MediaPlayer plays sound but screen is black

Discussion:

Brendan

2009-02-14 21:24:39 UTC

I'm just trying to play a local video that is a resource with the
MediaPlayer class in the most simple way possible. I have confirmed
that the video works with players that I download from the
marketplace, so I'm assuming that's not the issue.

The problem is that I just get a black screen with no video. There is
audio from the file playing though, so I know that the file resource
is being accessed correctly, it's just not showing anything on the
screen in the emulator.

The one other note is that at any time whenever I try to access
getVideoWidth() or getVideoHeight() I get this (non-blocking) error:

ERROR/MediaPlayerService(24): getVideoSize returned -1

Any ideas as to what I could be doing wrong?

import android.app.Activity;
import android.os.Bundle;
import android.view.SurfaceView;
import android.view.SurfaceHolder;
import android.media.MediaPlayer;

public class Example extends Activity {

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

SurfaceView sv = new SurfaceView(this);
setContentView(sv);

SurfaceHolder holder = sv.getHolder();
holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

new MediaPlayer();
MediaPlayer mp = MediaPlayer.create(this, R.raw.video);
//holder.setFixedSize(mp.getVideoWidth(), mp.getVideoHeight
());
mp.setDisplay(holder);
mp.start();
}
}

Marco Nelissen

2009-02-14 21:32:57 UTC

Permalink

Several things potentially wrong with your code:
- you're using MediaPlayer.create(), which calls prepare() for you. IIRC,
setDisplay() needs to be called *before* prepare(), so you won't be able to
use any of the MediaPlayer.create convenience methods.
- the way you create and use the SurfaceView, you'll probably end up with a
0-sized Surface, so try specifying the SurfaceView in an xml layout and
using that.
- depending on the type of video, size information may not be available
until decoding has started. There's a callback/listener for that.

Post by Brendan
I'm just trying to play a local video that is a resource with the
MediaPlayer class in the most simple way possible. I have confirmed
that the video works with players that I download from the
marketplace, so I'm assuming that's not the issue.
The problem is that I just get a black screen with no video. There is
audio from the file playing though, so I know that the file resource
is being accessed correctly, it's just not showing anything on the
screen in the emulator.
The one other note is that at any time whenever I try to access
ERROR/MediaPlayerService(24): getVideoSize returned -1
Any ideas as to what I could be doing wrong?
import android.app.Activity;
import android.os.Bundle;
import android.view.SurfaceView;
import android.view.SurfaceHolder;
import android.media.MediaPlayer;
public class Example extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
SurfaceView sv = new SurfaceView(this);
setContentView(sv);
SurfaceHolder holder = sv.getHolder();
holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
new MediaPlayer();
MediaPlayer mp = MediaPlayer.create(this, R.raw.video);
//holder.setFixedSize(mp.getVideoWidth(), mp.getVideoHeight
());
mp.setDisplay(holder);
mp.start();
}
}

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Marco Nelissen

2009-02-14 21:35:20 UTC

Permalink

Post by Marco Nelissen
- you're using MediaPlayer.create(), which calls prepare() for you. IIRC,
setDisplay() needs to be called *before* prepare(), so you won't be able to
use any of the MediaPlayer.create convenience methods.

Scratch that. There's actually a version of MediaPlayer.create() that allows
you to specify the SurfaceHolder. Use that one instead of the one you're
using currently.

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Brendan

2009-02-14 23:01:34 UTC

Permalink

Wow that sounds really convenient. Since the signature of the
MediaPlayer.create() that takes a SurfaceHolder requires the second
argument to be a URI and not a resource id, I tried creating a URI for
the resource by doing this:

Uri uri = Uri.parse("android.resource://com.example.www/" +
R.raw.video);

And this may be a total noob question, but is that the right way to
create a URI for a resource?
Because then when I passed it in like this:

MediaPlayer mp = MediaPlayer.create(this, uri, holder);

The app immediately closes after flashing up a black screen, with
these the last lines that the log gets:

INFO/ActivityManager(49): Process com.example.www (pid 642) has died.
DEBUG/Zygote(23): Process 642 terminated by signal (11)

Post by Marco Nelissen

Scratch that. There's actually a version of MediaPlayer.create() that allows
you to specify the SurfaceHolder. Use that one instead of the one you're
using currently.

