+/**
+ * @file common.h
+ * common internal api header.
+ */
+
#ifndef COMMON_H
#define COMMON_H
-#define FFMPEG_VERSION_INT 0x000406
-#define FFMPEG_VERSION "0.4.6"
-
#if defined(WIN32) && !defined(__MINGW32__) && !defined(__CYGWIN__)
-#define CONFIG_WIN32
+# define CONFIG_WIN32
#endif
//#define ALT_BITSTREAM_WRITER
//#define LIBMPEG2_BITSTREAM_READER
//#define A32_BITSTREAM_READER
-#ifdef ARCH_ALPHA
-#define ALT_BITSTREAM_READER
-#endif
-
-//#define ALIGNED_BITSTREAM
-#define FAST_GET_FIRST_VLC
-//#define DUMP_STREAM
-
#ifdef HAVE_AV_CONFIG_H
/* only include the following when compiling package */
-#include "config.h"
+# include "config.h"
+
+# include <stdlib.h>
+# include <stdio.h>
+# include <string.h>
+# ifndef __BEOS__
+# include <errno.h>
+# else
+# include "berrno.h"
+# endif
+# include <math.h>
+
+# ifndef ENODATA
+# define ENODATA 61
+# endif
+
+#ifndef M_PI
+#define M_PI 3.14159265358979323846
+#endif
-#include <stdlib.h>
-#include <stdio.h>
-#include <string.h>
-#include <errno.h>
-#include <math.h>
+#include <stddef.h>
+#ifndef offsetof
+# define offsetof(T,F) ((unsigned int)((char *)&((T *)0)->F))
+#endif
-#ifndef ENODATA
-#define ENODATA 61
+#define AVOPTION_CODEC_BOOL(name, help, field) \
+ { name, help, offsetof(AVCodecContext, field), FF_OPT_TYPE_BOOL }
+#define AVOPTION_CODEC_DOUBLE(name, help, field, minv, maxv, defval) \
+ { name, help, offsetof(AVCodecContext, field), FF_OPT_TYPE_DOUBLE, minv, maxv, defval }
+#define AVOPTION_CODEC_FLAG(name, help, field, flag, defval) \
+ { name, help, offsetof(AVCodecContext, field), FF_OPT_TYPE_FLAG, flag, 0, defval }
+#define AVOPTION_CODEC_INT(name, help, field, minv, maxv, defval) \
+ { name, help, offsetof(AVCodecContext, field), FF_OPT_TYPE_INT, minv, maxv, defval }
+#define AVOPTION_CODEC_STRING(name, help, field, str, val) \
+ { name, help, offsetof(AVCodecContext, field), FF_OPT_TYPE_STRING, .defval = val, .defstr = str }
+#define AVOPTION_CODEC_RCOVERRIDE(name, help, field) \
+ { name, help, offsetof(AVCodecContext, field), FF_OPT_TYPE_RCOVERRIDE, .defval = 0, .defstr = NULL }
+#define AVOPTION_SUB(ptr) { .name = NULL, .help = (const char*)ptr }
+#define AVOPTION_END() AVOPTION_SUB(NULL)
+
+struct AVOption;
+#ifdef HAVE_MMX
+extern const struct AVOption avoptions_common[3 + 5];
+#else
+extern const struct AVOption avoptions_common[3];
#endif
+extern const struct AVOption avoptions_workaround_bug[11];
#endif /* HAVE_AV_CONFIG_H */
/* Suppress restrict if it was not defined in config.h. */
#ifndef restrict
-#define restrict
+# define restrict
+#endif
+
+#if defined(__GNUC__) && (__GNUC__ > 3 || __GNUC__ == 3 && __GNUC_MINOR__ > 0)
+# define always_inline __attribute__((always_inline)) inline
+#else
+# define always_inline inline
#endif
#ifdef CONFIG_WIN32
/* windows */
-typedef unsigned short UINT16;
-typedef signed short INT16;
-typedef unsigned char UINT8;
-typedef unsigned int UINT32;
-typedef unsigned __int64 UINT64;
-typedef signed char INT8;
-typedef signed int INT32;
-typedef signed __int64 INT64;
-
-typedef UINT8 uint8_t;
-typedef INT8 int8_t;
