video_core: NVDEC Implementation

This commit aims to implement the NVDEC (Nvidia Decoder) functionality, with video frame decoding being handled by the FFmpeg library.

The process begins with Ioctl commands being sent to the NVDEC and VIC (Video Image Composer) emulated devices. These allocate the necessary GPU buffers for the frame data, along with providing information on the incoming video data. A Submit command then signals the GPU to process and decode the frame data.

To decode the frame, the respective codec's header must be manually composed from the information provided by NVDEC, then sent with the raw frame data to the ffmpeg library.

Currently, H264 and VP9 are supported, with VP9 having some minor artifacting issues related mainly to the reference frame composition in its uncompressed header.

Async GPU is not properly implemented at the moment.

Co-Authored-By: David <25727384+ogniK5377@users.noreply.github.com>

1 files changed, 114 insertions, 0 deletions

diff --git a/src/video_core/command_classes/codecs/codec.cpp b/src/video_core/command_classes/codecs/codec.cpp
new file mode 100644
index 000000000..2df410be8
--- /dev/null
+++ b/src/video_core/command_classes/codecs/codec.cpp
@@ -0,0 +1,114 @@
+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <cstring>
+#include <fstream>
+#include "common/assert.h"
+#include "video_core/command_classes/codecs/codec.h"
+#include "video_core/command_classes/codecs/h264.h"
+#include "video_core/command_classes/codecs/vp9.h"
+#include "video_core/gpu.h"
+#include "video_core/memory_manager.h"
+
+extern "C" {
+#include <libavutil/opt.h>
+}
+
+namespace Tegra {
+
+Codec::Codec(GPU& gpu_)
+    : gpu(gpu_), h264_decoder(std::make_unique<Decoder::H264>(gpu)),
+      vp9_decoder(std::make_unique<Decoder::VP9>(gpu)) {}
+
+Codec::~Codec() {
+    if (!initialized) {
+        return;
+    }
+    // Free libav memory
+    avcodec_send_packet(av_codec_ctx, nullptr);
+    avcodec_receive_frame(av_codec_ctx, av_frame);
+    avcodec_flush_buffers(av_codec_ctx);
+
+    av_frame_unref(av_frame);
+    av_free(av_frame);
+    avcodec_close(av_codec_ctx);
+}
+
+void Codec::SetTargetCodec(NvdecCommon::VideoCodec codec) {
+    LOG_INFO(Service_NVDRV, "NVDEC video codec initialized to {}", static_cast<u32>(codec));
+    current_codec = codec;
+}
+
+void Codec::StateWrite(u32 offset, u64 arguments) {
+    u8* const state_offset = reinterpret_cast<u8*>(&state) + offset * sizeof(u64);
+    std::memcpy(state_offset, &arguments, sizeof(u64));
+}
+
+void Codec::Decode() {
+    bool is_first_frame = false;
+
+    if (!initialized) {
+        if (current_codec == NvdecCommon::VideoCodec::H264) {
+            av_codec = avcodec_find_decoder(AV_CODEC_ID_H264);
+        } else if (current_codec == NvdecCommon::VideoCodec::Vp9) {
+            av_codec = avcodec_find_decoder(AV_CODEC_ID_VP9);
+        } else {
+            LOG_ERROR(Service_NVDRV, "Unknown video codec {}", static_cast<u32>(current_codec));
+            return;
+        }
+
+        av_codec_ctx = avcodec_alloc_context3(av_codec);
+        av_frame = av_frame_alloc();
+        av_opt_set(av_codec_ctx->priv_data, "tune", "zerolatency", 0);
+
+        // TODO(ameerj): libavcodec gpu hw acceleration
+
+        const auto av_error = avcodec_open2(av_codec_ctx, av_codec, nullptr);
+        if (av_error < 0) {
+            LOG_ERROR(Service_NVDRV, "avcodec_open2() Failed.");
+            av_frame_unref(av_frame);
+            av_free(av_frame);
+            avcodec_close(av_codec_ctx);
+            return;
+        }
+        initialized = true;
+        is_first_frame = true;
+    }
+    bool vp9_hidden_frame = false;
+
+    AVPacket packet{};
+    av_init_packet(&packet);
+    std::vector<u8> frame_data;
+
+    if (current_codec == NvdecCommon::VideoCodec::H264) {
+        frame_data = h264_decoder->ComposeFrameHeader(state, is_first_frame);
+    } else if (current_codec == NvdecCommon::VideoCodec::Vp9) {
+        frame_data = vp9_decoder->ComposeFrameHeader(state);
+        vp9_hidden_frame = vp9_decoder->WasFrameHidden();
+    }
+
+    packet.data = frame_data.data();
+    packet.size = static_cast<int>(frame_data.size());
+
+    avcodec_send_packet(av_codec_ctx, &packet);
+
+    if (!vp9_hidden_frame) {
+        // Only receive/store visible frames
+        avcodec_receive_frame(av_codec_ctx, av_frame);
+    }
+}
+
+AVFrame* Codec::GetCurrentFrame() {
+    return av_frame;
+}
+
+const AVFrame* Codec::GetCurrentFrame() const {
+    return av_frame;
+}
+
+NvdecCommon::VideoCodec Codec::GetCurrentCodec() const {
+    return current_codec;
+}
+
+} // namespace Tegra