivity= (float)1.0; 
c->rc_initial_cplx= 0.5; 

ffmpeg中VBR（可变率控制）的设置：

c->flags |= CODEC_FLAG_QSCALE; 
c->rc_min_rate =min; 
c->rc_max_rate = max; 
c->bit_rate = br;    

实际应用:

ptAvEncoder->ptAvStreamVideo->codec->codec_id=CODEC_ID_H264; 
ptAvEncoder->ptAvStreamVideo->codec->codec_type=AVMEDIA_TYPE_VIDEO; 
ptAvEncoder->ptAvStreamVideo->codec->pix_fmt=PIX_FMT_YUV420P; 
ptAvEncoder->ptAvStreamVideo->codec->width=s32Width; 
ptAvEncoder->ptAvStreamVideo->codec->height=s32Height; 
ptAvEncoder->ptAvStreamVideo->codec->time_base.den=s32Fps; 
ptAvEncoder->ptAvStreamVideo->codec->time_base.num=1; 
ptAvEncoder->ptAvStreamVideo->codec->gop_size=s32KeyMax; 
ptAvEncoder->ptAvStreamVideo->codec->keyint_min=5; 
ptAvEncoder->ptAvStreamVideo->codec->max_b_frames=0; 
ptAvEncoder->ptAvStreamVideo->codec->flags|=CODEC_FLAG_GLOBAL_HEADER; 
ptAvEncoder->ptAvStreamVideo->codec->level=30; 
ptAvEncoder->ptAvStreamVideo->codec->bit_rate=s32RateVideo; 
ptAvEncoder->ptAvStreamVideo->codec->rc_min_rate=s32RateVideo; 
ptAvEncoder->ptAvStreamVideo->codec->rc_max_rate=s32RateVideo; 
ptAvEncoder->ptAvStreamVideo->codec->bit_rate_tolerance=s32RateVideo; 
ptAvEncoder->ptAvStreamVideo->codec->rc_buffer_size=s32RateVideo; 
ptAvEncoder->ptAvStreamVideo->codec->rc_initial_buffer_occupancy
=ptAvEncoder->ptAvStreamVideo->codec->rc_buffer_size*3/4; 
ptAvEncoder->ptAvStreamVideo->codec->rc_buffer_aggressivity=(float)1.0; 
ptAvEncoder->ptAvStreamVideo->codec->rc_initial_cplx=0.5; 
/* 
ptAvEncoder->ptAvStreamVideo->codec->thread_count=1; 
ptAvEncoder->ptAvStreamVideo->codec->cqp=26; 
ptAvEncoder->ptAvStreamVideo->codec->refs=3; 
ptAvEncoder->ptAvStreamVideo->codec->flags2=CODEC_FLAG2_MIXED_REFS; 
ptAvEncoder->ptAvStreamVideo->codec->trellis=2; 
ptAvEncoder->ptAvStreamVideo->codec->flags2|=CODEC_FLAG2_8X8DCT; 
ptAvEncoder->ptAvStreamVideo->codec->me_method=8; 
ptAvEncoder->ptAvStreamVideo->codec->me_range=16; 
ptAvEncoder->ptAvStreamVideo->codec->me_subpel_quality=7; 
ptAvEncoder->ptAvStreamVideo->codec->qmin=10; 
ptAvEncoder->ptAvStreamVideo->codec->qmax=51; 
ptAvEncoder->ptAvStreamVideo->codec->rc_initial_buffer_occupancy=0.9; 
ptAvEncoder->ptAvStreamVideo->codec->i_quant_factor=1.0/1.40f; 
ptAvEncoder->ptAvStreamVideo->codec->b_quant_factor=1.30f; 
ptAvEncoder->ptAvStreamVideo->codec->chromaoffset=0; 
ptAvEncoder->ptAvStreamVideo->codec->max_qdiff=4; 
ptAvEncoder->ptAvStreamVideo->codec->qcompress=0.6f; 
ptAvEncoder->ptAvStreamVideo->codec->qblur=0.5f; 
ptAvEncoder->ptAvStreamVideo->codec->noise_reduction=0; 
ptAvEncoder->ptAvStreamVideo->codec->scenechange_threshold=40; 
ptAvEncoder->ptAvStreamVideo->codec->flags2|=CODEC_FLAG2_AUD; 
ptAvEncoder->ptAvStreamVideo->codec->coder_type=FF_CODER_TYPE_AC; 
ptAvEncoder->ptAvStreamVideo->codec->flags|=CODEC_FLAG_LOOP_FILTER; 
ptAvEncoder->ptAvStreamVideo->codec->me_cmp=FF_CMP_CHROMA; 
ptAvEncoder->ptAvStreamVideo->codec->flags2|=CODEC_FLAG2_FASTPSKIP; 
ptAvEncoder->ptAvStreamVideo->codec->flags2|=CODEC_FLAG2_BPYRAMID; 
ptAvEncoder->ptAvStreamVideo->codec->flags2|=CODEC_FLAG_NORMALIZE_AQP; 
ptAvEncoder->ptAvStreamVideo->codec->flags2|=CODEC_FLAG2_WPRED; 
ptAvEncoder->ptAvStreamVideo->codec->flags2|=CODEC_FLAG2_MBTREE; 
ptAvEncoder->ptAvStreamVideo->codec->b_frame_strategy=2; 
*/