C and C++ 基础

dll中最好不要用__declspec(thread)

玻璃小屋 — Wed, 10 Feb 2010 02:06:00 GMT

如果 DLL 将任何非本地数据或对象声明为 __declspec（线程），动态加载该 DLL 时会导致保护错误。使用 LoadLibrary 加载所有 DLL 后，每当代码引用非本地 __declspec（线程）数据时，将导致系统故障。由于线程的全局变量空间是在运行时分配的，因此此空间的大小是以应用程序的需求和所有静态链接的 DLL 的需求相加为基础计算出来的。使用 LoadLibrary 时，无法扩展此空间以允许放置用 __declspec（线程）声明的线程本地变量。如果 DLL 可能是用 LoadLibrary 加载的，请在 DLL 中使用 TLS API（如 TlsAlloc）来分配 TLS。

uafxcwd.lib LIBCMTD.lib 弱外部链接(ZT)

玻璃小屋 — Fri, 05 Feb 2010 09:09:00 GMT

今天debug一程序出现如下错误：

uafxcwd.lib(afxmem.obj) : error LNK2005: "void * __cdecl operator new(unsigned int)" (??2@YAPAXI@Z) already defined in LIBCMTD.lib(new.obj)
uafxcwd.lib(afxmem.obj) : error LNK2005: "void __cdecl operator delete(void *)" (??3@YAXPAX@Z) already defined in LIBCMTD.lib(dbgdel.obj)
uafxcwd.lib(afxmem.obj) : error LNK2005: "void __cdecl operator delete[](void *)" (??_V@YAXPAX@Z) already defined in LIBCMTD.lib(delete2.obj)

原因：

CRT 库对 new、delete 和 DllMain 函数使用弱外部链接。MFC 库也包含 new、delete 和 DllMain 函数。这些函数要求先链接 MFC 库，然后再链接 CRT 库。

当 C 运行时 (CRT) 库和 Microsoft 基础类 (MFC) 库的链接顺序有误时，可能会出现以下 LNK2005 错误。

解决方法：

强制链接器按照正确的顺序链接库！

project->properties->Linker->Ignore Specific Library 添加 uafxcwd.lib Libcmtd.lib

在Additional Dependencied添加uafxcwd.lib Libcmtd.lib

问题解决！

int Pcm16_2_Mp3()

玻璃小屋 — Fri, 22 Jan 2010 10:23:00 GMT

int Pcm16_2_Mp3()
{
int     iRet = 0;
int     i  = 0;
lame_global_flags* gf  = NULL;

    unsigned char  mp3buffer[LAME_MAXMP3BUFFER];
    int     Buffer[2][1152];
    int     iread = 0, imp3;

if (NULL == (gf = lame_init())) {
return 1;
}

/* turn off automatic writing of ID3 tag data into mp3 stream
* we have to call it before 'lame_init_params', because that
* function would spit out ID3v2 tag data.
*/
lame_set_write_id3tag_automatic(gf, 0);
lame_set_in_samplerate(gf,8000);   // 8kHz
lame_set_num_channels(gf,1);    // Mono
//gf->pcmbitwidth     = 8;
//gf->pcm_is_unsigned_8bit  = 1;

/* Now that all the options are set, lame needs to analyze them and
* set some more internal options and check for problems
*/
i = lame_init_params(gf);

/* encode */
imp3 = lame_encode_buffer_int(gf, Buffer[0], Buffer[1], iread,mp3buffer, sizeof(mp3buffer));

/* was our output buffer big enough? */
if (imp3 < 0) {
  if (imp3 == -1)
   assert(0);
  else
   assert(0);
  return 1;
}

imp3 = lame_encode_flush(gf, mp3buffer, sizeof(mp3buffer)); /* may return one more mp3 frame */

if (imp3 < 0) {
  if (imp3 == -1)
   assert(0);
  else
   assert(0);
  return 1;

