ffmpeg build is trying to compile 'neon' although this instruction set is disabled @ ./configure ( '--disable-neon' )

[nadavrub]

Environment

OS	Ubuntu 11.10
RELEASE	0.10.2.git
Platform	Android
neon	--disable-neon
optimizations	--disable-optimizations

Problem

Problem	ffmpeg build is trying to compile 'neon' although this instruction set is disabled @ ./configure ( '--disable-neon' )
Symptom	libavcodec/libavcodec.so: undefined reference to `ff_pred16x16_vert_neon' ...
Analysis	The problem is in affect ONLY when compiling with '--disable-optimizations', going though the code, at multiple places the line 'if (HAVE_NEON)' is used, my assumption is that when the optimizer is on, the 'if (HAVE_NEON)' phrases are omitted from compilation, and, when the optimization is disabled, they ( neon phrases ) are not, and thus, the import table for neon instructions @ 'if (false)' phrases is added the neon instructions ( although they are not used by the code ), and this, leads to the undefined reference linker error.

[nadavrub]

One additional comment, using '--disable-optimizations' with ffmpeg@Android is mandatory so I'll B able to step through ffmpeg code while debugging on the device.

[Carl Eugen Hoyos]

Which compiler and version are you using?

The error message you provide does not match the configure options you mentioned.

Please provide your configure line and please run make, run make again, then run "make V=1" and post the complete output (please do not post the complete output of the first make run).

[nadavrub]

compiler

The one provided with NDK7B ( arm-linux-androideabi-4.4.3 )

configure

../../Multimedia/ffmpeg/configure \
--logfile="configure.log" \
--cross-prefix=arm-linux-androideabi- \
--arch=arm \
--target-os=linux \
--disable-everything \
--disable-pthreads \
--disable-stripping \
--enable-debug=3 \
--enable-version3 \
--enable-libx264 \
--enable-demuxer=mov \
--enable-demuxer=rtsp \
--enable-muxer=asf \
--enable-muxer=asf_stream \
--enable-muxer=mov \
--enable-muxer=mp4 \
--enable-muxer=ffm \
--enable-encoder=h264 \
--enable-decoder=h264 \
--enable-demuxer=ffm \
--enable-parser=h264 \
--enable-protocol=file \
--enable-protocol=rtp \
--enable-nonfree \
--enable-gpl \
--enable-postproc \
--extra-cflags="-I/home/nadav/workspace/Android/x264 -I/home/nadav/workspace/Multimedia/x264 -gstabs+" \
--extra-ldflags="-L/home/nadav/workspace/Android/x264" \
--enable-static \
--enable-shared \
--disable-neon \
--disable-optimizations

make V=1

arm-linux-androideabi-gcc -Llibavcodec -Llibavdevice -Llibavfilter -Llibavformat -Llibavutil -Llibpostproc -Llibswscale -Llibswresample -L/home/nadav/workspace/Android/x264 -Wl,--as-needed -Wl,--warn-common -Wl,-rpath-link=libpostproc:libswresample:libswscale:libavfilter:libavdevice:libavformat:libavcodec:libavutil -o ffmpeg_g ffmpeg.o cmdutils.o -lavdevice -lavfilter -lavformat -lavcodec -lpostproc -lswresample -lswscale -lavutil -lx264 -lm -lz

