Set byte range to request
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_RANGE, char *range);
Pass a char * as parameter, which should contain the specified range you want to retrieve. It should be in the format "X-Y", where either X or Y may be left out and X and Y are byte indexes.
HTTP transfers also support several intervals, separated with commas as in "X-Y,N-M". Using this kind of multiple intervals will cause the HTTP server to send the response document in pieces (using standard MIME separation techniques). For RTSP, the formatting of a range should follow RFC2326 Section 12.29. For RTSP, byte ranges are not permitted. Instead, ranges should be given in npt, utc, or smpte formats.
Pass a NULL to this option to disable the use of ranges.
HTTP, FTP, FILE and RTSP
FILE since 7.18.0, RTSP since 7.20.0
Returns CURLE_OK on success or CURLE_OUT_OF_MEMORY if there was insufficient heap space.