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encode/hasvk_encode_test.c

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+/* vulkan H.264 encode test for hasvk.
+ *   ./hasvk_encode_test                            # flat-gray 176x144, dumps /tmp/hasvk_enc_out.h264
+ *   HASVK_ENC_GRADIENT=1 ./hasvk_encode_test       # luma gradient (real residuals)
+ *   HASVK_ENC_GRADIENT=1 HASVK_ENC_CHROMA=1 ./...  # + chroma gradient
+ * validate the output with ffmpeg:
+ *   ffmpeg -i /tmp/hasvk_enc_out.h264 -f rawvideo -pix_fmt yuv420p out.yuv
+ * The stream prepends the driver's own SPS/PPS 
+ * (vkGetEncodedVideoSessionParametersKHR) so it decodes standalone.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+
+#include <vulkan/vulkan.h>
+#include <vk_video/vulkan_video_codec_h264std.h>
+#include <vk_video/vulkan_video_codec_h264std_encode.h>
+
+#define CHECK(x) do { \
+      VkResult _r = (x); \
+      if (_r != VK_SUCCESS) { \
+         fprintf(stderr, "FAIL %s:%d: %s -> %d\n", __FILE__, __LINE__, #x, _r); \
+         exit(1); \
+      } \
+   } while (0)
+
+#define WIDTH 176
+#define HEIGHT 144
+#define WIDTH_MBS (WIDTH / 16)
+#define HEIGHT_MBS (HEIGHT / 16)
+#define LUMA_SZ   (WIDTH * HEIGHT)
+#define CHROMA_SZ ((WIDTH / 2) * (HEIGHT / 2) * 2)
+#define FRAME_SZ  (LUMA_SZ + CHROMA_SZ)
+
+static int
+load_frame(const char *path, int idx, int i420, uint8_t *dst)
+{
+   FILE *f = fopen(path, "rb");
+   if (!f) { fprintf(stderr, "cannot open '%s'\n", path); return 0; }
+   if (fseek(f, (long)idx * FRAME_SZ, SEEK_SET) != 0) {
+      fprintf(stderr, "'%s': cannot seek to frame %d\n", path, idx);
+      fclose(f); return 0;
+   }
+   uint8_t buf[FRAME_SZ];
+   size_t n = fread(buf, 1, FRAME_SZ, f);
+   fclose(f);
+   if (n != FRAME_SZ) {
+      fprintf(stderr, "'%s': frame %d short read (%zu of %d)\n", path, idx, n, FRAME_SZ);
+      return 0;
+   }
+   memcpy(dst, buf, LUMA_SZ);
+   if (i420) {
+      const uint8_t *cb = buf + LUMA_SZ, *cr = cb + CHROMA_SZ / 2;
+      for (int i = 0; i < CHROMA_SZ / 2; i++) {
+         dst[LUMA_SZ + i * 2 + 0] = cb[i];
+         dst[LUMA_SZ + i * 2 + 1] = cr[i];
+      }
+   } else {
+      memcpy(dst + LUMA_SZ, buf + LUMA_SZ, CHROMA_SZ);
+   }
+   return 1;
+}
+
+static void
+shift_frame(const uint8_t *src, uint8_t *dst, int dx, int dy)
+{
+   for (int y = 0; y < HEIGHT; y++) {
+      int sy = y - dy; sy = sy < 0 ? 0 : (sy >= HEIGHT ? HEIGHT - 1 : sy);
+      for (int x = 0; x < WIDTH; x++) {
+         int sx = x - dx; sx = sx < 0 ? 0 : (sx >= WIDTH ? WIDTH - 1 : sx);
+         dst[y * WIDTH + x] = src[sy * WIDTH + sx];
+      }
+   }
+   int cw = WIDTH / 2, ch = HEIGHT / 2, cdx = dx / 2, cdy = dy / 2;
+   for (int y = 0; y < ch; y++) {
+      int sy = y - cdy; sy = sy < 0 ? 0 : (sy >= ch ? ch - 1 : sy);
+      for (int x = 0; x < cw; x++) {
+         int sx = x - cdx; sx = sx < 0 ? 0 : (sx >= cw ? cw - 1 : sx);
+         dst[LUMA_SZ + (y * cw + x) * 2 + 0] = src[LUMA_SZ + (sy * cw + sx) * 2 + 0];
+         dst[LUMA_SZ + (y * cw + x) * 2 + 1] = src[LUMA_SZ + (sy * cw + sx) * 2 + 1];
+      }
+   }
+}
+
+static PFN_vkGetPhysicalDeviceVideoCapabilitiesKHR pGetPhysicalDeviceVideoCapabilitiesKHR;
+static PFN_vkGetPhysicalDeviceVideoFormatPropertiesKHR pGetPhysicalDeviceVideoFormatPropertiesKHR;
+static PFN_vkCreateVideoSessionKHR pCreateVideoSessionKHR;
+static PFN_vkDestroyVideoSessionKHR pDestroyVideoSessionKHR;
+static PFN_vkGetVideoSessionMemoryRequirementsKHR pGetVideoSessionMemoryRequirementsKHR;
+static PFN_vkBindVideoSessionMemoryKHR pBindVideoSessionMemoryKHR;
+static PFN_vkCreateVideoSessionParametersKHR pCreateVideoSessionParametersKHR;
+static PFN_vkDestroyVideoSessionParametersKHR pDestroyVideoSessionParametersKHR;
+static PFN_vkGetEncodedVideoSessionParametersKHR pGetEncodedVideoSessionParametersKHR;
+static PFN_vkCmdBeginVideoCodingKHR pCmdBeginVideoCodingKHR;
+static PFN_vkCmdEndVideoCodingKHR pCmdEndVideoCodingKHR;
+static PFN_vkCmdEncodeVideoKHR pCmdEncodeVideoKHR;
+
+static uint32_t
+find_memory_type(VkPhysicalDeviceMemoryProperties *mp, uint32_t type_bits, VkMemoryPropertyFlags want)
+{
+   for (uint32_t i = 0; i < mp->memoryTypeCount; i++) {
+      if ((type_bits & (1u << i)) &&
+          (mp->memoryTypes[i].propertyFlags & want) == want)
+         return i;
+   }
+   /* fall back: any type in the mask */
+   for (uint32_t i = 0; i < mp->memoryTypeCount; i++) {
+      if (type_bits & (1u << i))
+         return i;
+   }
+   fprintf(stderr, "FAIL: no matching memory type for bits 0x%x\n", type_bits);
+   exit(1);
+}
+
+static VkDeviceMemory
+alloc_and_bind_buffer(VkDevice dev, VkPhysicalDeviceMemoryProperties *mp,
+                      VkBuffer buf, VkMemoryPropertyFlags want)
+{
+   VkMemoryRequirements req;
+   vkGetBufferMemoryRequirements(dev, buf, &req);
+   VkMemoryAllocateInfo ai = {
+      .sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO,
+      .allocationSize = req.size,
+      .memoryTypeIndex = find_memory_type(mp, req.memoryTypeBits, want),
+   };
+   VkDeviceMemory mem;
+   CHECK(vkAllocateMemory(dev, &ai, NULL, &mem));
+   CHECK(vkBindBufferMemory(dev, buf, mem, 0));
+   return mem;
+}
+
+static VkDeviceMemory
+alloc_and_bind_image(VkDevice dev, VkPhysicalDeviceMemoryProperties *mp, VkImage img)
+{
+   VkMemoryRequirements req;
