diff --git a/src/Makefile.am b/src/Makefile.am
index edb95adb..5b857817 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -18,6 +18,8 @@ stream_core_files = \
 	stream/stream_proto.h \
 	stream/stream_media.h \
 	stream/stream_media.c \
+	stream/stream_media_buffer.h \
+	stream/stream_media_buffer.c \
 	stream/stream_playback_clock.h \
 	stream/stream_playback_clock.c \
 	stream/stream_block.h \
diff --git a/src/stream/stream_media_buffer.c b/src/stream/stream_media_buffer.c
index bafed38c..14d2e477 100644
--- a/src/stream/stream_media_buffer.c
+++ b/src/stream/stream_media_buffer.c
@@ -3,6 +3,7 @@
 
 #include "../../lib/debug_config.h"
 #include "../../lib/mem.h"
+#include "../../lib/u_async.h"
 #include "stream_media_buffer.h"
 
 struct media_position {
@@ -35,6 +36,7 @@ struct stream_media_cursor {
     uint8_t *scratch[2], *frame;
     size_t scratch_capacity, frame_capacity;
     uint64_t scratch_seq[2];
+    size_t scratch_length[2];
     int scratch_valid[2];
     unsigned scratch_next;
     uint8_t opus[STREAM_MEDIA_MAX_OPUS];
@@ -163,6 +165,11 @@ int stream_media_store_feed(struct stream_media_store *s, uint64_t seq, const ui
     for (unsigned i = 0; i < b.video_count; i++) {
         const struct stream_media_video *v = &b.video[i];
         if (!v->offset) {
+            if (s->video_us >= 0 && ((int64_t)v->pts_us <= s->video_us || v->frame_id <= s->last_frame_id)) {
+                DEBUG_WARN(DEBUG_CATEGORY_STREAM, "media index stale video seq=%llu frame=%llu pts=%llu",
+                           (unsigned long long)seq, (unsigned long long)v->frame_id, (unsigned long long)v->pts_us);
+                continue;
+            }
             if (s->pending_used) {
                 DEBUG_WARN(DEBUG_CATEGORY_STREAM, "media index incomplete frame=%llu before frame=%llu; require KEY",
                            (unsigned long long)s->pending.frame_id, (unsigned long long)v->frame_id);
@@ -281,16 +288,9 @@ static int cursor_block(struct stream_media_cursor *c, uint64_t seq, struct stre
         slot = c->scratch_next++ % 2;
         int result = stream_buffer_decode(s->buffer, seq, c->scratch[slot], c->scratch_capacity, &length);
         if (result != STREAM_OK) return result == STREAM_REJECTED ? STREAM_GAP : result;
-        c->scratch_seq[slot] = seq; c->scratch_valid[slot] = 1;
+        c->scratch_seq[slot] = seq; c->scratch_length[slot] = length; c->scratch_valid[slot] = 1;
     } else {
-        /* length сохраняется в первом поле зарезервированного хвоста не нужна: длину даёт metadata RS. */
-        const uint8_t *wire; uint64_t actual; size_t wire_length;
-        int found = STREAM_GAP;
-        for (unsigned sub = 0; sub < s->descriptor.n; sub++) {
-            found = stream_buffer_read(s->buffer, seq, (uint8_t)sub, &wire, &wire_length, &actual);
-            if (found == STREAM_OK) { length = (size_t)stream_read_be(wire + STREAM_BLOCK_LENGTH_OFF, 4); break; }
-        }
-        if (found != STREAM_OK) return found;
+        length = c->scratch_length[slot];
     }
     return stream_media_parse(c->scratch[slot], length, block);
 }
@@ -323,6 +323,8 @@ static int cursor_video(struct stream_media_cursor *c, struct stream_media_packe
         int result = cursor_peek(c, &c->video, 1, &b, &pts);
         if (result != STREAM_OK) return result;
         const struct stream_media_video *v = &b.video[c->video.entry++];
+        if (!c->key_delivered && !c->pending.frame_size
+            && (v->offset || !(v->flags & STREAM_MEDIA_KEY) || pts != c->start_us)) continue;
         if (!v->offset) {
             if (!c->key_delivered && (!(v->flags & STREAM_MEDIA_KEY) || pts != c->start_us)) continue;
             if (v->frame_size > c->frame_capacity) {
@@ -370,7 +372,7 @@ int stream_media_cursor_read(struct stream_media_cursor *c, int64_t position, in
     if (c->audio.ended && c->video.ended) {
         *packet = (struct stream_media_packet){.kind = STREAM_MEDIA_READ_END}; return STREAM_OK;
     }
-    int64_t limit = position < 0 ? c->start_us : position + lookahead;
+    int64_t limit = position < 0 ? c->start_us : position > INT64_MAX - lookahead ? INT64_MAX : position + lookahead;
     if (ar == STREAM_OK && audio_pts <= limit && (audio_pts < video_pts || vr != STREAM_OK)) {
         /* video peek мог переиспользовать scratch аудио: заново взять ту же пачку из двухэлементного cache. */
         result = cursor_block(c, c->audio.seq, &audio);