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34
sdk-android-tutorial-media-player.md
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@ -1,6 +1,6 @@
# Android tutorial 4: A basic media player # Android tutorial 4: A basic media player
### Goal ## Goal
![screenshot] ![screenshot]
@ -19,7 +19,7 @@ It also uses the knowledge gathered in the [](sdk-basic-tutorials.md) regarding:
- How to use `playbin` to play any kind of media - How to use `playbin` to play any kind of media
- How to handle network resilience problems - How to handle network resilience problems
### Introduction ## Introduction
From the previous tutorials, we already have almost all necessary pieces From the previous tutorials, we already have almost all necessary pieces
to build a media player. The most complex part is assembling a pipeline to build a media player. The most complex part is assembling a pipeline
@ -41,7 +41,7 @@ the video sink is not forced to draw black borders around the clip.
media content. You can still force the video surface to have a specific media content. You can still force the video surface to have a specific
size if you really want to. size if you really want to.
### A basic media player \[Java code\] ## A basic media player \[Java code\]
**src/com/gst\_sdk\_tutorials/tutorial\_4/Tutorial4.java** **src/com/gst\_sdk\_tutorials/tutorial\_4/Tutorial4.java**
@ -298,7 +298,7 @@ public class Tutorial4 extends Activity implements SurfaceHolder.Callback, OnSee
} }
``` ```
#### Supporting arbitrary media URIs ### Supporting arbitrary media URIs
The C code provides the `nativeSetUri()` method so we can indicate the The C code provides the `nativeSetUri()` method so we can indicate the
URI of the media to play. Since `playbin` will be taking care of URI of the media to play. Since `playbin` will be taking care of
@ -319,7 +319,7 @@ private void setMediaUri() {
We call `setMediaUri()` in the `onGStreamerInitialized()` callback, once We call `setMediaUri()` in the `onGStreamerInitialized()` callback, once
the pipeline is ready to accept commands. the pipeline is ready to accept commands.
#### Reporting media size ### Reporting media size
Every time the size of the media changes (which could happen mid-stream, Every time the size of the media changes (which could happen mid-stream,
for some kind of streams), or when it is first detected, C code calls for some kind of streams), or when it is first detected, C code calls
@ -349,7 +349,7 @@ the UI must be called from the main thread, and we are now in a
callback from some GStreamer internal thread. Hence, the usage of callback from some GStreamer internal thread. Hence, the usage of
[runOnUiThread()](http://developer.android.com/reference/android/app/Activity.html#runOnUiThread\(java.lang.Runnable\)). [runOnUiThread()](http://developer.android.com/reference/android/app/Activity.html#runOnUiThread\(java.lang.Runnable\)).
#### Refreshing the Seek Bar ### Refreshing the Seek Bar
[](sdk-basic-tutorial-toolkit-integration.md) [](sdk-basic-tutorial-toolkit-integration.md)
has already shown how to implement a [Seek has already shown how to implement a [Seek
@ -404,7 +404,7 @@ private void updateTimeWidget () {
} }
``` ```
#### Seeking with the Seek Bar ### Seeking with the Seek Bar
To perform the second function of the [Seek To perform the second function of the [Seek
Bar](http://developer.android.com/reference/android/widget/SeekBar.html) (allowing Bar](http://developer.android.com/reference/android/widget/SeekBar.html) (allowing
@ -479,7 +479,7 @@ desired playing state.
This concludes the User interface part of this tutorial. Let’s review This concludes the User interface part of this tutorial. Let’s review
now the under-the-hood C code that allows this to work. now the under-the-hood C code that allows this to work.
### A basic media player \[C code\] ## A basic media player \[C code\]
**jni/tutorial-4.c** **jni/tutorial-4.c**
@ -1054,7 +1054,7 @@ jint JNI_OnLoad(JavaVM *vm, void *reserved) {
} }
``` ```
#### Supporting arbitrary media URIs ### Supporting arbitrary media URIs
Java code will call `gst_native_set_uri()` whenever it wants to change Java code will call `gst_native_set_uri()` whenever it wants to change
the playing URI (in this tutorial the URI never changes, but it could): the playing URI (in this tutorial the URI never changes, but it could):
@ -1100,7 +1100,7 @@ not. Live sources must not use buffering (otherwise latency is
introduced which is inacceptable for them), so we keep track of this introduced which is inacceptable for them), so we keep track of this
information in the `is_live` variable. information in the `is_live` variable.
#### Reporting media size ### Reporting media size
Some codecs allow the media size (width and height of the video) to Some codecs allow the media size (width and height of the video) to
change during playback. For simplicity, this tutorial assumes that they change during playback. For simplicity, this tutorial assumes that they
@ -1152,7 +1152,7 @@ The helper functions `gst_video_format_parse_caps()` and
manageable integers, which we pass to Java through manageable integers, which we pass to Java through
its `onMediaSizeChanged()` callback. its `onMediaSizeChanged()` callback.
#### Refreshing the Seek Bar ### Refreshing the Seek Bar
To keep the UI updated, a GLib timer is installed in the To keep the UI updated, a GLib timer is installed in the
`app_function()` that fires 4 times per second (or every 250ms), right `app_function()` that fires 4 times per second (or every 250ms), right
@ -1201,7 +1201,7 @@ Bear in mind that all time-related measures returned by GStreamer are in
nanoseconds, whereas, for simplicity, we decided to make the UI code nanoseconds, whereas, for simplicity, we decided to make the UI code
work in milliseconds. work in milliseconds.
