Can anyone suggest how to handle a slow network when streaming video in a web view?
When the network strength is poor, a blank screen appears or video doesn't stream.
Is there a way to detect this condition so that we can alert the user? (Apart from using private API.)
Perhaps ifi_baudrate member of the if_data structure (declared in <net/if.h>) is what you need. If baudrate is less than some threshold value, then you can show an alert.
Please see the following answer to know how to obtain the if_data structure for a particular network interface:
https://stackoverflow.com/a/8014012/1310204
You can easily detect the state of the network connection via the HTML5 networking API
http://www.html5rocks.com/en/mobile/optimization-and-performance/#toc-network-detection
Also if you want to test the network speed, just set up some files on your server of a specific size, and do a ajax request for the file, while timing how long it takes to download.
You can use a simple:
var start = new Date();
$.get("someFile.jpg")
.done(function() {
var elapsed = (new Date() - start);
});
Or dig into the HTML5 performance API:
http://www.html5rocks.com/en/tutorials/webperformance/basics/
...if you not using javascript, the same applies. Just open a network connection with whatever is at your disposition, download a small file & do the math ;-)
Related
I want to prioritise Frame Detail over Frame Rate.
There is a parameter named contentHint in video media stream for it, but it may not be able to set by twilio sdk
https://www.w3.org/TR/mst-content-hint/
detail
The track should be treated as if video details are extra important.
This is generally applicable to presentations or web pages with text content,
painting or line art.
This setting would normally optimize for detail in the resulting individual frames
rather than smooth playback. Artefacts from quantization or downscaling
that make small text or line art unintelligible should be avoided.
https://github.com/twilio/twilio-video-ios/issues/59
In this github issue, I found that isScreencast is for it.
however Network Bandwidth Profile should be the official way to achieve it.
But as far as I tried, network bandwidth profile cannot achieve "Frame Detail over Frame Rate". What is the best way?
Twilio developer evangelist here.
the contentHint attribute is set on a MediaStreamTrack so you could set this in a Twilio Video application. For example:
const stream = await navigator.mediaDevices.getUserMedia({ video: true, audio: true });
const videoTrack = stream.getVideoTracks()[0];
const audioTrack = stream.getAudioTracks()[0];
videoTrack.contentHint = "detail";
const room = await Twilio.Video.connect(token, { tracks: [videoTrack, audioTrack] });
If you set the contentHint on the video track and then pass the tracks directly to the connect method, they will be used.
If you want to set this directly via the Twilio Video SDK, I would recommend raising a ticket in the Video.js repo.
I've jumped off the deep end, and have decided to figure out low-latency audio on iOS using Audio Units. I've read as much documentation (from Apple and forums galore) as I can find, and the overall concepts make sense, but I'm still scratching my head on some concepts that I need help with:
I saw somewhere that AU Graphs are deprecated and that I should instead connect Audio Units directly. I'm cool with that... but how? Do I just need to use the Connection property of an Audio Unit to connect it to a source AU, and off I go? Initialize and Start the Units, and watch the magic happen? (cause it doesn't for me...)
What's the best Audio Unit setup to use if I simply want to grab audio from my mic, do some processing to the audio data, and then store that audio data without sending it out to the RemoteIO speaker, bus 0 output? I tried hooking up a GenericOutput AudioUnit to catch the data in a callback without any luck...
That's it. I can provide code when requested, but it's way too late, and this has wiped me out. If there's know easy answer, that's cool. I'll send any code snippets at will. Suffice it to say, I can easily get a simple RemoteIO, mic in, speaker out setup working great. Latency seems non-existant (at least to my ears). I just want to do something with the mic data and store it in memory without it going out to the speaker. Eventually hooking in the eq and mixer would be hip, but one step at a time.
FWIW, I'm coding in Xamarin Forms/C# land, but code examples in Objective C, Swift or whatever is fine. I'm stuck on the concepts, not necessarily the exact code.
THANKS!
Working with audio units without a graph is pretty simple and very flexible. To connect two units, you call AudioUnitSetProperty this way :
AudioUnitConnection connection;
connection.sourceAudioUnit = sourceUnit;
connection.sourceOutputNumber = sourceOutputIndex;
connection.destInputNumber = destinationInputIndex;
AudioUnitSetProperty(
destinationUnit,
kAudioUnitProperty_MakeConnection,
kAudioUnitScope_Input,
destinationInputIndex,
&connection,
sizeof(connection)
);
Note that it is required for the units connected this way to have their Stream Format set uniformly and that it must be done before their initialization.
