问题
In my application, I record audio data from an ASIO driver:
void newData(void *buffer, int length)
where buffer is the buffer pointer and length is the number of samples in that buffer. In my case, I know that the samples are 4-byte integers and the buffer contains 1024 samples every run.
Now, I save these samples in two ways: little-endian binary (to be later used as a WAV file) and a text file. The text file saving words good, I get the numbers and they correspond to the samples form the waveform. But the binary file will always contain a little good data and the rest is just mangled.
Original data (original sound and text saving):
Mangled data (binary saving):
The code (I use std::ofstream):
//binary saving
tempOut.write((char *)buffer, length * 4);
//text saving
int *intBuf = (int *)buffer;
for(int i = 0; i < length; i++){
textOut << intBuf[i];
textOut << '\n';
}
Note that the problem is not with synchronization, as I save the binary data first and the text data second.
How the data are mangled:
Original binary (LE) binary (BE) binary to dec
206016 C0240300 000324C0 206016
815616 00720C00 000C7200 815616
1804032 00871B00 001B8700 1804032
3131392 00C82F00 002FC800 3131392
4741440 40594800 00485940 4741440
6567552 80366400 00643680 6567552
8531264 402D8200 00822D40 8531264
10545664 00EAA000 00A0EA00 10545664
12517632 0001BF00 00BF0100 12517632
14353920 0006DB00 00DB0600 14353920
15958976 C083F300 00F383C0 15958976
17241600 00160701 01071600 17241600
18119296 807A1401 01147A80 18119296
18514048 80801A01 011A8080 18514048
18365760 403D1801 01183D40 18365760
17622016 00E40C01 010CE400 17622016
16253632 C002F800 00F802C0 16253632
14246784 8063D900 00D96380 14246784
11605504 0016B100 00B11600 11605504
8355840 00807F00 007F8000 8355840
4541376 C04B4500 00454BC0 4541376
228096 007B0300 00037B00 228096
-4501376 8050BBFF FFBB5080 4290465920
-9549312 004A6EFF FF6E4A00 4285417984
-14798400 C0311EFF FF1E31C0 4280168896
-20126080 80E6CCFE FECCE680 4274841216
-25391232 808F7CFE FE7C8F80 4269576064
-30458624 003D2FFE FE2F3D00 4264508672
-35178624 8037E7FD FDE73780 4259788672
-39413760 0098A6FD FDA69800 4255553536
-43025024 807D6FFD FD6F7D80 4251942272
-45883392 00E043FD FD43E000 4249083904
-47872704 408525FD FD258540 4247094592
-48899072 00DC15FD FD15DC00 4246068224
-48881280 802116FD FD162180 4246086016
-47759616 003F27FD FD273F00 4247207680
-45503488 00AC49FD FD49AC00 4249463808
-42107648 007D7DFD FD7D7D00 4252859648
-37589760 006DC2FD FDC26D00 4257377536
-32005120 00A417FE FE17A400 4262962176
-25429184 40FB7BFE FE7BFB40 4269538112
-17961216 00EFEDFE FEEDEF00 4277006080
-9736576 806E6BFF FF6B6E80 4285230720
-909568 001FF2FF FFF21F00 4294057728
8349120 C0657F00 007F65C0 8349120
17843584 80451001 01104580 17843584
27378816 80C4A101 01A1C480 27378816
36731904 007C3002 02307C00 36731904
45697792 004BB902 02B94B00 45697792
54044800 80A83803 0338A880 54044800
61575360 C090AB03 03AB90C0 61575360
68087552 00EF0E04 040EEF00 68087552
73396096 80EF5F04 045FEF80 73396096
77338368 00179C04 049C1700 77338368
79784320 8069C104 04C16980 79784320
80611328 0008CE04 04CE0800 80611328
79763520 4018C104 04C11840 79763520
77187328 00C99904 0499C900 77187328
72884352 80205804 04582080 72884352
66885120 0096FC03 03FC9600 66885120
