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NIVIDIA 硬解码学习2

article 2025/8/26 8:10:42

NIVIDIA 硬解码学习2

做项目学习笔记

引言

在NIVIDIA 硬解码学习1中大概了解了硬解码的几个组成部分。
下载了最新的【Video_Codec_SDK_8.2.16】进行了简答的学习。
SDK Samples

最简单的硬解码器实现 AppDec

先看一下 main 函数的实现

int main(int argc, char **argv) 
{char szInFilePath[256] = "", szOutFilePath[256] = "";bool bOutPlanar = false;int iGpu = 0;Rect cropRect = {};Dim resizeDim = {};try{// 按命令行参数读取输入文件等，例如 test.h265ParseCommandLine(argc, argv, szInFilePath, szOutFilePath, bOutPlanar, iGpu, cropRect, resizeDim);CheckInputFile(szInFilePath); if (!*szOutFilePath) {sprintf(szOutFilePath, bOutPlanar ? "out.planar" : "out.native");}// 初始化cuda环境ck(cuInit(0));  int nGpu = 0;ck(cuDeviceGetCount(&nGpu));if (iGpu < 0 || iGpu >= nGpu) {std::cout << "GPU ordinal out of range. Should be within [" << 0 << ", " << nGpu - 1 << "]" << std::endl;return 1;}CUdevice cuDevice = 0;ck(cuDeviceGet(&cuDevice, iGpu));char szDeviceName[80];ck(cuDeviceGetName(szDeviceName, sizeof(szDeviceName), cuDevice));std::cout << "GPU in use: " << szDeviceName << std::endl;CUcontext cuContext = NULL;// 设置CUDA上下文！！！ck(cuCtxCreate(&cuContext, 0, cuDevice));std::cout << "Decode with demuxing." << std::endl;/// 进行解码（下面讲解）DecodeMediaFile(cuContext, szInFilePath, szOutFilePath, bOutPlanar, cropRect, resizeDim);}catch (const std::exception& ex){std::cout << ex.what();exit(1);}return 0;
}

具体硬解码流程 DecodeMediaFile 函数

void DecodeMediaFile(CUcontext cuContext, const char *szInFilePath, const char *szOutFilePath, bool bOutPlanar,const Rect &cropRect, const Dim &resizeDim)
{// 输出std::ofstream fpOut(szOutFilePath, std::ios::out | std::ios::binary);if (!fpOut){std::ostringstream err;err << "Unable to open output file: " << szOutFilePath << std::endl;throw std::invalid_argument(err.str());}// 解析输入的文件,FFmpegDemuxer是对FFmpeg封装的一个解析文件的类FFmpegDemuxer demuxer(szInFilePath);// 创建硬解码器 设置了三个重要的回调函数NvDecoder dec(cuContext/*CUDA上下文*/, demuxer.GetWidth(), demuxer.GetHeight(), false, FFmpeg2NvCodecId(demuxer.GetVideoCodec())/*获得对应解码器名称*/, NULL, false, false, &cropRect, &resizeDim);int nVideoBytes = 0, nFrameReturned = 0, nFrame = 0;uint8_t *pVideo = NULL, **ppFrame;do {// Demux 解析,获得每一帧码流的数据存在pVideo中,nVideoBytes为数据的字节数demuxer.Demux(&pVideo, &nVideoBytes);// 实际解码进入函数dec.Decode(pVideo, nVideoBytes, &ppFrame, &nFrameReturned);if (!nFrame && nFrameReturned)LOG(INFO) << dec.GetVideoInfo();// 硬解码是一个异步过程,nFrameReturned表示解码得到了多少帧for (int i = 0; i < nFrameReturned; i++) {if (bOutPlanar) {// 转换格式ConvertToPlanar(ppFrame[i], dec.GetWidth(), dec.GetHeight(), dec.GetBitDepth());}// 写文件fpOut.write(reinterpret_cast<char*>(ppFrame[i]), dec.GetFrameSize());}nFrame += nFrameReturned;} while (nVideoBytes);std::cout << "Total frame decoded: " << nFrame << std::endl<< "Saved in file " << szOutFilePath << " in "<< (dec.GetBitDepth() == 8 ? (bOutPlanar ? "iyuv" : "nv12") : (bOutPlanar ? "yuv420p16" : "p016"))<< " format" << std::endl;fpOut.close();
}

看一下初始化解码器的代码!!!