+   vkGetImageMemoryRequirements(dev, img, &req);
+   VkMemoryAllocateInfo ai = {
+      .sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO,
+      .allocationSize = req.size,
+      .memoryTypeIndex = find_memory_type(mp, req.memoryTypeBits, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT),
+   };
+   VkDeviceMemory mem;
+   CHECK(vkAllocateMemory(dev, &ai, NULL, &mem));
+   CHECK(vkBindImageMemory(dev, img, mem, 0));
+   return mem;
+}
+
+int
+main(void)
+{
+   /* instance */
+   VkApplicationInfo app = {
+      .sType = VK_STRUCTURE_TYPE_APPLICATION_INFO,
+      .apiVersion = VK_API_VERSION_1_3,
+   };
+   VkInstanceCreateInfo ici = {
+      .sType = VK_STRUCTURE_TYPE_INSTANCE_CREATE_INFO,
+      .pApplicationInfo = &app,
+   };
+   VkInstance instance;
+   CHECK(vkCreateInstance(&ici, NULL, &instance));
+
+   uint32_t pdev_count = 0;
+   CHECK(vkEnumeratePhysicalDevices(instance, &pdev_count, NULL));
+   if (pdev_count == 0) { fprintf(stderr, "no physical devices\n"); return 1; }
+   VkPhysicalDevice *pdevs = calloc(pdev_count, sizeof(*pdevs));
+   CHECK(vkEnumeratePhysicalDevices(instance, &pdev_count, pdevs));
+   VkPhysicalDevice pdev = pdevs[0];
+
+   VkPhysicalDeviceProperties pprops;
+   vkGetPhysicalDeviceProperties(pdev, &pprops);
+   printf("Device: %s\n", pprops.deviceName);
+
+   VkPhysicalDeviceMemoryProperties mem_props;
+   vkGetPhysicalDeviceMemoryProperties(pdev, &mem_props);
+
+   /* find encode queue family */
+   uint32_t qf_count = 0;
+   vkGetPhysicalDeviceQueueFamilyProperties2(pdev, &qf_count, NULL);
+   VkQueueFamilyVideoPropertiesKHR *video_props = calloc(qf_count, sizeof(*video_props));
+   VkQueueFamilyProperties2 *qfs = calloc(qf_count, sizeof(*qfs));
+   for (uint32_t i = 0; i < qf_count; i++) {
+      video_props[i].sType = VK_STRUCTURE_TYPE_QUEUE_FAMILY_VIDEO_PROPERTIES_KHR;
+      qfs[i].sType = VK_STRUCTURE_TYPE_QUEUE_FAMILY_PROPERTIES_2;
+      qfs[i].pNext = &video_props[i];
+   }
+   vkGetPhysicalDeviceQueueFamilyProperties2(pdev, &qf_count, qfs);
+
+   int32_t encode_qf = -1;
+   int32_t transfer_qf = -1;
+   for (uint32_t i = 0; i < qf_count; i++) {
+      if ((qfs[i].queueFamilyProperties.queueFlags & VK_QUEUE_VIDEO_ENCODE_BIT_KHR) &&
+          (video_props[i].videoCodecOperations & VK_VIDEO_CODEC_OPERATION_ENCODE_H264_BIT_KHR)) {
+         encode_qf = (int32_t)i;
+      }
+      if ((qfs[i].queueFamilyProperties.queueFlags & VK_QUEUE_TRANSFER_BIT) && transfer_qf < 0)
+         transfer_qf = (int32_t)i;
+   }
+   if (encode_qf < 0) { fprintf(stderr, "no H.264 encode queue family found\n"); return 1; }
+   if (transfer_qf < 0) { fprintf(stderr, "no transfer-capable queue family found\n"); return 1; }
+   printf("encode queue family = %d, transfer queue family = %d\n", encode_qf, transfer_qf);
+
+   /* ---- Device ---- */
+   const char *dev_exts[] = {
+      "VK_KHR_video_queue",
+      "VK_KHR_video_encode_queue",
+      "VK_KHR_video_encode_h264",
+      "VK_KHR_synchronization2",
+   };
+   float qprio = 1.0f;
+   VkDeviceQueueCreateInfo qcis[2] = {
+      {
+         .sType = VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO,
+         .queueFamilyIndex = (uint32_t)transfer_qf,
+         .queueCount = 1,
+         .pQueuePriorities = &qprio,
+      },
+      {
+         .sType = VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO,
+         .queueFamilyIndex = (uint32_t)encode_qf,
+         .queueCount = 1,
+         .pQueuePriorities = &qprio,
+      },
+   };
+   VkDeviceCreateInfo dci = {
+      .sType = VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO,
+      .queueCreateInfoCount = (encode_qf == transfer_qf) ? 1 : 2,
+      .pQueueCreateInfos = qcis,
+      .enabledExtensionCount = sizeof(dev_exts) / sizeof(dev_exts[0]),
+      .ppEnabledExtensionNames = dev_exts,
+   };
+   VkDevice dev;
+   CHECK(vkCreateDevice(pdev, &dci, NULL, &dev));
+
+#define LOAD(name) p##name = (PFN_vk##name)vkGetDeviceProcAddr(dev, "vk" #name)
+   LOAD(GetPhysicalDeviceVideoCapabilitiesKHR);
+   LOAD(GetPhysicalDeviceVideoFormatPropertiesKHR);
+   LOAD(CreateVideoSessionKHR);
+   LOAD(DestroyVideoSessionKHR);
+   LOAD(GetVideoSessionMemoryRequirementsKHR);
+   LOAD(BindVideoSessionMemoryKHR);
+   LOAD(CreateVideoSessionParametersKHR);
+   LOAD(DestroyVideoSessionParametersKHR);
+   LOAD(GetEncodedVideoSessionParametersKHR);
+   LOAD(CmdBeginVideoCodingKHR);
+   LOAD(CmdEndVideoCodingKHR);
+   LOAD(CmdEncodeVideoKHR);
+   pGetPhysicalDeviceVideoCapabilitiesKHR =
+      (PFN_vkGetPhysicalDeviceVideoCapabilitiesKHR)vkGetInstanceProcAddr(instance, "vkGetPhysicalDeviceVideoCapabilitiesKHR");
+   pGetPhysicalDeviceVideoFormatPropertiesKHR =
+      (PFN_vkGetPhysicalDeviceVideoFormatPropertiesKHR)vkGetInstanceProcAddr(instance, "vkGetPhysicalDeviceVideoFormatPropertiesKHR");
+#undef LOAD
+
+   VkQueue queue;
+   vkGetDeviceQueue(dev, (uint32_t)encode_qf, 0, &queue);
+   VkQueue transfer_queue;
+   vkGetDeviceQueue(dev, (uint32_t)transfer_qf, 0, &transfer_queue);
+
+   int use_cabac = getenv("HASVK_ENC_CABAC") ? 1 : 0;
+   int use_pframe = getenv("HASVK_ENC_PFRAME") ? 1 : 0;
+
+   /* H.264 encode, 4:2:0, 8-bit */
+   VkVideoEncodeH264ProfileInfoKHR h264_profile = {
+      .sType = VK_STRUCTURE_TYPE_VIDEO_ENCODE_H264_PROFILE_INFO_KHR,
