diff --git a/selfdrive/camerad/cameras/camera_replay.cc b/selfdrive/camerad/cameras/camera_replay.cc
index 825b1616bf..a1060ef178 100644
--- a/selfdrive/camerad/cameras/camera_replay.cc
+++ b/selfdrive/camerad/cameras/camera_replay.cc
@@ -48,16 +48,16 @@ void camera_close(CameraState *s) {
 void run_camera(CameraState *s) {
   uint32_t stream_frame_id = 0, frame_id = 0;
   size_t buf_idx = 0;
+  std::unique_ptr<uint8_t[]> rgb_buf = std::make_unique<uint8_t[]>(s->frame->getRGBSize());
   while (!do_exit) {
     if (stream_frame_id == s->frame->getFrameCount()) {
       // loop stream
       stream_frame_id = 0;
     }
-    if (auto dat = s->frame->get(stream_frame_id++)) {
-      auto [rgb_buf, yuv_buf] = *dat;
+    if (s->frame->get(stream_frame_id++, rgb_buf.get(), nullptr)) {
       s->buf.camera_bufs_metadata[buf_idx] = {.frame_id = frame_id};
       auto &buf = s->buf.camera_bufs[buf_idx];
-      CL_CHECK(clEnqueueWriteBuffer(buf.copy_q, buf.buf_cl, CL_TRUE, 0, s->frame->getRGBSize(), rgb_buf, 0, NULL, NULL));
+      CL_CHECK(clEnqueueWriteBuffer(buf.copy_q, buf.buf_cl, CL_TRUE, 0, s->frame->getRGBSize(), rgb_buf.get(), 0, NULL, NULL));
       s->buf.queue(buf_idx);
       ++frame_id;
       buf_idx = (buf_idx + 1) % FRAME_BUF_COUNT;
diff --git a/selfdrive/ui/replay/camera.cc b/selfdrive/ui/replay/camera.cc
index 39c41e2bd6..b7e91b9646 100644
--- a/selfdrive/ui/replay/camera.cc
+++ b/selfdrive/ui/replay/camera.cc
@@ -48,19 +48,14 @@ void CameraServer::thread() {
     }
 
     // send frame
-    if (auto dat = fr->get(eidx.getSegmentId())) {
-      auto [rgb_dat, yuv_dat] = *dat;
+    VisionBuf *rgb_buf = vipc_server_->get_buffer(cam.rgb_type);
+    VisionBuf *yuv_buf = vipc_server_->get_buffer(cam.yuv_type);
+    if (fr->get(eidx.getSegmentId(), (uint8_t *)rgb_buf->addr, (uint8_t *)yuv_buf->addr)) {
       VisionIpcBufExtra extra = {
           .frame_id = eidx.getFrameId(),
           .timestamp_sof = eidx.getTimestampSof(),
           .timestamp_eof = eidx.getTimestampEof(),
       };
-
-      VisionBuf *rgb_buf = vipc_server_->get_buffer(cam.rgb_type);
-      memcpy(rgb_buf->addr, rgb_dat, fr->getRGBSize());
-      VisionBuf *yuv_buf = vipc_server_->get_buffer(cam.yuv_type);
-      memcpy(yuv_buf->addr, yuv_dat, fr->getYUVSize());
-
       vipc_server_->send(rgb_buf, &extra, false);
       vipc_server_->send(yuv_buf, &extra, false);
     } else {
diff --git a/selfdrive/ui/replay/framereader.cc b/selfdrive/ui/replay/framereader.cc
index 4915dd9e87..ec61444d7c 100644
--- a/selfdrive/ui/replay/framereader.cc
+++ b/selfdrive/ui/replay/framereader.cc
@@ -1,6 +1,8 @@
 #include "selfdrive/ui/replay/framereader.h"
 
+#include <unistd.h>
 #include <cassert>
+#include <mutex>
 #include "libyuv.h"
 
 static int ffmpeg_lockmgr_cb(void **arg, enum AVLockOp op) {
@@ -21,15 +23,13 @@ static int ffmpeg_lockmgr_cb(void **arg, enum AVLockOp op) {
   return 0;
 }
 