59262720 00478803 03884700 59262720
50139648 0012FD02 02FD1200 50139648
39658752 00255D02 025D2500 39658752
28000256 0040AB01 01AB4000 28000256
15379520 40ACEA00 00EAAC40 15379520
2044416 00321F00 001F3200 2044416
-11740544 80DA4CFF FF4CDA80 4283226752
-25707264 00BD77FE FE77BD00 4269260032
-39540864 80A7A4FD FDA4A780 4255426432
-52953600 00FED7FC FCD7FE00 4242013696
-65651712 003C16FC FC163C00 4229315584
-77331456 000464FB FB640400 4217635840
-87716800 408CC5FA FAC58C40 4207250496
-96567040 00813EFA FA3E8100 4198400256
-103632000 80B3D2F9 F9D2B380 4191335296
-108724992 00FD84F9 F984FD00 4186242304
-111678336 80EC57F9 F957EC80 4183288960
-112379904 00384DF9 F94D3800 4182587392
-110761792 C0E865F9 F965E8C0 4184205504
-106792960 0078A2F9 F9A27800 4188174336
-100491840 C09D02FA FA029DC0 4194475456
-91944960 000885FA FA850800 4203022336
-81278912 40C827FB FB27C840 4213688384
-68651520 0076E8FB FBE87600 4226315776
-54296640 C07FC3FC FCC37FC0 4240670656
-38472960 00F3B4FD FDB4F300 4256494336
-21475776 404EB8FE FEB84E40 4273491520
-3638272 007CC8FF FFC87C00 4291329024
14684288 8010E000 00E01080 14684288
33120000 005FF901 01F95F00 33120000
51280320 C0790E03 030E79C0 51280320
68789504 00A51904 0419A500 68789504
85244544 80BA1405 0514BA80 85244544
100304768 8087FA05 05FA8780 100304768
113604800 C078C506 06C578C0 113604800
124833792 00D07007 0770D000 124833792
133720320 0069F807 07F86900 133720320
140022400 80925808 08589280 140022400
143561088 80918E08 088E9180 143561088
144198400 004B9808 08984B00 144198400
141871872 00CB7408 0874CB00 141871872
136572288 80ED2308 0823ED80 136572288
128333056 0035A607 07A63500 128333056
117298688 00D6FD06 06FDD600 117298688
103608960 80F22C06 062CF280 103608960
87533952 80A93705 0537A980 87533952
69342848 80162204 04221680 69342848
49372416 005DF102 02F15D00 49372416
28008640 C060AB01 01AB60C0 28008640
5674240 00955600 00569500 5674240
-17177472 80E4F9FE FEF9E480 4277789824
-40097792 00289CFD FD9C2800 4254869504
-62600192 00CC44FC FC44CC00 4232367104
-84225024 00D4FAFA FAFAD400 4210742272
-104489920 409CC5F9 F9C59C40 4190477376
-122963712 00B9ABF8 F8ABB900 4172003584
-139224384 C09AB3F7 F7B39AC0 4155742912
-152897792 00F7E2F6 F6E2F700 4142069504
-163660224 40BE3EF6 F63EBE40 4131307072
-171233280 0030CBF5 F5CB3000 4123734016
-175417088 00598BF5 F58B5900 4119550208
-176054784 009E81F5 F5819E00 4118912512
-173089536 00DDAEF5 F5AEDD00 4121877760
-166513152 003613F6 F6133600 4128454144
-156400000 8086ADF6 F6AD8680 4138567296
-142918272 803D7BF7 F77B3D80 4152049024
-126284736 400C79F8 F8790C40 4168682560
-106782720 00A0A2F9 F9A2A000 4188184576
-84789120 8038F2FA FAF23880 4210178176
-60711040 809F61FC FC619F80 4234256256
-35003200 C0E4E9FD FDE9E4C0 4259964096
-8186112 001783FF FF831700 4286781184
19211584 40252501 01252540 19211584
46627712 807BC702 02C77B80 46627712
73500480 40876104 04618740 73500480
99269120 00BAEA05 05EABA00 99269120
123365760 80695A07 075A6980 123365760
145304064 002AA908 08A92A00 145304064
164576000 003BCF09 09CF3B00 164576000
Here the mangling occurs:
180750080 0007C60D 0DC60700 231081728
193447488 0A40C687 87C6400A 2277916682
202362496 0B80CE0F 0FCE800B 265191435
207247040 0CC0565A 5A56C00C 1515634700
207959040 0C003465 6534000C 1697906700
