c->audio_pkt[0].size = 0; c->audio_pkt[1].size = 0;
DVDemuxContext* dv_init_demux(AVFormatContext *s){    DVDemuxContext *c;    c = av_mallocz(sizeof(DVDemuxContext));    if (!c)        return NULL;    c->vst = av_new_stream(s, 0);    if (!c->vst) {        av_free(c);                return NULL;    }    av_set_pts_info(c->vst, 64, 1, 30000);    c->fctx = s;    c->ast[0] = c->ast[1] = NULL;    c->ach = 0;    c->frames = 0;    c->abytes = 0;    c->audio_pkt[0].size = 0;    c->audio_pkt[1].size = 0;        c->vst->codec.codec_type = CODEC_TYPE_VIDEO;    c->vst->codec.codec_id = CODEC_ID_DVVIDEO;    c->vst->codec.bit_rate = 25000000;    c->vst->start_time = 0;        return c;}