Creating apps that use video and audio

Gabe FrostSenior Program Manager, Lead2-087

A recap of video and audioWhat’s new for 8.1Completing your audio experienceCompleting your video experienceBetter together with Xbox One

Agenda

Multimedia platformDesktop apps use IMFMediaEngine, etc.

Windows.Media namespace

Great battery life with hardware offload

Apps can extend formats and codecs

A recap of video and audio

Media Foundation

Playback & preview(IMFMediaEngine)

Windows Store app

Camera & mic capture(IMFCaptureEngine)

Streaming to Xbox(IMFMediaSharingEngine)

Transcode & trim(IMFTranscodeEngine)

Audio/video reader (source)

Videodecoder

Videoeffect 1

Videoencoder

Videoeffect n

Audio/video writer or render (sink)

Audiodecoder

Audioeffect 1

Audioencoder

Audioeffect n

HTML5 video & audio tags,XAML MediaElement

Windows Runtime (WinRT)

Content protection, e.g. PlayReadyBackground audioStream to Xbox, TVs and audio receiversConvert between popular formatsLow latency mode for communications and gamesVideo stabilizationZoom and mirror modesStereo 3DAnd more

A recap of video and audio

Improved quality, performance & batteryAdaptive bitrate and encrypted streaming with HTML5 standardsImproved online playlists and ad insertion in connected standbyCustom formats without native code

What’s new

Unconstrained download of large filesApp discovery and launching on Xbox OneAudio effect managementEdit media file metadata in local librariesAnd more

What’s new

Demo

Completing your audio experience

Simple background audio playlist// Create audio element that continues to play in the background<audio id=“audioplayer" msAudioCategory=“BackgroundCapableMedia” autoplay />

// First track is from local library, then 2nd is chosen by the app var picker = new Windows.Storage.FileOpenPicker();picker.pickSingleFileAsync(). then(function(file) { var url = URL.createObjectURL(file); document.getElementById(“audioplayer”).src = url;});audio.addEventListener("ended", function() { document.getElementById(“audioplayer”).src = "http://contoso.com/track2.m4a";}); /* If the device idles to connected standby, track2 can’t be fetched */

Set audio behavior using msAudioCategory

ForegroundOnlyMediaBackgroundCapableMediaCommunicationsAlertSoundEffectsGameEffectsGameMediaOther

Set attribute for best experience when app is not visible and when audio is mixed

Audio playlist while in connected standby// Create downloader and download instance for a given URI to download to “newFile”var nextItem = "http://contoso.com/track2.m4a";var downloader = new Windows.Networking.BackgroundTransfer.BackgroundDownloader();var download = downloader.createDownload(nextItem, newFile);

// Set priority so the download starts immediatelydownload.priority = Windows.Networking.BackgroundTransfer.BackgroundTransferPriority.high;download.startAsync();

// Play the resulting filevar url = URL.createObjectURL(newFile);document.getElementById(“audioplayer”).src = url;

Media playback controlsfunction initSystemMediaControls() { /* initialize at app activation */

SystemMediaControls =

Windows.Media.SystemMediaTransportControls.getForCurrentView();

SystemMediaControls. /* Events for both software and hardware buttons */

addEventListener(“buttonpressed”, systemMediaControlsButtonPressed, false);

SystemMediaControls.isPlayEnabled = true; /* Enable all buttons */

SystemMediaControls.isPauseEnabled = true;

// Reflect the current playback state in the system UI

SystemMediaControls.playbackStatus = Windows.Media.MediaPlaybackStatus.closed;

}

Media playback controlsfunction systemMediaControlsButtonPressed(e) {

var mediaButton = Windows.Media.SystemMediaTransportControlsButton;

switch (e.button) { /* Add case statements for

case mediaButton.play: audio.play(); break; /* each button */

case mediaButton.pause: audio.pause(); break;

}

}

function updateSystemMediaTransportControlsMetadata() {

displayUpdater.type = Windows.Media.MediaPlaybackType.music;

musicProperties.title = “my track title”; /* Add other metadata too */

displayUpdater.update();