-class AVInitializer {
-public:
+struct AVInitializer {
   AVInitializer() {
     int ret = av_lockmgr_register(ffmpeg_lockmgr_cb);
     assert(ret >= 0);
     av_register_all();
     avformat_network_init();
   }
-
   ~AVInitializer() { avformat_network_deinit(); }
 };
 
@@ -38,15 +38,6 @@ FrameReader::FrameReader() {
 }
 
 FrameReader::~FrameReader() {
-  // wait until thread is finished.
-  exit_ = true;
-  cv_decode_.notify_all();
-  cv_frame_.notify_all();
-  if (decode_thread_.joinable()) {
-    decode_thread_.join();
-  }
-
-  // free all.
   for (auto &f : frames_) {
     av_free_packet(&f.pkt);
   }
@@ -57,6 +48,9 @@ FrameReader::~FrameReader() {
   if (pFormatCtx_) {
     avformat_close_input(&pFormatCtx_);
   }
+  if (av_frame_) {
+    av_frame_free(&av_frame_);
+  }
 }
 
 bool FrameReader::load(const std::string &url) {
@@ -77,14 +71,18 @@ bool FrameReader::load(const std::string &url) {
   int ret = avcodec_copy_context(pCodecCtx_, pCodecCtxOrig);
   if (ret != 0) return false;
 
+  pCodecCtx_->thread_count = 0;
+  pCodecCtx_->thread_type = FF_THREAD_FRAME;
   ret = avcodec_open2(pCodecCtx_, pCodec, NULL);
   if (ret < 0) return false;
 
+  av_frame_ = av_frame_alloc();
+
   width = pCodecCtxOrig->width;
   height = pCodecCtxOrig->height;
 
   frames_.reserve(60 * 20);  // 20fps, one minute
-  do {
+  while (true) {
     Frame &frame = frames_.emplace_back();
     int err = av_read_frame(pFormatCtx_, &frame.pkt);
     if (err < 0) {
@@ -92,81 +90,77 @@ bool FrameReader::load(const std::string &url) {
       valid_ = (err == AVERROR_EOF);
       break;
     }
-  } while (!exit_);
-
-  if (valid_) {
-    decode_thread_ = std::thread(&FrameReader::decodeThread, this);
+    // some stream seems to contian no keyframes
+    key_frames_count_ += frame.pkt.flags & AV_PKT_FLAG_KEY;
   }
   return valid_;
 }
 
-std::optional<std::pair<uint8_t *, uint8_t *>> FrameReader::get(int idx) {
+bool FrameReader::get(int idx, uint8_t *rgb, uint8_t *yuv) {
+  assert(rgb != nullptr);
   if (!valid_ || idx < 0 || idx >= frames_.size()) {
-    return std::nullopt;
-  }
-  std::unique_lock lk(mutex_);
-  decode_idx_ = idx;
-  cv_decode_.notify_one();
-  cv_frame_.wait(lk, [=] { return exit_ || frames_[idx].rgb_data || frames_[idx].failed; });
-  if (!frames_[idx].rgb_data) {
-    return std::nullopt;
+    return false;
   }
-  return std::make_pair(frames_[idx].rgb_data.get(), frames_[idx].yuv_data.get());
+  return decode(idx, rgb, yuv);
 }
 
-void FrameReader::decodeThread() {
-  int idx = 0;
-  while (!exit_) {
-    const int from = std::max(idx - 15, 0);
-    const int to = std::min(idx + 20, (int)frames_.size());
-    for (int i = 0; i < frames_.size() && !exit_; ++i) {
-      Frame &frame = frames_[i];
-      if (i >= from && i < to) {
-        if (frame.rgb_data || frame.failed) continue;
-
-        auto [rgb_data, yuv_data] = decodeFrame(&frame.pkt);
-        std::unique_lock lk(mutex_);
-        frame.rgb_data.reset(rgb_data);
-        frame.yuv_data.reset(yuv_data);
-        frame.failed = !rgb_data;
-        cv_frame_.notify_all();
-      } else {
-        frame.rgb_data.reset(nullptr);
-        frame.yuv_data.reset(nullptr);
-        frame.failed = false;
-      }
+bool FrameReader::decode(int idx, uint8_t *rgb, uint8_t *yuv) {
+  auto get_keyframe = [=](int idx) {
+    for (int i = idx; i >= 0 && key_frames_count_ > 1; --i) {
+      if (frames_[i].pkt.flags & AV_PKT_FLAG_KEY) return i;
     }
+    return idx;
+  };
 
