我在OpenEuler上编译ffmpeg出现了这个问题。
我试了三个版本4,4.4,7.0其中7.0没有出现这个问题，但是我需要编译libvlc不能用那么高的版本，4和4.4都有那个问题

解决办法:
将mathops.h中的内容替换为如下内容:

/*
* simple math operations
* Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at> et al
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/

#ifndef AVCODEC_X86_MATHOPS_H
#define AVCODEC_X86_MATHOPS_H

#include "config.h"

#include "libavutil/common.h"
#include "libavutil/x86/asm.h"

#if HAVE_INLINE_ASM

#if ARCH_X86_32

#define MULL MULL
static av_always_inline av_const int MULL(int a, int b, unsigned shift)
{
int rt, dummy;
if (__builtin_constant_p(shift))
__asm__ (
"imull %3               \n\t"
"shrdl %4, %%edx, %%eax \n\t"
:"=a"(rt), "=d"(dummy)
:"a"(a), "rm"(b), "i"(shift & 0x1F)
);
else
__asm__ (
"imull %3               \n\t"
"shrdl %4, %%edx, %%eax \n\t"
:"=a"(rt), "=d"(dummy)
:"a"(a), "rm"(b), "c"((uint8_t)shift)
);
return rt;
}

#define MULH MULH
static av_always_inline av_const int MULH(int a, int b)
{
int rt, dummy;
__asm__ (
"imull %3"
:"=d"(rt), "=a"(dummy)
:"a"(a), "rm"(b)
);
return rt;
}

#define MUL64 MUL64
static av_always_inline av_const int64_t MUL64(int a, int b)
{
int64_t rt;
__asm__ (
"imull %2"
:"=A"(rt)
:"a"(a), "rm"(b)
);
return rt;
}

#endif /* ARCH_X86_32 */

#if HAVE_I686
/* median of 3 */
#define mid_pred mid_pred
static inline av_const int mid_pred(int a, int b, int c)
{
int i=b;
__asm__ (
"cmp    %2, %1 \n\t"
"cmovg  %1, %0 \n\t"
"cmovg  %2, %1 \n\t"
"cmp    %3, %1 \n\t"
"cmovl  %3, %1 \n\t"
"cmp    %1, %0 \n\t"
"cmovg  %1, %0 \n\t"
:"+&r"(i), "+&r"(a)
:"r"(b), "r"(c)
);
return i;
}

#if HAVE_6REGS
#define COPY3_IF_LT(x, y, a, b, c, d)\
__asm__ volatile(\
"cmpl  %0, %3       \n\t"\
"cmovl %3, %0       \n\t"\
"cmovl %4, %1       \n\t"\
"cmovl %5, %2       \n\t"\
: "+&r" (x), "+&r" (a), "+r" (c)\
: "r" (y), "r" (b), "r" (d)\
);
#endif /* HAVE_6REGS */

#endif /* HAVE_I686 */

#define MASK_ABS(mask, level)                   \
__asm__ ("cdq                    \n\t"      \
"xorl %1, %0            \n\t"      \
"subl %1, %0            \n\t"      \
: "+a"(level), "=&d"(mask))

// avoid +32 for shift optimization (gcc should do that ...)
#define NEG_SSR32 NEG_SSR32
static inline  int32_t NEG_SSR32( int32_t a, int8_t s){
if (__builtin_constant_p(s))
__asm__ ("sarl %1, %0\n\t"
: "+r" (a)
: "i" (-s & 0x1F)
);
else
__asm__ ("sarl %1, %0\n\t"
: "+r" (a)
: "c" ((uint8_t)(-s))
);
return a;
}

#define NEG_USR32 NEG_USR32
static inline uint32_t NEG_USR32(uint32_t a, int8_t s){
if (__builtin_constant_p(s))
__asm__ ("shrl %1, %0\n\t"
: "+r" (a)
: "i" (-s & 0x1F)
);
else
__asm__ ("shrl %1, %0\n\t"
: "+r" (a)
: "c" ((uint8_t)(-s))
);
return a;
}

#endif /* HAVE_INLINE_ASM */
#endif /* AVCODEC_X86_MATHOPS_H */

完美解决!!!