}

Stream to, and remotely control Xbox// Step 1: Obtain PlayToManager object for app’s current view

var ptm = Windows.Media.PlayToManager.getForCurrentView();

// Step 2: Register for the “sourcerequested” event (when user selects Devices charm)

ptm.addEventListener(“sourcerequested”, function(e) {

var request = e.sourceRequest;

var deferral = request.getDeferral();

// Step 3: Specify the media to be streamed

request.setSource(document.getElementById(“audioplayer”).msPlayToSource);

deferral.complete();

// The media will then be streamed to the device chosen by the user in the Charm.

});

Clarity on what devices are supported: Play, Print, ProjectAdd a device from the charmAdobe Flash video and audio now works from the browserAudio from a video can be streamed to audio-only receivers (e.g. music videos)

What’s new for the Devices charm

Multimedia platformApp is responsible for retrieving audio samples and parsing file format

MediaStreamSource takes elementary stream samples as input

Decoding and rendering by platform

Add a custom file or stream format

Media Foundation

Playback & preview(IMFMediaEngine)

Windows Store app

Camera & mic capture(IMFCaptureEngine)

Streaming to Xbox(IMFMediaSharingEngine)

Transcode & trim(IMFTranscodeEngine)

Videodecoder

Videoeffect 1

Videoencoder

Videoeffect n

Audio/video writer (sink)

Audiodecoder

Audioeffect 1

Audioencoder

Audioeffect n

HTML5 video & audio tagsXAML MediaElement

Windows Runtime (WinRT)

Media Stream Source

Windows.Media.Core.MediaStreamSource

Audio/video reader (source)

Get audio samples (e.g. sockets) and parse file format

Add a custom file or stream format// Audio sample details and encoding properties:

// Raw AAC data, 48KHz sampling rate, 2 channel and approx 124Kbps

var sampleSize = 1024;

var sampleDuration = 20;

var audioProps = Windows.Media.MediaProperties.AudioEncodingProperties.

createAac(48000, 2, 124338);

// Create the media source with specific encoding properties.

var streamSource = new Windows.Media.Core.MediaStreamSource(new

Windows.Media.Core.AudioStreamDescriptor(audioProps));

Add a custom file or stream format// Register handlers

streamSource.addEventListener(“samplerequested”, sampleRequestedHandler, false);

streamSource.canSeek = true;

streamSource.musicProperties.title = “My track title”;

var songDuration = 60000;

// Attach media source to the audio tag and start playing

var audio = document.getElementById(“audiotag”);

audio.src = URL.createObjectURL(streamSource);

audio.play();

Add a custom file or stream formatfunction sampleRequestedHandler(e) {

var request = e.request;

if (!MyCustomFormatParser.IsAtEndOfStream(randomAccessStream)) {

var deferral = request.getDeferral();

var inputStream = MyCustomFormatParser.getInputStream(randomAccessStream);

MediaStreamSample.createFromStreamAsync(inputStream, sampleSize, timeOffset).

then(function(sample) {

sample.duration = sampleDuration; /* When sample is requested, your */

sample.keyFrame = true; /* custom parser extracts audio data */

request.sample = sample; /* from RandomAccessStream and returns */

deferral.complete(); /* an InputStream of only audio samples */

});

}

}

Add audio declaration in app manifest and set msAudioCategory attributeHandle media button events for play and pause at minimumSet high priority on background downloader for online playlists

In review

PlayTo app contract for streaming to XboxUse MediaStreamSource for advanced streaming or custom formats

In review

Demo

Completing your video experience

Simple video playback, Windows 8.1<MediaElement Name=“VideoPlayer” Source=“http://contoso.com/movie1.m4v” PosterSource=“movie1_artwork.png” AreTransportControlsEnabled=“true” />

/* No longer necessary to create buttons and handlers for each. All transport control buttons, including Zoom and Fullscreen are free, as are power and performance optimizations */

