GNU Radio on Android

Hi,

Has a patched version of GNU Radio which runs on Android been released?

I’m working on a project where I’m transmitting information over audio
from a desktop system to an Android device, and since setting up the
transmitter end with GNU Radio was such a snap I would love to leverage
the GNU Radio system to build the receiver as well.

Thanks,
Vijay

On Fri, Mar 13, 2015 at 5:04 PM, Vijay G. [email protected]
wrote:

Vijay

Just yesterday, in fact:

http://gnuradio.org/redmine/projects/gnuradio/wiki/Android

I’ll try to release some of my apps soon. One of them captures from the
audio device, even. It’s not too hard since there’s the gr-grand opensl
audio source block to talk to the audio system.

Tom

Thanks for the quick reply Tom! I’ll start with this right away. Looking
forward to seeing your apps when you get a chance.

Thanks again,

Vijay

From: [email protected] [mailto:[email protected]] On Behalf Of
Tom
Rondeau
Sent: March-13-15 14:41
To: Vijay G.
Cc: GNURadio D.ion List
Subject: Re: [Discuss-gnuradio] GNU Radio on Android

On Fri, Mar 13, 2015 at 5:04 PM, Vijay G. [email protected]
wrote:

Hi,

Has a patched version of GNU Radio which runs on Android been released?

I’m working on a project where I’m transmitting information over audio
from a desktop system to an Android device, and since setting up the
transmitter end with GNU Radio was such a snap I would love to leverage
the GNU Radio system to build the receiver as well.

Thanks,
Vijay

Just yesterday, in fact:

http://gnuradio.org/redmine/projects/gnuradio/wiki/Android

I’ll try to release some of my apps soon. One of them captures from the
audio device, even. It’s not too hard since there’s the gr-grand opensl
audio source block to talk to the audio system.

Tom

On Mon, Mar 16, 2015 at 3:28 AM, Vijay G. [email protected]
wrote:

the shared library build:

Any tips appreciated,
Vijay

Yep, you have to add all of the libraries into the Android.mk file. I’ve
updated the wiki:

http://gnuradio.org/redmine/projects/gnuradio/wiki/GRAndApps

You can go there and simply download GrAndroid.mk that does all of this
for
you and include it in your Android.mk file. Just follow the
instructions.

Hope that helps,

Tom

Hi Tom,

I have been following your notes on the wiki in an attempt to build a
test
app (a dial tone flowgraph.) I’m hitting a snag on the ndk-build step
though – when I use your example Android.mk listing, the linker isn’t
finding any of the static libraries we built (gnuradio, grand, boost,
fftw.)
Instead I’m getting a pile of undefined reference errors.

I tried editing the example Android.mk file by adding the following
before
the shared library build:

include $(CLEAR_VARS)
LOCAL_MODULE := grand_static_lib #for example
LOCAL_SRC_FILES := /opt/grandroid/lib/libgnuradio-grand.a
include $(PREBUILT_STATIC_LIBRARY)

However I quickly realised that while there are only a few gnuradio
libraries to add this way, there are a ton of boost libraries… Is
there a
smarter way to add all the prebuilt .a libraries at once? Or am I headed
in
the wrong direction entirely?

Any tips appreciated,
Vijay

From: [email protected] [mailto:[email protected]] On Behalf Of
Tom
Rondeau
Sent: March-13-15 14:41
To: Vijay G.
Cc: GNURadio D.ion List
Subject: Re: [Discuss-gnuradio] GNU Radio on Android

On Fri, Mar 13, 2015 at 5:04 PM, Vijay G. [email protected]
wrote:
Hi,

Has a patched version of GNU Radio which runs on Android been released?

I’m working on a project where I’m transmitting information over audio
from a desktop system to an Android device, and since setting up the
transmitter end with GNU Radio was such a snap I would love to leverage
the GNU Radio system to build the receiver as well.

Thanks,
Vijay

Just yesterday, in fact:

http://gnuradio.org/redmine/projects/gnuradio/wiki/Android

I’ll try to release some of my apps soon. One of them captures from the
audio device, even. It’s not too hard since there’s the gr-grand opensl
audio source block to talk to the audio system.

Tom

Thanks Tom, that sorted it out. My audio output is a bit choppy but no
matter – time to move on to some more complex flowgraphs in my Android
app.