Your question mentions Audio Units, and Graphs. As said in the comments, the graph concept has been replaced with the idea of attaching "nodes" to an AVAudioEngine. These nodes then "connect" to other nodes. Connecting nodes creates signal paths and starting the engine makes it all happen. This may be obvious, but I am trying to respond generally here.
You can do this all in Swift or in Objective-C.
Two high level perspectives to consider with iOS audio are the idea of a "host" and that of a "plugin". The host is an app and it hosts plugins. The plugin is usually created as an "app extension" and you can look up audio unit extensions for more about that as needed. You said you have one doing what you want, so this is all explaining the code used in a host
Attach AudioUnit to an AVaudioEngine
var components = [AVAudioUnitComponent]()
let description =
AudioComponentDescription(
componentType: 0,
componentSubType: 0,
componentManufacturer: 0,
componentFlags: 0,
componentFlagsMask: 0
)
components = AVAudioUnitComponentManager.shared().components(matching: description)
.compactMap({ au -> AVAudioUnitComponent? in
if AudioUnitTypes.codeInTypes(
au.audioComponentDescription.componentType,
AudioUnitTypes.instrumentAudioUnitTypes,
AudioUnitTypes.fxAudioUnitTypes,
AudioUnitTypes.midiAudioUnitTypes
) && !AudioUnitTypes.isApplePlugin(au.manufacturerName) {
return au
}
return nil
})
guard let component = components.first else { fatalError("bugs") }
let description = component.audioComponentDescription
AVAudioUnit.instantiate(with: description) { (audioUnit: AVAudioUnit?, error: Error?) in
if let e = error {
return print("\(e)")
}
// save and connect
guard let audioUnit = audioUnit else {
print("Audio Unit was Nil")
return
}
let hardwareFormat = self.engine.outputNode.outputFormat(forBus: 0)
self.engine.attach(au)
self.engine.connect(au, to: self.engine.mainMixerNode, format: hardwareFormat)
}
Once you have your AudioUnit loaded, you can connect your Athe AVAudioNodeTapBlock below, it has more to it since it need to be a binary or something that other host apps that aren't yours can load.
Recording an AVAudioInputNode
(You can replace the audio unit with the input node.)
In an app, you can record audio by creating an AVAudioInputNode or just reference the 'inputNode' property of the AVAudioEngine, which is going to be connected to the system's selected input device(mic, line in, etc) by default
Once you have the input node you want to process the audio of, next "install a tap" on the node. You can also connect your input node to a mixer node and install a tap there.
https://developer.apple.com/documentation/avfoundation/avaudionode/1387122-installtap
func installTap(onBus bus: AVAudioNodeBus,
bufferSize: AVAudioFrameCount,
format: AVAudioFormat?,
block tapBlock: #escaping AVAudioNodeTapBlock)
The installed tap will basically split your audio stream into two signal paths. It will keep sending the audio to the AvaudioEngine's output device and also send the audio to a function that you define. This function(AVAudioNodeTapBlock) is passed to 'installTap' from AVAudioNode. The AVFoundation subsystem calls the AVAudioNodeTapBlock and passes you the input data one buffer at a time along with the time at which the data arrived.
https://developer.apple.com/documentation/avfoundation/avaudionodetapblock
typealias AVAudioNodeTapBlock = (AVAudioPCMBuffer, AVAudioTime) -> Void
Now the system is sending the audio data to a programmable context, and you can do what you want with it.
To use it elsewhere, you can create a separate AVAudioPCMBuffer and write each of the passed in buffers to it in the AVAudioNodeTapBlock.
I am trying to upload so many files via Azure Blob Storage .NET api and using with the current latest version 4.0.1. In ASP.NET MVC application i use async action method to upload via await blobFile.UploadFromStreamAsync but it really doesn't work and even i don't see an exception. It silently stops in that method without success.
But if i change action method to none-async and upload via blobFile.UploadFromStream method then everything to works well. I may uploaded via async way with 1% success rate that means very very low stability.
Do you experience same thing ? Is it bug in Storage Api implementation ?
