memset(s, 0, sizeof(AVCodecContext));
void avcodec_get_context_defaults(AVCodecContext *s){    s->bit_rate= 800*1000;    s->bit_rate_tolerance= s->bit_rate*10;    s->qmin= 2;    s->qmax= 31;    s->mb_qmin= 2;    s->mb_qmax= 31;    s->rc_eq= "tex^qComp";    s->qcompress= 0.5;    s->max_qdiff= 3;    s->b_quant_factor=1.25;    s->b_quant_offset=1.25;    s->i_quant_factor=-0.8;    s->i_quant_offset=0.0;    s->error_concealment= 3;    s->error_resilience= 1;    s->workaround_bugs= FF_BUG_AUTODETECT;    s->frame_rate_base= 1;    s->frame_rate = 25;    s->gop_size= 50;    s->me_method= ME_EPZS;    s->get_buffer= avcodec_default_get_buffer;    s->release_buffer= avcodec_default_release_buffer;    s->get_format= avcodec_default_get_format;    s->execute= avcodec_default_execute;    s->thread_count=1;    s->me_subpel_quality=8;    s->lmin= FF_QP2LAMBDA * s->qmin;    s->lmax= FF_QP2LAMBDA * s->qmax;    s->sample_aspect_ratio= (AVRational){0,1};    s->ildct_cmp= FF_CMP_VSAD;        s->intra_quant_bias= FF_DEFAULT_QUANT_BIAS;    s->inter_quant_bias= FF_DEFAULT_QUANT_BIAS;    s->palctrl = NULL;    s->reget_buffer= avcodec_default_reget_buffer;}