diff options
Diffstat (limited to 'mpeglib/lib/mpegplay/mpegExtension.cpp')
| -rw-r--r-- | mpeglib/lib/mpegplay/mpegExtension.cpp | 258 |
1 files changed, 258 insertions, 0 deletions
diff --git a/mpeglib/lib/mpegplay/mpegExtension.cpp b/mpeglib/lib/mpegplay/mpegExtension.cpp new file mode 100644 index 00000000..657fe683 --- /dev/null +++ b/mpeglib/lib/mpegplay/mpegExtension.cpp @@ -0,0 +1,258 @@ +/* + parses extension data (picture and sequence) + Copyright (C) 2000 Martin Vogt + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU Library General Public License as published by + the Free Software Foundation. + + For more information look at the file COPYRIGHT in this package + + */ + + +#include "mpegExtension.h" + +#include <iostream> + +using namespace std; + +MpegExtension::MpegExtension() { + userData=NULL; + extData=NULL; + extraBit=NULL; +} + + +MpegExtension::~MpegExtension() { + if (userData != NULL) { + delete userData; + } + if (extData != NULL) { + delete extData; + } + if (extraBit != NULL) { + delete extraBit; + } +} + + +int MpegExtension::processExtensionData(MpegVideoStream* mpegVideoStream) { + + /* Goto next start code. */ + mpegVideoStream->next_start_code(); + + /* + * If next start code is extension/user start code, + * parse off extension data. + */ + + /* + * If next start code is extension start code, parse off extension data. + */ + if (next_bits(32, EXT_START_CODE,mpegVideoStream)) { + mpegVideoStream->flushBits(32); + if (extData != NULL) { + delete extData; + extData = NULL; + } + cout << "ext"<<endl; + extData = get_ext_data(mpegVideoStream); + } + + /* + * If next start code is user start code, parse off user data. + */ + if (next_bits(32, USER_START_CODE,mpegVideoStream)) { + mpegVideoStream->flushBits(32); + if (userData != NULL) { + delete userData; + userData=NULL; + } + userData =get_ext_data(mpegVideoStream); + } + + return true; +} + + + +int MpegExtension::processExtra_bit_info(MpegVideoStream* mpegVideoStream) { + if (extraBit != NULL) { + delete extraBit; + extraBit = NULL; + } + get_extra_bit_info(mpegVideoStream); + return true; +} + + + + +int MpegExtension::next_bits(int num,unsigned int mask, + MpegVideoStream* input) { + unsigned int data; + + /* Get next num bits, no buffer pointer advance. */ + + data=input->showBits(num); + + /* Compare bit stream and mask. Set return value toTRUE if equal, FALSE if + differs. + */ + + if (mask == data) { + return true; + } + return false; +} + +/* + *-------------------------------------------------------------- + * + * get_ext_data -- + * + * Assumes that bit stream is at begining of extension + * data. Parses off extension data into dynamically + * allocated space until start code is hit. + * + * Results: + * Pointer to dynamically allocated memory containing + * extension data. + * + * Side effects: + * Bit stream irreversibly parsed. + * + *-------------------------------------------------------------- + */ +char* MpegExtension::get_ext_data(MpegVideoStream* mpegVideoStream) { + unsigned int size, marker; + char *dataPtr; + unsigned int data; + + /* Set initial ext data buffer size. */ + + size = EXT_BUF_SIZE; + + /* Allocate ext data buffer. */ + + dataPtr = (char *) malloc(size); + + /* Initialize marker to keep place in ext data buffer. */ + + marker = 0; + + /* While next data is not start code... */ + while (!next_bits(24, 0x000001,mpegVideoStream )) { + + /* Get next byte of ext data. */ + + data=mpegVideoStream->getBits(8); + + + + /* Put ext data into ext data buffer. Advance marker. */ + + dataPtr[marker] = (char) data; + marker++; + + /* If end of ext data buffer reached, resize data buffer. */ + + if (marker == size) { + size += EXT_BUF_SIZE; + dataPtr = (char *) realloc(dataPtr, size); + } + } + + /* Realloc data buffer to free any extra space. */ + + dataPtr = (char *) realloc(dataPtr, marker); + delete dataPtr; + dataPtr=NULL; + /* Return pointer to ext data buffer. */ + return dataPtr; +} + +void MpegExtension::processExtBuffer(MpegVideoStream* mpegVideoStream){ + unsigned int size, marker; + char *dataPtr; + unsigned int data=1; + + /* Initialize size of extra bit info buffer and allocate. */ + + + size = EXT_BUF_SIZE; + dataPtr = (char *) malloc(size); + + /* Reset marker to hold place in buffer. */ + + marker = 0; + + /* While flag bit is true. */ + + while (data) { + + /* Get next 8 bits of data. */ + data=mpegVideoStream->getBits(8); + + /* Place in extra bit info buffer. */ + + dataPtr[marker] = (char) data; + marker++; + + /* If buffer is full, reallocate. */ + + if (marker == size) { + size += EXT_BUF_SIZE; + dataPtr = (char *) realloc(dataPtr, size); + } + + /* Get next flag bit. */ + data=mpegVideoStream->getBits(1); + } + + /* Reallocate buffer to free extra space. */ + + dataPtr = (char *) realloc(dataPtr, marker); + delete dataPtr; + dataPtr=NULL; + /* Return pointer to extra bit info buffer. */ +} + + +/* + *-------------------------------------------------------------- + * + * get_extra_bit_info -- + * + * Parses off extra bit info stream into dynamically + * allocated memory. Extra bit info is indicated by + * a flag bit set to 1, followed by 8 bits of data. + * This continues until the flag bit is zero. Assumes + * that bit stream set to first flag bit in extra + * bit info stream. + * + * Results: + * Pointer to dynamically allocated memory with extra + * bit info in it. Flag bits are NOT included. + * + * Side effects: + * Bit stream irreversibly parsed. + * + *-------------------------------------------------------------- + */ + +char* MpegExtension::get_extra_bit_info(MpegVideoStream* mpegVideoStream) { + unsigned int data; + + /* Get first flag bit. */ + data=mpegVideoStream->getBits(1); + + /* If flag is false, return NULL pointer (i.e. no extra bit info). */ + + if (!data) { + return NULL; + } + processExtBuffer(mpegVideoStream); + return NULL; +} |