diff --git a/src/filters/out_http.c b/src/filters/out_http.c
index c8f3aa6241..501c65c430 100644
--- a/src/filters/out_http.c
+++ b/src/filters/out_http.c
@@ -836,20 +836,39 @@ static Bool httpout_sess_parse_range(GF_HTTPOutSession *sess, char *range)
 	}
 	if (!request_ok) return GF_FALSE;
 
+	known_file_size = 0;
 	if (sess->in_source && !sess->resource) {
 		//cannot fetch end of file it is not yet known !
 		if (has_file_end) return GF_FALSE;
 		known_file_size = sess->in_source->nb_write;
 	} else {
-		known_file_size = sess->file_size;
+		//HTTP does not allow for "range: X-" to resolve in "content-range: X-/*"
+		//we support this in GPAC and allow other clients too if they set "X-Allow-Open-Partial-Range" (GPAC specific)
+		Bool allow_partial_unknown_size = GF_FALSE;
+		const char *str = gf_dm_sess_get_header(sess->http_sess, "User-Agent");
+		if (str && !strncmp(str, "GPAC/", 5))
+			allow_partial_unknown_size = GF_TRUE;
+		str = gf_dm_sess_get_header(sess->http_sess, "X-Allow-Open-Partial-Range");
+		if (str && (!strcmp(str, "1") || !strcmp(str, "true") || !strcmp(str, "yes")))
+			allow_partial_unknown_size = GF_TRUE;
+
+		if (!allow_partial_unknown_size || !sess->file_in_progress) {
+			known_file_size = sess->file_size;
+		}
 	}
 	sess->bytes_in_req = 0;
 	for (i=0; i<sess->nb_ranges; i++) {
 		if (sess->ranges[i].start>=0) {
 			//if start, end is a pos in bytes in size (0-based)
 			if (sess->ranges[i].end==-1) {
+				if (known_file_size==0) continue;
+
 				sess->ranges[i].end = known_file_size-1;
 			}
+			if (known_file_size==0) {
+				request_ok = GF_FALSE;
+				break;
+			}
 
 			if (sess->ranges[i].end >= (s64) known_file_size) {
 				request_ok = GF_FALSE;
@@ -860,6 +879,10 @@ static Bool httpout_sess_parse_range(GF_HTTPOutSession *sess, char *range)
 				break;
 			}
 		} else {
+			if (known_file_size==0) {
+				request_ok = GF_FALSE;
+				break;
+			}
 			//no start, end is a file size
 			if (sess->ranges[i].end >= (s64) known_file_size) {
 				request_ok = GF_FALSE;
@@ -1977,7 +2000,9 @@ static void httpout_sess_io(void *usr_cbk, GF_NETIO_Parameter *parameter)
 			char *ranges = NULL;
 			gf_dynstrcat(&ranges, "bytes=", NULL);
 			for (i=0; i<sess->nb_ranges; i++) {
-				if (sess->in_source || !sess->file_size) {
+				if (sess->ranges[i].end==-1) {
+					sprintf(szFmt, LLD"-/*", sess->ranges[i].start);
+				} else if (sess->in_source || !sess->file_size) {
 					sprintf(szFmt, LLD"-"LLD"/*", sess->ranges[i].start, sess->ranges[i].end);
 				} else {
 					sprintf(szFmt, LLD"-"LLD"/"LLU, sess->ranges[i].start, sess->ranges[i].end, sess->file_size);
@@ -3114,7 +3139,11 @@ static GF_Err httpout_sess_data_upload(GF_HTTPOutSession *sess, const u8 *data,
 	}
 	remain = size;
 	while (remain) {
-		to_write = (u32) (sess->ranges[sess->range_idx].end + 1 - sess->file_pos);
+		if (sess->ranges[sess->range_idx].end<0)
+			to_write = remain;
+		else
+			to_write = (u32) (sess->ranges[sess->range_idx].end + 1 - sess->file_pos);
+
 		if (to_write>=remain) {
 			write = (u32) gf_fwrite(data, remain, sess->resource);
 			if (write != remain) {
@@ -3166,17 +3195,6 @@ static void log_request_done(GF_HTTPOutSession *sess)
 			unit = "kbps";
 			bps/=1000;
 		}
-#if 0
-		assert(sess->nb_bytes);
-		if (sess->nb_ranges) {
-			u32 i;
-			u64 tot_bytes = 0;
-			for (i=0; i<sess->nb_ranges; i++) {
-				tot_bytes += sess->ranges[i].end - sess->ranges[i].start + 1;
-			}
-			assert(tot_bytes==sess->nb_bytes);
-		}
-#endif
 		GF_LOG(GF_LOG_INFO, GF_LOG_ALL, ("[HTTPOut] %sREQ#"LLU" %s done: reply %d - "LLU" bytes in %d ms at %g %s\n", sprefix, sess->req_id, get_method_name(sess->method_type), sess->reply_code, sess->nb_bytes, (u32) (diff_us/1000), bps, unit));
 	}
 }
@@ -3186,6 +3204,7 @@ static void httpout_process_session(GF_Filter *filter, GF_HTTPOutCtx *ctx, GF_HT
 	u32 read;
 	u64 to_read=0;
 	GF_Err e = GF_OK;
+	Bool file_in_progress, last_range;
 	Bool close_session = ctx->close;
 