Thanks again,
Vijay

From: [email protected] [mailto:[email protected]] On Behalf Of
Tom
Rondeau
Sent: March-16-15 06:37
To: Vijay G.
Cc: GNURadio D.ion List
Subject: Re: [Discuss-gnuradio] GNU Radio on Android

On Mon, Mar 16, 2015 at 3:28 AM, Vijay G. [email protected]
wrote:
Hi Tom,

I have been following your notes on the wiki in an attempt to build a
test
app (a dial tone flowgraph.) I’m hitting a snag on the ndk-build step
though – when I use your example Android.mk listing, the linker isn’t
finding any of the static libraries we built (gnuradio, grand, boost,
fftw.)
Instead I’m getting a pile of undefined reference errors.

I tried editing the example Android.mk file by adding the following
before
the shared library build:

include $(CLEAR_VARS)
LOCAL_MODULE := grand_static_lib #for example
LOCAL_SRC_FILES := /opt/grandroid/lib/libgnuradio-grand.a
include $(PREBUILT_STATIC_LIBRARY)

However I quickly realised that while there are only a few gnuradio
libraries to add this way, there are a ton of boost libraries… Is
there a
smarter way to add all the prebuilt .a libraries at once? Or am I headed
in
the wrong direction entirely?

Any tips appreciated,
Vijay

Yep, you have to add all of the libraries into the Android.mk file. I’ve
updated the wiki:

http://gnuradio.org/redmine/projects/gnuradio/wiki/GRAndApps

You can go there and simply download GrAndroid.mk that does all of this
for
you and include it in your Android.mk file. Just follow the
instructions.

Hope that helps,

Tom

From: [email protected] [mailto:[email protected]] On Behalf Of
Tom
Rondeau
Sent: March-13-15 14:41
To: Vijay G.
Cc: GNURadio D.ion List
Subject: Re: [Discuss-gnuradio] GNU Radio on Android
On Fri, Mar 13, 2015 at 5:04 PM, Vijay G. [email protected]
wrote:
Hi,

Has a patched version of GNU Radio which runs on Android been released?

I’m working on a project where I’m transmitting information over audio
from a desktop system to an Android device, and since setting up the
transmitter end with GNU Radio was such a snap I would love to leverage
the GNU Radio system to build the receiver as well.

Thanks,
Vijay

Just yesterday, in fact:

http://gnuradio.org/redmine/projects/gnuradio/wiki/Android

I’ll try to release some of my apps soon. One of them captures from the
audio device, even. It’s not too hard since there’s the gr-grand opensl
audio source block to talk to the audio system.

Tom

On Tue, Mar 17, 2015 at 12:10 AM, Vijay G. [email protected]
wrote:

Thanks Tom, that sorted it out. My audio output is a bit choppy but no
matter – time to move on to some more complex flowgraphs in my Android app.

Thanks again,
Vijay

Yes, the skipping in the audio output is a known bug, and apparently
known
to be difficult in Android. It’s going to take some kind of double
buffering to fix it at this level. I did not experience any problems
with
the audio source, though; I just saved it to a file, brought it back to
my
computer, and played it there and it sounded fine.

Tom

Tom,

What kind of sample rate / setup are you using for your opensl_source?
I’ve
set up a flowgraph that is just an opensl_source (sampling at 48kHz)
connected to a file sink, and when I play back the file through GRC on
my
desktop my audio is coming out pretty garbled, as if samples are being
dropped. I’ve also tried a couple other sampling rates (44.1kHz, 32kHz,
16kHz to name a few.) I’m using a Nexus 4 running Android 5.0.1. Pasted
below is some of my code.

Vijay

Flowgraph code:
JNIEXPORT void JNICALL
Java_com_example_grrecordmic_GrRecordMic_InitFlowgraph(JNIEnv* env,
jobject
thiz, jstring jsinkfilename)
{
int rate = 48000;
const char *sinkfilename = env->GetStringUTFChars(jsinkfilename, 0);

global_tb = gr::make_top_block("Record_Mic");

gr::grand::opensl_source::sptr micSource =

gr::grand::opensl_source::make(rate);
gr::blocks::file_sink::sptr fileSink =
gr::blocks::file_sink::make(sizeof(float), sinkfilename, false);

global_tb->connect(micSource, 0, fileSink, 0);

env->ReleaseStringUTFChars(jsinkfilename, sinkfilename);

}

From: [email protected] [mailto:[email protected]] On Behalf Of
Tom
Rondeau
Sent: March-17-15 07:37
To: Vijay G.
Cc: GNURadio D.ion List
Subject: Re: [Discuss-gnuradio] GNU Radio on Android

On Tue, Mar 17, 2015 at 12:10 AM, Vijay G. [email protected]
wrote:
Thanks Tom, that sorted it out. My audio output is a bit choppy but no
matter – time to move on to some more complex flowgraphs in my Android
app.

