1 files changed, 38 insertions, 3 deletions

diff --git a/src/video_core/command_classes/codecs/vp8.cpp b/src/video_core/command_classes/codecs/vp8.cpp
index 976e9f9b7..3ee269948 100644
--- a/src/video_core/command_classes/codecs/vp8.cpp
+++ b/src/video_core/command_classes/codecs/vp8.cpp
@@ -6,15 +6,50 @@
 #include <vector>
 
 #include "video_core/command_classes/codecs/vp8.h"
+#include "video_core/gpu.h"
+#include "video_core/memory_manager.h"
 
 namespace Tegra::Decoder {
 VP8::VP8(GPU& gpu_) : gpu(gpu_) {}
 
 VP8::~VP8() = default;
 
-const std::vector<u8>& VP8::ComposeFrameHeader(const NvdecCommon::NvdecRegisters& state,
-                                               bool is_first_frame) {
-    return {};
+const std::vector<u8>& VP8::ComposeFrameHeader(const NvdecCommon::NvdecRegisters& state) {
+    VP8PictureInfo info;
+    gpu.MemoryManager().ReadBlock(state.picture_info_offset, &info, sizeof(VP8PictureInfo));
+
+    const bool is_key_frame = info.key_frame == 1u;
+    const auto bitstream_size = static_cast<size_t>(info.vld_buffer_size);
+    const size_t header_size = is_key_frame ? 10u : 3u;
+    frame.resize(header_size + bitstream_size);
+
+    // Based on page 30 of the VP8 specification.
+    // https://datatracker.ietf.org/doc/rfc6386/
+    frame[0] = is_key_frame ? 0u : 1u; // 1-bit frame type (0: keyframe, 1: interframes).
+    frame[0] |= static_cast<u8>((info.version & 7u) << 1u); // 3-bit version number
+    frame[0] |= static_cast<u8>(1u << 4u);                  // 1-bit show_frame flag
+
+    // The next 19-bits are the first partition size
+    frame[0] |= static_cast<u8>((info.first_part_size & 7u) << 5u);
+    frame[1] = static_cast<u8>((info.first_part_size & 0x7f8u) >> 3u);
+    frame[2] = static_cast<u8>((info.first_part_size & 0x7f800u) >> 11u);
+
+    if (is_key_frame) {
+        frame[3] = 0x9du;
+        frame[4] = 0x01u;
+        frame[5] = 0x2au;
+        // TODO(ameerj): Horizontal/Vertical Scale
+        // 16 bits: (2 bits Horizontal Scale << 14) | Width (14 bits)
+        frame[6] = static_cast<u8>(info.frame_width & 0xff);
+        frame[7] = static_cast<u8>(((info.frame_width >> 8) & 0x3f));
+        // 16 bits:(2 bits Vertical Scale << 14) | Height (14 bits)
+        frame[8] = static_cast<u8>(info.frame_height & 0xff);
+        frame[9] = static_cast<u8>(((info.frame_height >> 8) & 0x3f));
+    }
+    const u64 bitstream_offset = state.frame_bitstream_offset;
+    gpu.MemoryManager().ReadBlock(bitstream_offset, frame.data() + header_size, bitstream_size);
+
+    return frame;
 }
 
 } // namespace Tegra::Decoder