 	if (sess->force_destroy) {
@@ -3460,23 +3479,40 @@ static void httpout_process_session(GF_Filter *filter, GF_HTTPOutCtx *ctx, GF_HT
 	}
 
 resend:
-
+	last_range=GF_FALSE;
+	file_in_progress = sess->file_in_progress;
+	to_read=0;
 	//we have ranges
 	if (sess->nb_ranges) {
+		Bool range_done=GF_FALSE;
 		//current range is done
-		if ((s64) sess->file_pos >= sess->ranges[sess->range_idx].end) {
+		if ((sess->ranges[sess->range_idx].end>0)
+			&& ((s64) sess->file_pos >= sess->ranges[sess->range_idx].end)
+		) {
 			//load next range, seeking file
 			if (sess->range_idx+1<sess->nb_ranges) {
 				sess->range_idx++;
 				sess->file_pos = (u64) sess->ranges[sess->range_idx].start;
 				gf_fseek(sess->resource, sess->file_pos, SEEK_SET);
+			} else {
+				range_done = GF_TRUE;
+				file_in_progress = GF_FALSE;
 			}
 		}
-		if (sess->range_idx<sess->nb_ranges) {
-			to_read = sess->ranges[sess->range_idx].end + 1 - sess->file_pos;
+		if (!range_done && (sess->range_idx<sess->nb_ranges)) {
+			if (sess->ranges[sess->range_idx].end>0) {
+				to_read = sess->ranges[sess->range_idx].end + 1 - sess->file_pos;
+				//we have an explicit closed range request, stop even if file is still being produced
+				file_in_progress = GF_FALSE;
+				if (sess->range_idx+1 == sess->nb_ranges)
+					last_range = GF_TRUE;
+			} else if (sess->file_size > sess->file_pos) {
+				to_read = sess->file_size - sess->file_pos;
+			}
 		}
 	} else if (sess->file_pos < sess->file_size) {
 		to_read = sess->file_size - sess->file_pos;
+		last_range = GF_TRUE;
 	}
 #ifdef GPAC_HAS_QJS
 	else if (sess->cbk_read) {
@@ -3493,6 +3529,7 @@ static void httpout_process_session(GF_Filter *filter, GF_HTTPOutCtx *ctx, GF_HT
 #endif
 
 	if (to_read) {
+		u64 remain = to_read;
 		//rescedule asap while we send
 		ctx->next_wake_us = 1;
 
@@ -3540,6 +3577,10 @@ static void httpout_process_session(GF_Filter *filter, GF_HTTPOutCtx *ctx, GF_HT
 		} else {
 			GF_LOG(GF_LOG_DEBUG, GF_LOG_HTTP, ("[HTTPOut] sending data to %s for %s: "LLU"/"LLU" bytes\n", sess->peer_address, sess->path, sess->nb_bytes, sess->bytes_in_req));
 
+			//not in progress and we are done, notify (for chunk-transfer or h2) right away
+			if (!file_in_progress && last_range && (remain==read))
+				goto session_done;
+
 			if (gf_dm_sess_flush_async(sess->http_sess, GF_FALSE)==GF_OK) {
 				goto resend;
 			}
@@ -3547,7 +3588,7 @@ static void httpout_process_session(GF_Filter *filter, GF_HTTPOutCtx *ctx, GF_HT
 		return;
 	}
 	//file not done yet ...
-	if (sess->file_in_progress || (sess->put_in_progress==1)) {
+	if (file_in_progress || (sess->put_in_progress==1)) {
 		sess->last_active_time = gf_sys_clock_high_res();
 		return;
 	}
@@ -4601,7 +4642,6 @@ static void httpout_process_inputs(GF_HTTPOutCtx *ctx)
 					}
 					in->nb_write += nb_write;
 				}
-				GF_LOG(GF_LOG_DEBUG, GF_LOG_HTTP, ("[HTTPOut] Pushed %d bytes\n", pck_size));
 			} else if (hwf) {
 				u32 w, h, stride, stride_uv, pf;
 				u32 nb_planes, uv_height;