Simple video playback, before 8.1<MediaElement Name=“VideoPlayer” Source=“http://contoso.com/movie1.m4v” PosterSource=“movie1_artwork.png” />

/* Before 8.1, Media playback buttons had to be manual. You can still do this for custom controls */<StackPanel x:Name=“mtcPanel” Orientation=“Horizontal”> <Button Name=“btnPlay” Click=“btnPlay_Click” Content=“Play” /> <Button Name=“btnStop” Click=“btnStop_Click” Content=“Stop” /> <Button Name=“btnZoom” Click=“btnZoom_Click” Content=“Zoom” /> <Button Name=“btnFull” Click=“btnFull_Click” Content=“Full” /></StackPanel>

Simple video playback, before 8.1private DisplayRequest dispRequest = null;private void btnPlay_Click(object sender, RoutedEventArgs e) { VideoPlayer.Play(); /* Before 8.1, button handlers */ if (dispRequest == null) /* had to be manual, and a */ { /* display request had to be made */ dispRequest = new DisplayRequest(); /* to prevent the screen from */ dispRequest.RequestActive(); /* turning off after 2 minutes */ }}private void btnStop_Click(object sender, RoutedEventArgs e) { VideoPlayer.Stop(); if (dispRequest != null) { dispRequest.RequestRelease(); }}

Full screen video, Windows 8.1/* Full screen is free using AreTransportControlsEnabled. This hides all UI and stretches to screen perfectly to ensure hardware offload */<MediaElement Name=“VideoPlayer” Source=“http://contoso.com/movie1.m4v” PosterSource=“movie1_artwork.png” AreTransportControlsEnabled=“true” />

/* For custom controls, let Windows optimize for hardware offload and set display request using the new IsFullWindow */private void btnFull_Click(object sender, RoutedEventArgs e) { VideoPlayer.IsFullWindow = “true”;}

Video zoom for small screen tablets/* Zoom is free using AreTransportControlsEnabled */<MediaElement Name=“VideoPlayer” Source=“http://contoso.com/movie1.m4v” PosterSource=“movie1_artwork.png” AreTransportControlsEnabled=“true” />

/* For custom controls, use Stretch */private void btnZoom_Click(object sender, RoutedEventArgs e) { VideoPlayer.Stretch = “UniformToFill”;}

Media playback controlsprivate SystemMediaTransportControls SystemMediaControls = null;

public void InitSystemMediaControls()

{

SystemMediaControls = SystemMediaTransportControls.getForCurrentView();

/* The new SystemMediaTransportControls events for software and hardware buttons */

SystemMediaControls.ButtonPressed += SystemMediaControls_ButtonPressed;

/* Enable specific media playback buttons (for brevity, only play and pause are shown) */

SystemMediaControls.IsPlayEnabled = true;

SystemMediaControls.IsPauseEnabled = true;

/* Reflect the current playback state in the system UI */

SystemMediaControls.PlaybackStatus = MediaPlaybackStatus.Closed;

}

Media playback controlsprivate async void SystemMediaControls_ButtonPressed(SystemMediaTransportControls sender,

SystemMediaTransportControlsButtonPressedEventArgs args)

{

switch

{

case SystemMediaTransportControlsButton.Play: /* Add case statements for */

VideoPlayer.Play(); break; /* each button – both system UI */

} /* and hardware buttons will event the same */

}

/* Sets metadata from properties in the passed StorageFile */

private async Task UpdateSystemMediaControlsDisplayAsync(StorageFile mediaFile)

{

copyFromFileAsyncSuccessful = await

SystemMediaControls.DisplayUpdater.CopyFromFileAsync(Music, mediaFile);

}

Mute or pause when app is not visible<MediaElement Name=“VideoPlayer” Source=“http://contoso.com/movie1.m4v” PosterSource=“movie1_artwork.png” AudioCategory=“ForegroundOnlyMedia” /> /* Audio will mute when app */ /* is not visible */