-typedef UINT16 uint16_t;
-typedef INT16 int16_t;
-typedef UINT32 uint32_t;
-typedef INT32 int32_t;
-typedef UINT64 uint64_t;
-typedef INT64 int64_t;
-
-#ifndef __MINGW32__
-#define INT64_C(c) (c ## i64)
-#define UINT64_C(c) (c ## i64)
-
-#define inline __inline
+typedef unsigned short uint16_t;
+typedef signed short int16_t;
+typedef unsigned char uint8_t;
+typedef unsigned int uint32_t;
+typedef unsigned __int64 uint64_t;
+typedef signed char int8_t;
+typedef signed int int32_t;
+typedef signed __int64 int64_t;
-#else
-#define INT64_C(c) (c ## LL)
-#define UINT64_C(c) (c ## ULL)
-#endif /* __MINGW32__ */
+# ifndef __MINGW32__
+# define int64_t_C(c) (c ## i64)
+# define uint64_t_C(c) (c ## i64)
-#define M_PI 3.14159265358979323846
-#define M_SQRT2 1.41421356237309504880 /* sqrt(2) */
+# define inline __inline
-#ifdef _DEBUG
-#define DEBUG
-#endif
+# else
+# define int64_t_C(c) (c ## LL)
+# define uint64_t_C(c) (c ## ULL)
+# endif /* __MINGW32__ */
-#define snprintf _snprintf
+# ifdef _DEBUG
+# define DEBUG
+# endif
-#else /* CONFIG_WIN32 */
+# define snprintf _snprintf
+# define vsnprintf _vsnprintf
-/* unix */
+/* CONFIG_WIN32 end */
+#elif defined (CONFIG_OS2)
+/* OS/2 EMX */
#include <inttypes.h>
-#ifndef __WINE_WINDEF16_H
-/* workaround for typedef conflict in MPlayer (wine typedefs) */
-typedef unsigned short UINT16;
-typedef signed short INT16;
-#endif
-
-typedef unsigned char UINT8;
-typedef unsigned int UINT32;
-typedef unsigned long long UINT64;
-typedef signed char INT8;
-typedef signed int INT32;
-typedef signed long long INT64;
-
#ifdef HAVE_AV_CONFIG_H
-#ifdef __FreeBSD__
-#include <sys/param.h>
-#endif
-
-#ifndef INT64_C
-#define INT64_C(c) (c ## LL)
-#define UINT64_C(c) (c ## ULL)
+#ifndef int64_t_C
+#define int64_t_C(c) (c ## LL)
+#define uint64_t_C(c) (c ## ULL)
#endif
#ifdef USE_FASTMEMCPY
#include "fastmemcpy.h"
#endif
+#include <float.h>
+
#endif /* HAVE_AV_CONFIG_H */
-#endif /* !CONFIG_WIN32 */
+/* CONFIG_OS2 end */
+#else
+
+/* unix */
+
+# include <inttypes.h>
+
+# ifdef HAVE_AV_CONFIG_H
+# ifndef int64_t_C
+# define int64_t_C(c) (c ## LL)
+# define uint64_t_C(c) (c ## ULL)
+# endif
+
+# ifdef USE_FASTMEMCPY
+# include "fastmemcpy.h"
+# endif
+# endif /* HAVE_AV_CONFIG_H */
+
+#endif /* !CONFIG_WIN32 && !CONFIG_OS2 */
#ifdef HAVE_AV_CONFIG_H
-#include "bswap.h"
+# include "bswap.h"
-#if defined(__MINGW32__) || defined(__CYGWIN__) || \
- defined(__OS2__) || defined (__OpenBSD__)
-#define MANGLE(a) "_" #a
-#else
-#define MANGLE(a) #a
-#endif
+# if defined(__MINGW32__) || defined(__CYGWIN__) || \
+ defined(__OS2__) || defined (__OpenBSD__)
+# define MANGLE(a) "_" #a
+# else
+# define MANGLE(a) #a
+# endif
/* debug stuff */
-#ifndef DEBUG
-#define NDEBUG
-#endif
-#include <assert.h>
+# ifndef DEBUG
+# define NDEBUG
+# endif
/* dprintf macros */
-#if defined(CONFIG_WIN32) && !defined(__MINGW32__)
+# if defined(CONFIG_WIN32) && !defined(__MINGW32__)
inline void dprintf(const char* fmt,...) {}
-#else
+# else
-#ifdef DEBUG
-#define dprintf(fmt,args...) printf(fmt, ## args)
-#else
-#define dprintf(fmt,args...)