Here is short example. One is async and the other one is none async action methods. There is no any problem if i upload small files but problem appears on large downloads. In this example UploadBlobSec method upload in short time but UploadBlob takes endless time.
public async Task UploadBlob()
{
var storageAccount = CloudStorageAccount.Parse(ConfigurationManager.ConnectionStrings["AzureStorage"].ConnectionString);
var blobContainer = storageAccount.CreateCloudBlobClient().GetContainerReference("files");
var blobFile = blobContainer.GetBlockBlobReference("song.mp3");
using (var stream = new WebClient().OpenRead("http://apolyonstorage.blob.core.windows.net/files/e8b1a1fa-8791-44dc-92ce-1a67a62f7b0f.mp3"))
{
await blobFile.UploadFromStreamAsync(stream);
}
}
public void UploadBlobSec()
{
var storageAccount = CloudStorageAccount.Parse(ConfigurationManager.ConnectionStrings["AzureStorage"].ConnectionString);
var blobContainer = storageAccount.CreateCloudBlobClient().GetContainerReference("files");
var blobFile = blobContainer.GetBlockBlobReference("song.mp3");
using (var stream = new WebClient().OpenRead("http://apolyonstorage.blob.core.windows.net/files/e8b1a1fa-8791-44dc-92ce-1a67a62f7b0f.mp3"))
{
blobFile.UploadFromStream(stream);
}
}
Code snippet looks fine - although I am not sure what the application around it is doing. Have you turned on server logs to see what is happening server side? For large files you should see the async upload translated into a couple of PutBlocks and then a PutBlockList. If you don't see the PutBlockList them maybe something strange is happening in your application.
Then assuming you do see the operations in the server logs that obviously means the operations are occurring. At that point look at the E2ELatency numbers vs ServerLatency I think you will see a large difference with E2Latency being much higher as it incorporates the time spent client side - and it would be interesting to see if your client network could be contributing to the problem. For example on my connection the e2elatency on the first PutBlock was 1346 ms vs 137 for ServerLatency.
For more information on logging take a look here.
Jason
My understanding currently is that:
CameraUI
I can use the CameraUI to access the built in camera for MediaType.VIDEO and that delegates to the built-in video camera app and lets me record a video. My app does that now.
When I stop recording and click the "Use" button, I am returned to my app and theoretically I have a valid MediaPromise.
iOS does -not- provide a valid/usable url/filename to the recorded video (or to photos) and so I would have to use a Loader to bring-in/use/access the 'recorded' video... AND... iOS does not actually create a file anywhere on the device, most importantly, in the Camera Roll where one would expect by the normal behavior when uses the system native camera/video app.
The documentation says that the Loader can load various image types and SWFs but nothing about video data, so I conclude from that that I cannot actually use the CameraUI to generate a valid MediaPromise that I can then pass to a Loader class or similar to read in the information created by the system camera and then manipulate (upload, save to applicationStorageDirectory, and/or display in one of the two video player components available in the API).
CameraRoll
I can have video entities in the iOS Camera Roll but the AS3/Air3.5 CameraRoll class won't let me view/access/reference them in any way.
Normal File I/O
All my attempts to use the Air3.5 File classes to browse to the storage location of the iOS Camera Roll have been rebuffed.
------- Questions -------
Am I correct in believing that there is a way to take video but no way to use the video that's been captured. (No way to use the resulting MediaPromise successfully).
I believe you can take video and access it using Android, but there's nothing in the documentation that says that you cannot using iOS.
Am I correct in believing that iOS sandboxes apps so that they cannot browse to video/photo storage using standard File I/O, but only through the apparently non-workable means I've tried (CameraUI & CameraRoll)
Am I wrong to think that these should be rather obvious NEEDS that one can achieve using the XCode Objective C++ etc route but the AIR Mobile Framework does not allow either because of Apple blocking functionality or because Adobe has failed to meet reasonable expectations?
One item of ironic note to convey. If I use the iOS system camera app to record a video, a thumnail of that video then appears in the Gallery/Camera Roll, and of course, I can share it or view it, or whatever... If I use AIR's CameraRoll.browseForImage(), provided I haven't used the camera to take another image, when it shows me the folder where the pictures are stored, the folder icon uses the thumbnail of the last object added... in this case, the video I took, but if I then enter the folder, the video cannot be found. It's teasing us. It knows it's there, but it is apparently forbidden fruit.
I can't answer all your questions, so this entry may not be acceptable, but I found this page while searching a solution for some the problems you described and thought that someone else may find this answer (partially) useful.
To save the movie you just took you need to open and read the data from the promise.
The iOS won't save the file anywere, so the MediaPromise.file is always null.