-    // sleep & wait
-    std::unique_lock lk(mutex_);
-    cv_decode_.wait(lk, [=] { return exit_ || decode_idx_ != -1; });
-    idx = decode_idx_;
-    decode_idx_ = -1;
+  int from_idx = idx;
+  if (idx > 0 && !frames_[idx].decoded && !frames_[idx - 1].decoded) {
+    // find the previous keyframe
+    from_idx = get_keyframe(idx);
   }
-}
 
-std::pair<uint8_t *, uint8_t *> FrameReader::decodeFrame(AVPacket *pkt) {
-  uint8_t *rgb_data = nullptr, *yuv_data = nullptr;
-  int gotFrame = 0;
-  AVFrame *f = av_frame_alloc();
-  avcodec_decode_video2(pCodecCtx_, f, &gotFrame, pkt);
-  if (gotFrame) {
-    rgb_data = new uint8_t[getRGBSize()];
-    yuv_data = new uint8_t[getYUVSize()];
-    int i, j, k;
-    for (i = 0; i < f->height; i++) {
-      memcpy(yuv_data + f->width * i, f->data[0] + f->linesize[0] * i, f->width);
-    }
-    for (j = 0; j < f->height / 2; j++) {
-      memcpy(yuv_data + f->width * i + f->width / 2 * j, f->data[1] + f->linesize[1] * j, f->width / 2);
+  for (int i = from_idx; i <= idx; ++i) {
+    Frame &frame = frames_[i];
+    if ((!frame.decoded || i == idx) && !frame.failed) {
+      while (true) {
+        int ret = avcodec_decode_video2(pCodecCtx_, av_frame_, &frame.decoded, &(frame.pkt));
+        if (ret > 0 && !frame.decoded) {
+          // decode thread is still receiving the initial packets
+          usleep(0);
+        } else {
+          break;
+        }
+      }
+      frame.failed = !frame.decoded;
+      if (frame.decoded && i == idx) {
+        return decodeFrame(av_frame_, rgb, yuv);
+      }
     }
-    for (k = 0; k < f->height / 2; k++) {
-      memcpy(yuv_data + f->width * i + f->width / 2 * j + f->width / 2 * k, f->data[2] + f->linesize[2] * k, f->width / 2);
+  }
+  return false;
+}
+
+bool FrameReader::decodeFrame(AVFrame *f, uint8_t *rgb, uint8_t *yuv) {
+  uint8_t *y = yuv;
+  if (!yuv) {
+    if (yuv_buf_.empty()) {
+      yuv_buf_.resize(getYUVSize());
     }
-    uint8_t *u = yuv_data + f->width * f->height;
-    uint8_t *v = u + (f->width / 2) * (f->height / 2);
-    libyuv::I420ToRGB24(yuv_data, f->width, u, f->width / 2, v, f->width / 2, rgb_data, f->width * 3, f->width, f->height);
+    y = yuv_buf_.data();
   }
-  av_frame_free(&f);
-  return {rgb_data, yuv_data};
+
+  int i, j, k;
+  for (i = 0; i < f->height; i++) {
+    memcpy(y + f->width * i, f->data[0] + f->linesize[0] * i, f->width);
+  }
+  for (j = 0; j < f->height / 2; j++) {
+    memcpy(y + f->width * i + f->width / 2 * j, f->data[1] + f->linesize[1] * j, f->width / 2);
+  }
+  for (k = 0; k < f->height / 2; k++) {
+    memcpy(y + f->width * i + f->width / 2 * j + f->width / 2 * k, f->data[2] + f->linesize[2] * k, f->width / 2);
+  }
+
+  uint8_t *u = yuv + f->width * f->height;
+  uint8_t *v = u + (f->width / 2) * (f->height / 2);
+  libyuv::I420ToRGB24(yuv, f->width, u, f->width / 2, v, f->width / 2, rgb, f->width * 3, f->width, f->height);
+  return true;
 }
diff --git a/selfdrive/ui/replay/framereader.h b/selfdrive/ui/replay/framereader.h
index 785e2fef53..81459618a6 100644
--- a/selfdrive/ui/replay/framereader.h
+++ b/selfdrive/ui/replay/framereader.h
@@ -1,14 +1,8 @@
 #pragma once
 