}

return iRet;
}

淘宝网站 IE8 显示 TB 未定义或 YAHOO 未定义，显示宝贝：读取中...的问题。

玻璃小屋 — Mon, 18 Jan 2010 02:46:00 GMT

这个问题是由于 IE 的 Internet 安全增强选项的问题，在工具-》Internet选项 -》安全 -》可信任站点中加入如下网址就行了。
http://a.tbcdn.cn

这个网址是提供部分taobao js脚本的，如果不对其开放权限，是不行的。

speex压缩之后就不用再使用LZW压缩了。。

玻璃小屋 — Mon, 28 Dec 2009 06:11:00 GMT

测试了一下，speex压缩之后，用lzw也起不到压缩效果了。。speex算法中已经包含了类似于 lzw的算法了？

(zt) speex带宽占用~

玻璃小屋 — Mon, 28 Dec 2009 05:27:00 GMT

Speex Actual Bandwidth Calculation

We have finally almost finished Speex coding on AR1688 DSP. This open source voice codec turned out to be much more complicated than we expected. There are 8 different bitrate with 8k sampling, from 2.15kpbs to 24.6kpbs. I am writing this article to answer a question of how much bandwidth this codec actually use during a call.

Let us calculate based on 802.3 ethernet, using SIP protocol:

Ethernet CRC: 4 bytes

MAC header: 14 bytes

IP header: 20 bytes

UDP header: 8 bytes

RTP header: 12 bytes

Speex data: x bytes, x depends on bitrate used and number of frames packed in an ethernet packet ("Voice Frames per TX" option in AR1688)

Total: (58 + x) bytes

Speex uses 20ms as a frame, the size of compressed data in a frame with different bitrate are:

2.15kbps: 6 bytes

3.95kbps: 10 bytes

5.95kbps: 15 bytes

8kbps: 20 bytes

11kbps: 28 bytes

15kbps: 38 bytes

18.2kbps: 46 bytes

24.6kbps: 62 bytes

When only 1 frame is included in an ethernet frame, the actually used bandwidth are:

2.15k: 25.6k

3.95k: 27.2k

5.95k: 29.2k

8k: 31.2k

11k: 34.4k

15k: 38.4k

18.2k: 41.6k

24.6k: 48k

When 2 frames are included in an ethernet frame, the actually used bandwidth are:

2.15k: 14k

3.95k: 15.6k

5.95k: 17.6k

8k: 19.6k

11k: 22.8k

15k: 26.8k

18.2k: 30k

24.6k: 36.4k

When 3 frames are included in an ethernet frame, the actually used bandwidth are:

2.15k: 10.1k

3.95k: 11.7k

5.95k: 13.7k

8k: 15.7k

11k: 18.9k

15k: 22.9k

18.2k: 26.1k

24.6k: 32.5k

When 4 frames are included in an ethernet frame, the actually used bandwidth are:

2.15k: 8.2k

3.95k: 9.8k

5.95k: 11.8k

8k: 13.8k

11k: 17k

15k: 21k

18.2k: 24.2k

24.6k: 30.6k

为啥SpeeX也是把8kHz 8bit 的raw PCM数据转成 8kHz 16bit呢？？

玻璃小屋 — Wed, 23 Dec 2009 05:05:00 GMT

在 SpeeX的
/* Convert input audio bits, endians and channels */
static int read_samples(FILE *fin,int frame_size, int bits, int channels, int lsb, short * input, char *buff, spx_int32_t *size)

中有如下代码，目的是把   8kHz 8bit 的PCM数据转成 8kHz 16bit的PCM数据。好象mp3算法，g729算法，都没有直接转8kHz 8bit 的PCM数据的方法，都是转成 16bit，不知道为什么？转成 16bit的话，PCM数据不是多了一倍么？？对以后的压缩不会产生影响？？

if(bits==8)
   {
      /* Convert 8->16 bits */
      for(i=frame_size*channels-1;i>=0;i--)
      {
         s[i]=(in[i]<<8)^0x8000;
      }
   } else
   {
      /* convert to our endian format */
      for(i=0;i<frame_size*channels;i++)
      {
         if(lsb)
            s[i]=le_short(s[i]);
         else
            s[i]=be_short(s[i]);
      }
   }

dshow用avi mux filter 和 file writer filter 写AVI文件的问题？难道是bug?

