const char *av_get_string(void *obj, const char *name, const AVOption **o_out, char *buf, int buf_len){ const AVOption *o= av_find_opt(obj, name, NULL, 0, 0); void *dst; if(!o || o->offset<=0) return NULL; if(o->type != FF_OPT_TYPE_STRING && (!buf || !buf_len)) return NULL; dst= ((uint8_t*)obj) + o->offset; if(o_out) *o_out= o; if(o->type == FF_OPT_TYPE_STRING) return dst; switch(o->type){ case FF_OPT_TYPE_FLAGS: snprintf(buf, buf_len, "0x%08X",*(int *)dst);break; case FF_OPT_TYPE_INT: snprintf(buf, buf_len, "%d" , *(int *)dst);break; case FF_OPT_TYPE_INT64: snprintf(buf, buf_len, "%"PRId64, *(int64_t*)dst);break; case FF_OPT_TYPE_FLOAT: snprintf(buf, buf_len, "%f" , *(float *)dst);break; case FF_OPT_TYPE_DOUBLE: snprintf(buf, buf_len, "%f" , *(double *)dst);break; case FF_OPT_TYPE_RATIONAL: snprintf(buf, buf_len, "%d/%d", ((AVRational*)dst)->num, ((AVRational*)dst)->den);break; default: return NULL; } return buf; }