I'm trying to learn how to do pseudo streaming for MP4 files. I can't think of a good way to do it, but I just found a great example app has similar implementation (except I don't understand how it does it yet)
Here's the scenario:
Alice can send a video to Bob in the app
Bob can open it immediately and see Alice's video, from beginning, while Alice is still recording it
Also, Bob can choose to view the video later after Alice finished recording. But Bob should be able to view the video instantly without waiting too much time, even when the whole size of the video is large.
Thus, my hunch is, it's using some sort of pseudo streaming for mp4.
Here's the screenshots of the requests Alice's phone makes while using the example app:
The screenshot suggests, the example app is making an array of PATCH requests to their server, every 0.x seconds. And finally, the very last request will make a PATCH to update the moov information for this MP4.
Thus my question is, how is this implemented (any educated guess will be welcomed)? Or is there any sort of existing protocol/iOS encoder that I didn't know is doing this already?
Thanks a lot!
Reading the text of your question rather than the title, I think there are a number of likely steps:
Alice is recording video
She is ending the video to a streaming server
Alice notifies Bob that the stream is available and sends the URL on the streaming server that Bob can access to retrieve the stream
Bob's video client requests the stream, using range request to download it chunk by chunk
Have a server in the middle like this is a typical approach for any stream which may have more than one client watching it.
More sophisticated streaming servers may also support delivery the stream in different bit rates and even encoded with different codecs for maximum device reach.
There are commercial (e.g. https://www.wowza.com) and open source streaming servers (e.g. https://gstreamer.freedesktop.org) you can look at to get more info on streaming servers and to see some examples.
Related
I am a newbie in video streaming and I just build a sample website which plays videos. Here i just give the video file location to the video tag in html5. I just noticed that in youtube the video tag contains the blob url and had a look into this. I found that the video data comes in segments and came across a term called pseudo streaming. Whereas it seems likes the website that i build downloads the whole file and plays the video. I am not trying to do any live streaming, just trying to stream local videos. I thought maybe the way video data is received in segments is done by a video streaming server. I came across RED5 open source streaming server, but most of the examples that is given is for live streaming which I am not experimenting on. Its been few days and I am not sure whether i am on the right track
The segmented approach you refer to is to support Adaptive Bit Rate streaming - ABR.
ABR allows the client device or player download the video in chunks, e.g 10 second chunks, and select the next chunk from the bit rate most appropriate to the current network conditions. See here for an example:
https://stackoverflow.com/a/42365034/334402
For your existing site, so long as your server supports range requests then you probably are not actually downloading the whole video. With Range Requests, the browser or player will request just part of the file at a time so it can start playback before the whole file is downloaded.
For MP4 files, it is worth noting that you need to have the header information, which is contained in a 'block' or 'atom' called MOOV atom, at the start of the file rather than the end - it is at the end for regular MP4 files. There are a number of tools which will allow you move it to the start - e.g.:
http://multimedia.cx/eggs/improving-qt-faststart/
You are definitely on the right track with your investigations - video hosting and streaming is a specialist area so it is generally easier to leverage existing streaming technologies and services rather than to build them your self. Some good places to look to get a feel for open source solutions:
https://gstreamer.freedesktop.org
http://www.videolan.org/vlc/streaming.html
I have a question, my app is a short video share application just like vine, but now I encounter questions when used in subway or some places with weak signals, it will fail sometimes and have poor user experience.
I am a newbie for network programming and iOS. I did a lot search on Google, and have some general sense, let me sum up my finds and pls help to give some suggestions for it.
My requirement is：1. support resume when uploading interrupt. 2. can success upload in weak signal. Actually I do NOT need to think about the realtime problems or how to compress the video, just think the video as a file is totally ok. BTW the server is a REST style, I use post to upload datas.
Questions:
which is the better way for my requirement, using stream(stream NOT mean live stream video just data stream like NSOutStream&NSInputStream, just play the video after all of it has uploaded, NOT the live stream video playing and downloading at meantime) or divide the whole file into several chunks and upload chunk by chunk.
someone said, using stream is good for resource efficiency since the stream will read files into memory and control the size of the buffer and after setup connection with server we use delegate to control the failure so easy to use.
Upload chunk by chunk is good at speed, I have puzzled with this statement, upload by chunks after successfully upload one chunk we need to release the connection resources and setup another connection then do upload I think this will spend time to do these preparation stuffs.
If upload by chunks which size should be good, one video file is almost 1M bytes, someone said 8k is a safe choice, but......
since the app needs to adapt to different signal strength, is there any way? for example the chunk size is depended on the bandwidth or other ways
Is there any private API already support resume uploading interrupt or is there any apple api can support this, my app needs to run on iOS 5 and above so can NOT use NSURLSession
Concurrent uploading is a way to speed up? If so how to implement or any API available?
Thank you in advance for helping a newbie like me. Thank you very much.
It takes o lot of topics your question. iOS doesn't have an public API to stream video (such as the face time components). The main issue here is sending frame by frame will require a lot of network traffic, instead if you use the normal video writer you get hardware compression, that will be a lot better. There's more and you can check here: Realtime Audio/Video Streaming FROM iPhone to another device (Browser, or iPhone), Upload live streaming video from iPhone like Ustream or Qik, How send to stream video from iOS device to server? and here
If real time is not your problem I would suggest you just to use a good network manager such as: MKNetworkkit or AFNetworking 2.0 . They will take care of most of the aspect that you asked.
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.
When programs such as Skype streams video from a user to another and vice versa, how is that usually accomplished?
Does client A stream to a server, and server sends it to client B?
or does it go directly from client A to B?
Feel free to correct me if i am way off and none of those is correct.
Skype is much more complicated than that, because it is Peer to Peer, meaning that your stream may travel through several other skype clients, acting as several servers. Skype does not have a huge central system for this. Skype always keeps track of multiple places that it can deliver your stream to, so that if one of these places disappear (that Skype client disappears), then it will continue sending through another server/skype-client. This is done so efficiently, that you don't notice the interruption.
Basically , this is how its achieved.
1) encode video / audio using the best compression you can get. Go lossy compression and plenty of aliasing to throw away portions of video and audio which is not usable. Like removing background hiss
2) pack video / audio into packets and put a timestamp on them. The packets are usually datagrams.
3) send packets directly to destination. Use the most appropriate route. You dont have to send all packets the same way. Use many routes if possible. P2P networks often use many routes to the same destination
4) re-encode on the destination. If a packet is too old , throw it away. If packets are lost , dont bother about it since its too late.
5) join the video back and fill in the missing frames the best you can.