我有一张图片,想用OpenH264对其进行编码。
到目前为止,这是我从他们的wiki导出的代码:
#include <fstream>
#include <iterator>
#include <iostream>
#include <codec_api.h> //standard api for openh264
//additional libaries used by sample code
#include <codec_app_def.h>
#include <codec_def.h>
#include <codec_ver.h>
#include <assert.h>
#include <vector>
#include <cstring>
int main()
{
//parameter values
int width = 1920;
int height = 1080;
int framerate = 60;
int bitrate = 5000000;
int total_num = 500; //what does this value do?
//end parameter values
//Read in the File from bmp
std::vector<char> buf; //to store the image information
std::basic_ifstream<char> file("/home/megamol/Git/h264_sample/build/test.bmp", std::ios::binary); //opens bitstream to source
buf = std::vector<char>((std::istreambuf_iterator<char>(file)), std::istreambuf_iterator<char>()); // reads in data to the vector
std::cout << "sizeof buf: " << buf.size() << std::endl;
//Step 1: set up Encoder
ISVCEncoder* encoder_; //declaration of encoder pointer
int rv = WelsCreateSVCEncoder (&encoder_);
//Step 2: initialize with basic parameter
SEncParamBase param;
memset(¶m, 0, sizeof (SEncParamBase));
param.iUsageType = EUsageType::SCREEN_CONTENT_REAL_TIME;
param.fMaxFrameRate = framerate;
param.iPicWidth = width;
param.iPicHeight = height;
param.iTargetBitrate = bitrate; //default value of example
encoder_->Initialize(¶m);
//Step 3: set video format
int videoFormat = videoFormatI420;
encoder_->SetOption (ENCODER_OPTION_DATAFORMAT, &videoFormat);
//Step 4: encocode and store output bitstream
int frameSize = width * height * 3 / 2;
buf.resize(frameSize);
SFrameBSInfo info;
std::vector<char> compressedData;
memset (&info, 0, sizeof (SFrameBSInfo));
SSourcePicture pic;
memset (&pic, 0, sizeof (SSourcePicture));
pic.iPicWidth = width;
pic.iPicHeight = height;
pic.iColorFormat = videoFormatI420;
pic.iStride[0] = pic.iPicWidth;
pic.iStride[1] = pic.iStride[2] = pic.iPicWidth >> 1;
pic.pData[0] = reinterpret_cast<unsigned char*>(&buf[0]);
pic.pData[1] = pic.pData[0] + width * height;
pic.pData[2] = pic.pData[1] + (width * height >> 2);
//encodes the frame
rv = encoder_->EncodeFrame (&pic, &info); // encodes the Frame
//encoding done encoded Frame should be stored in &info
//begin decoding block
ISVCDecoder *pSvcDecoder;
unsigned char *pBuf= &info;
return 0;
}
我不完全确定这是否是 OpenH264 的正确用法,但我也不确定如何正确测试它。
现在代码示例的文档记录很差。
BufferedData buf;
例如什么?我知道这应该是输入,但那是什么类型?就像我如何将我的 test.bmp 加载为 BufferedData 一样?我认为我还没有正确地做到这一点。
我很困惑的另一件事是如何在编码后访问输出?在示例中,它只是说//output bitstream
并没有将这个输出保存在任何地方。我认为输出info
就像它在codec_api.h
头文件中所说的那样:
/**
* @brief Encode one frame
* @param kpSrcPic the pointer to the source luminance plane
* chrominance data:
* CbData = kpSrc + m_iMaxPicWidth * m_iMaxPicHeight;
* CrData = CbData + (m_iMaxPicWidth * m_iMaxPicHeight)/4;
* the application calling this interface needs to ensure the data validation between the location
* @param pBsInfo output bit stream
* @return 0 - success; otherwise -failed;
*/
virtual int EXTAPI EncodeFrame (const SSourcePicture* kpSrcPic, SFrameBSInfo* pBsInfo) = 0;
但显然它只保存有关输出的信息。我真的对这一切感到困惑。