+static int opt_size(enum AVOptionType type)
+{
+ switch(type) {
+ case AV_OPT_TYPE_INT:
+ case AV_OPT_TYPE_FLAGS: return sizeof(int);
+ case AV_OPT_TYPE_DURATION:
+ case AV_OPT_TYPE_CHANNEL_LAYOUT:
+ case AV_OPT_TYPE_INT64: return sizeof(int64_t);
+ case AV_OPT_TYPE_DOUBLE: return sizeof(double);
+ case AV_OPT_TYPE_FLOAT: return sizeof(float);
+ case AV_OPT_TYPE_STRING: return sizeof(uint8_t*);
+ case AV_OPT_TYPE_VIDEO_RATE:
+ case AV_OPT_TYPE_RATIONAL: return sizeof(AVRational);
+ case AV_OPT_TYPE_BINARY: return sizeof(uint8_t*) + sizeof(int);
+ case AV_OPT_TYPE_IMAGE_SIZE:return sizeof(int[2]);
+ case AV_OPT_TYPE_PIXEL_FMT: return sizeof(enum AVPixelFormat);
+ case AV_OPT_TYPE_SAMPLE_FMT:return sizeof(enum AVSampleFormat);
+ case AV_OPT_TYPE_COLOR: return 4;
+ }
+ return 0;
+}
+
+int av_opt_copy(void *dst, void *src)
+{
+ const AVOption *o = NULL;
+ const AVClass *c;
+ int ret = 0;
+
+ if (!src)
+ return 0;
+
+ c = *(AVClass**)src;
+ if (*(AVClass**)dst && c != *(AVClass**)dst)
+ return AVERROR(EINVAL);
+
+ while ((o = av_opt_next(src, o))) {
+ void *field_dst = ((uint8_t*)dst) + o->offset;
+ void *field_src = ((uint8_t*)src) + o->offset;
+ uint8_t **field_dst8 = (uint8_t**)field_dst;
+ uint8_t **field_src8 = (uint8_t**)field_src;
+
+ if (o->type == AV_OPT_TYPE_STRING) {
+ set_string(dst, o, *field_src8, field_dst8);
+ if (*field_src8 && !*field_dst8)
+ ret = AVERROR(ENOMEM);
+ } else if (o->type == AV_OPT_TYPE_BINARY) {
+ int len = *(int*)(field_src8 + 1);
+ if (*field_dst8 != *field_src8)
+ av_freep(field_dst8);
+ *field_dst8 = av_memdup(*field_src8, len);
+ if (len && !*field_dst8) {
+ ret = AVERROR(ENOMEM);
+ len = 0;
+ }
+ *(int*)(field_dst8 + 1) = len;
+ } else if (o->type == AV_OPT_TYPE_CONST) {
+ // do nothing
+ } else {
+ memcpy(field_dst, field_src, opt_size(o->type));
+ }
+ }
+ return ret;
+}
+