Thanks again,
Vijay

Yes, the skipping in the audio output is a known bug, and apparently
known
to be difficult in Android. It’s going to take some kind of double
buffering
to fix it at this level. I did not experience any problems with the
audio
source, though; I just saved it to a file, brought it back to my
computer,
and played it there and it sounded fine.

Tom

From: [email protected] [mailto:[email protected]] On Behalf Of
Tom
Rondeau
Sent: March-16-15 06:37
To: Vijay G.
Cc: GNURadio D.ion List
Subject: Re: [Discuss-gnuradio] GNU Radio on Android

On Mon, Mar 16, 2015 at 3:28 AM, Vijay G. [email protected]
wrote:
Hi Tom,

I have been following your notes on the wiki in an attempt to build a
test
app (a dial tone flowgraph.) I’m hitting a snag on the ndk-build step
though – when I use your example Android.mk listing, the linker isn’t
finding any of the static libraries we built (gnuradio, grand, boost,
fftw.)
Instead I’m getting a pile of undefined reference errors.

I tried editing the example Android.mk file by adding the following
before
the shared library build:

include $(CLEAR_VARS)
LOCAL_MODULE := grand_static_lib #for example
LOCAL_SRC_FILES := /opt/grandroid/lib/libgnuradio-grand.a
include $(PREBUILT_STATIC_LIBRARY)

However I quickly realised that while there are only a few gnuradio
libraries to add this way, there are a ton of boost libraries… Is
there a
smarter way to add all the prebuilt .a libraries at once? Or am I headed
in
the wrong direction entirely?

Any tips appreciated,
Vijay

Yep, you have to add all of the libraries into the Android.mk file. I’ve
updated the wiki:

http://gnuradio.org/redmine/projects/gnuradio/wiki/GRAndApps

You can go there and simply download GrAndroid.mk that does all of this
for
you and include it in your Android.mk file. Just follow the
instructions.

Hope that helps,

Tom

From: [email protected] [mailto:[email protected]] On Behalf Of
Tom
Rondeau
Sent: March-13-15 14:41
To: Vijay G.
Cc: GNURadio D.ion List
Subject: Re: [Discuss-gnuradio] GNU Radio on Android
On Fri, Mar 13, 2015 at 5:04 PM, Vijay G. [email protected]
wrote:
Hi,

Has a patched version of GNU Radio which runs on Android been released?

I’m working on a project where I’m transmitting information over audio
from a desktop system to an Android device, and since setting up the
transmitter end with GNU Radio was such a snap I would love to leverage
the GNU Radio system to build the receiver as well.

Thanks,
Vijay

Just yesterday, in fact:

http://gnuradio.org/redmine/projects/gnuradio/wiki/Android

I’ll try to release some of my apps soon. One of them captures from the
audio device, even. It’s not too hard since there’s the gr-grand opensl
audio source block to talk to the audio system.

Tom

On Thu, Mar 19, 2015 at 3:28 AM, Vijay G. [email protected]
wrote:

audio
will be very choppy (dropped samples?)

Vijay

Ah, ok, that makes sense. I think I was just playing around with those
parameters and must have checked them in at that state.

I’ll make those updates to the repo.

Thanks.
Tom

On Wed, Mar 18, 2015 at 1:46 AM, Vijay G. [email protected]
wrote:

Vijay

gr::grand::opensl_source::sptr micSource =

gr::grand::opensl_source::make(rate);
gr::blocks::file_sink::sptr fileSink =
gr::blocks::file_sink::make(sizeof(float), sinkfilename, false);

global_tb->connect(micSource, 0, fileSink, 0);

env->ReleaseStringUTFChars(jsinkfilename, sinkfilename);

}

I believe that I used either 32k and/or 44.1k. I was using a Nexus 7,
though, and the codec might play a significant role with this between
the
two devices.

Perhaps try setting the file sink to unbuffered mode?

fileSink->set_unbuffered(true);

Frankly, I feel like this is unlikely to help, but it’ll be interesting
to
know what happens.

