From 5f16c795590f79587bd9d8cabba002d8ce3346d8 Mon Sep 17 00:00:00 2001
From: evgeny <evgeny@adaptto.ru>
Date: Wed, 14 Oct 2026 23:19:18 +0200
Subject: [PATCH] Preserve bitrate bounds on format changes and discard late
 desktop pictures

---
 .../src/main/java/com/utun/chat/data/CallVideoEngine.kt  | 7 +++++--
 tools/chatgui/src/call_video_engine.cpp                  | 9 +++++++--
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/tools/chatgui-android/app/src/main/java/com/utun/chat/data/CallVideoEngine.kt b/tools/chatgui-android/app/src/main/java/com/utun/chat/data/CallVideoEngine.kt
index 8b0e9b57..6b9e0f87 100644
--- a/tools/chatgui-android/app/src/main/java/com/utun/chat/data/CallVideoEngine.kt
+++ b/tools/chatgui-android/app/src/main/java/com/utun/chat/data/CallVideoEngine.kt
@@ -155,6 +155,8 @@ class CallVideoEngine(private val context: Context, private val id: Long) {
         val desired = CallVideoFormat(++generation, wanted.width, wanted.height, rotation = rotation, codec = wanted.codec)
         val previous = encoder; val previousFormat = format; val previousSettings = active
         val previousName = previous?.name; val previousRate = previous?.bitrate
+        val range = mutable.value.range
+        val initialRate = (previousRate ?: 1_000_000).coerceIn(range.minimum * 1000, range.maximum * 1000)
         previous?.close(); encoder = null
         for (codec in if (wanted.codec == 0) listOf(2, 1) else listOf(wanted.codec)) {
             if (codec in excluded) continue
@@ -162,7 +164,7 @@ class CallVideoEngine(private val context: Context, private val id: Long) {
             val selected = CallVideoNative.choose(caps, peer, desired.copy(codec = codec).array()) ?: continue
             var candidate: CallVideoCodec? = null
             try {
-                candidate = CallVideoCodec(CallVideoFormat.from(selected), 1_000_000, implementation.name)
+                candidate = CallVideoCodec(CallVideoFormat.from(selected), initialRate, implementation.name)
                 candidate.prepare()
                 val next = candidate.format
                 check(CallVideoNative.supported(caps, peer, next.array())) { "Actual encoder format exceeds peer capabilities: $next" }
@@ -178,7 +180,8 @@ class CallVideoEngine(private val context: Context, private val id: Long) {
             }
         }
         if (previousFormat != null && previousFormat.codec !in excluded && previousSettings != null && previousName != null && previousRate != null) {
-            encoder = CallVideoCodec(previousFormat, previousRate, previousName).also { it.prepare(); check(it.format == previousFormat) }
+            encoder = CallVideoCodec(previousFormat, previousRate, previousName)
+            encoder!!.prepare(); check(encoder!!.format == previousFormat)
             wanted = previousSettings; needKey = true
             mutable.value = mutable.value.copy(settings = wanted)
             report("Selected mode unavailable; previous video restored")
diff --git a/tools/chatgui/src/call_video_engine.cpp b/tools/chatgui/src/call_video_engine.cpp
index 9e10ee05..85fd5f36 100644
--- a/tools/chatgui/src/call_video_engine.cpp
+++ b/tools/chatgui/src/call_video_engine.cpp
@@ -179,10 +179,13 @@ void CallVideoEngine::transmit() {
             if (lastKey >= 0 && pts - lastKey < 1000000) { idle(); continue; }
             call_video_format next{format.generation + 1, (uint16_t)width, (uint16_t)height, 30, 0, (uint8_t)codec, 0, 4000000, 0};
             bool opened = false;
+            uint32_t minimum = state.minimum_bps ? state.minimum_bps : 300000;
+            uint32_t maximum = state.maximum_bps ? state.maximum_bps : 4000000;
+            uint32_t initialRate = std::max(minimum, std::min(maximum, encoder.bitrate() ? encoder.bitrate() : 1000000));
             for (int candidate = 2; candidate >= 1; --candidate) {
                 if ((codec && codec != candidate) || (excluded & (1u << candidate))) continue;
                 next.codec = candidate; next.level = next.profile = 0;
-                if (call_video_choose(&caps, &state.peer, &next) > 0 && encoder.open(next, 1000000)) { opened = true; break; }
+                if (call_video_choose(&caps, &state.peer, &next) > 0 && encoder.open(next, initialRate)) { opened = true; break; }
             }
             if (!opened) {
                 m->report(tr("Selected video mode is unavailable to the peer"));
@@ -240,7 +243,9 @@ void CallVideoEngine::receive() {
             sourceEpoch = clock.source_epoch;
             QImage selected;
             while (!pictures.empty() && pictures.front().pts <= clock.pts_us) {
-                if (pictures.front().pts > lastShown) { selected = pictures.front().image; lastShown = pictures.front().pts; }
+                if (pictures.front().pts > lastShown && pictures.front().pts >= clock.pts_us - 500000) {
+                    selected = pictures.front().image; lastShown = pictures.front().pts;
+                }
                 pictures.pop_front();
             }
             if (!selected.isNull()) { std::lock_guard<std::mutex> guard(m->lock); m->shown = selected; ++m->shownSerial; ++shown; }