iOS webRTC library supporting both armv7 & arm64

Question

How can I get the webRTC library which will support for both armv7 & arm64 in iOS?

Denise

Answer 1

You are lucky. I have just finished to integrate webrtc in my project for couple days. My solution as below:

1. Combine all *.a you built for armv7 to libWebRTC-armv7.a: Using command lines as below

   libtool -static -o src/out_ios_armv7/Release-iphoneos/libWebRTC-temp.a src/out_ios_armv7/Release-iphoneos/*.a

   strip -S -x -o src/out_ios_armv7/Release-iphoneos/libWebRTC-armv7.a -r src/out_ios_armv7/Release-iphoneos/libWebRTC-temp.a

2. Combine all *.a you built for arm64 to libWebRTC-arm64.a:

   libtool -static -o src/out_ios/Release-iphoneos/libWebRTC-temp.a src/out_ios/Release-iphoneos/*.a

   strip -S -x -o src/out_ios/Release-iphoneos/libWebRTC-arm64.a -r src/out_ios/Release-iphoneos/libWebRTC-temp.a

3. Create your libWebRTC supported both armv7 and arm64:

   lipo -create src/out_ios_armv7/Release-iphoneos/libWebRTC-armv7.a src/out_ios/Release-iphoneos/libWebRTC-arm64.a -output libWebRTC.a

P.s: Just build your armv7 library to separated folder with arm64:

export GYP_GENERATORS="ninja"
export GYP_DEFINES="build_with_libjingle=1 build_with_chromium=0 libjingle_objc=1 OS=ios target_arch=armv7"
export GYP_GENERATOR_FLAGS="$GYP_GENERATOR_FLAGS output_dir=out_ios_armv7"
export GYP_CROSSCOMPILE=1
pushd src
gclient runhooks
ninja -C out_ios_armv7/Release-iphoneos AppRTCDemo
popd

Biamonte

Answer 2

You can refer to our blog:

http://io.diveinedu.com/2015/02/02/%E7%AC%AC%E4%BA%94%E7%AB%A0-WebRTC%E7%9A%84iOS%E6%A1%86%E6%9E%B6%E7%BC%96%E8%AF%91.html

I have wrote a shell script to build WebRTC sources to a framework(excluding the apprtc signaling library) for iOS use.

If you cann't read Chinese, you just read that script embedded in that blog, it's enough! aha.

./build_webrtc.sh build_all

There may be a bug in armv7 device. that bug was caused by a stack over flow issue in VP8 decoding in armv7 neon function.

You can confirm this patch to fixes crash for it:

diff --git a/source/libvpx/vp8/common/arm/neon/vp8_subpixelvariance_neon.c b/source/libvpx/vp8/common/arm/neon/vp8_subpixelvariance_neon.c
index 8308d55..a66b6f5 100644
--- a/source/libvpx/vp8/common/arm/neon/vp8_subpixelvariance_neon.c
+++ b/source/libvpx/vp8/common/arm/neon/vp8_subpixelvariance_neon.c
@@ -1003,7 +1003,7 @@ unsigned int vp8_sub_pixel_variance8x8_neon(
         const unsigned char *dst,
         int dst_stride,
         unsigned int *sse) {
-  DECLARE_ALIGNED_ARRAY(kAlign16, uint8_t, temp2, kHeight8 * kWidth8);
+  DECLARE_ALIGNED_ARRAY(kAlign16, uint8_t, temp2, kHeight8PlusOne * kWidth8);
   DECLARE_ALIGNED_ARRAY(kAlign16, uint8_t, fdata3, kHeight8PlusOne * kWidth8);
   if (xoffset == 0) {
     var_filter_block2d_bil_w8(src, temp2, src_stride, kWidth8, kHeight8,

Wish this can help you!

The students of diveinedu.com have just overcome and fixed this bug.

Subcontinent

I have followed your tutorial, but when the script works on combining the libraries armv7 and arm64, there and error comes up that both libs can't be of the same structure. Also I tried running the arm64 build on iPhone 6 and iPad 3, the error I receive is of invalid architecture. – Nidifugous

Answer 3

thanks phuongle, this really works...

...but with a twist...

...as Omer Waqas Khan noticed, there might be a case where one might encounter the error message (while lipo-ing): both libs can't be of the same structure.

Of course, I went WTF...lipo, what's wrong with you...they are of different structure...I BUILT THEM THAT WAY...

But then I set out to double check it:
- I went in the folder where I had the arm64_merged lib and...

lipo -info lib's_name.a

It reported back of being of both armv7 and arm64 type. Puzzled, I then...

lipo -info *.a

...all the libraries (72 of them) reported being of type arm64 except for 2...

libisac_fix.a
libisac_neon.a

For whatever reason they were armv7. Earlier in the day, I was using a "a few days old" clone of the webrtc thingy. Back then, I remember always obtaining only 70 libraries. But then, for other reasons, I decided to

gclient sync

After that, I ended up with 72...as such, I just removed the libisac nonsense. Now the 2 fat_libs were of different types and I could successfully lipo.

Ceramic