/* If pause is appropriate when the video is not in view, listen for sound level changes similar to listening for button presses */SystemMediaTransportControls SystemMediaControls = SystemMediaTransportControls.getForCurrentView();

SystemMediaControls.PropertyChanged += SystemMediaControls_PropertyChanged;

Mute or pause when app is not visibleprivate async void SystemMediaControls_PropertyChanged(SystemMediaTransportControls sender,

SystemMediaTransportControlsPropertyChangedEventArgs args)

{

if (args.Property == SystemMediaTransportControlsProperty.SoundLevel)

{

if (sender.SoundLevel == SoundLevel.Muted)

{ /* SoundLevel will only report ‘Muted’ when the app is not visible */

VideoPlayer.Pause();

}

else

{ /* If SoundLevel isn’t ‘Muted’ the app must be visible */

VideoPlayer.Play();

}

}

}

Unconstrained downloadStorageFile offlineMovie = /* path for saving downloaded file */;

BackgroundDownloader downloader = new BackgroundTransfer.BackgroundDownloader();

var download = downloader.CreateDownload(new

Windows.Foundation.Uri(“http://contoso.com/movie1.m4v”), offlineMovie);

List<DownloadOperation> operations = new List<DownloadOperation>();

operations.Add(download); /* Add as many downloads as you like */

var result = await BackgroundDownloader.RequestUnconstrainedDownloadsAsync(operations);

if (result.IsUnconstrained)

{ /* If user accepts prompt, downloads are unconstrained. If no; constrained */

}

Download.StartAsync().AsTask( /* Implement progress indicator, etc. */ );

Stream to, and remotely control Xbox/* Step 1: Obtain PlayToManager object for app’s current view */

PlayToManager ptm = PlayToManager.GetForCurrentView();

/* Step 2: Register for SourceRequested event (fires when Devices charm selected) */

ptm.SourceRequested += (PlayToManager sender, PlayToSourceRequestedEventArgs e) =>

{

request = e.SourceRequest;

PlayToSourceDeferral deferral = request.GetDeferral();

request.SetSource(VideoPlayer.PlayToSource); /* Step 3: Set source of media */

deferral.Complete();

}

/* The media will then be streamed to the device chosen by the user */

Add a custom file or stream format/* Audio sample details and encoding properties:

Raw AAC data, 48KHz sampling rate, 2 channel and approx 124Kbps */

AudioEncodingProperties AudioProps =

new MediaProperties.AudioEncodingProperties.CreateAac(48000, 2, 124338);

/* Create the media source with specific encoding properties. */

MediaStreamSource StreamSource = new Windows.Media.Core.MediaStreamSource(new

Windows.Media.Core.AudioStreamDescriptor(AudioProps));

Add a custom file or stream format/* Handle events on the media source. Only SampleRequested is shown for brevity */

StreamSource.SampleRequested += StreamSource_SampleRequested;

/* Set higher level properties */

StreamSource.canSeek = true;

StreamSource.MusicProperties.title = “My track title”;

TimeSpan songDuration = new TimeSpan(600000000);

StreamSource.duration = SongDuration;

/* Attach media source to XAML MediaElement and start playing */

AudioPlayer.SetMediaStreamSource(StreamSource);

AudioPlayer.Play();

Add a custom file or stream formatasync void StreamSource_SampleRequested(MediaStreamSource sender, MediaStreamSourceSampleRequestedEventArgs args)

{ /* Whenever a sample is requested, */

MediaStreamSourceSampleRequest request = args.Request; /* MyCustomFormatParser parses the */

if (!MyCustomFormatParser.IsAtEndOfStream(RandomAccessStream)) /* RandomAccessStream to retrieve only raw audio */

{ /* data then returns it as an InputStream */

Windows.Media.Core.StartingRequestDeferral deferral = request.GetDeferral();

IInputStream InputStream = MyCustomFormatParser.GetInputStream(RandomAccessStream);

MediaStreamSample Sample = await MediaStreamSample.CreateFromStreamAsync(InputStream, sampleSize, timeOffset);

