1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
|
/*!
************************************************************************
* \file nal.c
*
* \brief
* Converts Encapsulated Byte Sequence Packets (EBSP) to Raw Byte
* Sequence Packets (RBSP), and then onto String Of Data Bits (SODB)
*
* \author
* Main contributors (see contributors.h for copyright, address and affiliation details)
* - Shankar L. Regunathan <shanre@microsoft.com>
* - Tobias Oelbaum <oelbaum@drehvial.de>
************************************************************************
*/
#include "contributors.h"
#include "global.h"
/*!
************************************************************************
* \brief
* Converts RBSP to string of data bits
* \param streamBuffer
* pointer to buffer containing data
* \param last_byte_pos
* position of the last byte containing data.
* \return last_byte_pos
* position of the last byte pos. If the last-byte was entirely a stuffing byte,
* it is removed, and the last_byte_pos is updated.
*
************************************************************************/
int RBSPtoSODB(byte *streamBuffer, int last_byte_pos)
{
int ctr_bit, bitoffset;
bitoffset = 0;
//find trailing 1
ctr_bit = (streamBuffer[last_byte_pos-1] & (0x01<<bitoffset)); // set up control bit
while (ctr_bit==0)
{ // find trailing 1 bit
bitoffset++;
if(bitoffset == 8)
{
if(last_byte_pos == 0)
printf(" Panic: All zero data sequence in RBSP \n");
assert(last_byte_pos != 0);
last_byte_pos -= 1;
bitoffset = 0;
}
ctr_bit= streamBuffer[last_byte_pos-1] & (0x01<<(bitoffset));
}
// We keep the stop bit for now
/* if (remove_stop)
{
streamBuffer[last_byte_pos-1] -= (0x01<<(bitoffset));
if(bitoffset == 7)
return(last_byte_pos-1);
else
return(last_byte_pos);
}
*/
return(last_byte_pos);
}
/*!
************************************************************************
* \brief
* Converts Encapsulated Byte Sequence Packets to RBSP
* \param streamBuffer
* pointer to data stream
* \param end_bytepos
* size of data stream
* \param begin_bytepos
* Position after beginning
************************************************************************/
// TODO: benski> optimize using BitScanReverse
int EBSPtoRBSP(byte *streamBuffer, int end_bytepos)
{
int i, j, count;
int begin_bytepos = 1;
count = 0;
if(end_bytepos < begin_bytepos)
return end_bytepos;
j = begin_bytepos;
for(i = begin_bytepos; i < end_bytepos; i++)
{ //starting from begin_bytepos to avoid header information
//in NAL unit, 0x000000, 0x000001 or 0x000002 shall not occur at any byte-aligned position
if(count == ZEROBYTES_SHORTSTARTCODE && streamBuffer[i] < 0x03)
return j;//-1;
if(count == ZEROBYTES_SHORTSTARTCODE && streamBuffer[i] == 0x03)
{
//check the 4th byte after 0x000003, except when cabac_zero_word is used, in which case the last three bytes of this NAL unit must be 0x000003
if((i < end_bytepos-1) && (streamBuffer[i+1] > 0x03))
return -1;
//if cabac_zero_word is used, the final byte of this NAL unit(0x03) is discarded, and the last two bytes of RBSP must be 0x0000
if(i == end_bytepos-1)
return j;
i++;
count = 0;
}
streamBuffer[j] = streamBuffer[i];
if(streamBuffer[i] == 0x00)
count++;
else
count = 0;
j++;
}
return j;
}
|