204410560 0CC00E2F 2F0EC00C 789495820
196625792 0C8045B8 B845800C 3091562508
184697856 0B004402 0244000B 38010891
168819456 0B00FB0F 0FFB000B 268107787
149276544 0D0A80C7 C7800A0D 3347057165
126403200 E50880C2 C28008E5 3263170789
100631232 8807C082 82C00788 2193622920
72473600 FF0500DC DC0005FF 3690989055
42428736 51044069 69400451 1765803089
11137280 870200F1 F1000287 4043309703
-20792320 A90000BC BC0000A9 3154116777
-52715520 C2FE00A0 A000FEC2 2684419778
-83981184 DBFC808C 8C80FCDB 2357263579
-113911680 FEFA80D8 D880FAFE 3632331518
-141894144 35F900DE DE00F935 3724605749
-167331840 8AF700B8 B800F78A 3087071114
-189665728 06F640EE EE40F606 3997234694
-208386432 B1F48046 4680F4B1 1182856369
-223077888 94F3001A 1A00F394 436269972
-233389056 B4F200C4 C400F2B4 3288396468
-239046720 16F2C06F 6FC0F216 1874915862
-239889920 C0F10092 9200F1C0 2449535424
-235830720 B3F14082 8240F1B3 2185294259
-226899456 F1F100CA CA00F1F1 3389059569
-213204992 79F200C0 C000F279 3221287545
-195002240 4AF38080 8080F34A 2155934538
-172597824 60F4C05D 5DC0F460 1572926560
-146384384 B6F5005A 5A00F5B6 1510012342
-116876032 46F7009D 9D00F746 2634086214
-84644736 08F9806C 6C80F908 1820391688
-50310400 F4FA0053 5300FAF4 1392573172
You can see how the wave is represented, positive and negative values alternate, until certain point. Then it becomes rubbish.
回答1:
You forgot to open the output file for binary data in binary mode. Therefore every time a byte 0x0A is sent to output the file receives (in a windows system) 0x0D 0x0A.
回答2:
If I'm interpreting your first line of information on the data correctly:
Original binary (LE) binary (BE) binary to dec
206016 C0240300 000324C0 206016
Then the correct value is the big-endian data. If what you are seeing on disk is the 0xC0240300, then you are working on a little-endian machine (an Intel CPU), and you need to write the data in a big-endian format (and read it back in big-endian format too).
The way you're currently doing it is:
//binary saving
tempOut.write((char *)buffer, length * 4);
I assume 'buffer' is an array of 4-byte integers (in my work, it would most commonly be an array of char, but then the cast would be irrelevant).
I think that one way to do it 'better' might be:
enum { MAX_SAMPLES = 1024 };
char binbuff[4 * MAX_SAMPLES];
assert(length <= MAX_SAMPLES);
char *dst = binbuff;
for (int i = 0; i < length; i++)
{
*dst++ = (buffer[i] >> 24) & 0xFF;
*dst++ = (buffer[i] >> 16) & 0xFF;
*dst++ = (buffer[i] >> 8) & 0xFF;
*dst++ = (buffer[i] >> 0) & 0xFF;
}
tempOut.write(binbuff, 4 * length);
There are multiple more or less equivalent mechanisms available to achieve the same result.
Reading would be the inverse operation. You'd read the data into a character (byte) array, and then assemble each four bytes into a value:
int sample[MAX_SAMPLES];
char binbuff[4 * MAX_SAMPLES];
tempIn.read(binbuff, sizeof(binbuff));
char *src = binbuff;
for (int i = 0; i < MAX_SAMPLES; i++, src += 4)
{
sample[i] = (src[0] & 0xFF) << 24 |
(src[1] & 0xFF) << 16 |
(src[2] & 0xFF) << 8 |
(src[3] & 0xFF) << 0;
}
The optimizer will remove the shifts by zero; they make the symmetry of the operations clear in the source code.
来源：https://stackoverflow.com/questions/10464824/writing-binary-mangles-data