Sample.duration = SampleDuration;

Sample.keyFrame = true;

timeOffset.Ticks += SampleDuration.Ticks;

Request.Sample = Sample;

deferral.Complete();

}

}

AreTransportControlsEnabled for integrated controls and best performanceWith custom controls, optimize for full screen using IsFullWindowHandle media button events for play and pause at minimum

In review

SoundLevelChanged events to pause when not visibleUnconstrained background downloader for large filesPlayTo app contract for streaming to XboxMediaStreamSource for advanced streaming and custom formats

In review

Video is offloaded to GPU, even when not full screenBest performance when full screenDelay setting source URI until ready to playIf you control video encoding, match encoded resolution with device resolutions

Video performance

Follow touch target size guidelinesSupport video zoom for letterbox removalConsider playing full screen as defaultConsider locking screen orientation to landscape when playing full screen

Small screen tablets

Demo

Your Windows 8.1 and Xbox One apps are better together

Better together with Xbox OneBoth apps and sites, and for protected contentTransition is fast and continues at current positionPlayback controls persist in app, lock screen, Kinect voice, game controller or SmartGlassControls work when other apps are being usedBest quality and battery life because streaming is direct from the web

From the Devices charm, users see Xbox One if your console app is installed

Xbox Music and Video apps are first to implement

Xbox One app manifest<!-- Register ms-playtoapp protocol handler to enable app launching. Apps can register multiple protocol handlers --><Extensions> <Extension Category=“windows.protocol” StartPage=“main.html”> <Protocol Name=“ms-playtoapp-myapp” /> </Extension></Extensions>

Windows 8.1 app/* Pass custom meta info used to initiate streaming from Xbox One app

using x-ms-playToPreferredUri */

<video id=“player”

src=“http://contoso.com/movie.m4v”

x-ms-playToPreferredUri=“ms-playtoapp-myapp://media?id=12345”

controls />

Xbox One app contractptreceiver = new Windows.Media.PlayTo.PlayToReceiver(); /* Receiver accepts commands */

ptreceiver.supportsVideo = true; /* from home network, and */

ptreceiver.friendlyName = “My Movies App”; /* advertises playback state */

// Subscribe to events on the PlayToReceiver so you know when to control the video tag

ptreceiver.addEventListener("playrequested", playRequestedHandler, false);

ptreceiver.addEventListener("sourcechangerequested", sourceChangeRequestedHandler, false);

// Subscribe to events on the video tag so you can update playback state on home network

videoplayer.addEventListener("playing“, playingStateHandler, false);

// Advertise the receiver on the home network and start receiving playback commands

ptreceiver.startAsync().then( /* notify of current volume level, etc. */ );

Xbox One app contractfunction playRequestedHandler(e) { document.getElementById(“videoplayer”).play(); }

function sourceChangeRequestedHandler(e) { /* Set the source based on whether a preferred URI

if (e.stream) { /* is provided or not */

if (e.properties["System.ItemUrl"] != null &&

e.properties["System.ItemUrl"].indexOf("ms-playtoapp") > -1) {

// Parse custom Uri to extract variables encoded to initiate streaming

else {

var blob = MSApp.createBlobFromRandomAccessStream(e.stream.contentType, e.stream);

document.getElementById(“videoplayer").src = URL.createObjectURL(blob);

} /* If x-ms-playToPreferredUri isn’t specified, just set source normally */

}

}

Xbox One app contract/* Call associated notifying method to update the home network whenever the state

of the video tag change, such as: volumechange, ratechange, loadedmetadata,

durationchange, seeking, seeked, playing, pause, ended, error */

function playingStateHandler(e) {

ptreceiver.notifyPlaying();

}

Related sessions• 3-088: Building apps that use the camera• 3-089: Building media streaming apps and sites

without plug-ins using MPEG-DASH

Resources• Designing great entertainment apps for Windows• Playing and previewing audio and video• Creating a media player app• Handling hardware media buttons

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