+      .stdProfileIdc = use_cabac ? STD_VIDEO_H264_PROFILE_IDC_MAIN
+                                 : STD_VIDEO_H264_PROFILE_IDC_BASELINE,
+   };
+   VkVideoProfileInfoKHR profile = {
+      .sType = VK_STRUCTURE_TYPE_VIDEO_PROFILE_INFO_KHR,
+      .pNext = &h264_profile,
+      .videoCodecOperation = VK_VIDEO_CODEC_OPERATION_ENCODE_H264_BIT_KHR,
+      .chromaSubsampling = VK_VIDEO_CHROMA_SUBSAMPLING_420_BIT_KHR,
+      .lumaBitDepth = VK_VIDEO_COMPONENT_BIT_DEPTH_8_BIT_KHR,
+      .chromaBitDepth = VK_VIDEO_COMPONENT_BIT_DEPTH_8_BIT_KHR,
+   };
+   VkVideoProfileListInfoKHR profile_list = {
+      .sType = VK_STRUCTURE_TYPE_VIDEO_PROFILE_LIST_INFO_KHR,
+      .profileCount = 1,
+      .pProfiles = &profile,
+   };
+
+   /* capability */
+   VkVideoEncodeH264CapabilitiesKHR h264_caps = { .sType = VK_STRUCTURE_TYPE_VIDEO_ENCODE_H264_CAPABILITIES_KHR };
+   VkVideoEncodeCapabilitiesKHR enc_caps = { .sType = VK_STRUCTURE_TYPE_VIDEO_ENCODE_CAPABILITIES_KHR, .pNext = &h264_caps };
+   VkVideoCapabilitiesKHR caps = { .sType = VK_STRUCTURE_TYPE_VIDEO_CAPABILITIES_KHR, .pNext = &enc_caps };
+   CHECK(pGetPhysicalDeviceVideoCapabilitiesKHR(pdev, &profile, &caps));
+   printf("caps: minBitstreamBufferOffsetAlignment=%llu minBitstreamBufferSizeAlignment=%llu maxDpbSlots=%u\n",
+          (unsigned long long)caps.minBitstreamBufferOffsetAlignment,
+          (unsigned long long)caps.minBitstreamBufferSizeAlignment,
+          caps.maxDpbSlots);
+   printf("enc caps: supportedEncodeFeedbackFlags=0x%x rateControlModes=0x%x\n",
+          enc_caps.supportedEncodeFeedbackFlags, enc_caps.rateControlModes);
+
+   /* src/dpb images */
+   VkPhysicalDeviceVideoFormatInfoKHR fmt_info = {
+      .sType = VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_VIDEO_FORMAT_INFO_KHR,
+      .pNext = &profile_list,
+      .imageUsage = VK_IMAGE_USAGE_VIDEO_ENCODE_SRC_BIT_KHR | VK_IMAGE_USAGE_VIDEO_ENCODE_DPB_BIT_KHR,
+   };
+   uint32_t fmt_count = 0;
+   CHECK(pGetPhysicalDeviceVideoFormatPropertiesKHR(pdev, &fmt_info, &fmt_count, NULL));
+   if (fmt_count == 0) { fprintf(stderr, "no video formats reported\n"); return 1; }
+   VkVideoFormatPropertiesKHR *fmts = calloc(fmt_count, sizeof(*fmts));
+   for (uint32_t i = 0; i < fmt_count; i++)
+      fmts[i].sType = VK_STRUCTURE_TYPE_VIDEO_FORMAT_PROPERTIES_KHR;
+   CHECK(pGetPhysicalDeviceVideoFormatPropertiesKHR(pdev, &fmt_info, &fmt_count, fmts));
+   VkFormat pic_format = fmts[0].format;
+   printf("picture format = %d\n", pic_format);
+
+   /* video sessions */
+   VkExtensionProperties std_hdr = {
+      .extensionName = VK_STD_VULKAN_VIDEO_CODEC_H264_ENCODE_EXTENSION_NAME,
+      .specVersion = VK_STD_VULKAN_VIDEO_CODEC_H264_ENCODE_SPEC_VERSION,
+   };
+   VkVideoSessionCreateInfoKHR sess_ci = {
+      .sType = VK_STRUCTURE_TYPE_VIDEO_SESSION_CREATE_INFO_KHR,
+      .queueFamilyIndex = (uint32_t)encode_qf,
+      .pVideoProfile = &profile,
+      .pictureFormat = pic_format,
+      .maxCodedExtent = { WIDTH, HEIGHT },
+      .referencePictureFormat = pic_format,
+      .maxDpbSlots = 1,
+      .maxActiveReferencePictures = 0,
+      .pStdHeaderVersion = &std_hdr,
+   };
+   VkVideoSessionKHR session;
+   CHECK(pCreateVideoSessionKHR(dev, &sess_ci, NULL, &session));
+
+   uint32_t req_count = 0;
+   CHECK(pGetVideoSessionMemoryRequirementsKHR(dev, session, &req_count, NULL));
+   printf("video session memory requirement count = %u\n", req_count);
+   VkVideoSessionMemoryRequirementsKHR *reqs = calloc(req_count, sizeof(*reqs));
+   for (uint32_t i = 0; i < req_count; i++)
+      reqs[i].sType = VK_STRUCTURE_TYPE_VIDEO_SESSION_MEMORY_REQUIREMENTS_KHR;
+   CHECK(pGetVideoSessionMemoryRequirementsKHR(dev, session, &req_count, reqs));
+
+   VkDeviceMemory *sess_mems = calloc(req_count, sizeof(*sess_mems));
+   VkBindVideoSessionMemoryInfoKHR *binds = calloc(req_count, sizeof(*binds));
+   for (uint32_t i = 0; i < req_count; i++) {
+      VkMemoryAllocateInfo ai = {
+         .sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO,
+         .allocationSize = reqs[i].memoryRequirements.size,
+         .memoryTypeIndex = find_memory_type(&mem_props, reqs[i].memoryRequirements.memoryTypeBits,
+                                             VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT),
+      };
+      CHECK(vkAllocateMemory(dev, &ai, NULL, &sess_mems[i]));
+      binds[i] = (VkBindVideoSessionMemoryInfoKHR) {
+         .sType = VK_STRUCTURE_TYPE_BIND_VIDEO_SESSION_MEMORY_INFO_KHR,
+         .memoryBindIndex = reqs[i].memoryBindIndex,
+         .memory = sess_mems[i],
+         .memoryOffset = 0,
+         .memorySize = reqs[i].memoryRequirements.size,
+      };
+      printf("  bindIndex=%u size=%llu\n", reqs[i].memoryBindIndex,
+             (unsigned long long)reqs[i].memoryRequirements.size);
+   }
+   CHECK(pBindVideoSessionMemoryKHR(dev, session, req_count, binds));
+
+   /* SPS / PPS */
+   int crop_r = getenv("HASVK_ENC_CROP_R") ? atoi(getenv("HASVK_ENC_CROP_R")) : 0;
+   int crop_b = getenv("HASVK_ENC_CROP_B") ? atoi(getenv("HASVK_ENC_CROP_B")) : 0;
+   crop_r &= ~1; crop_b &= ~1;
+
+   StdVideoH264SequenceParameterSet sps = {
+      .profile_idc = use_cabac ? STD_VIDEO_H264_PROFILE_IDC_MAIN
+                               : STD_VIDEO_H264_PROFILE_IDC_BASELINE,