NvDecoder::NvDecoder(CUcontext cuContext, int nWidth, int nHeight, bool bUseDeviceFrame, cudaVideoCodec eCodec, std::mutex *pMutex,bool bLowLatency, bool bDeviceFramePitched, const Rect *pCropRect, const Dim *pResizeDim, int maxWidth, int maxHeight) :m_cuContext(cuContext), m_bUseDeviceFrame(bUseDeviceFrame), m_eCodec(eCodec), m_pMutex(pMutex), m_bDeviceFramePitched(bDeviceFramePitched),m_nMaxWidth (maxWidth), m_nMaxHeight(maxHeight)
{if (pCropRect) m_cropRect = *pCropRect;if (pResizeDim) m_resizeDim = *pResizeDim;NVDEC_API_CALL(cuvidCtxLockCreate(&m_ctxLock, cuContext));// CUVIDPARSERPARAMS：该接口用来创建VideoParser// 主要参数是设置三个回调函数 实现对解析出来的数据的处理CUVIDPARSERPARAMS videoParserParameters = {};videoParserParameters.CodecType = eCodec;videoParserParameters.ulMaxNumDecodeSurfaces = 1;videoParserParameters.ulMaxDisplayDelay = bLowLatency ? 0 : 1;videoParserParameters.pUserData = this;// 三个回调函数videoParserParameters.pfnSequenceCallback = HandleVideoSequenceProc; // Callback function to be registered for getting a callback when decoding of sequence startsvideoParserParameters.pfnDecodePicture = HandlePictureDecodeProc; // 准备开始解码的时候调用videoParserParameters.pfnDisplayPicture = HandlePictureDisplayProc; // 解码出数据调用if (m_pMutex) m_pMutex->lock();NVDEC_API_CALL(cuvidCreateVideoParser(&m_hParser, &videoParserParameters));if (m_pMutex) m_pMutex->unlock();
}

看一下实际进行解码的函数 Decode

bool NvDecoder::Decode(const uint8_t *pData, int nSize, uint8_t ***pppFrame, int *pnFrameReturned, uint32_t flags, int64_t **ppTimestamp, int64_t timestamp, CUstream stream)
{if (!m_hParser){NVDEC_THROW_ERROR("Parser not initialized.", CUDA_ERROR_NOT_INITIALIZED);return false;}m_nDecodedFrame = 0;// AVPacket转CUVIDSOURCEDATAPACKET,并交给cuvidParseVideoData进行CUVIDSOURCEDATAPACKET packet = {0};packet.payload = pData;packet.payload_size = nSize;packet.flags = flags | CUVID_PKT_TIMESTAMP;packet.timestamp = timestamp;if (!pData || nSize == 0) {packet.flags |= CUVID_PKT_ENDOFSTREAM;}m_cuvidStream = stream;if (m_pMutex) m_pMutex->lock(); // 解码要加锁printf("------> cuvidParseVideoData\n");// cuvidParseVideoData 一直将数据传递给解码NVDEC_API_CALL(cuvidParseVideoData(m_hParser, &packet));printf("------> cuvidParseVideoData done!\n");if (m_pMutex) m_pMutex->unlock(); // 解锁m_cuvidStream = 0;// 检测是否解码的帧数大于0了。if (m_nDecodedFrame > 0){printf("m_nDecodedFrame:%d\n", m_nDecodedFrame);if (pppFrame) {m_vpFrameRet.clear(); // 将返回的队列清空std::lock_guard<std::mutex> lock(m_mtxVPFrame);// 将m_vpFrame传给m_vpFrameRet;m_vpFrameRet.insert(m_vpFrameRet.begin(), m_vpFrame.begin(), m_vpFrame.begin() + m_nDecodedFrame);*pppFrame = &m_vpFrameRet[0];// }if (ppTimestamp) {*ppTimestamp = &m_vTimestamp[0];}}if (pnFrameReturned){*pnFrameReturned = m_nDecodedFrame;}return true;
}

