Cross-Compile alsa-lib and alsa-utils to Android

Walkthrough

1) Download the git repoitory

git clone https://<username>@bitbucket.org/devnullians/latent_variable.git

2) Compile alsa-lib and test/latency

$ cd <YOUR_SYSTEM_PATH>/latent_variable/alsa/alsa-lib-1.1.0/

$ export PATH=<YOUR_SYSTEM_PATH>/latent_variable/alsa/toolchain/bin/:$PATH
$ export CC=arm-linux-androideabi-gcc 
$ export CXX=arm-linux-androideabi-g++
$ export LD_LIBRARY_PATH=<YOUR_SYSTEM_PATH>/latent_variable/alsa/alsa-lib-1.1.0/src/.libs/

$ CC=arm-linux-androideabi-gcc CFLAGS=-fPIC LDFLAGS=-pie ./configure --host=arm-linux --enable-shared=yes --enable-static=no --disable-python
$ make
$ cd test/
$ make latency

3) Compile alsa-util (and aplay)

$ cd <YOUR_SYSTEM_PATH>/latent_variable/alsa/alsa-utils-1.1.0/

$ CC=arm-linux-androideabi-gcc CFLAGS=-fPIC LDFLAGS=-pie ./configure --host=arm-linux --prefix=/data --with-alsa-inc-prefix=<YOUR_SYSTEM_PATH>/latent_variable/alsa/alsa-lib-1.1.0/include --with-alsa-prefix=<YOUR_SYSTEM_PATH>/latent_variable/alsa/alsa-lib-1.1.0/src/.libs --disable-alsamixer --disable-xmlto --disable-nls --disable-bat

$ make

4) Copy the relevant binaries to the phone (via griffin.ini.cmu.edu)

$ cd <YOUR_SYSTEM_PATH>/latent_variable/alsa/alsa-lib-1.1.0/
$ scp test/.libs/latency devnullian@griffin.ini.cmu.edu:workbench/sandbox
$ scp src/.libs/libasound.so.2.0.0 devnullian@griffin.ini.cmu.edu:workbench/sandbox

$ cd <YOUR_SYSTEM_PATH>/latent_variable/alsa/alsa-utils-1.1.0/
$ scp aplay/aplay devnullian@griffin.ini.cmu.edu:workbench/sandbox/

4.1) (while on griffin.ini.cmu.edu)

$ cd workbench
$ adb push sandbox /sdcard/sandbox/
$ adb shell
$ su root
$ cp /sdcard/sandbox/ /data/
$ cd /data/
$ chmod 765 latency
$ chmod 765 aplay
$ chmod 765 libasound.so.2.0.0
$ ln -s libasound.so.2.0.0 libasound.so.2
$ mkdir share/alsa
$ cp alsa.conf share/alsa

5) Run the applications (on the phone)

$ export LD_LIBRARY_PATH=/data
$ ./latency -P "hw:0,0" -C "hw:0,0" -r 44100 -m 128 -M 128 -p -s 1

WARNING: linker: ./latency: unused DT entry: type 0x1d arg 0x505
WARNING: linker: ./latency: unused DT entry: type 0x6ffffffe arg 0xd3c
WARNING: linker: ./latency: unused DT entry: type 0x6fffffff arg 0x1
Scheduler set to Round Robin with priority 99...
Playback device is hw:0,0
Capture device is hw:0,0
Parameters are 44100Hz, S16_LE, 2 channels, non-blocking mode
Poll mode: yes
Loop limit is 44100 frames, minimum latency = 128, maximum latency = 128
Playback open error: Invalid argument

IMPORTANT: to get ./latency to work, make sure you don't have the 64 bit version of libasound2-plugins installed. You should only have libasound2-plugins:i386, which you can install using the following command:

$ apt-get purge libasound2-plugins
$ apt-get install libasound2-plugins:i386

Just to be safe, add the path to the 32 bit ALSA libraries to the LD_LIBRARY_PATH:

$ export LD_LIBRARY_PATH=<PATH_TO_libasound_module_conf_pulse.so>

$ ./aplay -l

WARNING: linker: ./aplay: unused DT entry: type 0x6ffffffe arg 0x1d20
WARNING: linker: ./aplay: unused DT entry: type 0x6fffffff arg 0x1
**** List of PLAYBACK Hardware Devices ****
card 0: msm8226tapan930 [msm8226-tapan9302-snd-card], device 0: MultiMedia1 (*) []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: msm8226tapan930 [msm8226-tapan9302-snd-card], device 1: MultiMedia2 (*) []
  Subdevices: 1/1
  Subdevice #0: subdevice #0

(...)

$ ./aplay -L

WARNING: linker: ./aplay: unused DT entry: type 0x6ffffffe arg 0x1d20
WARNING: linker: ./aplay: unused DT entry: type 0x6fffffff arg 0x1
null
    Discard all samples (playback) or generate zero samples (capture)

What's next?

alsa-lib/test/latency still doesn't run successfully on the Moto G. A (work-in-progress) solution is presented in this page.

UPDATE 1 : 2015-11-30

As an alternative to manual cross-compilation, you can build an image of CyanogenMod which includes ALSA-like tools.

tinyalsa

Instead of a 'full-fledged' ALSA lib, Cyanogen uses a stripped-down version called tinyalsa. Besides providing a compact PCM API (similar to alsa-lib), it also provides a set of utilities: * tinyplay: eq. to aplay -D * tinycap: eq. to arecord -D * tinypcminfo: eq. to aplay -L

Enable tinyalsa utils in Cyanogen build

In the Cyanogen sources, the code for external libraries like tynialsa can be found in the external/ directory (relative to Cyanogen's main build folder, in our repo that would be cyanogenmod/android/system/). Each one of these folders has an Android.mk file, in which you can find statements like this:

include $(CLEAR_VARS)
LOCAL_C_INCLUDES:= external/tinyalsa/include
LOCAL_SRC_FILES:= tinyplay.c
LOCAL_MODULE := tinyplay
LOCAL_SHARED_LIBRARIES:= libcutils libutils libtinyalsa
LOCAL_MODULE_TAGS := optional

include $(BUILD_EXECUTABLE)

Note how LOCAL_MODULE_TAGS is set to 'optional'. In order to make tinyaplay appear as a built-in application which can be run directly from the phone's CLI, you need to mark it for compilation and installation in /system/bin/. To do so, edit the file vendor/motorola/msm8226-common/msm8226-common-vendor.mk and add the desired tinyalsa LOCAL_MODULES (should this be done after running breakfast ?):

# Pick up overlay for features that depend on non-open-source files
PRODUCT_PACKAGES += \
    com.qualcomm.location \
    com.qualcomm.services.location \
    MotGeoFenceSvc \
    TimeService \
    qcrilmsgtunnel \
    qcnvitems \
    qcrilhook \
    libHevcSwDecoder \
    tinyplay \
    tinypcminfo \
    tinycap

Building Cyanogen and installing image on the Moto G

After this, just run the setup script again, and wait for the image to compile.

$ cd <YOUR_SYSTEM_PATH>/latent_variable/cyanogenmod/
$ setup -b

The image shall be available as a .zip file in cyanogenmod/android/system/out/target/product/peregrine/. Copy it to the Moto G's SD card:

$ cd <YOUR_SYSTEM_PATH>/latent_variable/cyanogenmod/android/system/out/target/product/peregrine/
$ export PATH=$PATH:~/Android/Sdk/platform-tools
$ adb push cm-12.1-20151130-UNOFFICIAL-peregrine.zip /sdcard

TBC

Wiki

latent_variable / Cross-compile alsa-lib and alsa-utils to Android