+      .level_idc = getenv("HASVK_ENC_LEVEL0") ? STD_VIDEO_H264_LEVEL_IDC_1_0
+                                              : STD_VIDEO_H264_LEVEL_IDC_3_0,
+      .chroma_format_idc = STD_VIDEO_H264_CHROMA_FORMAT_IDC_420,
+      .seq_parameter_set_id = 0,
+      .log2_max_frame_num_minus4 = getenv("HASVK_ENC_LOG2MAXFN")
+                                     ? atoi(getenv("HASVK_ENC_LOG2MAXFN")) : 0,
+      .pic_order_cnt_type = getenv("HASVK_ENC_POC2") ? STD_VIDEO_H264_POC_TYPE_2
+                                                     : STD_VIDEO_H264_POC_TYPE_0,
+      .log2_max_pic_order_cnt_lsb_minus4 = 0,
+      .max_num_ref_frames = 0,
+      .pic_width_in_mbs_minus1 = WIDTH_MBS - 1,
+      .pic_height_in_map_units_minus1 = HEIGHT_MBS - 1,
+      .frame_crop_right_offset = (uint32_t)(crop_r / 2),
+      .frame_crop_bottom_offset = (uint32_t)(crop_b / 2),
+   };
+   sps.flags.frame_mbs_only_flag = 1;
+   sps.flags.direct_8x8_inference_flag = 1;
+   sps.flags.frame_cropping_flag = (crop_r || crop_b) ? 1 : 0;
+
+   StdVideoH264PictureParameterSet pps = {
+      .seq_parameter_set_id = 0,
+      .pic_parameter_set_id = 0,
+      .num_ref_idx_l0_default_active_minus1 = 0,
+      .num_ref_idx_l1_default_active_minus1 = 0,
+      .weighted_bipred_idc = STD_VIDEO_H264_WEIGHTED_BIPRED_IDC_DEFAULT,
+      .pic_init_qp_minus26 = 0, /* pic_init_qp = 26 */
+      .pic_init_qs_minus26 = 0,
+      .chroma_qp_index_offset = 0,
+      .second_chroma_qp_index_offset = 0,
+   };
+   pps.flags.deblocking_filter_control_present_flag =
+      getenv("HASVK_ENC_NODEBLOCKCTRL") ? 0 : 1;
+   pps.flags.entropy_coding_mode_flag = use_cabac ? 1 : 0;
+
+   VkVideoEncodeH264SessionParametersAddInfoKHR add_info = {
+      .sType = VK_STRUCTURE_TYPE_VIDEO_ENCODE_H264_SESSION_PARAMETERS_ADD_INFO_KHR,
+      .stdSPSCount = 1,
+      .pStdSPSs = &sps,
+      .stdPPSCount = 1,
+      .pStdPPSs = &pps,
+   };
+   VkVideoEncodeH264SessionParametersCreateInfoKHR h264_params_ci = {
+      .sType = VK_STRUCTURE_TYPE_VIDEO_ENCODE_H264_SESSION_PARAMETERS_CREATE_INFO_KHR,
+      .maxStdSPSCount = 1,
+      .maxStdPPSCount = 1,
+      .pParametersAddInfo = &add_info,
+   };
+   VkVideoSessionParametersCreateInfoKHR params_ci = {
+      .sType = VK_STRUCTURE_TYPE_VIDEO_SESSION_PARAMETERS_CREATE_INFO_KHR,
+      .pNext = &h264_params_ci,
+      .videoSession = session,
+   };
+   VkVideoSessionParametersKHR params;
+   CHECK(pCreateVideoSessionParametersKHR(dev, &params_ci, NULL, &params));
+
+   static uint8_t hdr_buf[512];
+   size_t hdr_size = 0;
+   {
+      VkVideoEncodeH264SessionParametersGetInfoKHR h264_get = {
+         .sType = VK_STRUCTURE_TYPE_VIDEO_ENCODE_H264_SESSION_PARAMETERS_GET_INFO_KHR,
+         .writeStdSPS = VK_TRUE,
+         .stdSPSId = 0,
+         .writeStdPPS = VK_TRUE,
+         .stdPPSId = 0,
+      };
+      VkVideoEncodeSessionParametersGetInfoKHR get_info = {
+         .sType = VK_STRUCTURE_TYPE_VIDEO_ENCODE_SESSION_PARAMETERS_GET_INFO_KHR,
+         .pNext = &h264_get,
+         .videoSessionParameters = params,
+      };
+      size_t data_size = 0;
+      VkResult gr = pGetEncodedVideoSessionParametersKHR(dev, &get_info, NULL,
+                                                         &data_size, NULL);
+      printf("GetEncoded SPS+PPS: result=%d size=%zu\n", gr, data_size);
+      if (gr == VK_SUCCESS && data_size > 0 && data_size <= sizeof(hdr_buf)) {
+         gr = pGetEncodedVideoSessionParametersKHR(dev, &get_info, NULL,
+                                                   &data_size, hdr_buf);
+         if (gr == VK_SUCCESS) hdr_size = data_size;
+      }
+   }
+
+   /* source + recon/DPB */
+   VkImageCreateInfo img_ci = {
+      .sType = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO,
+      .pNext = &profile_list,
+      .imageType = VK_IMAGE_TYPE_2D,
+      .format = pic_format,
+      .extent = { WIDTH, HEIGHT, 1 },
+      .mipLevels = 1,
+      .arrayLayers = 1,
+      .samples = VK_SAMPLE_COUNT_1_BIT,
+      .tiling = VK_IMAGE_TILING_OPTIMAL,
+      .usage = VK_IMAGE_USAGE_VIDEO_ENCODE_SRC_BIT_KHR,
+      .sharingMode = VK_SHARING_MODE_EXCLUSIVE,
+      .initialLayout = VK_IMAGE_LAYOUT_UNDEFINED,
+   };
+   VkImage src_image;
+   CHECK(vkCreateImage(dev, &img_ci, NULL, &src_image));
+   VkDeviceMemory src_image_mem = alloc_and_bind_image(dev, &mem_props, src_image);
+
+   VkImageCreateInfo dpb_ci = img_ci;
+   dpb_ci.usage = VK_IMAGE_USAGE_VIDEO_ENCODE_DPB_BIT_KHR;
+   VkImage dpb_image;
+   CHECK(vkCreateImage(dev, &dpb_ci, NULL, &dpb_image));
+   VkDeviceMemory dpb_image_mem = alloc_and_bind_image(dev, &mem_props, dpb_image);
+
+   VkImageViewCreateInfo src_view_ci = {
+      .sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO,
+      .image = src_image,
+      .viewType = VK_IMAGE_VIEW_TYPE_2D,
+      .format = pic_format,
+      .subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1 },
+   };
+   VkImageView src_view;
+   CHECK(vkCreateImageView(dev, &src_view_ci, NULL, &src_view));
+
+   VkImageViewCreateInfo dpb_view_ci = src_view_ci;
+   dpb_view_ci.image = dpb_image;
+   VkImageView dpb_view;
+   CHECK(vkCreateImageView(dev, &dpb_view_ci, NULL, &dpb_view));
+
+   VkImage dpb_image2 = VK_NULL_HANDLE;
+   VkImageView dpb_view2 = VK_NULL_HANDLE;
+   if (use_pframe) {
