FFmpeg: compat/msvcrt/snprintf.c Source File

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snprintf.c

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1 /*

2 * C99-compatible snprintf() and vsnprintf() implementations

4 *

5 * This file is part of FFmpeg.

6 *

7 * FFmpeg is free software; you can redistribute it and/or

8 * modify it under the terms of the GNU Lesser General Public

9 * License as published by the Free Software Foundation; either

10 * version 2.1 of the License, or (at your option) any later version.

11 *

12 * FFmpeg is distributed in the hope that it will be useful,

13 * but WITHOUT ANY WARRANTY; without even the implied warranty of

14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

15 * Lesser General Public License for more details.

16 *

17 * You should have received a copy of the GNU Lesser General Public

18 * License along with FFmpeg; if not, write to the Free Software

19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

20 */

22 #include <stdio.h>

23 #include <stdarg.h>

24 #include <limits.h>

25 #include <string.h>

27 #include "compat/va_copy.h"

28 #include "libavutil/error.h"

30 #if defined(__MINGW32__)

31 #define EOVERFLOW EFBIG

32 #endif

34 int avpriv_snprintf(char *s, size_t n, const char *fmt, ...)

35 {

36 va_list ap;

37 int ret;

39 va_start(ap, fmt);

40 ret = avpriv_vsnprintf(s, n, fmt, ap);

41 va_end(ap);

43 return ret;

44 }

46 int avpriv_vsnprintf(char *s, size_t n, const char *fmt,

47 va_list ap)

48 {

49 int ret;

50 va_list ap_copy;

52 if (n == 0)

53 return _vscprintf(fmt, ap);

54 else if (n > INT_MAX)

55 return AVERROR(EOVERFLOW);

57 /* we use n - 1 here because if the buffer is not big enough, the MS

58 * runtime libraries don't add a terminating zero at the end. MSDN

59 * recommends to provide _snprintf/_vsnprintf() a buffer size that

60 * is one less than the actual buffer, and zero it before calling

61 * _snprintf/_vsnprintf() to workaround this problem.

62 * See https://web.archive.org/web/20151214111935/http://msdn.microsoft.com/en-us/library/1kt27hek(v=vs.80).aspx */

63 memset(s, 0, n);

64 va_copy(ap_copy, ap);

65 ret = _vsnprintf(s, n - 1, fmt, ap_copy);

66 va_end(ap_copy);

67 if (ret == -1)

68 ret = _vscprintf(fmt, ap);

70 return ret;

71 }

AVERROR

Filter the word "frame" indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions

va_copy.h

avpriv_vsnprintf

int avpriv_vsnprintf(char *s, size_t n, const char *fmt, va_list ap)

Definition: snprintf.c:46

#define s(width, name)

Definition: cbs_vp9.c:257

limits.h

error.h

avpriv_snprintf

int avpriv_snprintf(char *s, size_t n, const char *fmt,...)

Definition: snprintf.c:34

va_copy

#define va_copy(dst, src)

Definition: va_copy.h:31

ret

Definition: filter_design.txt:187

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