130 lines
4.1 KiB
C++
130 lines
4.1 KiB
C++
#ifndef _GNU_SOURCE
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#define _GNU_SOURCE
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#endif
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#include <cstdlib>
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#include <cstring>
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#include <math.h> //for log
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#include "bitfields.h"
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#include "bitstream.h"
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#include "defines.h"
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#include "nal.h"
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namespace nalu{
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std::deque<int> parseNalSizes(DTSC::Packet &pack){
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std::deque<int> result;
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char *data;
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size_t dataLen;
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pack.getString("data", data, dataLen);
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int offset = 0;
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while (offset < dataLen){
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int nalSize = Bit::btohl(data + offset);
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result.push_back(nalSize + 4);
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offset += nalSize + 4;
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}
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return result;
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}
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std::string removeEmulationPrevention(const std::string &data){
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std::string result;
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result.resize(data.size());
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result[0] = data[0];
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result[1] = data[1];
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size_t dataPtr = 2;
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size_t dataLen = data.size();
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size_t resPtr = 2;
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while (dataPtr + 2 < dataLen){
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if (!data[dataPtr] && !data[dataPtr + 1] && data[dataPtr + 2] == 3){// We have found an emulation prevention
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result[resPtr++] = data[dataPtr++];
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result[resPtr++] = data[dataPtr++];
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dataPtr++; // Skip the emulation prevention byte
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}else{
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result[resPtr++] = data[dataPtr++];
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}
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}
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while (dataPtr < dataLen){result[resPtr++] = data[dataPtr++];}
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return result.substr(0, resPtr);
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}
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unsigned long toAnnexB(const char *data, unsigned long dataSize, char *&result){
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// toAnnexB keeps the same size.
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if (!result){result = (char *)malloc(dataSize);}
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int offset = 0;
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while (offset < dataSize){
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// Read unit size
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unsigned long unitSize = Bit::btohl(data + offset);
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// Write annex b header
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memset(result + offset, 0x00, 3);
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result[offset + 3] = 0x01;
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// Copy the nal unit
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memcpy(result + offset + 4, data + offset + 4, unitSize);
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// Update the offset
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offset += 4 + unitSize;
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}
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return dataSize;
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}
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/// Scans data for the last non-zero byte, returning a pointer to it.
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const char *nalEndPosition(const char *data, uint32_t dataSize){
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while (dataSize && !data[dataSize - 1]){--dataSize;}
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return data + dataSize;
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}
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/// Scan data for Annex B start code. Returns pointer to it when found, null otherwise.
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const char *scanAnnexB(const char *data, uint32_t dataSize){
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char *offset = (char *)data;
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const char *maxData = data + dataSize - 2;
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while (offset < maxData){
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if (offset[2] > 1){
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// We have no zero in the third byte, so we need to skip at least 3 bytes forward
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offset += 3;
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continue;
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}
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if (!offset[2]){
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// We COULD skip forward 1 or 2 bytes depending on contents of the second byte
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// offset += (offset[1]?2:1);
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//... but skipping a single byte (removing the 'if') is actually faster (benchmarked).
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++offset;
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continue;
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}
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if (!offset[0] && !offset[1]){return offset;}
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// We have no zero in the third byte, so we need to skip at least 3 bytes forward
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offset += 3;
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}
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return 0;
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}
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unsigned long fromAnnexB(const char *data, unsigned long dataSize, char *&result){
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const char *lastCheck = data + dataSize - 3;
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if (!result){
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FAIL_MSG("No output buffer given to FromAnnexB");
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return 0;
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}
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int offset = 0;
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int newOffset = 0;
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while (offset < dataSize){
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const char *begin = data + offset;
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while (begin < lastCheck && !(!begin[0] && !begin[1] && begin[2] == 0x01)){
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begin++;
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if (begin < lastCheck && begin[0]){begin++;}
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}
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begin += 3; // Initialize begin after the first 0x000001 pattern.
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if (begin > data + dataSize){
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offset = dataSize;
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continue;
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}
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const char *end = (const char *)memmem(begin, dataSize - (begin - data), "\000\000\001", 3);
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if (!end){end = data + dataSize;}
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// Check for 4-byte lead in's. Yes, we access -1 here
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if (end > begin && (end - data) != dataSize && end[-1] == 0x00){end--;}
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unsigned int nalSize = end - begin;
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Bit::htobl(result + newOffset, nalSize);
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memcpy(result + newOffset + 4, begin, nalSize);
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newOffset += 4 + nalSize;
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offset = end - data;
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}
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return newOffset;
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}
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}// namespace nalu
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