-#endif
+# ifdef DEBUG
+# define dprintf(fmt,args...) printf(fmt, ## args)
+# else
+# define dprintf(fmt,args...)
+# endif
-#endif /* !CONFIG_WIN32 */
+# endif /* !CONFIG_WIN32 */
-#define av_abort() do { fprintf(stderr, "Abort at %s:%d\n", __FILE__, __LINE__); abort(); } while (0)
+# define av_abort() do { fprintf(stderr, "Abort at %s:%d\n", __FILE__, __LINE__); abort(); } while (0)
+//rounded divison & shift
+#define RSHIFT(a,b) ((a) > 0 ? ((a) + (1<<((b)-1)))>>(b) : ((a) + (1<<((b)-1))-1)>>(b))
/* assume b>0 */
#define ROUNDED_DIV(a,b) (((a)>0 ? (a) + ((b)>>1) : (a) - ((b)>>1))/(b))
#define ABS(a) ((a) >= 0 ? (a) : (-(a)))
-#define MAX(a,b) ((a) > (b) ? (a) : (b))
-#define MIN(a,b) ((a) > (b) ? (b) : (a))
+
+#define FFMAX(a,b) ((a) > (b) ? (a) : (b))
+#define FFMIN(a,b) ((a) > (b) ? (b) : (a))
#ifdef ARCH_X86
// avoid +32 for shift optimization (gcc should do that ...)
return a;
}
#else
-#define NEG_SSR32(a,s) ((( int32_t)(a))>>(32-(s)))
-#define NEG_USR32(a,s) (((uint32_t)(a))>>(32-(s)))
+# define NEG_SSR32(a,s) ((( int32_t)(a))>>(32-(s)))
+# define NEG_USR32(a,s) (((uint32_t)(a))>>(32-(s)))
#endif
/* bit output */
struct PutBitContext;
-typedef void (*WriteDataFunc)(void *, UINT8 *, int);
+typedef void (*WriteDataFunc)(void *, uint8_t *, int);
typedef struct PutBitContext {
#ifdef ALT_BITSTREAM_WRITER
- UINT8 *buf, *buf_end;
+ uint8_t *buf, *buf_end;
int index;
#else
- UINT32 bit_buf;
+ uint32_t bit_buf;
int bit_left;
- UINT8 *buf, *buf_ptr, *buf_end;
+ uint8_t *buf, *buf_ptr, *buf_end;
#endif
- INT64 data_out_size; /* in bytes */
+ int64_t data_out_size; /* in bytes */
} PutBitContext;
void init_put_bits(PutBitContext *s,
- UINT8 *buffer, int buffer_size,
+ uint8_t *buffer, int buffer_size,
void *opaque,
- void (*write_data)(void *, UINT8 *, int));
+ void (*write_data)(void *, uint8_t *, int));
-INT64 get_bit_count(PutBitContext *s); /* XXX: change function name */
+int64_t get_bit_count(PutBitContext *s); /* XXX: change function name */
void align_put_bits(PutBitContext *s);
void flush_put_bits(PutBitContext *s);
void put_string(PutBitContext * pbc, char *s);
-/* jpeg specific put_bits */
-void jflush_put_bits(PutBitContext *s);
-
/* bit input */
typedef struct GetBitContext {
- UINT8 *buffer, *buffer_end;
+ const uint8_t *buffer, *buffer_end;
#ifdef ALT_BITSTREAM_READER
int index;
#elif defined LIBMPEG2_BITSTREAM_READER
- UINT8 *buffer_ptr;
- UINT32 cache;
+ uint8_t *buffer_ptr;
+ uint32_t cache;
int bit_count;
#elif defined A32_BITSTREAM_READER
- UINT32 *buffer_ptr;
- UINT32 cache0;
- UINT32 cache1;
+ uint32_t *buffer_ptr;
+ uint32_t cache0;
+ uint32_t cache1;
int bit_count;
#endif
- int size;
+ int size_in_bits;
} GetBitContext;
static inline int get_bits_count(GetBitContext *s);
-#define VLC_TYPE INT16
+#define VLC_TYPE int16_t
typedef struct VLC {
int bits;
- VLC_TYPE (*table)[2]; // code, bits
