I'm going to build an iOS application in which you can download audio files and listen to them in offline mode. so far I found out the following process can be done to build the app: creating an xml file with list of audio files on the server and fetch xml with ASIHTTPRequest and parse it into the app (well I still have problem doing this, but my question is something else!)
Before start coding I want to know
what is the right data format for audio files to choose (I know that .mp3, .aac, .m4a, .mp4, .3gp, CAF, MPEG, WAVE, NeXT,... could be used), but I need to know if there is a best format to choose to have better functionality in the app.
is there special consideration that I should take about 3G and wifi connection to download files( I need to know about limitations or techniques for implementing them)
I ask these questions to be able to estimate the time for creating the app regarding techniques that I should use.
Related
I develop an iOS application where i should call web service and return audio file ( as byte array ) then play it to user .
I have problem with audio file format as it has 8 Kbps bit rate and no player inside app can play it. when I convert it to any other bit rate for example (13 Kbps) from server side to test it works properly . However i have a huge number of file where converting them manually is impossible . is there any way to convert file inside iOS app code ?
To address your comment about converting the files manually: Is it a plausible solution for you to do it automatically, server side? If so, you probably have a few options.
One would be to install Audacity, which handles all of these bit rates, and use the Chains feature for batch processing. If it's a one-off conversion you could initiate it manually, otherwise you may need to find a way of scripting the process (if new files come in from an external source, that is).
As for playing these files in iOS, have you considered embedding libpd (just one example of many, but one that you can get up and running in minutes)? It has a fairly open approach to file playback, and may handle these file formats. If you send me an example I can test right away!
Is there any way, using currently available SDK frameworks on Cocoa (touch) to create a streaming solution where I would host my mp4 content on some server and stream it to my iOS client app?
I know how to write such a client, but it's a bit confusing on server side.
AFAIK cloudKit is not suitable for that task because behind the scenes it keeps a synced local copy of datastore which is NOT what I want. I want to store media content remotely and stream it to the client so that it does not takes precious space on a poor 16 GB iPad mini.
Can I accomplish that server solution using Objective-C / Cocoa Touch at all?
Should I instead resort to Azure and C#?
It's not 100% clear why would you do anything like that?
If you have control over the server side, why don't you just set up a basic HTTP server, and on client side use AVPlayer to fetch the mp4 and play it back to the user? It is very simple. A basic apache setup would do the job.
If it is live media content you want to stream, then it is worth to read this guide as well:
https://developer.apple.com/Library/ios/documentation/NetworkingInternet/Conceptual/StreamingMediaGuide/StreamingMediaGuide.pdf
Edited after your comment:
If you would like to use AVPlayer as a player, then I think those two things don't fit that well. AVPlayer needs to buffer different ranges ahead (for some container formats the second/third request is reading the end of the stream). As far as I can see CKFetchRecordsOperation (which you would use to fetch the content from the server) is not capable of seeking in the stream.
If you have your private player which doesn't require seeking, then you might be able to use CKFetchRecordsOperation's perRecordProgressBlock to feed your player with data.
Yes, you could do that with CloudKit. First, it is not true that CloudKit keeps a local copy of the data. It is up to you what you do with the downloaded data. There isn't even any caching in CloudKit.
To do what you want to do, assuming the content is shared between users, you could upload it to CloudKit in the public database of your app. I think you could do this with the CloudKit web interface, but otherwise you could create a simple Mac app to manage the uploads.
The client app could then download the files. It couldn't stream them though, as far as I know. It would have to download all the files.
If you want a streaming solution, you would probably have to figure out how to split the files into small chunks, and recombine them on the client app.
I'm not sure whether this document is up-to-date, but there is paragraph "Requirements for Apps" which demands using HTTP Live Streaming if you deliver any video exceeding 10min. or 5MB.
It is possible to implement a feature that allows users to watch videos as they are uploaded to server by others. Is html 5 suitable for this task? But flash? Are there any read to go solutions, don't want to reinvent the wheel. The application will be hosted on a dedicated server.
Thanks.
Of course it is possible, the data is there isnt it?
However it will be very hard to implement.
Also I am not so into python and I am not aware of a library or service suiting your requirements, but I can cover the basics of video streaming.
I assume you are talking about video files that are uploaded and not streams. Because, for that, there are obviously thousands of solutions out there...
In the most simple case the video being uploaded is already ready to be served to your clients and has a so called "faststart atom". They are container format specific and there are sometimes a bunch of them. The most common is the moov-atom. It contains a lot of data and is very complex, however in our use case, in a nutshell, it holds the data that enables the client to begin playing the video right away using the data available from the beginning.
You need that if you have progressive download videos (youtube...), meaning where a file is served from a Webserver. You obviously have not downloaded the full file and the player already can start playing.
If the fastastart atom was not present, that would not be possible.
Sometimes it is, but the player for example cannot display a progress bar, because it doesnt know how long the file is.
Having that covered the file could be uploaded. You will need an upload solution that writes the data directly to a buffer or a file. (file will be easier...).
This is almost always the case, for example PHP creates a file in the tmp_dir. You can also specify it if you want to find the video while its being uploaded.
Well, now you can start reading that file byte by byte and print that data to a connection to another client. Just be sure not to go ahead of what has already been recieved and written. You would probaby initiate your upload with a metadata set in memory that holds the current recieved byte position and location of the file.