+      CHECK(vkCreateImage(dev, &dpb_ci, NULL, &dpb_image2));
+      alloc_and_bind_image(dev, &mem_props, dpb_image2);
+      VkImageViewCreateInfo v = dpb_view_ci;
+      v.image = dpb_image2;
+      CHECK(vkCreateImageView(dev, &v, NULL, &dpb_view2));
+   }
+
+   int shift_px = getenv("HASVK_ENC_SHIFT") ? atoi(getenv("HASVK_ENC_SHIFT")) : 0;
+   int src_step = getenv("HASVK_ENC_SRC_STEP") ? atoi(getenv("HASVK_ENC_SRC_STEP")) : 0;
+   int two_src = use_pframe && (shift_px || src_step);
+   VkImage src_image2 = VK_NULL_HANDLE;
+   VkImageView src_view2 = VK_NULL_HANDLE;
+   if (two_src) {
+      CHECK(vkCreateImage(dev, &img_ci, NULL, &src_image2));
+      alloc_and_bind_image(dev, &mem_props, src_image2);
+      VkImageViewCreateInfo v = src_view_ci;
+      v.image = src_image2;
+      CHECK(vkCreateImageView(dev, &v, NULL, &src_view2));
+   }
+
+   /* fill source image with flat gray via staging buffer */
+   VkDeviceSize luma_size = (VkDeviceSize)WIDTH * HEIGHT;
+   VkDeviceSize chroma_size = (VkDeviceSize)(WIDTH / 2) * (HEIGHT / 2) * 2;
+   VkDeviceSize frame_size = luma_size + chroma_size;
+   VkDeviceSize staging_size = frame_size * (two_src ? 2 : 1);
+   VkBufferCreateInfo staging_ci = {
+      .sType = VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO,
+      .size = staging_size,
+      .usage = VK_BUFFER_USAGE_TRANSFER_SRC_BIT,
+      .sharingMode = VK_SHARING_MODE_EXCLUSIVE,
+   };
+   VkBuffer staging_buf;
+   CHECK(vkCreateBuffer(dev, &staging_ci, NULL, &staging_buf));
+   VkDeviceMemory staging_mem = alloc_and_bind_buffer(dev, &mem_props, staging_buf,
+                                                      VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT);
+   void *staging_map;
+   CHECK(vkMapMemory(dev, staging_mem, 0, staging_size, 0, &staging_map));
+   const char *src_in = getenv("HASVK_ENC_SRC_IN");
+   int src_i420 = getenv("HASVK_ENC_SRC_I420") ? 1 : 0;
+   int src_frame = getenv("HASVK_ENC_SRC_FRAME") ? atoi(getenv("HASVK_ENC_SRC_FRAME")) : 0;
+   if (src_in) {
+      if (!load_frame(src_in, src_frame, src_i420, (uint8_t *)staging_map))
+         return 1;
+   } else if (getenv("HASVK_ENC_GRADIENT")) {
+      uint8_t *sm = (uint8_t *)staging_map;
+      for (uint32_t yy = 0; yy < HEIGHT; yy++)
+         for (uint32_t xx = 0; xx < WIDTH; xx++)
+            sm[yy * WIDTH + xx] = (uint8_t)((xx * 255) / (WIDTH - 1));
+      if (getenv("HASVK_ENC_CHROMA")) {
+         uint8_t *ch = sm + luma_size;
+         uint32_t cw = WIDTH / 2, chh = HEIGHT / 2;
+         for (uint32_t cy = 0; cy < chh; cy++)
+            for (uint32_t cx = 0; cx < cw; cx++) {
+               ch[(cy * cw + cx) * 2 + 0] = (uint8_t)((cx * 255) / (cw - 1));
+               ch[(cy * cw + cx) * 2 + 1] = (uint8_t)((cy * 255) / (chh - 1));
+            }
+      } else {
+         memset(sm + luma_size, 128, (size_t)chroma_size);
+      }
+   } else {
+      memset(staging_map, 128, (size_t)frame_size);
+   }
+
+   if (two_src) {
+      uint8_t *f0 = (uint8_t *)staging_map, *f1 = f0 + frame_size;
+      if (shift_px) {
+         shift_frame(f0, f1, shift_px, 0);
+      } else if (!src_in) {
+         fprintf(stderr, "HASVK_ENC_SRC_STEP needs HASVK_ENC_SRC_IN\n");
+         return 1;
+      } else if (!load_frame(src_in, src_frame + src_step, src_i420, f1)) {
+         return 1;
+      }
+   }
+
+   const char *src_out = getenv("HASVK_ENC_SRC_OUT");
+   if (src_out) {
+      const uint8_t *sm = (const uint8_t *)staging_map;
+      const uint8_t *ch = sm + luma_size;
+      uint32_t cw = WIDTH / 2, chh = HEIGHT / 2;
+      FILE *sf = fopen(src_out, "wb");
+      if (sf) {
+         fwrite(sm, 1, (size_t)luma_size, sf);
+         for (uint32_t i = 0; i < cw * chh; i++)
+            fputc(ch[i * 2 + 0], sf);
+         for (uint32_t i = 0; i < cw * chh; i++)
+            fputc(ch[i * 2 + 1], sf);
+         fclose(sf);
+      }
+   }
+   vkUnmapMemory(dev, staging_mem);
+
+   VkDeviceSize dst_align = caps.minBitstreamBufferSizeAlignment ? caps.minBitstreamBufferSizeAlignment : 4096;
+   VkDeviceSize dst_size = ((VkDeviceSize)1 << 20);
+   dst_size = (dst_size + dst_align - 1) & ~(dst_align - 1);
+   VkBufferCreateInfo dst_ci = {
+      .sType = VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO,
+      .pNext = &profile_list,
+      .size = dst_size,
+      .usage = VK_BUFFER_USAGE_VIDEO_ENCODE_DST_BIT_KHR,
+      .sharingMode = VK_SHARING_MODE_EXCLUSIVE,
+   };
+   VkBuffer dst_buf;
+   CHECK(vkCreateBuffer(dev, &dst_ci, NULL, &dst_buf));
+   VkDeviceMemory dst_mem = alloc_and_bind_buffer(dev, &mem_props, dst_buf,
+                                                  VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT);
+   void *dst_map;
+   CHECK(vkMapMemory(dev, dst_mem, 0, dst_size, 0, &dst_map));
+   memset(dst_map, 0xCD, (size_t)dst_size);
+
+   VkCommandPoolCreateInfo xfer_pool_ci = {
+      .sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO,
+      .flags = VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT,
+      .queueFamilyIndex = (uint32_t)transfer_qf,
+   };
+   VkCommandPool xfer_pool;
+   CHECK(vkCreateCommandPool(dev, &xfer_pool_ci, NULL, &xfer_pool));
+   VkCommandBufferAllocateInfo xfer_cb_ai = {
+      .sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO,
+      .commandPool = xfer_pool,
