Added MPEG library

lib/mpeg.cpp

@@ -0,0 +1,63 @@
+#include "mpeg.h"
+
+namespace Mpeg{
+
+  MP2Info parseMP2Header(const std::string &hdr){return parseMP2Header(hdr.c_str());}
+  MP2Info parseMP2Header(const char *hdr){
+    MP2Info res;
+    // mpeg version is on the bits 0x18 of header[1], but only 0x08 is important --> 0 is version 2,
+    // 1 is version 1
+    // leads to 2 - value == version, -1 to get the right index for the array
+    int mpegVersion = 1 - ((hdr[1] >> 3) & 0x01);
+    // samplerate is encoded in bits 0x0C of header[2];
+    res.sampleRate = sampleRates[mpegVersion][((hdr[2] >> 2) & 0x03)] * 1000;
+    res.channels = 2 - (hdr[3] >> 7);
+    return res;
+  }
+
+  void MPEG2Info::clear(){
+    width = 0;
+    height = 0;
+    fps = 0;
+    tempSeq = 0;
+    frameType = 0;
+    isHeader = false;
+  }
+
+  MPEG2Info parseMPEG2Header(const std::string &hdr){return parseMPEG2Header(hdr.data());}
+  MPEG2Info parseMPEG2Header(const char *hdr){
+    MPEG2Info res;
+    parseMPEG2Header(hdr, res);
+    return res;
+  }
+  bool parseMPEG2Header(const char *hdr, MPEG2Info &mpInfo){
+    // Check for start code
+    if (hdr[0] != 0 || hdr[1] != 0 || hdr[2] != 1){return false;}
+    if (hdr[3] == 0xB3){// Sequence header
+      mpInfo.isHeader = true;
+      mpInfo.width = (hdr[4] << 4) | ((hdr[5] >> 4) & 0x0F);
+      mpInfo.height = ((hdr[5] & 0x0F) << 8) | hdr[6];
+      mpInfo.fps = frameRate[hdr[7] & 0x0F];
+      return true;
+    }
+    if (hdr[3] == 0x00){// Picture header
+      mpInfo.tempSeq = (((uint16_t)hdr[4]) << 2) || (hdr[5] >> 6);
+      mpInfo.frameType = (hdr[5] & 0x38) >> 3;
+      return true;
+    }
+    // Not parsed
+    return false;
+  }
+  void parseMPEG2Headers(const char *hdr, uint32_t len, MPEG2Info &mpInfo){
+    mpInfo.clear();
+    for (uint32_t i = 0; i < len-5; ++i){
+      parseMPEG2Header(hdr+i, mpInfo);
+    }
+  }
+  MPEG2Info parseMPEG2Headers(const char *hdr, uint32_t len){
+    MPEG2Info res;
+    parseMPEG2Headers(hdr, len, res);
+    return res;
+  }
+}
+