Anyone who requests the file after the uploaded has started can just recieve the entire file, or if the upload is not yet finished, get it from your application.
You will have to throttle the data delivery or pause it when the data becomes short. This will appear to the client almost as a "slow connection". However you will have to echo some data from time to time to prevent the connection from closing. But if your upload doesnt stall, and why shoud it?, that shouldnt be a problem.
Now if you want to have someting like on the fly transcoding of various input formats into your desired output format, things get interesting.
AFAIK ffmpeg has neat apis which lets you directly deal with datasterams.
Also handbrake is a very good tool, however you would need to take the long road using external executeables.
I am not really aware of your requirements, however if your clients are already tuned in, for example on a red 5 streaming server, feeding data into a stream should also work fine.
Yes, take a look at Qik, http://qik.com/
"Instant Video Sharing ... Videos can be viewed live (right as they are being recorded) or anytime later."
Qik provides developer APIs, including ones like these:
qik.stream.subscribe_public_recent -- Subscribe to the videos (live and recorded)
qik.user.following -- Provides the list of people the user is following
qik.stream.public_info -- Get public information for a specific video
It is most certainly to do this, but it won't be trivial. And no, I don't think that you will find an "out of the box" solution that will require little effort on your behalf.
You say you want to let:
users watch videos as they are uploaded to server by others
Well, this could be interpreted two different ways:
Do you mean that you don't want a user to have to refresh the page before seeing new videos that other users have just finished uploading?
Or do you mean that you want one user to be able to watch a partially uploaded video (aka another user is still in the process of uploading it and right now the server only contains a partial upload of the video)?
Implementing #1 wouldn't be hard at all whatsoever. You would just need an AJAX script to check for newly uploaded videos, and those videos could then be served to the user in whatever way you choose. HTML5 vs. Flash isn't really a consideration here.
The second scenario, on the other hand, would require quite a bit of effort. I am guessing that HTML5 might not be mature enough to handle this type of situation. If you are not looking
to reinvent the wheel and don't have a lot of time to dedicate to this feature than I would say that you would be out of luck. You may be able to use ffmpeg to parse partial video files and feed them to a Flash player, but I would think of this as a large task.
A potential client has come to me asking for a an app which will stream a six hour audio file. The user needs to be able to set the "playback head" to any position along the file. Presumably, this means that the app must not be forced to download the entire file before it beings playing back starting at an arbitrary
An added complication -- there are actually four files which need to be streamed and mixed simultaneously.
My questions are:
1) Is there an out-of-the box technology which will allow me random access of streaming audio, on iOS? Can this be done with standard server technology and a single long file, or will it involve some fancy server tech?
2) Which iOS framework is best suited for this. Is there anything high-level that would allow me to easily mix these four audio files?
3) Can this be done entirely with standard browser technology on the client side? (i.e. HTML5)
Have a close look at the MP3 format. It is remarkably easy and efficient to parse, chop up into little bits, and reassemble into a custom stream.
Hence rolling your own server-side code to grab what you want and send to the client will not be as crazy or difficult as it may sound.
MP3 is also widely supported by various clients. I strongly suspect any HTML5 capable browser will be able of play the stream you generate via a long-lived bit-rate regulated HTTP request.
I am building a CDN. I want to be able to stream to an iPhone and iPad. Is this possible using Amazon Cloudfront?
Let me clarify. Is there any documentation anywhere or an example anywhere of someone doing this?
Progressive download works if you ensure that the media's metadata is at the beginning of the file. Google "ffmpeg qtfastart" to accomplish this in the easiest manner (in my experience). If this is not done, the player (in iOS) must download the complete file before it gets to the metadata that it needs to read in order to play. If you are not doing this step in your production workflow, then your progressive download is not functioning as "progressive download", it is actually downloading the entire file (as stated before...so it can get to the metadata) and then playing. This can be done with any video/audio file supported by your platform.
NOTE: I am not sure how this affects any attempts at high-speed scrubbing. It seems the file would need to be downloaded to the point that the app is trying to scrub to.
Another alternative may be to create the format needed for iOS streaming (using a segmenter/transcoder), and serving up those files through http on your regular Cloudfront distribution. Theoretically that should work.
To be more clear - Cloudfront uses and older version of Flash Media Server(v 3.5) that supports streaming through various RTMP protocols. These can be enabled by creating a Streaming Distribution (that is how we do streaming for web and Android) and using something like JW Player on the front end.
http://help.adobe.com/en_US/FlashMediaServer/3.5_TechOverview/WS5b3ccc516d4fbf351e63e3d119ed944a1a-7ffa.html
http://www.adobe.com/devnet/logged_in/ktowes_fms35.html
IOS streaming is done using HTTP Live Streaming which is different. https://developer.apple.com/streaming/
Your options would be to do as I mentioned above, or use EC2 and stand up your own FMS 4.5 instance ( http://aws.typepad.com/aws/2012/03/live-streaming-cloudfront-fms-4-5.html ).
Have struggled a lot over this..
Finally got it working through Audio Streamer.. Love this ...
http://www.cocoawithlove.com/2009/06/revisiting-old-post-streaming-and.html
Awesome way ....
You simply want to use Progressive Download, which means upload the file to S3, create a distribution, and go! It's super simple.