+      .level = VK_COMMAND_BUFFER_LEVEL_PRIMARY,
+      .commandBufferCount = 1,
+   };
+   VkCommandBuffer xfer_cmd;
+   CHECK(vkAllocateCommandBuffers(dev, &xfer_cb_ai, &xfer_cmd));
+
+   VkCommandBufferBeginInfo xfer_begin_info = { .sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO };
+   CHECK(vkBeginCommandBuffer(xfer_cmd, &xfer_begin_info));
+
+   VkImageMemoryBarrier to_xfer = {
+      .sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER,
+      .srcAccessMask = 0,
+      .dstAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT,
+      .oldLayout = VK_IMAGE_LAYOUT_UNDEFINED,
+      .newLayout = VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL,
+      .srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
+      .dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
+      .image = src_image,
+      .subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1 },
+   };
+   VkImageMemoryBarrier to_xfer_both[2] = { to_xfer, to_xfer };
+   to_xfer_both[1].image = src_image2;
+   vkCmdPipelineBarrier(xfer_cmd, VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT, VK_PIPELINE_STAGE_TRANSFER_BIT,
+                       0, 0, NULL, 0, NULL, two_src ? 2 : 1, to_xfer_both);
+
+   VkBufferImageCopy regions[2] = {
+      { /* luma plane */
+         .bufferOffset = 0,
+         .imageSubresource = { VK_IMAGE_ASPECT_PLANE_0_BIT, 0, 0, 1 },
+         .imageExtent = { WIDTH, HEIGHT, 1 },
+      },
+      { /* chroma plane (interleaved UV, half res) */
+         .bufferOffset = luma_size,
+         .imageSubresource = { VK_IMAGE_ASPECT_PLANE_1_BIT, 0, 0, 1 },
+         .imageExtent = { WIDTH / 2, HEIGHT / 2, 1 },
+      },
+   };
+   vkCmdCopyBufferToImage(xfer_cmd, staging_buf, src_image, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, 2, regions);
+   if (two_src) {
+      VkBufferImageCopy r2[2] = { regions[0], regions[1] };
+      r2[0].bufferOffset = frame_size;
+      r2[1].bufferOffset = frame_size + luma_size;
+      vkCmdCopyBufferToImage(xfer_cmd, staging_buf, src_image2, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, 2, r2);
+   }
+
+   VkImageMemoryBarrier to_encode_src = to_xfer;
+   to_encode_src.srcAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT;
+   to_encode_src.dstAccessMask = 0;
+   to_encode_src.oldLayout = VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL;
+   to_encode_src.newLayout = VK_IMAGE_LAYOUT_VIDEO_ENCODE_SRC_KHR;
+   VkImageMemoryBarrier to_encode_dpb = {
+      .sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER,
+      .oldLayout = VK_IMAGE_LAYOUT_UNDEFINED,
+      .newLayout = VK_IMAGE_LAYOUT_VIDEO_ENCODE_DPB_KHR,
+      .srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
+      .dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
+      .image = dpb_image,
+      .subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1 },
+   };
+   VkImageMemoryBarrier barriers2[4] = { to_encode_src, to_encode_dpb };
+   uint32_t barrier2_count = 2;
+   if (use_pframe) {
+      VkImageMemoryBarrier to_encode_dpb2 = to_encode_dpb;
+      to_encode_dpb2.image = dpb_image2;
+      barriers2[barrier2_count++] = to_encode_dpb2;
+   }
+   if (two_src) {
+      VkImageMemoryBarrier to_encode_src2 = to_encode_src;
+      to_encode_src2.image = src_image2;
+      barriers2[barrier2_count++] = to_encode_src2;
+   }
+   vkCmdPipelineBarrier(xfer_cmd, VK_PIPELINE_STAGE_TRANSFER_BIT, VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT,
+                       0, 0, NULL, 0, NULL, barrier2_count, barriers2);
+
+   CHECK(vkEndCommandBuffer(xfer_cmd));
+
+   /* HASVK_ENC_SEMSYNC */
+   int use_semsync = getenv("HASVK_ENC_SEMSYNC") ? 1 : 0;
+   VkSemaphore xfer_sem = VK_NULL_HANDLE;
+   if (use_semsync) {
+      VkSemaphoreCreateInfo sci = { .sType = VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO };
+      CHECK(vkCreateSemaphore(dev, &sci, NULL, &xfer_sem));
+   }
+
+   VkFenceCreateInfo xfer_fence_ci = { .sType = VK_STRUCTURE_TYPE_FENCE_CREATE_INFO };
+   VkFence xfer_fence;
+   CHECK(vkCreateFence(dev, &xfer_fence_ci, NULL, &xfer_fence));
+   VkSubmitInfo xfer_submit = {
+      .sType = VK_STRUCTURE_TYPE_SUBMIT_INFO,
+      .commandBufferCount = 1,
+      .pCommandBuffers = &xfer_cmd,
+      .signalSemaphoreCount = use_semsync ? 1u : 0u,
+      .pSignalSemaphores = use_semsync ? &xfer_sem : NULL,
+   };
+   printf("submitting transfer prep...\n");
+   fflush(stdout);
+   CHECK(vkQueueSubmit(transfer_queue, 1, &xfer_submit, xfer_fence));
+   if (!use_semsync) {
+      VkResult xfer_wait = vkWaitForFences(dev, 1, &xfer_fence, VK_TRUE, 10ull * 1000 * 1000 * 1000);
+      printf("transfer wait result = %d\n", xfer_wait);
+      if (xfer_wait != VK_SUCCESS) { fprintf(stderr, "transfer prep failed/hung\n"); return 3; }
+   } else {
+      printf("transfer submitted (semaphore sync, no CPU wait)\n");
+   }
+
+   VkCommandPoolCreateInfo pool_ci = {
+      .sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO,
+      .flags = VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT,
+      .queueFamilyIndex = (uint32_t)encode_qf,
+   };
+   VkCommandPool pool;
+   CHECK(vkCreateCommandPool(dev, &pool_ci, NULL, &pool));
+   VkCommandBufferAllocateInfo cb_ai = {
+      .sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO,