#### Seeking with the Seek Bar ### Seeking with the Seek Bar
The Java UI code already takes care of most of the complexity of seeking The Java UI code already takes care of most of the complexity of seeking
by dragging the thumb of the Seek Bar. From C code, we just need to by dragging the thumb of the Seek Bar. From C code, we just need to
@ -1215,7 +1215,7 @@ Bar can generate a very high number of seek requests in a short period
of time, which is visually useless and will impair responsiveness. Let’s of time, which is visually useless and will impair responsiveness. Let’s
see how to overcome these problems. see how to overcome these problems.
##### Delayed seeks #### Delayed seeks
In In
`gst_native_set_position()`: `gst_native_set_position()`:
@ -1255,7 +1255,7 @@ Once the pipeline moves from the READY to the PAUSED state, we check if
there is a pending seek operation and execute it. The there is a pending seek operation and execute it. The
`desired_position` variable is reset inside `execute_seek()`. `desired_position` variable is reset inside `execute_seek()`.
##### Seek throttling #### Seek throttling
A seek is potentially a lengthy operation. The demuxer (the element A seek is potentially a lengthy operation. The demuxer (the element
typically in charge of seeking) needs to estimate the appropriate byte typically in charge of seeking) needs to estimate the appropriate byte
@ -1331,7 +1331,7 @@ The one-shot timer calls `delayed_seek_cb()`, which simply calls
> >
> This is not a complete solution: the scheduled seek will still be executed, even though a more-recent seek has already been executed that should have cancelled it. However, it is a good tradeoff between functionality and simplicity. > This is not a complete solution: the scheduled seek will still be executed, even though a more-recent seek has already been executed that should have cancelled it. However, it is a good tradeoff between functionality and simplicity.
#### Network resilience ### Network resilience
[](sdk-basic-tutorial-streaming.md) has already [](sdk-basic-tutorial-streaming.md) has already
shown how to adapt to the variable nature of the network bandwidth by shown how to adapt to the variable nature of the network bandwidth by
@ -1373,7 +1373,7 @@ pipeline, which might be different to the current state, because
buffering forces us to go to PAUSED. Once buffering is complete we set buffering forces us to go to PAUSED. Once buffering is complete we set
the pipeline to the `target_state`. the pipeline to the `target_state`.
### A basic media player \[Android.mk\] ## A basic media player \[Android.mk\]
The only line worth mentioning in the makefile The only line worth mentioning in the makefile
is `GSTREAMER_PLUGINS`: is `GSTREAMER_PLUGINS`:
@ -1388,7 +1388,7 @@ In which all plugins required for playback are loaded, because it is not
known at build time what would be needed for an unspecified URI (again, known at build time what would be needed for an unspecified URI (again,
in this tutorial the URI does not change, but it will in the next one). in this tutorial the URI does not change, but it will in the next one).
### Conclusion ## Conclusion
This tutorial has shown how to embed a `playbin` pipeline into an This tutorial has shown how to embed a `playbin` pipeline into an
Android application. This, effectively, turns such application into a Android application. This, effectively, turns such application into a

12
sdk-legal-information.md
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@ -104,11 +104,11 @@ and on an aggregate basis only.
## Frequently Asked Questions ## Frequently Asked Questions
##### What licenses are there? #### What licenses are there?
GStreamer binaries containst software under various licenses. See above. GStreamer binaries containst software under various licenses. See above.
##### How does this relate to the packaging system? #### How does this relate to the packaging system?
The packaging is only a more convenient way to install software and The packaging is only a more convenient way to install software and
decide what's good for you. GStreamer is meant to be modular, making use decide what's good for you. GStreamer is meant to be modular, making use
@ -128,7 +128,7 @@ reference, but we cannot guarantee that our selection is 100% correct,
so it is up to the user to verify the actual licensing conditions before so it is up to the user to verify the actual licensing conditions before
distributing works that utilize GStreamer. distributing works that utilize GStreamer.
##### Can I / must I distribute GStreamer along with my application? #### Can I / must I distribute GStreamer along with my application?
You surely can. All software is Free/Open Source software, and can be You surely can. All software is Free/Open Source software, and can be
distributed freely. You are not **required** to distribute it. Only, distributed freely. You are not **required** to distribute it. Only,
@ -142,7 +142,7 @@ entire source code, you might want to include it (or the directories
containing the source code) with your application as a safe way to containing the source code) with your application as a safe way to
comply with this requirement of the license. comply with this requirement of the license.
##### What happens when I modify the GStreamer's source code? #### What happens when I modify the GStreamer's source code?
You are invited to do so, as the licenses (unless you are dealing with You are invited to do so, as the licenses (unless you are dealing with
proprietary bits, but in that case you will not find the corresponding proprietary bits, but in that case you will not find the corresponding
@ -157,7 +157,7 @@ to fork the code, if at all possible. he Cerbero build system has a
containing all of the complete corresponding machine readable source containing all of the complete corresponding machine readable source
code that you are required to provide. code that you are required to provide.
##### How does licensing relate to software patents? What about software patents in general? #### How does licensing relate to software patents? What about software patents in general?
This is a tricky question. We believe software patents should not exist, This is a tricky question. We believe software patents should not exist,
so that by distributing and using software on a general purpose machine so that by distributing and using software on a general purpose machine
@ -185,7 +185,7 @@ This is why GStreamer has taken a modular approach, so that you can use
a Free plugins or a proprietary, patent royalty bearing, plugin for a a Free plugins or a proprietary, patent royalty bearing, plugin for a
given standard. given standard.
##### What about static vs. dynamic linking and copyleft? #### What about static vs. dynamic linking and copyleft?
We cannot provide one single answer to that question. Since copyright in We cannot provide one single answer to that question. Since copyright in
software works as copyright in literature, static linking means software works as copyright in literature, static linking means