This is my solution to the problem:
private var camera:CameraUI;
private var dataInput:IDataInput;
public function recordVideo():void
{
// Start the camera and ask for a video
camera = new CameraUI();
camera.addEventListener(MediaEvent.COMPLETE, onCameraComplete);
camera.launch(MediaType.VIDEO);
}
private function onCameraComplete(event:MediaEvent):void
{
// event.data is a MediaPromise and MediaPromise.open() returns a IDataInput
// Let's cast it to a dispatcher and check when it's complete
dataInput = event.data.open();
var dispatcher:IEventDispatcher = IEventDispatcher(dataInput);
dispatcher.addEventListener(Event.COMPLETE, onDataInputComplete);
}
private function onDataInputComplete(event:Event):void
{
// We can do whatever we want with the data, so we'll store it in a File
var file:File = new File();
var bytes:ByteArray = new ByteArray();
var stream:FileStream = new FileStream();
// Reading the data from the opened MediaPromise
dataInput.readBytes(bytes);
stream.open(file, FileMode.WRITE);
stream.writeBytes(bytes, 0, bytes.bytesAvailable);
stream.close();
}
Also, I'm still looking for a way to put the movie in the CameraRoll
I'm totally new to iOS programing (I'm more an Android guy..) and have to build an application dealing with audio DSP. (I know it's not the easiest way to approach iOS dev ;) )
The app needs to be able to accept inputs both from :
1- built-in microphone
2- iPod library
Then filters may be applied to the input sound and the resulting is to be outputed to :
1- Speaker
2- Record to a file
My question is the following : Is an AUGraph necessary in order to be able for example to apply multiple filters to the input or can these different effects be applied by processing the samples with different render callbacks ?
If I go with AUGraph do I need : 1 Audio Unit for each input, 1 Audio Unit for the output and 1 Audio Input for each effect/filter ?
And finally if I don't may I only have 1 Audio Unit and reconfigure it in order to select the source/destination ?
Many thanks for your answers ! I'm getting lost with this stuff...
You may indeed use render callbacks if you so wished to but the built in Audio Units are great (and there are things coming that I can't say here yet under NDA etc., I've said too much, if you have access to the iOS 5 SDK I recommend you have a look).
You can implement the behavior you wish without using AUGraph, however it is recommended you do as it takes care of a lot of things under the hood and saves you time and effort.
Using AUGraph
From the Audio Unit Hosting Guide (iOS Developer Library):
The AUGraph type adds thread safety to the audio unit story: It enables you to reconfigure a processing chain on the fly. For example, you could safely insert an equalizer, or even swap in a different render callback function for a mixer input, while audio is playing. In fact, the AUGraph type provides the only API in iOS for performing this sort of dynamic reconfiguration in an audio app.
Choosing A Design Pattern (iOS Developer Library) goes into some detail on how you would choose how to implement your Audio Unit environment. From setting up the audio session, graph and configuring/adding units, writing callbacks.
As for which Audio Units you would want in the graph, in addition to what you already stated, you will want to have a MultiChannel Mixer Unit (see Using Specific Audio Units (iOS Developer Library)) to mix your two audio inputs and then hook up the mixer to the Output unit.
Direct Connection
Alternatively, if you were to do it directly without using AUGraph, the following code is a sample to hook up Audio units together yourself. (From Constructing Audio Unit Apps (iOS Developer Library))
You can, alternatively, establish and break connections between audio
units directly by using the audio unit property mechanism. To do so,
use the AudioUnitSetProperty function along with the
kAudioUnitProperty_MakeConnection property, as shown in Listing 2-6.
This approach requires that you define an AudioUnitConnection
structure for each connection to serve as its property value.
/*Listing 2-6*/
AudioUnitElement mixerUnitOutputBus = 0;
AudioUnitElement ioUnitOutputElement = 0;
AudioUnitConnection mixerOutToIoUnitIn;
mixerOutToIoUnitIn.sourceAudioUnit = mixerUnitInstance;
mixerOutToIoUnitIn.sourceOutputNumber = mixerUnitOutputBus;
mixerOutToIoUnitIn.destInputNumber = ioUnitOutputElement;
AudioUnitSetProperty (
ioUnitInstance, // connection destination
kAudioUnitProperty_MakeConnection, // property key
kAudioUnitScope_Input, // destination scope
ioUnitOutputElement, // destination element
&mixerOutToIoUnitIn, // connection definition
sizeof (mixerOutToIoUnitIn)
);