Marco Nelissen

2009-02-14 23:16:17 UTC

Permalink

Post by Brendan
Wow that sounds really convenient. Since the signature of the
MediaPlayer.create() that takes a SurfaceHolder requires the second
argument to be a URI and not a resource id, I tried creating a URI for

Oh, right, of course. My original comment stands then :)
You'll have to use "new MediaPlayer" instead of the MediaPlayer.create
convenience method.

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Brendan

2009-02-15 00:28:53 UTC

Permalink

Thanks for all your help! I've been trying out your original idea, but
I still seem to be having issues.

I have moved the SurfaceView to main.xml, it looks like this:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/
android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
<SurfaceView android:id="@+id/surface_view"
android:layout_height="fill_parent"
android:layout_width="fill_parent"></SurfaceView>
</LinearLayout>

And now onCreate looks like this:

setContentView(R.layout.main);
SurfaceView sv = (SurfaceView) findViewById
(R.id.surface_view);

SurfaceHolder holder = sv.getHolder();
holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

try {
MediaPlayer mp = new MediaPlayer();
AssetFileDescriptor afd = getResources().openRawResourceFd
(R.raw.video);
mp.setDataSource(afd.getFileDescriptor(), afd.getStartOffset(),
afd.getLength());
afd.close();
mp.setDisplay(holder);
mp.prepare();
mp.start();
} catch {...}

There are no errors ever thrown, but the process dies on mp.prepare()
without any warning or useful debug info. Is there potentially some
other way I should be setting the data source for a resource? Or
something else I'm forgetting to do that would make prepare
mysteriously kill the entire process?

Post by Marco Nelissen

Oh, right, of course. My original comment stands then :)
You'll have to use "new MediaPlayer" instead of the MediaPlayer.create
convenience method.

Marco Nelissen

2009-02-15 00:38:41 UTC

Permalink

I think you have to use the SurfaceHolder callbacks to find out when the
surface has actually been created, and *then* call setDisplay/prepare/start

Post by Brendan
Thanks for all your help! I've been trying out your original idea, but
I still seem to be having issues.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/
android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_height="fill_parent"
android:layout_width="fill_parent"></SurfaceView>
</LinearLayout>
setContentView(R.layout.main);
SurfaceView sv = (SurfaceView) findViewById
(R.id.surface_view);
SurfaceHolder holder = sv.getHolder();
holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
try {
MediaPlayer mp = new MediaPlayer();
AssetFileDescriptor afd = getResources().openRawResourceFd
(R.raw.video);
mp.setDataSource(afd.getFileDescriptor(), afd.getStartOffset(),
afd.getLength());
afd.close();
mp.setDisplay(holder);
mp.prepare();
mp.start();
} catch {...}
There are no errors ever thrown, but the process dies on mp.prepare()
without any warning or useful debug info. Is there potentially some
other way I should be setting the data source for a resource? Or
something else I'm forgetting to do that would make prepare
mysteriously kill the entire process?

Post by Marco Nelissen

Oh, right, of course. My original comment stands then :)
You'll have to use "new MediaPlayer" instead of the MediaPlayer.create
convenience method.

Brendan

2009-02-15 05:48:07 UTC

Permalink

Wow, thank you for helping me through this. That was the little last
little bit I needed. I finally got the video playing successfully by
waiting until surfaceCreated to try calling prepare.

Though I have to admit that it feels like a lot of code to just to
play a video.

Thanks again, I hope this helps anyone else who was having similar
issues.

Post by Marco Nelissen
I think you have to use the SurfaceHolder callbacks to find out when the
surface has actually been created, and *then* call setDisplay/prepare/start

Post by Marco Nelissen

Oh, right, of course. My original comment stands then :)
You'll have to use "new MediaPlayer" instead of the MediaPlayer.create
convenience method.

Marco Nelissen

2009-02-15 17:59:16 UTC

Permalink

Post by Brendan
Wow, thank you for helping me through this. That was the little last
little bit I needed. I finally got the video playing successfully by
waiting until surfaceCreated to try calling prepare.
Though I have to admit that it feels like a lot of code to just to
play a video.

That's why you'd normally use VideoView, which does all this for you.
VideoView doesn't support playing from a resource though, so you have to
jump through some extra hoops for that case.

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