Package: libavcodec-dev
Version: 0.cvs20050626-2
Severity: important
Tags: patch
In the Debian package of ffmpeg, some MMX code parts are patched in order to
make it compile with -fPIC. Unfortunately one of the patches introduces a bug,
when trying to encode to MPEG.
This is the buggy patch for mpegvideo_mmx_template.c:
@@ -157,7 +168,14 @@
"psubw %%mm1, %%mm0 \n\t" // ABS(block[i])
"movq (%3, %%"REG_a"), %%mm6 \n\t" // bias[0]
"paddusw %%mm6, %%mm0 \n\t" // ABS(block[i]) + bias[0]
+#if defined(PIC) && !defined(ARCH_X86_64)
+ "push %%"REG_a" \n\t"
+ "movl %2, %%"REG_a" \n\t"
+ "movq (%%"REG_a", %%"REG_a"), %%mm5 \n\t" // qmat[i]
+ "pop %%"REG_a" \n\t"
+#else
"movq (%2, %%"REG_a"), %%mm5 \n\t" // qmat[i]
+#endif
"pmulhw %%mm5, %%mm0 \n\t" // (ABS(block[i])*qmat[0]
+ bias[0]*qmat[0])>>16
"por %%mm0, %%mm4 \n\t"
"pxor %%mm1, %%mm0 \n\t"
@@ -179,7 +197,11 @@
REG_a can't be reused here, a different register has to be taken to get the
operand from memory instead of from the register, which is not available with
-fPIC.
I've solved this by using REG_b, which needs to be defined in mmx.h, so the
correct patch looks like this:
@@ -157,7 +168,14 @@
"psubw %%mm1, %%mm0 \n\t" // ABS(block[i])
"movq (%3, %%"REG_a"), %%mm6 \n\t" // bias[0]
"paddusw %%mm6, %%mm0 \n\t" // ABS(block[i]) + bias[0]
+#if defined(PIC) && !defined(ARCH_X86_64)
+ "push %%"REG_b" \n\t"
+ "movl %2, %%"REG_b" \n\t"
+ "movq (%%"REG_b", %%"REG_a"), %%mm5 \n\t" // qmat[i]
+ "pop %%"REG_b" \n\t"
+#else
"movq (%2, %%"REG_a"), %%mm5 \n\t" // qmat[i]
+#endif
"pmulhw %%mm5, %%mm0 \n\t" // (ABS(block[i])*qmat[0]
+ bias[0]*qmat[0])>>16
"por %%mm0, %%mm4 \n\t"
"pxor %%mm1, %%mm0 \n\t"
See the difference? Here is the complete patch:
--- ffmpeg-0.cvs20050626.orig/libavcodec/i386/mmx.h
+++ ffmpeg-0.cvs20050626/libavcodec/i386/mmx.h
@@ -9,6 +9,9 @@
# define REG_a "rax"
#else
# define REG_a "eax"
+# if defined(PIC)
+# define REG_b "ebx"
+# endif
#endif
/*
--- ffmpeg-0.cvs20050626.orig/libavcodec/i386/mpegvideo_mmx_template.c
+++ ffmpeg-0.cvs20050626/libavcodec/i386/mpegvideo_mmx_template.c
@@ -95,7 +95,14 @@
SPREADW(%%mm3)
"pxor %%mm7, %%mm7 \n\t" // 0
"pxor %%mm4, %%mm4 \n\t" // 0
+#if defined(PIC) && !defined(ARCH_X86_64)
+ "push %%"REG_a" \n\t"
+ "movl %2, %%"REG_a" \n\t"
+ "movq (%%"REG_a"), %%mm5 \n\t" // qmat[0]
+ "pop %%"REG_a" \n\t"
+#else
"movq (%2), %%mm5 \n\t" // qmat[0]
+#endif
"pxor %%mm6, %%mm6 \n\t"
"psubw (%3), %%mm6 \n\t" // -bias[0]
"mov $-128, %%"REG_a" \n\t"
@@ -128,7 +135,11 @@
"movd %%mm3, %%"REG_a" \n\t"
"movzb %%al, %%"REG_a" \n\t" // last_non_zero_p1
: "+a" (last_non_zero_p1)
+#if defined(PIC) && !defined(ARCH_X86_64)
+ : "r" (block+64), "m" (qmat), "r" (bias),
+#else
: "r" (block+64), "r" (qmat), "r" (bias),
+#endif
"r" (inv_zigzag_direct16+64), "r" (temp_block+64)
);
// note the asm is split cuz gcc doesnt like that many operands ...
@@ -157,7 +168,14 @@
"psubw %%mm1, %%mm0 \n\t" // ABS(block[i])
"movq (%3, %%"REG_a"), %%mm6 \n\t" // bias[0]
"paddusw %%mm6, %%mm0 \n\t" // ABS(block[i]) + bias[0]
+#if defined(PIC) && !defined(ARCH_X86_64)
+ "push %%"REG_b" \n\t"
+ "movl %2, %%"REG_b" \n\t"
+ "movq (%%"REG_b", %%"REG_a"), %%mm5 \n\t" // qmat[i]
+ "pop %%"REG_b" \n\t"
+#else
"movq (%2, %%"REG_a"), %%mm5 \n\t" // qmat[i]
+#endif
"pmulhw %%mm5, %%mm0 \n\t" // (ABS(block[i])*qmat[0]
+ bias[0]*qmat[0])>>16
"por %%mm0, %%mm4 \n\t"
"pxor %%mm1, %%mm0 \n\t"
@@ -179,7 +197,11 @@
"movd %%mm3, %%"REG_a" \n\t"
"movzb %%al, %%"REG_a" \n\t" // last_non_zero_p1
: "+a" (last_non_zero_p1)
+#if defined(PIC) && !defined(ARCH_X86_64)
+ : "r" (block+64), "m" (qmat+64), "r" (bias+64),
+#else
: "r" (block+64), "r" (qmat+64), "r" (bias+64),
+#endif
"r" (inv_zigzag_direct16+64), "r" (temp_block+64)
);
// note the asm is split cuz gcc doesnt like that many operands ...
bye,
Tobias
-- System Information:
Debian Release: 3.1
APT prefers testing
APT policy: (500, 'testing')
Architecture: i386 (i686)
Shell: /bin/sh linked to /bin/bash
Kernel: Linux 2.6.11-1-tobi
Locale: [EMAIL PROTECTED], [EMAIL PROTECTED] (charmap=ISO-8859-15)
Versions of packages libavcodec-dev depends on:
ii liba52-0.7.4-dev [liba5 0.7.4-1 Development library and headers fo
ii libdc1394-11-dev 1.0.0-4 high level programming interface f
ii libdts-dev 0.0.2-svn-1 development files for libdts
ii libogg-dev 1.1.2-1 Ogg Bitstream Library Development
ii libraw1394-dev 0.10.1-1.1 library for direct access to IEEE
ii libtheora-dev 0.0.0.alpha4-1.1 The Theora Video Compression Codec
ii libvorbis-dev 1.1.0-1 The Vorbis General Audio Compressi
ii zlib1g-dev 1:1.2.2-4 compression library - development
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