+      .commandPool = pool,
+      .level = VK_COMMAND_BUFFER_LEVEL_PRIMARY,
+      .commandBufferCount = 1,
+   };
+   VkCommandBuffer cmd;
+   CHECK(vkAllocateCommandBuffers(dev, &cb_ai, &cmd));
+
+   VkQueryPoolVideoEncodeFeedbackCreateInfoKHR fb_ci = {
+      .sType = VK_STRUCTURE_TYPE_QUERY_POOL_VIDEO_ENCODE_FEEDBACK_CREATE_INFO_KHR,
+      .pNext = &profile,
+      .encodeFeedbackFlags =
+         VK_VIDEO_ENCODE_FEEDBACK_BITSTREAM_BUFFER_OFFSET_BIT_KHR |
+         VK_VIDEO_ENCODE_FEEDBACK_BITSTREAM_BYTES_WRITTEN_BIT_KHR,
+   };
+   VkQueryPoolCreateInfo qp_ci = {
+      .sType = VK_STRUCTURE_TYPE_QUERY_POOL_CREATE_INFO,
+      .pNext = &fb_ci,
+      .queryType = VK_QUERY_TYPE_VIDEO_ENCODE_FEEDBACK_KHR,
+      .queryCount = 2,
+   };
+   VkQueryPool qpool;
+   CHECK(vkCreateQueryPool(dev, &qp_ci, NULL, &qpool));
+
+   VkCommandBufferBeginInfo begin_info = { .sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO };
+   CHECK(vkBeginCommandBuffer(cmd, &begin_info));
+
+   vkCmdResetQueryPool(cmd, qpool, 0, 2);
+
+   if (getenv("HASVK_BISECT_TRULY_EMPTY")) {
+      CHECK(vkEndCommandBuffer(cmd));
+      VkFenceCreateInfo fci = { .sType = VK_STRUCTURE_TYPE_FENCE_CREATE_INFO };
+      VkFence f;
+      CHECK(vkCreateFence(dev, &fci, NULL, &f));
+      VkSubmitInfo si = { .sType = VK_STRUCTURE_TYPE_SUBMIT_INFO, .commandBufferCount = 1, .pCommandBuffers = &cmd };
+      printf("submitting TRULY EMPTY (no video calls at all)...\n");
+      fflush(stdout);
+      CHECK(vkQueueSubmit(queue, 1, &si, f));
+      VkResult r = vkWaitForFences(dev, 1, &f, VK_TRUE, 15ull * 1000 * 1000 * 1000);
+      printf("truly-empty wait result = %d\n", r);
+      return r == VK_SUCCESS ? 0 : 2;
+   }
+
+   int qp = getenv("HASVK_ENC_QP") ? atoi(getenv("HASVK_ENC_QP")) : 26;
+   uint64_t bitrate = getenv("HASVK_ENC_BITRATE")
+                         ? strtoull(getenv("HASVK_ENC_BITRATE"), NULL, 10) : 0;
+   if (qp < 0) qp = 0;
+   if (qp > 51) qp = 51;
+
+   int num_slices = getenv("HASVK_ENC_SLICES") ? atoi(getenv("HASVK_ENC_SLICES")) : 1;
+   if (num_slices < 1) num_slices = 1;
+   if (num_slices > HEIGHT_MBS) num_slices = HEIGHT_MBS;
+
+   VkVideoPictureResourceInfoKHR src_res = {
+      .sType = VK_STRUCTURE_TYPE_VIDEO_PICTURE_RESOURCE_INFO_KHR,
+      .codedExtent = { WIDTH, HEIGHT }, .baseArrayLayer = 0, .imageViewBinding = src_view,
+   };
+   VkVideoPictureResourceInfoKHR src_res2 = src_res;
+   src_res2.imageViewBinding = two_src ? src_view2 : src_view;
+   VkVideoPictureResourceInfoKHR dpb_res0 = {
+      .sType = VK_STRUCTURE_TYPE_VIDEO_PICTURE_RESOURCE_INFO_KHR,
+      .codedExtent = { WIDTH, HEIGHT }, .baseArrayLayer = 0, .imageViewBinding = dpb_view,
+   };
+   VkVideoPictureResourceInfoKHR dpb_res1 = {
+      .sType = VK_STRUCTURE_TYPE_VIDEO_PICTURE_RESOURCE_INFO_KHR,
+      .codedExtent = { WIDTH, HEIGHT }, .baseArrayLayer = 0, .imageViewBinding = dpb_view2,
+   };
+
+   int num_frames = use_pframe ? 2 : 1;
+   VkDeviceSize base_off = getenv("HASVK_ENC_DSTOFF")
+                             ? (VkDeviceSize)atoi(getenv("HASVK_ENC_DSTOFF")) : 0;
+   VkDeviceSize frame_dst_offset[2] = { base_off, dst_size / 2 };
+
+   for (int frame = 0; frame < num_frames; frame++) {
+      bool is_p_frame = (frame == 1) && !getenv("HASVK_ENC_FORCE_I");
+
+      VkVideoReferenceSlotInfoKHR begin_slots[2];
+      uint32_t begin_slot_count = 0;
+      if (is_p_frame) {
+         begin_slots[begin_slot_count++] = (VkVideoReferenceSlotInfoKHR){
+            .sType = VK_STRUCTURE_TYPE_VIDEO_REFERENCE_SLOT_INFO_KHR,
+            .slotIndex = 0, .pPictureResource = &dpb_res0 };
+         begin_slots[begin_slot_count++] = (VkVideoReferenceSlotInfoKHR){
+            .sType = VK_STRUCTURE_TYPE_VIDEO_REFERENCE_SLOT_INFO_KHR,
+            .slotIndex = 1, .pPictureResource = &dpb_res1 };
+      } else {
+         begin_slots[begin_slot_count++] = (VkVideoReferenceSlotInfoKHR){
+            .sType = VK_STRUCTURE_TYPE_VIDEO_REFERENCE_SLOT_INFO_KHR,
+            .slotIndex = 0, .pPictureResource = &dpb_res0 };
+      }
+      VkVideoEncodeH264RateControlLayerInfoKHR h264_rc_layer = {
+         .sType = VK_STRUCTURE_TYPE_VIDEO_ENCODE_H264_RATE_CONTROL_LAYER_INFO_KHR,
+      };
+      VkVideoEncodeRateControlLayerInfoKHR rc_layer = {
+         .sType = VK_STRUCTURE_TYPE_VIDEO_ENCODE_RATE_CONTROL_LAYER_INFO_KHR,
+         .pNext = &h264_rc_layer,
+         .averageBitrate = bitrate,
+         .maxBitrate = bitrate,
+         .frameRateNumerator = 30,
+         .frameRateDenominator = 1,
+      };
+      VkVideoEncodeRateControlInfoKHR rc_info = {
+         .sType = VK_STRUCTURE_TYPE_VIDEO_ENCODE_RATE_CONTROL_INFO_KHR,
+         .rateControlMode = getenv("HASVK_ENC_VBR")
+                               ? VK_VIDEO_ENCODE_RATE_CONTROL_MODE_VBR_BIT_KHR
+                               : VK_VIDEO_ENCODE_RATE_CONTROL_MODE_CBR_BIT_KHR,
+         .layerCount = 1,
+         .pLayers = &rc_layer,
+      };
+      VkVideoBeginCodingInfoKHR begin_coding = {
+         .sType = VK_STRUCTURE_TYPE_VIDEO_BEGIN_CODING_INFO_KHR,
+         .pNext = bitrate ? &rc_info : NULL,
+         .videoSession = session,
+         .videoSessionParameters = params,
+         .referenceSlotCount = begin_slot_count,
+         .pReferenceSlots = begin_slots,
+      };