玻璃小屋 — Thu, 03 Dec 2009 01:30:00 GMT

这几天用自己写了个源filter，推rgb或是yv12数据给下级的filter。后来想把这些数据写到avi文件中，自然就想到了 avi mux filter + file writer filter来写了。但是遇到一个问题。但每秒帧数设置的大于等于3时，右键盘查看avi文件的属性显示的是正常的。但是当每秒帧数设置为2时，AVI文件属性确显示 14帧/秒，当设置为1时，属性显示7帧/秒，不过播放时，貌似是正常的，我的系统是win2003 sp2，后来在winxp sp2上试，也是这样(另外从暴风中查看属性帧数也不对，用一个叫做 avi mux GUI的软件查看，是正常的)。但是vista中是正常的(不管是系统的AVI文件属性，还是暴风的)。。奇怪死了。难道是系统计算属性时溢出了？？留带以后详细测试吧。。。这次凑合着用吧。

sscanf 获得字符间隔开的数据~

玻璃小屋 — Mon, 23 Nov 2009 09:30:00 GMT

_stscanf(_T("xxx_xxx_xxx"),_T("%[^_]_%[^_]_%[^_]"),tcMarket,tcKind,tcCode);

无语。。char对应的二进制（printf）

玻璃小屋 — Wed, 18 Nov 2009 14:26:00 GMT

#include "stdafx.h"
#include <iostream>

void printBin(int integer)
{
    int k,a=31;
    int b[32] = {0};
    memset(b,0,sizeof(b));
    while (integer!=0)
    {
        k=integer%2;
        b[a--]=k;
        integer=integer/2;
    }
    a = 0;
    while (a<32)
    {
        std::cout<<b[a++];
    }
    std::cout << "" << std::endl;
}

void printBin(unsigned char integer)
{
    unsigned char k,a=sizeof(a)*8 - 1;
    int b[sizeof(char)*8] = {0};
    memset(b,0,sizeof(b));
    while (integer!=0)
    {
        k=integer%2;
        b[a--]=k;
        integer=integer/2;
    }
    a = 0;
    while (a<sizeof(a)*8)
    {
        std::cout<<b[a++];
    }
    std::cout << "" << std::endl;
}

int _tmain(int argc, _TCHAR* argv[])
{
    int i = 0;
    for(i = 0; i < 256; i++)
    {
        printf("%3d = ",i);
        printBin((unsigned char)i);
    }
    return 0;
}