Tom

Tom,

As you expected, disabling buffering on the file sink did not have any
effect. I have fixed the issue though by making two changes to
opensl_source_impl.cc:

  1. change scale_factor to 32768 (1/2^14 doesn’t make sense, it causes
    clipping because the volk conversion method divides by scale_factor.)
  2. change buffer size (d_size) to 8k (2k was too small, tested
    32/44.1/48kHz
    on Nexus 4 and Nexus 7 2012 version.) Without this change the recorded
    audio
    will be very choppy (dropped samples?)

Vijay

From: [email protected] [mailto:[email protected]] On Behalf Of
Tom
Rondeau
Sent: March-18-15 07:11
To: Vijay G.
Cc: GNURadio D.ion List
Subject: Re: [Discuss-gnuradio] GNU Radio on Android

On Wed, Mar 18, 2015 at 1:46 AM, Vijay G. [email protected]
wrote:
Tom,

What kind of sample rate / setup are you using for your opensl_source?
I’ve
set up a flowgraph that is just an opensl_source (sampling at 48kHz)
connected to a file sink, and when I play back the file through GRC on
my
desktop my audio is coming out pretty garbled, as if samples are being
dropped. I’ve also tried a couple other sampling rates (44.1kHz, 32kHz,
16kHz to name a few.) I’m using a Nexus 4 running Android 5.0.1. Pasted
below is some of my code.

Vijay

Flowgraph code:
JNIEXPORT void JNICALL
Java_com_example_grrecordmic_GrRecordMic_InitFlowgraph(JNIEnv* env,
jobject
thiz, jstring jsinkfilename)
{
int rate = 48000;
const char *sinkfilename = env->GetStringUTFChars(jsinkfilename, 0);

global_tb = gr::make_top_block("Record_Mic");

gr::grand::opensl_source::sptr micSource =

gr::grand::opensl_source::make(rate);
gr::blocks::file_sink::sptr fileSink =
gr::blocks::file_sink::make(sizeof(float), sinkfilename, false);

global_tb->connect(micSource, 0, fileSink, 0);

env->ReleaseStringUTFChars(jsinkfilename, sinkfilename);

}

I believe that I used either 32k and/or 44.1k. I was using a Nexus 7,
though, and the codec might play a significant role with this between
the
two devices.

Perhaps try setting the file sink to unbuffered mode?

fileSink->set_unbuffered(true);

Frankly, I feel like this is unlikely to help, but it’ll be interesting
to
know what happens.

Tom

From: [email protected] [mailto:[email protected]] On Behalf Of
Tom
Rondeau
Sent: March-17-15 07:37
To: Vijay G.
Cc: GNURadio D.ion List
Subject: Re: [Discuss-gnuradio] GNU Radio on Android

On Tue, Mar 17, 2015 at 12:10 AM, Vijay G. [email protected]
wrote:
Thanks Tom, that sorted it out. My audio output is a bit choppy but no
matter – time to move on to some more complex flowgraphs in my Android
app.

Thanks again,
Vijay

Yes, the skipping in the audio output is a known bug, and apparently
known
to be difficult in Android. It’s going to take some kind of double
buffering
to fix it at this level. I did not experience any problems with the
audio
source, though; I just saved it to a file, brought it back to my
computer,
and played it there and it sounded fine.

Tom

From: [email protected] [mailto:[email protected]] On Behalf Of
Tom
Rondeau
Sent: March-16-15 06:37
To: Vijay G.
Cc: GNURadio D.ion List
Subject: Re: [Discuss-gnuradio] GNU Radio on Android

On Mon, Mar 16, 2015 at 3:28 AM, Vijay G. [email protected]
wrote:
Hi Tom,

I have been following your notes on the wiki in an attempt to build a
test
app (a dial tone flowgraph.) I’m hitting a snag on the ndk-build step
though – when I use your example Android.mk listing, the linker isn’t
finding any of the static libraries we built (gnuradio, grand, boost,
fftw.)
Instead I’m getting a pile of undefined reference errors.

I tried editing the example Android.mk file by adding the following
before
the shared library build:

include $(CLEAR_VARS)
LOCAL_MODULE := grand_static_lib #for example
LOCAL_SRC_FILES := /opt/grandroid/lib/libgnuradio-grand.a
include $(PREBUILT_STATIC_LIBRARY)

However I quickly realised that while there are only a few gnuradio
libraries to add this way, there are a ton of boost libraries… Is
there a
smarter way to add all the prebuilt .a libraries at once? Or am I headed
in
the wrong direction entirely?