+ VLC_TYPE (*table)[2]; ///< code, bits
int table_size, table_allocated;
} VLC;
+typedef struct RL_VLC_ELEM {
+ int16_t level;
+ int8_t len;
+ uint8_t run;
+} RL_VLC_ELEM;
+
+#ifdef ARCH_SPARC64
+#define UNALIGNED_STORES_ARE_BAD
+#endif
+
/* used to avoid missaligned exceptions on some archs (alpha, ...) */
#ifdef ARCH_X86
-#define unaligned32(a) (*(UINT32*)(a))
+# define unaligned32(a) (*(uint32_t*)(a))
#else
-#ifdef __GNUC__
+# ifdef __GNUC__
static inline uint32_t unaligned32(const void *v) {
struct Unaligned {
uint32_t i;
return ((const struct Unaligned *) v)->i;
}
-#elif defined(__DECC)
+# elif defined(__DECC)
static inline uint32_t unaligned32(const void *v) {
return *(const __unaligned uint32_t *) v;
}
-#else
+# else
static inline uint32_t unaligned32(const void *v) {
return *(const uint32_t *) v;
}
-#endif
+# endif
#endif //!ARCH_X86
#ifndef ALT_BITSTREAM_WRITER
} else {
bit_buf<<=bit_left;
bit_buf |= value >> (n - bit_left);
- *(UINT32 *)s->buf_ptr = be2me_32(bit_buf);
+#ifdef UNALIGNED_STORES_ARE_BAD
+ if (3 & (int) s->buf_ptr) {
+ s->buf_ptr[0] = bit_buf >> 24;
+ s->buf_ptr[1] = bit_buf >> 16;
+ s->buf_ptr[2] = bit_buf >> 8;
+ s->buf_ptr[3] = bit_buf ;
+ } else
+#endif
+ *(uint32_t *)s->buf_ptr = be2me_32(bit_buf);
//printf("bitbuf = %08x\n", bit_buf);
s->buf_ptr+=4;
bit_left+=32 - n;
#ifdef ALT_BITSTREAM_WRITER
static inline void put_bits(PutBitContext *s, int n, unsigned int value)
{
-#ifdef ALIGNED_BITSTREAM_WRITER
-#ifdef ARCH_X86
+# ifdef ALIGNED_BITSTREAM_WRITER
+# ifdef ARCH_X86
asm volatile(
"movl %0, %%ecx \n\t"
"xorl %%eax, %%eax \n\t"
: "r" (s->buf), "r" (n), "0" (s->index), "1" (value<<(-n))
: "%eax", "%ecx"
);
-#else
+# else
int index= s->index;
uint32_t *ptr= ((uint32_t *)s->buf)+(index>>5);
//if(n>24) printf("%d %d\n", n, value);
index+= n;
s->index= index;
-#endif
-#else //ALIGNED_BITSTREAM_WRITER
-#ifdef ARCH_X86
+# endif
+# else //ALIGNED_BITSTREAM_WRITER
+# ifdef ARCH_X86
asm volatile(
"movl $7, %%ecx \n\t"
"andl %0, %%ecx \n\t"
: "r" (s->buf), "r" (n), "0" (s->index), "1" (value)
: "%ecx"
);
-#else
+# else
int index= s->index;
uint32_t *ptr= (uint32_t*)(((uint8_t *)s->buf)+(index>>3));
//if(n>24) printf("%d %d\n", n, value);
index+= n;
s->index= index;
-#endif
-#endif //!ALIGNED_BITSTREAM_WRITER
-}
-#endif
-
-#ifndef ALT_BITSTREAM_WRITER
-/* for jpeg : escape 0xff with 0x00 after it */
-static inline void jput_bits(PutBitContext *s, int n, unsigned int value)
-{
- unsigned int bit_buf, b;
- int bit_left, i;
-
- assert(n == 32 || value < (1U << n));
-
- bit_buf = s->bit_buf;
- bit_left = s->bit_left;
-
- //printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
- /* XXX: optimize */
- if (n < bit_left) {
- bit_buf = (bit_buf<<n) | value;
- bit_left-=n;
- } else {
- bit_buf<<=bit_left;
- bit_buf |= value >> (n - bit_left);
- /* handle escape */
- for(i=0;i<4;i++) {
- b = (bit_buf >> 24);
- *(s->buf_ptr++) = b;
