<heng.hu.1...@gmail.com> 于2024年4月26日周五 20:21写道：
>
> From: huheng <heng.hu.1...@gmail.com>
>
> rename old inline yuv2yuvX to yuv2yuv_X, to avoid conflicts with
> the names of standalone asm functions. When ffmpeg is compiled with
> --disable-x86asm, using the scale function will cause the video to
> be blurred. The reason is that when disable-x86asm, INLINE_MMXEXT
> is 1 and use_mmx_vfilter is 1, but c->yuv2planeX uses the c language
> version, which causes a problem of mismatch with the vfilter. This
> problem has persisted from version 4.4 to the present. Fix it by using
> inline yuv2yuv_X_mmxext, that can maintain the consistency of
> use_mmx_vfilter.
>
> reproduce the issue:
> 1. ./configure --disable-x86asm --enable-gpl --enable-libx264
> 2. ./ffmpeg -i input.mp4 -vf "scale=1280x720" -c:v libx264 output.mp4
> the output.mp4 is abnormal
>
> Signed-off-by: huheng <heng.hu.1...@gmail.com>
> ---
> libswscale/x86/swscale.c | 6 +++-
> libswscale/x86/swscale_template.c | 53 +++++++++++++++++++++++++++++++
> 2 files changed, 58 insertions(+), 1 deletion(-)
>
> diff --git a/libswscale/x86/swscale.c b/libswscale/x86/swscale.c
> index ff16398988..1bb9d1d51a 100644
> --- a/libswscale/x86/swscale.c
> +++ b/libswscale/x86/swscale.c
> @@ -452,8 +452,12 @@ av_cold void ff_sws_init_swscale_x86(SwsContext *c)
> int cpu_flags = av_get_cpu_flags();
>
> #if HAVE_MMXEXT_INLINE
> - if (INLINE_MMXEXT(cpu_flags))
> + if (INLINE_MMXEXT(cpu_flags)) {
> sws_init_swscale_mmxext(c);
> + if (c->use_mmx_vfilter && !(c->flags & SWS_ACCURATE_RND)) {
> + c->yuv2planeX = yuv2yuv_X_mmxext;
> + }
> + }
> #endif
> if(c->use_mmx_vfilter && !(c->flags & SWS_ACCURATE_RND)) {
> #if HAVE_MMXEXT_EXTERNAL
> diff --git a/libswscale/x86/swscale_template.c
> b/libswscale/x86/swscale_template.c
> index 6190fcb4fe..1b8794480d 100644
> --- a/libswscale/x86/swscale_template.c
> +++ b/libswscale/x86/swscale_template.c
> @@ -33,6 +33,59 @@
> #define MOVNTQ2 "movntq "
> #define MOVNTQ(a,b) REAL_MOVNTQ(a,b)
>
> +static void RENAME(yuv2yuv_X)(const int16_t *filter, int filterSize,
> + const int16_t **src, uint8_t *dest, int dstW,
> + const uint8_t *dither, int offset)
> +{
> + filterSize--;
> + __asm__ volatile(
> + "movd %0, %%mm1\n\t"
> + "punpcklwd %%mm1, %%mm1\n\t"
> + "punpckldq %%mm1, %%mm1\n\t"
> + "psllw $3, %%mm1\n\t"
> + "paddw %%mm1, %%mm3\n\t"
> + "paddw %%mm1, %%mm4\n\t"
> + "psraw $4, %%mm3\n\t"
> + "psraw $4, %%mm4\n\t"
> + ::"m"(filterSize)
> + );
> +
> + __asm__ volatile(\
> + "movq %%mm3, %%mm6\n\t"
> + "movq %%mm4, %%mm7\n\t"
> + "movl %3, %%ecx\n\t"
> + "mov %0, %%"FF_REG_d" \n\t"\
> + "mov (%%"FF_REG_d"), %%"FF_REG_S" \n\t"\
> + ".p2align 4 \n\t" /*
> FIXME Unroll? */\
> + "1: \n\t"\
> + "movq 8(%%"FF_REG_d"), %%mm0 \n\t" /*
> filterCoeff */\
> + "movq (%%"FF_REG_S", %%"FF_REG_c", 2), %%mm2 \n\t" /*
> srcData */\
> + "movq 8(%%"FF_REG_S", %%"FF_REG_c", 2), %%mm5 \n\t" /*
> srcData */\
> + "add $16, %%"FF_REG_d" \n\t"\
> + "mov (%%"FF_REG_d"), %%"FF_REG_S" \n\t"\
> + "test %%"FF_REG_S", %%"FF_REG_S" \n\t"\
> + "pmulhw %%mm0, %%mm2 \n\t"\
> + "pmulhw %%mm0, %%mm5 \n\t"\
> + "paddw %%mm2, %%mm3 \n\t"\
> + "paddw %%mm5, %%mm4 \n\t"\
> + " jnz 1b \n\t"\
> + "psraw $3, %%mm3 \n\t"\
> + "psraw $3, %%mm4 \n\t"\
> + "packuswb %%mm4, %%mm3 \n\t"
> + MOVNTQ2 " %%mm3, (%1, %%"FF_REG_c")\n\t"
> + "add $8, %%"FF_REG_c" \n\t"\
> + "cmp %2, %%"FF_REG_c" \n\t"\
> + "movq %%mm6, %%mm3\n\t"
> + "movq %%mm7, %%mm4\n\t"
> + "mov %0, %%"FF_REG_d" \n\t"\
> + "mov (%%"FF_REG_d"), %%"FF_REG_S" \n\t"\
> + "jb 1b \n\t"\
> + :: "g" (filter),
> + "r" (dest-offset), "g" ((x86_reg)(dstW+offset)), "m" (offset)
> + : "%"FF_REG_d, "%"FF_REG_S, "%"FF_REG_c
> + );
> +}
> +
> #define YSCALEYUV2PACKEDX_UV \
> __asm__ volatile(\
> "xor %%"FF_REG_a", %%"FF_REG_a" \n\t"\
> --
> 2.20.1
>
Request for review and some additional information:
I found that when compiling ffmpeg with the '-disable-x86asm' option,
there is an issue with the scale function causing video distortion.
This issue is very easily reproducible. I used bisect to identify the
problem and found that it was introduced after commit 554c2bc7086f49.
This commit moved the inline assembly function yuv2yuvX_sse3 to
standalone assembly, which broke the scale function under the
'disable-x86asm' option. My patch restores the original inline
assembly code under the 'disable-x86asm' option, fixing this issue.
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