Any tips appreciated,
Vijay

Yep, you have to add all of the libraries into the Android.mk file. I’ve
updated the wiki:

http://gnuradio.org/redmine/projects/gnuradio/wiki/GRAndApps

You can go there and simply download GrAndroid.mk that does all of this
for
you and include it in your Android.mk file. Just follow the
instructions.

Hope that helps,

Tom

From: [email protected] [mailto:[email protected]] On Behalf Of
Tom
Rondeau
Sent: March-13-15 14:41
To: Vijay G.
Cc: GNURadio D.ion List
Subject: Re: [Discuss-gnuradio] GNU Radio on Android
On Fri, Mar 13, 2015 at 5:04 PM, Vijay G. removed_email_addres[email protected]
wrote:
Hi,

Has a patched version of GNU Radio which runs on Android been released?

I’m working on a project where I’m transmitting information over audio
from a desktop system to an Android device, and since setting up the
transmitter end with GNU Radio was such a snap I would love to leverage
the GNU Radio system to build the receiver as well.

Thanks,
Vijay

Just yesterday, in fact:

http://gnuradio.org/redmine/projects/gnuradio/wiki/Android

I’ll try to release some of my apps soon. One of them captures from the
audio device, even. It’s not too hard since there’s the gr-grand opensl
audio source block to talk to the audio system.

Tom

Hi guys,

Still stuck, but some relevant details have changed that may help answer
my
question. So I’m trying to implement a sink block for gnuradio-android
that
takes integers on its input (not chars as I had erroneously written
before)
and stores the last ‘length’ items in a LIFO buffer; the buffer’s
contents
are written to an Android TextView object every time the block’s work
function is called. Following is the constructor I have written in order
to
pass this block the JNIEnv and jobject variables it needs in order to
access
the methods of my TextView instance:

stream_to_tv_sink_impl::stream_to_tv_sink_impl(JNIEnv *env, jobject 

jtv,
int length)
: gr::sync_block(“stream_to_tv_sink”,
gr::io_signature::make(1, 1, sizeof(int),
gr::io_signature::make(0, 0, 0)),
d_env(env),
d_jtv(jtv),
d_length(length)
{
d_buffer = new string[length];
for(int i = 0; i < length; i++) {
d_buffer[i] = “0”;
}
d_output = “Nothing yet…”;
jclass d_cls = env->GetObjectClass(jtv);
jmethodID d_mid = env->GetMethodID(d_cls, “setText”,
“(Ljava/lang/CharSequence;)V”);
}

And here is my work function:

int
stream_to_tv_sink_impl::work(int noutput_items,
    gr_vector_const_void_star &input_items,
    gr_vector_void_star &output_items)
{
    const int *in = (const int *) input_items[0];

    // Update LIFO
    for(int i = d_length - 1; i > 0; i--) {
        d_buffer[i] = d_buffer[i-1];
    }
    d_buffer[0] = to_string(in[0]);

    // Construct output string, newest >> oldest (left to right)
    d_output = d_buffer[0];
    for(int i = 1; i < d_length; i++) {
    d_output += " " + d_buffer[i];
    }

    // Display output string -- Invoke setText method
    d_env->CallVoidMethod(d_jtv, d_mid,

d_env->NewStringUTF(d_output.c_str())); // Might need to do this j times
for
j < noutput_items

    // Tell runtime system how many output items we produced.
    return noutput_items;
}

Where I am stuck is I cannot figure out how to come up with the
appropriate
makefile (using cmake or otherwise) to build this block into a prebuilt
static library so that I may use it in my Android flowgraph, as shown
for
example in the instructions for building GNU Radio for Android and GRAnd
at
https://gnuradio.org/redmine/projects/gnuradio/wiki/GRAndBuild. I don’t
have
much experience tinkering with cmake but I’ve been looking over the
cmake
files in GRAnd and the android fork of gnuradio and I can’t figure out
how
to properly link to the JNI library to build this thing – or if
statically
linking to JNI types and methods in this manner is even possible. If it
isn’t, I’m open to suggestions for alternative methods of displaying the
flowgraph’s end results in my Android app; at the moment my flowgraph
terminates in a file sink, and the app reads/displays a few entries from
the
file, but this not a good solution for when the flowgraph is running for
more than 10 or 15 seconds.