  0 = 00000000
  1 = 00000001
  2 = 00000010
  3 = 00000011
  4 = 00000100
  5 = 00000101
  6 = 00000110
  7 = 00000111
  8 = 00001000
  9 = 00001001
10 = 00001010
11 = 00001011
12 = 00001100
13 = 00001101
14 = 00001110
15 = 00001111
16 = 00010000
17 = 00010001
18 = 00010010
19 = 00010011
20 = 00010100
21 = 00010101
22 = 00010110
23 = 00010111
24 = 00011000
25 = 00011001
26 = 00011010
27 = 00011011
28 = 00011100
29 = 00011101
30 = 00011110
31 = 00011111
32 = 00100000
33 = 00100001
34 = 00100010
35 = 00100011
36 = 00100100
37 = 00100101
38 = 00100110
39 = 00100111
40 = 00101000
41 = 00101001
42 = 00101010
43 = 00101011
44 = 00101100
45 = 00101101
46 = 00101110
47 = 00101111
48 = 00110000
49 = 00110001
50 = 00110010
51 = 00110011
52 = 00110100
53 = 00110101
54 = 00110110
55 = 00110111
56 = 00111000
57 = 00111001
58 = 00111010
59 = 00111011
60 = 00111100
61 = 00111101
62 = 00111110
63 = 00111111
64 = 01000000
65 = 01000001
66 = 01000010
67 = 01000011
68 = 01000100
69 = 01000101
70 = 01000110
71 = 01000111
72 = 01001000
73 = 01001001
74 = 01001010
75 = 01001011
76 = 01001100
77 = 01001101
78 = 01001110
79 = 01001111
80 = 01010000
81 = 01010001
82 = 01010010
83 = 01010011
84 = 01010100
85 = 01010101
86 = 01010110
87 = 01010111
88 = 01011000
89 = 01011001
90 = 01011010
91 = 01011011
92 = 01011100
93 = 01011101
94 = 01011110
95 = 01011111
96 = 01100000
97 = 01100001
98 = 01100010
99 = 01100011
100 = 01100100
101 = 01100101
102 = 01100110
103 = 01100111
104 = 01101000
105 = 01101001
106 = 01101010
107 = 01101011
108 = 01101100
109 = 01101101
110 = 01101110
111 = 01101111
112 = 01110000
113 = 01110001
114 = 01110010
115 = 01110011
116 = 01110100
117 = 01110101
118 = 01110110
119 = 01110111
120 = 01111000
121 = 01111001
122 = 01111010
123 = 01111011
124 = 01111100
125 = 01111101
126 = 01111110
127 = 01111111
128 = 10000000
129 = 10000001
130 = 10000010
131 = 10000011
132 = 10000100
133 = 10000101
134 = 10000110
135 = 10000111
136 = 10001000
137 = 10001001
138 = 10001010
139 = 10001011
140 = 10001100
141 = 10001101
142 = 10001110
143 = 10001111
144 = 10010000
145 = 10010001
146 = 10010010
147 = 10010011
148 = 10010100
149 = 10010101
150 = 10010110
151 = 10010111
152 = 10011000
153 = 10011001
154 = 10011010
155 = 10011011
156 = 10011100
157 = 10011101
158 = 10011110
159 = 10011111
160 = 10100000
161 = 10100001
162 = 10100010
163 = 10100011
164 = 10100100
165 = 10100101
166 = 10100110
167 = 10100111
168 = 10101000
169 = 10101001
170 = 10101010
171 = 10101011
172 = 10101100
173 = 10101101
174 = 10101110
175 = 10101111
176 = 10110000
177 = 10110001
178 = 10110010
179 = 10110011
180 = 10110100
181 = 10110101
182 = 10110110
183 = 10110111
184 = 10111000
185 = 10111001
186 = 10111010
187 = 10111011
188 = 10111100
189 = 10111101
190 = 10111110
191 = 10111111
192 = 11000000
193 = 11000001
194 = 11000010
195 = 11000011
196 = 11000100
197 = 11000101
198 = 11000110
199 = 11000111
200 = 11001000
201 = 11001001
202 = 11001010
203 = 11001011
204 = 11001100
205 = 11001101
206 = 11001110
207 = 11001111
208 = 11010000
209 = 11010001
210 = 11010010
211 = 11010011
212 = 11010100
213 = 11010101
214 = 11010110
215 = 11010111
216 = 11011000
217 = 11011001
218 = 11011010
219 = 11011011
220 = 11011100
221 = 11011101
222 = 11011110
223 = 11011111
224 = 11100000
225 = 11100001
226 = 11100010
227 = 11100011
228 = 11100100
229 = 11100101
230 = 11100110
231 = 11100111
232 = 11101000
233 = 11101001
234 = 11101010
235 = 11101011
236 = 11101100
237 = 11101101
238 = 11101110
239 = 11101111
240 = 11110000
241 = 11110001
242 = 11110010
243 = 11110011
244 = 11110100
245 = 11110101
246 = 11110110
247 = 11110111
248 = 11111000
249 = 11111001
250 = 11111010
251 = 11111011
252 = 11111100
253 = 11111101
254 = 11111110
255 = 11111111
请按任意键继续. . .