- if (b == 0xff)
- *(s->buf_ptr++) = 0;
- bit_buf <<= 8;
- }
-
- bit_left+= 32 - n;
- bit_buf = value;
- }
-
- s->bit_buf = bit_buf;
- s->bit_left = bit_left;
+# endif
+# endif //!ALIGNED_BITSTREAM_WRITER
}
#endif
-#ifdef ALT_BITSTREAM_WRITER
-static inline void jput_bits(PutBitContext *s, int n, int value)
-{
- int index= s->index;
- uint32_t *ptr= (uint32_t*)(((uint8_t *)s->buf)+(index>>3));
- int v= ptr[0];
-//if(n>24) printf("%d %d\n", n, value);
-
- v |= be2me_32(value<<(32-n-(index&7) ));
- if(((v+0x01010101)^0xFFFFFFFF)&v&0x80808080)
- {
- /* handle idiotic (m)jpeg escapes */
- uint8_t *bPtr= (uint8_t*)ptr;
- int numChecked= ((index+n)>>3) - (index>>3);
-
- v= be2me_32(v);
-
- *(bPtr++)= v>>24;
- if((v&0xFF000000)==0xFF000000 && numChecked>0){
- *(bPtr++)= 0x00;
- index+=8;
- }
- *(bPtr++)= (v>>16)&0xFF;
- if((v&0x00FF0000)==0x00FF0000 && numChecked>1){
- *(bPtr++)= 0x00;
- index+=8;
- }
- *(bPtr++)= (v>>8)&0xFF;
- if((v&0x0000FF00)==0x0000FF00 && numChecked>2){
- *(bPtr++)= 0x00;
- index+=8;
- }
- *(bPtr++)= v&0xFF;
- if((v&0x000000FF)==0x000000FF && numChecked>3){
- *(bPtr++)= 0x00;
- index+=8;
- }
- *((uint32_t*)bPtr)= 0;
- }
- else
- {
- ptr[0] = v;
- ptr[1] = 0;
- }
-
- index+= n;
- s->index= index;
- }
-#endif
-
static inline uint8_t* pbBufPtr(PutBitContext *s)
{
#ifdef ALT_BITSTREAM_WRITER
}
void init_get_bits(GetBitContext *s,
- UINT8 *buffer, int buffer_size);
+ const uint8_t *buffer, int buffer_size);
-int check_marker(GetBitContext *s, char *msg);
+int check_marker(GetBitContext *s, const char *msg);
void align_get_bits(GetBitContext *s);
int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
const void *bits, int bits_wrap, int bits_size,
const void *codes, int codes_wrap, int codes_size);
void free_vlc(VLC *vlc);
-//note table will be trashed (pointer increased)
+/**
+ *
+ * if the vlc code is invalid and max_depth=1 than no bits will be removed
+ * if the vlc code is invalid and max_depth>1 than the number of bits removed
+ * is undefined
+ */
#define GET_VLC(code, name, gb, table, bits, max_depth)\
{\
int n, index, nb_bits;\
UPDATE_CACHE(name, gb)\
\
nb_bits = -n;\
- table += code;\
\
- index= SHOW_UBITS(name, gb, nb_bits);\
+ index= SHOW_UBITS(name, gb, nb_bits) + code;\
code = table[index][0];\
n = table[index][1];\
if(max_depth > 2 && n < 0){\
UPDATE_CACHE(name, gb)\
\
nb_bits = -n;\
- table += code;\
\
- index= SHOW_UBITS(name, gb, nb_bits);\
+ index= SHOW_UBITS(name, gb, nb_bits) + code;\
code = table[index][0];\
n = table[index][1];\
}\
SKIP_BITS(name, gb, n)\
}
+#define GET_RL_VLC(level, run, name, gb, table, bits, max_depth)\
+{\
+ int n, index, nb_bits;\
+\
+ index= SHOW_UBITS(name, gb, bits);\
+ level = table[index].level;\
+ n = table[index].len;\
+\
+ if(max_depth > 1 && n < 0){\
+ LAST_SKIP_BITS(name, gb, bits)\
+ UPDATE_CACHE(name, gb)\
+\
+ nb_bits = -n;\
+\
