最近帮别人做了个东西，这里分享一下pcm原始数据绘图的思路
1、pcm数据采样位数，根据采样位数选取适合自己绘图的采样点的数量
2、计算出最大最小的的采样点的值差
3、根据要显示pcm数据的控件宽高，根据pcm原始数据的在pcm数据的偏移计算出x坐标，根据pcm数据采样的数值大小计算出y坐标
4、绘图，依次进行相邻数据点绘图
以下是在Duilb中绘图的代码：
1 std::vector<char> pcm_buffer; 2 FILE * file = NULL; 3 file = fopen("pcm\\20180601155322.pcm", "rb"); 4 5 if (file != NULL) { 6 // 7 pcm_buffer.clear(); 8 pcm_buffer.shrink_to_fit(); 9 10 fseek(file, 0, SEEK_END); 11 unsigned int size_byte = ftell(file); 12 fseek(file, 0, SEEK_SET); 13 pcm_buffer.resize(size_byte); 14 fread(&pcm_buffer[0], size_byte, 1, file); 15 fclose(file); 16 size_byte /= 2; 17 int step = 1, len = size_byte; 18 if (size_byte > 20000) { 19 len = 20000; 20 step = (int)(size_byte / len); 21 } 22 short * pcm_16 = (short*)(&pcm_buffer[0]); 23 std::vector<float> pcm_float; 24 pcm_float.resize(20000); 25 for (int i = 0, n = 0; n < len; i += step, n++) { 26 pcm_float[n] = pcm_16[i]; 27 } 28 29 float max = pcm_float[0], min = pcm_float[0]; 30 for (int i = 1; i< pcm_float.size(); i++){ 31 if (max < pcm_float[i]){ 32 max = pcm_float[i]; 33 } 34 if (min > pcm_float[i]){ 35 min = pcm_float[i]; 36 } 37 } 38 int w = m_rcItem.right - m_rcItem.left; 39 int h = m_rcItem.bottom - m_rcItem.top; 40 std::vector<PointF> points; 41 float diffVal = max - min; 42 for (int i = 0; i < pcm_float.size(); i++){ 43 points.push_back(PointF(i * w / pcm_float.size(), h - (pcm_float[i] - min) / diffVal * h)); 44 } 45 46 const DWORD backColor = 0xFFC9C9C9; 47 CRenderEngine::DrawColor(hDC, m_rcItem, backColor); 48 const DWORD backLineColor = 0xFF0000FF; 49 for (int i = 0; i < points.size() - 1; i++){ 50 RECT rect; 51 rect.left = points[i].X; 52 rect.top = points[i].Y + m_rcItem.top; 53 rect.right = points[i + 1].X; 54 rect.bottom = points[i + 1].Y + m_rcItem.top; 55 CRenderEngine::DrawLine(hDC, rect, 1, backLineColor); 56 } 57 }
绘图效果:
测试绘图代码: https://github.com/karllen/cef3-duilib-YDDemo/tree/master/PcmMediaDemo
原文：https://www.cnblogs.com/Forever-Kenlen-Ja/p/9217215.html