因为我准备是为了获得解码后的显存数据所以重点看了第三个回调函数.HandlePictureDisplay

int NvDecoder::HandlePictureDisplay(CUVIDPARSERDISPINFO *pDispInfo) {CUVIDPROCPARAMS videoProcessingParameters = {};videoProcessingParameters.progressive_frame = pDispInfo->progressive_frame;videoProcessingParameters.second_field = pDispInfo->repeat_first_field + 1;videoProcessingParameters.top_field_first = pDispInfo->top_field_first;videoProcessingParameters.unpaired_field = pDispInfo->repeat_first_field < 0;videoProcessingParameters.output_stream = m_cuvidStream;CUdeviceptr dpSrcFrame = 0;unsigned int nSrcPitch = 0;// MapVideoFrame:拿到解码后数据在显存的指针 --> dpSrcFrameNVDEC_API_CALL(cuvidMapVideoFrame(m_hDecoder, pDispInfo->picture_index, &dpSrcFrame,&nSrcPitch, &videoProcessingParameters));CUVIDGETDECODESTATUS DecodeStatus;memset(&DecodeStatus, 0, sizeof(DecodeStatus));CUresult result = cuvidGetDecodeStatus(m_hDecoder, pDispInfo->picture_index, &DecodeStatus);if (result == CUDA_SUCCESS && (DecodeStatus.decodeStatus == cuvidDecodeStatus_Error || DecodeStatus.decodeStatus == cuvidDecodeStatus_Error_Concealed)){printf("Decode Error occurred for picture %d\n", m_nPicNumInDecodeOrder[pDispInfo->picture_index]);}printf("HandlePictureDisplay::m_nDecodedFrame:%d\n", m_nDecodedFrame);uint8_t *pDecodedFrame = nullptr;{// lock_guard 自动解锁 当控件离开lock_guard创建对象的范围时，lock_guard被破坏并释放互斥体。std::lock_guard<std::mutex> lock(m_mtxVPFrame);// 解出一帧 m_nDecodedFrame+1,且若不够空间了,则开辟空间if ((unsigned)++m_nDecodedFrame > m_vpFrame.size()) {printf("HandlePictureDisplay::m_nDecodedFrame:%d\n", m_nDecodedFrame);// Not enough frames in stockm_nFrameAlloc++;uint8_t *pFrame = NULL;if (m_bUseDeviceFrame) //m_bUseDeviceFrame 初始化解码器的时候设置的,是否使用显卡内存,是得解码出来的数据不转到CPU内存{CUDA_DRVAPI_CALL(cuCtxPushCurrent(m_cuContext));if (m_bDeviceFramePitched){CUDA_DRVAPI_CALL(cuMemAllocPitch((CUdeviceptr *)&pFrame, &m_nDeviceFramePitch, m_nWidth * (m_nBitDepthMinus8 ? 2 : 1), m_nHeight * 3 / 2, 16));}else {unsigned int FrameSize = GetFrameSize(); // h*w*3/2;int inputWidth = GetWidth();int inputHeight = GetHeight(); CUDA_DRVAPI_CALL(cuMemAlloc((CUdeviceptr *)&pFrame, GetFrameSize()));}CUDA_DRVAPI_CALL(cuCtxPopCurrent(NULL));}else // cpu内存{pFrame = new uint8_t[GetFrameSize()]; // 开辟空间}m_vpFrame.push_back(pFrame);}pDecodedFrame = m_vpFrame[m_nDecodedFrame - 1]; // 取到最后一个}CUDA_DRVAPI_CALL(cuCtxPushCurrent(m_cuContext)); // 启用contextprintf("cuCtxPushCurrent!\n");CUDA_MEMCPY2D m = { 0 };m.srcMemoryType = CU_MEMORYTYPE_DEVICE;m.srcDevice = dpSrcFrame;m.srcPitch = nSrcPitch;m.dstMemoryType = m_bUseDeviceFrame ? CU_MEMORYTYPE_DEVICE : CU_MEMORYTYPE_HOST;m.dstDevice = (CUdeviceptr)(m.dstHost = pDecodedFrame);m.dstPitch = m_nDeviceFramePitch ? m_nDeviceFramePitch : m_nWidth * (m_nBitDepthMinus8 ? 2 : 1);m.WidthInBytes = m_nWidth * (m_nBitDepthMinus8 ? 2 : 1);m.Height = m_nHeight;CUDA_DRVAPI_CALL(cuMemcpy2DAsync(&m, m_cuvidStream));m.srcDevice = (CUdeviceptr)((uint8_t *)dpSrcFrame + m.srcPitch * m_nSurfaceHeight);m.dstDevice = (CUdeviceptr)(m.dstHost = pDecodedFrame + m.dstPitch * m_nHeight);m.Height = m_nHeight / 2;CUDA_DRVAPI_CALL(cuMemcpy2DAsync(&m, m_cuvidStream));CUDA_DRVAPI_CALL(cuStreamSynchronize(m_cuvidStream));// 解码完成,NV12格式 pDecodedFrame// NV12TORGBACUDA_DRVAPI_CALL(cuCtxPopCurrent(NULL)); // 拷贝结束,取消上下文if ((int)m_vTimestamp.size() < m_nDecodedFrame) {m_vTimestamp.resize(m_vpFrame.size());}m_vTimestamp[m_nDecodedFrame - 1] = pDispInfo->timestamp;NVDEC_API_CALL(cuvidUnmapVideoFrame(m_hDecoder, dpSrcFrame));return 1;
}