undefined reference

libavcodec/libavcodec.so: undefined reference to `ff_pred16x16_vert_neon'
libavcodec/libavcodec.so: undefined reference to `ff_pred8x8_l0t_dc_neon'
libavcodec/libavcodec.so: undefined reference to `ff_biweight_h264_pixels_4_neon'
libavcodec/libavcodec.so: undefined reference to `ff_pred16x16_left_dc_neon'
libavcodec/libavcodec.so: undefined reference to `ff_h264_idct_add16_neon'
libavcodec/libavcodec.so: undefined reference to `ff_h264_idct8_add4_neon'
libavcodec/libavcodec.so: undefined reference to `ff_pred8x8_dc_neon'
libavcodec/libavcodec.so: undefined reference to `ff_pred8x8_0l0_dc_neon'
libavcodec/libavcodec.so: undefined reference to `ff_h264_v_loop_filter_luma_neon'
libavcodec/libavcodec.so: undefined reference to `ff_pred8x8_top_dc_neon'
libavcodec/libavcodec.so: undefined reference to `ff_biweight_h264_pixels_16_neon'
libavcodec/libavcodec.so: undefined reference to `ff_pred8x8_0lt_dc_neon'
libavcodec/libavcodec.so: undefined reference to `ff_pred8x8_hor_neon'
libavcodec/libavcodec.so: undefined reference to `ff_pred8x8_128_dc_neon'
libavcodec/libavcodec.so: undefined reference to `ff_pred8x8_plane_neon'
libavcodec/libavcodec.so: undefined reference to `ff_pred16x16_hor_neon'
libavcodec/libavcodec.so: undefined reference to `ff_weight_h264_pixels_8_neon'
libavcodec/libavcodec.so: undefined reference to `ff_biweight_h264_pixels_8_neon'
libavcodec/libavcodec.so: undefined reference to `ff_h264_v_loop_filter_chroma_neon'
libavcodec/libavcodec.so: undefined reference to `ff_pred16x16_top_dc_neon'
libavcodec/libavcodec.so: undefined reference to `ff_pred16x16_dc_neon'
libavcodec/libavcodec.so: undefined reference to `ff_weight_h264_pixels_4_neon'
libavcodec/libavcodec.so: undefined reference to `ff_pred8x8_left_dc_neon'
libavcodec/libavcodec.so: undefined reference to `ff_pred16x16_128_dc_neon'
libavcodec/libavcodec.so: undefined reference to `ff_h264_h_loop_filter_luma_neon'
libavcodec/libavcodec.so: undefined reference to `ff_pred8x8_vert_neon'
libavcodec/libavcodec.so: undefined reference to `ff_h264_idct_add8_neon'
libavcodec/libavcodec.so: undefined reference to `ff_pred8x8_l00_dc_neon'
libavcodec/libavcodec.so: undefined reference to `ff_h264_idct8_add_neon'
libavcodec/libavcodec.so: undefined reference to `ff_h264_idct_add16intra_neon'
libavcodec/libavcodec.so: undefined reference to `ff_h264_idct_dc_add_neon'
libavcodec/libavcodec.so: undefined reference to `ff_pred16x16_plane_neon'
libavcodec/libavcodec.so: undefined reference to `ff_h264_idct_add_neon'
libavcodec/libavcodec.so: undefined reference to `ff_weight_h264_pixels_16_neon'
libavcodec/libavcodec.so: undefined reference to `ff_h264_h_loop_filter_chroma_neon'
libavcodec/libavcodec.so: undefined reference to `ff_h264_idct8_dc_add_neon'

[Carl Eugen Hoyos]

Could you test if attached patch makes any difference?

[nadavrub]

~/workspace/Multimedia/ffmpeg$ patch -p1 -i patchneondsp.diff
patching file libavcodec/arm/h264dsp_init_arm.c
Hunk #1 succeeded at 68 (offset 1 line).
Hunk #2 FAILED at 96.
1 out of 2 hunks FAILED -- saving rejects to file libavcodec/arm/h264dsp_init_arm.c.rej
patching file libavcodec/arm/h264pred_init_arm.c
Hunk #1 succeeded at 43 (offset 1 line).
Hunk #2 FAILED at 74.
1 out of 2 hunks FAILED -- saving rejects to file libavcodec/arm/h264pred_init_arm.c.rej

Also, attached, 'h264dsp_init_arm.c.rej' and 'h264pred_init_arm.c.rej'

[Carl Eugen Hoyos]

Please test current git head with (and without) the patch.

[Carl Eugen Hoyos]

Could you test if this problem is still reproducible?
Build problems can be important, but this is unlikely to get fixed without some help (I don't have an arm environment).

[Mike Z]

similar patch against git head

[Mike Z]

with this patch applied, --enable-optimize works, --enable-optimise --disable-neon also works.

This is the config line, which is about the simplest I could manage and have it build:

--prefix=/home/notzed/svn/ffmpeg-build/build/armeabi-v7a --cross-prefix=/usr/local/android-ndk-r7c/toolchains/arm-linux-androideabi-4.4.3/prebuilt/linux-x86/bin/arm-linux-androideabi- --enable-cross-compile --target-os=linux --sysroot=/usr/local/android-ndk-r7c/platforms/android-8/arch-arm/ --arch=arm --disable-optimizations

[Carl Eugen Hoyos]

Replying to notzed:

with this patch applied, --enable-optimize works, --enable-optimise --disable-neon also works.

--enable-optimize ?

Your patch adds an externally visible symbol, does my new patch work for you?

[Mike Z]

Sure it does - it was copying the patch you provided: https://ffmpeg.org/trac/ffmpeg/attachment/ticket/1241/patchneondsp.diff

The new patch also works.

[Michael Niedermayer]

Which patch fixes what ?
ive tested several patches and configurations on NDK and none fixed anything.

[Michael Niedermayer]

update summary based on dscription of the original report

[Mike Z]

Sorry I mean to update this a while ago but I couldn't find the bug number.

Without the patchneondsp2 diff, the command line i gave fails to build, with those neon_* symbols missing. With the patch it succeeds.

But I actually wanted neon turned on, so my case was slightly different, sorry if i just confused the matter by trying to help.

[Michael Niedermayer]

Replying to notzed:

Without the patchneondsp2 diff, the command line i gave fails to build, with those neon_* symbols missing. With the patch it succeeds.

thanks, ive been able to reproduce and fix the issue