Any advice appreciated,
Vijay

On Sun, Mar 22, 2015 at 6:29 PM, Vijay G. [email protected]
wrote:

the methods of my TextView instance:
{
And here is my work function:
d_buffer[i] = d_buffer[i-1];
d_env->CallVoidMethod(d_jtv, d_mid,
static library so that I may use it in my Android flowgraph, as shown for
the
file, but this not a good solution for when the flowgraph is running for
more than 10 or 15 seconds.

Any advice appreciated,
Vijay

Hi Vijay,

So at this point I think you might be the person with the second most
experience with GNU Radio on Android and therefore the second most
qualified to answer the question :slight_smile:

I’m sitting in Android sessions at ELC right now, though, so I can’t go
into details really here. All I’ll say is to look closer at gr-grand.
Specifically, look at the float_array block that I wrote. It uses
jfloatArray and JNIEnv in creating this block, very much like how you
want
to handle your block. I might suggest adding your block (using
gr_modtool
add in your checkout of gr-grand) directly to gr-grand and try and build
it
there, since that CMake handles the necessary includes/libs/etc that you
need to get the linking to work. That might at least get you to a
buildable
block for your purposes. It might then help you understand what you need
to
do with your own OOT projects CMake files.

Tom

Hi guys,

I am attempting to write an OOT module to be implemented on Android and
am
finding myself out of my depth here.

As a first step I was able to make and execute my flowgraph on my
android
device following the instructions on the wiki, using a file sink to
store my
end result (demodulated string.)

Now I would like to create my own sink which takes char inputs and
updates a
TextView object as they are ‘spat out’ by the flowgraph. I followed the
general instructions on the wiki for coding an OOT module/object, so
gr_modtool generated all the boiler plate code and I have modified it
accordingly.

Where I am hitting an issue is that I must pass JNIEnv* and jobject
arguments to my make (hence impl) functions in order to interact with
the
TextView object in my work function… but when I try to build the module
I
get the following error for example: “error: ‘JNIEnv’ has not been
declared”,
and similarly for all the jobject, jclass, and jmethodID occurrences. It
would seem make doesn’t know how to find the JNI libraries (and I’m
guessing
volk is missing too,) and I’m unsure how to tell it where to look. Any
thoughts? Or is there a smarter / less roundabout way altogether to
display
my flowgraph output in my Android activity?

Thanks,
Vijay

From: [email protected] [mailto:[email protected]] On Behalf Of
Tom
Rondeau
Sent: March-19-15 07:36
To: Vijay G.
Cc: GNURadio D.ion List
Subject: Re: [Discuss-gnuradio] GNU Radio on Android

On Thu, Mar 19, 2015 at 3:28 AM, Vijay G. [email protected]
wrote:
Tom,

As you expected, disabling buffering on the file sink did not have any
effect. I have fixed the issue though by making two changes to
opensl_source_impl.cc:

  1. change scale_factor to 32768 (1/2^14 doesn’t make sense, it causes
    clipping because the volk conversion method divides by scale_factor.)
  2. change buffer size (d_size) to 8k (2k was too small, tested
    32/44.1/48kHz
    on Nexus 4 and Nexus 7 2012 version.) Without this change the recorded
    audio
    will be very choppy (dropped samples?)

Vijay

Ah, ok, that makes sense. I think I was just playing around with those
parameters and must have checked them in at that state.

I’ll make those updates to the repo.

Thanks.
Tom

From: [email protected] [mailto:[email protected]] On Behalf Of
Tom
Rondeau
Sent: March-18-15 07:11
To: Vijay G.
Cc: GNURadio D.ion List
Subject: Re: [Discuss-gnuradio] GNU Radio on Android

On Wed, Mar 18, 2015 at 1:46 AM, Vijay G. [email protected]
wrote:
Tom,

What kind of sample rate / setup are you using for your opensl_source?
I’ve
set up a flowgraph that is just an opensl_source (sampling at 48kHz)
connected to a file sink, and when I play back the file through GRC on
my
desktop my audio is coming out pretty garbled, as if samples are being
dropped. I’ve also tried a couple other sampling rates (44.1kHz, 32kHz,
16kHz to name a few.) I’m using a Nexus 4 running Android 5.0.1. Pasted
below is some of my code.