-#include <atomic>
-#include <condition_variable>
-#include <mutex>
-#include <optional>
 #include <string>
-#include <thread>
 #include <vector>
 
-// independent of QT, needs ffmpeg
 extern "C" {
 #include <libavcodec/avcodec.h>
 #include <libavformat/avformat.h>
@@ -19,7 +13,7 @@ public:
   FrameReader();
   ~FrameReader();
   bool load(const std::string &url);
-  std::optional<std::pair<uint8_t *, uint8_t*>> get(int idx);
+  bool get(int idx, uint8_t *rgb, uint8_t *yuv);
   int getRGBSize() const { return width * height * 3; }
   int getYUVSize() const { return width * height * 3 / 2; }
   size_t getFrameCount() const { return frames_.size(); }
@@ -28,24 +22,19 @@ public:
   int width = 0, height = 0;
 
 private:
-  void decodeThread();
-  std::pair<uint8_t *, uint8_t *> decodeFrame(AVPacket *pkt);
+  bool decode(int idx, uint8_t *rgb, uint8_t *yuv);
+  bool decodeFrame(AVFrame *f, uint8_t *rgb, uint8_t *yuv);
+
   struct Frame {
     AVPacket pkt = {};
-    std::unique_ptr<uint8_t[]> rgb_data = nullptr;
-    std::unique_ptr<uint8_t[]> yuv_data = nullptr;
+    int decoded = false;
     bool failed = false;
   };
   std::vector<Frame> frames_;
-
+  AVFrame *av_frame_ = nullptr;
   AVFormatContext *pFormatCtx_ = nullptr;
   AVCodecContext *pCodecCtx_ = nullptr;
-
-  std::mutex mutex_;
-  std::condition_variable cv_decode_;
-  std::condition_variable cv_frame_;
-  int decode_idx_ = 0;
-  std::atomic<bool> exit_ = false;
+  int key_frames_count_ = 0;
+  std::vector<uint8_t> yuv_buf_;
   bool valid_ = false;
-  std::thread decode_thread_;
 };
diff --git a/selfdrive/ui/replay/tests/test_replay.cc b/selfdrive/ui/replay/tests/test_replay.cc
index 3f80d0a35f..f164b9838b 100644
--- a/selfdrive/ui/replay/tests/test_replay.cc
+++ b/selfdrive/ui/replay/tests/test_replay.cc
@@ -53,10 +53,14 @@ TEST_CASE("Segment") {
     // LogReader & FrameReader
     REQUIRE(segment.log->events.size() > 0);
     REQUIRE(std::is_sorted(segment.log->events.begin(), segment.log->events.end(), Event::lessThan()));
-    // sequence get 50 frames {
-    REQUIRE(segment.frames[RoadCam]->getFrameCount() == 1200);
+
+    auto &fr = segment.frames[RoadCam];
+    REQUIRE(fr->getFrameCount() == 1200);
+    std::unique_ptr<uint8_t[]> rgb_buf = std::make_unique<uint8_t[]>(fr->getRGBSize());
+    std::unique_ptr<uint8_t[]> yuv_buf = std::make_unique<uint8_t[]>(fr->getYUVSize());
+    // sequence get 50 frames
     for (int i = 0; i < 50; ++i) {
-      REQUIRE(segment.frames[RoadCam]->get(i));
+      REQUIRE(fr->get(i, rgb_buf.get(), yuv_buf.get()));
     }
     loop.quit();
   });