+ index= SHOW_UBITS(name, gb, nb_bits) + level;\
+ level = table[index].level;\
+ n = table[index].len;\
+ }\
+ run= table[index].run;\
+ SKIP_BITS(name, gb, n)\
+}
+
+// deprecated, dont use get_vlc for new code, use get_vlc2 instead or use GET_VLC directly
static inline int get_vlc(GetBitContext *s, VLC *vlc)
{
int code;
return code;
}
+/**
+ * parses a vlc code, faster then get_vlc()
+ * @param bits is the number of bits which will be read at once, must be
+ * identical to nb_bits in init_vlc()
+ * @param max_depth is the number of times bits bits must be readed to completly
+ * read the longest vlc code
+ * = (max_vlc_length + bits - 1) / bits
+ */
+static always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2],
+ int bits, int max_depth)
+{
+ int code;
+
+ OPEN_READER(re, s)
+ UPDATE_CACHE(re, s)
+
+ GET_VLC(code, re, s, table, bits, max_depth)
+
+ CLOSE_READER(re, s)
+ return code;
+}
+
+
/* define it to include statistics code (useful only for optimizing
codec efficiency */
//#define STATS
#endif
/* misc math functions */
+extern const uint8_t ff_log2_tab[256];
static inline int av_log2(unsigned int v)
{
v >>= 8;
n += 8;
}
- if (v & 0xf0) {
- v >>= 4;
- n += 4;
- }
- if (v & 0xc) {
- v >>= 2;
- n += 2;
- }
- if (v & 0x2) {
- n++;
+ n += ff_log2_tab[v];
+
+ return n;
+}
+
+static inline int av_log2_16bit(unsigned int v)
+{
+ int n;
+
+ n = 0;
+ if (v & 0xff00) {
+ v >>= 8;
+ n += 8;
}
+ n += ff_log2_tab[v];
+
return n;
}
+
/* median of 3 */
static inline int mid_pred(int a, int b, int c)
{
}
/* math */
-int ff_gcd(int a, int b);
+extern const uint8_t ff_sqrt_tab[128];
+
+int64_t ff_gcd(int64_t a, int64_t b);
static inline int ff_sqrt(int a)
{
int ret=0;
int s;
int ret_sq=0;
-
+
+ if(a<128) return ff_sqrt_tab[a];
+
for(s=15; s>=0; s--){
int b= ret_sq + (1<<(s*2)) + (ret<<s)*2;
if(b<=a){
}
return ret;
}
+
+/**
+ * converts fourcc string to int
+ */
+static inline int ff_get_fourcc(const char *s){
+ assert( strlen(s)==4 );
+
+ return (s[0]) + (s[1]<<8) + (s[2]<<16) + (s[3]<<24);
+}
+
+#define MKTAG(a,b,c,d) (a | (b << 8) | (c << 16) | (d << 24))
+#define MKBETAG(a,b,c,d) (d | (c << 8) | (b << 16) | (a << 24))
+
+
+void ff_float2fraction(int *nom_arg, int *denom_arg, double f, int max);
+
+
+#ifdef ARCH_X86
+#define MASK_ABS(mask, level)\
+ asm volatile(\
+ "cdq \n\t"\
+ "xorl %1, %0 \n\t"\
+ "subl %1, %0 \n\t"\
+ : "+a" (level), "=&d" (mask)\
+ );
+#else
+#define MASK_ABS(mask, level)\
+ mask= level>>31;\
+ level= (level^mask)-mask;
+#endif
+
+
#if __CPU__ >= 686 && !defined(RUNTIME_CPUDETECT)
#define COPY3_IF_LT(x,y,a,b,c,d)\
asm volatile (\
#define CLAMP_TO_8BIT(d) ((d > 0xff) ? 0xff : (d < 0) ? 0 : d)
+/* avoid usage of various functions */
+#define malloc please_use_av_malloc
+#define free please_use_av_free
+#define realloc please_use_av_realloc
+
#endif /* HAVE_AV_CONFIG_H */
#endif /* COMMON_H */
projects / ffmpeg / blobdiff