Vijay

Flowgraph code:
JNIEXPORT void JNICALL
Java_com_example_grrecordmic_GrRecordMic_InitFlowgraph(JNIEnv* env,
jobject
thiz, jstring jsinkfilename)
{
int rate = 48000;
const char *sinkfilename = env->GetStringUTFChars(jsinkfilename, 0);

global_tb = gr::make_top_block("Record_Mic");

gr::grand::opensl_source::sptr micSource =

gr::grand::opensl_source::make(rate);
gr::blocks::file_sink::sptr fileSink =
gr::blocks::file_sink::make(sizeof(float), sinkfilename, false);

global_tb->connect(micSource, 0, fileSink, 0);

env->ReleaseStringUTFChars(jsinkfilename, sinkfilename);

}

I believe that I used either 32k and/or 44.1k. I was using a Nexus 7,
though, and the codec might play a significant role with this between
the
two devices.

Perhaps try setting the file sink to unbuffered mode?

fileSink->set_unbuffered(true);

Frankly, I feel like this is unlikely to help, but it’ll be interesting
to
know what happens.

Tom

From: [email protected] [mailto:[email protected]] On Behalf Of
Tom
Rondeau
Sent: March-17-15 07:37
To: Vijay G.
Cc: GNURadio D.ion List
Subject: Re: [Discuss-gnuradio] GNU Radio on Android

On Tue, Mar 17, 2015 at 12:10 AM, Vijay G. [email protected]
wrote:
Thanks Tom, that sorted it out. My audio output is a bit choppy but no
matter – time to move on to some more complex flowgraphs in my Android
app.

Thanks again,
Vijay

Yes, the skipping in the audio output is a known bug, and apparently
known
to be difficult in Android. It’s going to take some kind of double
buffering
to fix it at this level. I did not experience any problems with the
audio
source, though; I just saved it to a file, brought it back to my
computer,
and played it there and it sounded fine.

Tom

From: [email protected] [mailto:[email protected]] On Behalf Of
Tom
Rondeau
Sent: March-16-15 06:37
To: Vijay G.
Cc: GNURadio D.ion List
Subject: Re: [Discuss-gnuradio] GNU Radio on Android

On Mon, Mar 16, 2015 at 3:28 AM, Vijay G. [email protected]
wrote:
Hi Tom,

I have been following your notes on the wiki in an attempt to build a
test
app (a dial tone flowgraph.) I’m hitting a snag on the ndk-build step
though – when I use your example Android.mk listing, the linker isn’t
finding any of the static libraries we built (gnuradio, grand, boost,
fftw.)
Instead I’m getting a pile of undefined reference errors.

I tried editing the example Android.mk file by adding the following
before
the shared library build:

include $(CLEAR_VARS)
LOCAL_MODULE := grand_static_lib #for example
LOCAL_SRC_FILES := /opt/grandroid/lib/libgnuradio-grand.a
include $(PREBUILT_STATIC_LIBRARY)

However I quickly realised that while there are only a few gnuradio
libraries to add this way, there are a ton of boost libraries… Is
there a
smarter way to add all the prebuilt .a libraries at once? Or am I headed
in
the wrong direction entirely?

Any tips appreciated,
Vijay

Yep, you have to add all of the libraries into the Android.mk file. I’ve
updated the wiki:

http://gnuradio.org/redmine/projects/gnuradio/wiki/GRAndApps

You can go there and simply download GrAndroid.mk that does all of this
for
you and include it in your Android.mk file. Just follow the
instructions.

Hope that helps,

Tom

From: [email protected] [mailto:[email protected]] On Behalf Of
Tom
Rondeau
Sent: March-13-15 14:41
To: Vijay G.
Cc: GNURadio D.ion List
Subject: Re: [Discuss-gnuradio] GNU Radio on Android
On Fri, Mar 13, 2015 at 5:04 PM, Vijay G. [email protected]
wrote:
Hi,

Has a patched version of GNU Radio which runs on Android been released?

I’m working on a project where I’m transmitting information over audio
from a desktop system to an Android device, and since setting up the
transmitter end with GNU Radio was such a snap I would love to leverage
the GNU Radio system to build the receiver as well.

Thanks,
Vijay

Just yesterday, in fact:

http://gnuradio.org/redmine/projects/gnuradio/wiki/Android

I’ll try to release some of my apps soon. One of them captures from the
audio device, even. It’s not too hard since there’s the gr-grand opensl
audio source block to talk to the audio system.

Tom

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