+      pCmdBeginVideoCodingKHR(cmd, &begin_coding);
+
+      StdVideoEncodeH264PictureInfo std_pic_info = {
+         .seq_parameter_set_id = 0,
+         .pic_parameter_set_id = 0,
+         .idr_pic_id = 0,
+         .primary_pic_type = is_p_frame ? STD_VIDEO_H264_PICTURE_TYPE_P
+                                        : STD_VIDEO_H264_PICTURE_TYPE_IDR,
+         .frame_num = (uint16_t)frame,
+         .PicOrderCnt = (int32_t)(frame * 2),
+      };
+      std_pic_info.flags.IdrPicFlag = is_p_frame ? 0 : 1;
+      std_pic_info.flags.is_reference = 1;
+
+      StdVideoEncodeH264SliceHeader std_slice_hdr[HEIGHT_MBS];
+      VkVideoEncodeH264NaluSliceInfoKHR nalu_slice[HEIGHT_MBS];
+      for (int s = 0; s < num_slices; s++) {
+         uint32_t start_row = (uint32_t)s * HEIGHT_MBS / num_slices;
+         std_slice_hdr[s] = (StdVideoEncodeH264SliceHeader){
+            .first_mb_in_slice = start_row * WIDTH_MBS,
+            .slice_type = is_p_frame ? STD_VIDEO_H264_SLICE_TYPE_P
+                                     : STD_VIDEO_H264_SLICE_TYPE_I,
+            .slice_qp_delta = qp - 26,
+            .cabac_init_idc = STD_VIDEO_H264_CABAC_INIT_IDC_0,
+            /* value 1 ("_ENABLED") == H.264 disable_deblocking_filter_idc==1. */
+            .disable_deblocking_filter_idc = STD_VIDEO_H264_DISABLE_DEBLOCKING_FILTER_IDC_ENABLED,
+         };
+         nalu_slice[s] = (VkVideoEncodeH264NaluSliceInfoKHR){
+            .sType = VK_STRUCTURE_TYPE_VIDEO_ENCODE_H264_NALU_SLICE_INFO_KHR,
+            .constantQp = qp,
+            .pStdSliceHeader = &std_slice_hdr[s],
+         };
+      }
+
+      VkVideoEncodeH264PictureInfoKHR h264_pic_info = {
+         .sType = VK_STRUCTURE_TYPE_VIDEO_ENCODE_H264_PICTURE_INFO_KHR,
+         .naluSliceEntryCount = (uint32_t)num_slices,
+         .pNaluSliceEntries = nalu_slice,
+         .pStdPictureInfo = &std_pic_info,
+      };
+
+      VkVideoReferenceSlotInfoKHR setup_slot = {
+         .sType = VK_STRUCTURE_TYPE_VIDEO_REFERENCE_SLOT_INFO_KHR,
+         .slotIndex = is_p_frame ? 1 : 0,
+         .pPictureResource = is_p_frame ? &dpb_res1 : &dpb_res0,
+      };
+      VkVideoReferenceSlotInfoKHR ref_slot = {
+         .sType = VK_STRUCTURE_TYPE_VIDEO_REFERENCE_SLOT_INFO_KHR,
+         .slotIndex = 0,
+         .pPictureResource = &dpb_res0,
+      };
+
+      VkVideoEncodeInfoKHR encode_info = {
+         .sType = VK_STRUCTURE_TYPE_VIDEO_ENCODE_INFO_KHR,
+         .pNext = &h264_pic_info,
+         .dstBuffer = dst_buf,
+         .dstBufferOffset = frame_dst_offset[frame],
+         .dstBufferRange = dst_size / 2,
+         .srcPictureResource = is_p_frame ? src_res2 : src_res,
+         .pSetupReferenceSlot = &setup_slot,
+         .referenceSlotCount = is_p_frame ? 1 : 0,
+         .pReferenceSlots = is_p_frame ? &ref_slot : NULL,
+      };
+      vkCmdBeginQuery(cmd, qpool, frame, 0);
+      pCmdEncodeVideoKHR(cmd, &encode_info);
+      vkCmdEndQuery(cmd, qpool, frame);
+
+      VkVideoEndCodingInfoKHR end_coding = { .sType = VK_STRUCTURE_TYPE_VIDEO_END_CODING_INFO_KHR };
+      pCmdEndVideoCodingKHR(cmd, &end_coding);
+   }
+
+   CHECK(vkEndCommandBuffer(cmd));
+
+   VkFenceCreateInfo fence_ci = { .sType = VK_STRUCTURE_TYPE_FENCE_CREATE_INFO };
+   VkFence fence;
+   CHECK(vkCreateFence(dev, &fence_ci, NULL, &fence));
+
+   VkPipelineStageFlags enc_wait_stage = VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT;
+   VkSubmitInfo submit = {
+      .sType = VK_STRUCTURE_TYPE_SUBMIT_INFO,
+      .commandBufferCount = 1,
+      .pCommandBuffers = &cmd,
+      .waitSemaphoreCount = use_semsync ? 1u : 0u,
+      .pWaitSemaphores = use_semsync ? &xfer_sem : NULL,
+      .pWaitDstStageMask = use_semsync ? &enc_wait_stage : NULL,
+   };
+   printf("submitting...\n");
+   fflush(stdout);
+   CHECK(vkQueueSubmit(queue, 1, &submit, fence));
+
+   VkResult wait_result = vkWaitForFences(dev, 1, &fence, VK_TRUE, 15ull * 1000 * 1000 * 1000);
+   printf("wait result = %d (%s)\n", wait_result,
+          wait_result == VK_SUCCESS ? "SUCCESS" :
+          wait_result == VK_TIMEOUT ? "TIMEOUT" :
+          wait_result == VK_ERROR_DEVICE_LOST ? "DEVICE_LOST" : "OTHER");
+
+   if (wait_result == VK_SUCCESS) {
+      const uint8_t *bytes = (const uint8_t *)dst_map;
+      const char *out_path = getenv("HASVK_ENC_OUT");
+      if (!out_path) out_path = "/tmp/hasvk_enc_out.h264";
+      FILE *of = fopen(out_path, "wb");
+      if (of && hdr_size > 0)
+         fwrite(hdr_buf, 1, hdr_size, of);
+
+      for (int f = 0; f < num_frames; f++) {
+         struct { uint32_t offset; uint32_t bytesWritten; } fb = { 0, 0 };
+         VkResult qr = vkGetQueryPoolResults(dev, qpool, f, 1, sizeof(fb), &fb,
+                                             sizeof(fb), VK_QUERY_RESULT_WAIT_BIT);
+         printf("frame %d (%s): bytesWritten=%u (query result %d)\n",
+                f, f == 0 ? "I" : "P", fb.bytesWritten, qr);
+         if (of && qr == VK_SUCCESS)
+            fwrite(bytes + frame_dst_offset[f], 1, fb.bytesWritten, of);
+      }
+      if (of) {
+         fclose(of);
+         printf("wrote %zu (SPS/PPS) + %d frame(s) to %s\n",
+                hdr_size, num_frames, out_path);
+      }
+   }
+
+   vkUnmapMemory(dev, dst_mem);
+   printf("done.\n");
+   return wait_result == VK_SUCCESS ? 0 : 2;
+}