[Libav-user] Reference app with ffmpeg n1.2 libs that works on IOS ?

[Will Price]

The gas linked below from the mansr github fork did not resolve this error
that occurs throughout the build process for ffmpeg for iOS:

Unable to identify target architecture at /usr/bin/gas-preprocessor.pl line
82.
AS libavcodec/arm/dsputil_arm.o
[and hundreds more like that afterwards...]

Yet, it sounds like Lars has gotten past that error somehow. I put the
mansr version of gas into both /usr/bin and /usr/local/bin just to be safe,
but no luck. I am sure that is the gas being used because if I introduce
intentional bugs in that script everything fails immediately. It sure feels
like a remaining bug in the gas script itself, but perhaps I'm missing
something?

The build completes even with those errors. The errors occur when building
armv7 and armv7s architectures, but not i386. It feels like this gas may
not understand armv7 vs armv7s?




> 2013/4/5 Alexey Belkevich
> >
> > On Friday, April 5, 2013 at 4:26 PM, Lars Hammarstrand wrote:
> > >
> > Got some new errors with the new gas-preprocessor. Full log at:
> > http://pastebin.com/wF4aZGis. Brief summary:
> > >
> > Version info - ffmpeg e820e3a (n1.2), gas-preprocessor
> > f4a42dc077 (Oct 03, 2012)
> > >
> > 1. LD ffmpeg_g ld: warning: ARM function not 4-byte aligned:
> > empty_row from libavcodec/libavcodec.a(jrevdct_arm.o) ld:
> > warning: ARM function not 4-byte aligned: end_of_row_loop from
> > libavcodec/libavcodec.a(jrevdct_arm.o) ld: warning: ARM
> > function not 4-byte aligned: start_column_loop from
> > libavcodec/libavcodec.a(jrevdct_arm.o) ld: warning: ARM
> > function not 4-byte aligned: column_loop from
> > libavcodec/libavcodec.a(jrevdct_arm.o) ld: warning: ARM
> > function not 4-byte aligned: empty_odd_column from
> > libavcodec/libavcodec.a(jrevdct_arm.o) ld: warning: ARM
> > function not 4-byte aligned: the_end from
> > libavcodec/libavcodec.a(jrevdct_arm.o) ld: warning: ARM
> > function not 4-byte aligned: __b_evaluation from
> > libavcodec/libavcodec.a(simple_idct_arm.o) ld: warning: ARM
> > function not 4-byte aligned: __end_b_evaluation from
> > libavcodec/libavcodec.a(simple_idct_arm.o) ld: warning: ARM
> > function not 4-byte aligned: __a_evaluation from
> > libavcodec/libavcodec.a(simple_idct_arm.o) ld: warning: ARM
> > function not 4-byte aligned: __almost_empty_row from
> > libavcodec/libavcodec.a(simple_idct_arm.o) ld: warning: ARM
> > function not 4-byte aligned: __end_row_loop from
> > libavcodec/libavcodec.a(simple_idct_arm.o) ld: warning: ARM
> > function not 4-byte aligned: __end_b_evaluation2 from
> > libavcodec/libavcodec.a(simple_idct_arm.o) ld: warning: ARM
> > function not 4-byte aligned: __a_evaluation2 from
> > libavcodec/libavcodec.a(simple_idct_arm.o) ld: warning: ARM
> > function not 4-byte aligned: __end_simple_idct_arm from
> > libavcodec/libavcodec.a(simple_idct_arm.o) ld: in
> > libavcodec/libavcodec.a(h264qpel_neon.o), in section
> > __TEXT,__text reloc 12: R_ABS reloc but no absolute symbol at
> > target address for architecture armv7 collect2: ld returned 1
> > exit status make: *** [ffmpeg_g] Error 1
> > >
> > Try updated gas-preprocessor -
> > https://github.com/mansr/gas-preprocessor.git It should fix
> > error with "R_ABS reloc"
> > >
> Success!!  Finally is the last piece of the root cause identified
> and solved :D *Big Smile*. I'm pretty sure this will solve the
> xbmc problem as well but let me come back with a final
> confirmation later on. Found also this link regarding the same
> error:
> http://ffmpeg.org/pipermail/ffmpeg-user/2012-December/012307.html
> . May I suggest one of the following changes regarding the
> gas-processor.pl: 1) Distribute a prepackaged version of
> gas-processor.pl that works, together with ffmpeg. 2) At the very
> least, update the docs (docs/platform.texi) regarding the
> gas-processor.p referense to
> "https://github.com/mansr/gas-preprocessor" and also add some
> controls to "Configure" that verifies that the correct version of
> gas-processor.pl is used. Personally, I would prefer point nr 1.
> And finally, many Big Thanks to all who helped and assisted with
> this problem, especially to Carl that came up with a lot of
> different ideas and managed to find the right track
> (gas-processor.pl) and to Alexey that found a solution to the
> last error. /Regards, Lars.
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