定義用到的變量
nvjpegHandle_t nvjpeg_handle; // nvjpeg句柄
nvjpegEncoderState_t encoder_state; //
nvjpegEncoderParams_t encoder_params; //
准備圖像數據,輸入數據指針應該是顯存指針,每個顏色分量分別存儲
nvjpegImage_t input;
nvjpegInputFormat_t input_format = NVJPEG_INPUT_BGR;
int image_width = 2448;
int image_height = 2048;
int channel_size = image_width * image_height;
for (int i = 0; i < 3; i++)
{
input.pitch[i] = image_width;
cudaMalloc((void**)&(input.channel[i]), channel_size);
// set value of this channel
cudaMemset(input.channel[i], 50 * 40 * i, channel_size);
}
准備環境
nvjpegBackend_t backend = NVJPEG_BACKEND_DEFAULT;
nvjpegCreate(backend, nullptr, &nvjpeg_handle));
nvjpegEncoderStateCreate(nvjpeg_handle, &encoder_state, NULL);
nvjpegEncoderParamsCreate(nvjpeg_handle, &encoder_params, NULL);
設置參數
nvjpegEncoderParamsSetEncoding(encoder_params, nvjpegJpegEncoding_t::NVJPEG_ENCODING_PROGRESSIVE_DCT_HUFFMAN, NULL);
nvjpegEncoderParamsSetOptimizedHuffman(encoder_params, 1, NULL);
nvjpegEncoderParamsSetQuality(encoder_params, 70, NULL);
nvjpegEncoderParamsSetSamplingFactors(encoder_params, nvjpegChromaSubsampling_t::NVJPEG_CSS_420, NULL);
執行壓縮
nvjpegEncodeImage(nvjpeg_handle, encoder_state, encoder_params, &input, input_format, image_width, image_height, NULL)
取出二進制數據
std::vector<unsigned char> obuffer;
size_t length;
nvjpegEncodeRetrieveBitstream( nvjpeg_handle, encoder_state, NULL, &length, NULL);
obuffer.resize(length);
nvjpegEncodeRetrieveBitstream( nvjpeg_handle, encoder_state, obuffer.data(), &length, NULL));
保存二進制數據
std::ofstream outputFile("result.jpg", std::ios::out | std::ios::binary);
outputFile.write(reinterpret_cast<const char *>(obuffer.data()), static_cast<int>(length));
完整代碼
int testEncodeImage()
{
nvjpegHandle_t nvjpeg_handle;
nvjpegEncoderState_t encoder_state;
nvjpegEncoderParams_t encoder_params;
cudaEvent_t ev_start, ev_end;
CHECK_CUDA(cudaEventCreate(&ev_start));
CHECK_CUDA(cudaEventCreate(&ev_end));
size_t pdata_len = 1024 * 1024;
unsigned char *pdata_dev = nullptr;
CHECK_CUDA(cudaMalloc((void**)&pdata_dev, pdata_len));
nvjpegImage_t input;
nvjpegInputFormat_t input_format = NVJPEG_INPUT_BGR;
int image_width = 2448;
int image_height = 2048;
int channel_size = image_width * image_height;
for (int i = 0; i < 3; i++)
{
input.pitch[i] = image_width;
CHECK_CUDA(cudaMalloc((void**)&(input.channel[i]), channel_size));
CHECK_CUDA(cudaMemset(input.channel[i], 50 * 40 * i, channel_size));
}
nvjpegBackend_t backend = NVJPEG_BACKEND_DEFAULT;
CHECK_NVJPEG(nvjpegCreate(backend, nullptr, &nvjpeg_handle));
CHECK_NVJPEG(nvjpegEncoderParamsCreate(nvjpeg_handle, &encoder_params, NULL));
CHECK_NVJPEG(nvjpegEncoderStateCreate(nvjpeg_handle, &encoder_state, NULL));
// set params
nvjpegEncoderParamsSetEncoding(encoder_params, nvjpegJpegEncoding_t::NVJPEG_ENCODING_PROGRESSIVE_DCT_HUFFMAN, NULL);
nvjpegEncoderParamsSetOptimizedHuffman(encoder_params, 1, NULL);
nvjpegEncoderParamsSetQuality(encoder_params, 70, NULL);
nvjpegEncoderParamsSetSamplingFactors(encoder_params, nvjpegChromaSubsampling_t::NVJPEG_CSS_420, NULL);
CHECK_CUDA(cudaEventRecord(ev_start));
CHECK_NVJPEG(nvjpegEncodeImage(nvjpeg_handle, encoder_state, encoder_params, &input, input_format, image_width, image_height, NULL));
CHECK_CUDA(cudaEventRecord(ev_end));
std::vector<unsigned char> obuffer;
size_t length;
CHECK_NVJPEG(nvjpegEncodeRetrieveBitstream(
nvjpeg_handle,
encoder_state,
NULL,
&length,
NULL));
obuffer.resize(length);
CHECK_NVJPEG(nvjpegEncodeRetrieveBitstream(
nvjpeg_handle,
encoder_state,
obuffer.data(),
&length,
NULL));
std::ofstream outputFile("a.jpg", std::ios::out | std::ios::binary);
outputFile.write(reinterpret_cast<const char *>(obuffer.data()), static_cast<int>(length));
cudaEventSynchronize(ev_end);
float ms;
cudaEventElapsedTime(&ms, ev_start, ev_end);
std::cout << "time spend " << ms << " ms" << std::endl;
return 0;
}
時間消耗
2440*2048大小的RGB三色圖像壓縮耗時4.33ms,使用CPU單線程壓縮耗時98ms(opencv)。