From: 卜弋天
Sent: Monday, February 27, 2012 5:33 PM
To: [email protected]
Subject: Re: [Libav-user] question about libavcodec
Hi Experts:
plase help, thanks very much.
Best Regards
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From: [email protected]
To: [email protected]
Subject: question about libavcodec
Date: Sun, 26 Feb 2012 22:19:38 +0800
Hi experts:
i have some questions about the libavcodec.so:
1. when compiling, how can i specify this library is compiled for ARM? and
it includes NEON instruction supports?
run configure �Chelp or search in google
2. suppose ARCH_ARM and HAVE_NEON are defined, which i mentioned in
question 1, does it mean this library can only be executed on ARM platform and
the chipset must have NEON module?
yes
3. suppose the answer of quesion 2 is yes, then how can user choose
libavcodec.so as they want? for example, there is an Android application
"ROAMSAVE", it will use libavcodec.so, then how can i choose a suitable version
libavcodec.so for roamsave? suppose i do not have any source code, and just
want to download this library from internet?
ask your mentor
4. if the appl ication roamsave together with a specific libavcodec run
well on Samsung smart phone, and i am sure this version libavcodec support ARM
and execute NEON instruction. but when i use them on another smart
phone(Motorola), it crashs in libavcodec.so, the problem is alignment of second
parameter of function ff_scalarproduct_int16_neon(), how can i find the root
cause?the libavcodec runs NEON instruction well on Samsumg phone, so it means
this library compiled with correct GCC version and can handle stack alignment
well , right? but why it crashs because of alignment problem when run on
another smart phone which also support NEON instruction? i am very confused
about this issue, please help me, thanks very much.
recompile for motor and try it again.
Best Regards
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