I can get individual frames from the iPhone's cameras just fine. what I need is a way to package them up with sound for streaming to the server. Sending the files once I have them isn't much of an issue. Its the generation of the files for streaming that I am having problems with. I've been trying to get FFMpeg to work without much luck.
Anyone have any ideas on how I can pull this off? I would like a known working API or instructions on getting FFMpeg to compile properly in an iPhone app.
You could divide your recording to separate files with a length of say, 10sec, then send them separately. If you use AVCaptureSession's beginConfiguration and commitConfiguration methods to batch your output change you shouldn't drop any frames between the files. This has many advantages over frame by frame upload:
The files can be directly used for HTTP live streaming without any server side processing.
The gap between data transfers allow the antennas to sleep in between if the connection is fast enough, saving battery life.
Conversely, if the connection is slow so upload is slower than recording, managing delayed upload of a set of files is much easier than a stream of bytes.
Related
I was reading about the thin clients and streaming videos. How is it different from downloading a file locally and then playing it on a browser. I mean internally how does streaming work? does streaming take less CPU and memory than playing from a file?
The concept behind streaming is very simple - essentially you can imagine the server sending the video either byte by byte, or in 'chunks' and the client receiving the bytes or chunks into a 'first in first out' queue and then playing them in the order they are received (and at the speed required to play the video properly).
More sophisticated streaming techniques will allow the client switch between different bit rate encodings while downloading the chunks of a file - this means that if the network conditions change during video playback the client can choose a lower or higher bit rate chunk as the next chunk to download appropriately. This is referred to as Adaptive Bit Rate streaming.
Advantages of streaming include fast video start up and seeking, better utilisation of bandwidth and no need to download the whole video if the user decides to seek or stop watching.
The following article gives a very good overview: http://www.jwplayer.com/blog/what-is-video-streaming/
I've m3u8 file with all the TS files. MPMoviePlayerController play them fine via http request on the streaming server. But I'd like to get the files locally in order to play them again later without any connection.
I managed to download m3u8 file and all the TS files locally on my device, I edited m3u8 files to point to local .ts instead of http ones, but I can't read them from this emplacement.
(VLC can do it well)
Is there a way to download the segments while playing (to avoid 2 downloads) and then to play them locally with MPMoviePlayerController or else.
.m3u8 is Apple HTTP Live Streaming, right? I think what you're trying to do simply goes against the design of that technology. You should expose the original file and allow it to be downloaded.
From what I understand, it's in the design of streaming that you don't get explicit access to the pieces in order to put them back together. For instance, Netflix uses streaming via Silverlight, and one of the benefits (to Netflix) is that it protects the data from being saved as if it were downloaded. Also, since HTTP Live Streaming allows a stream to switch bitrates on the fly, it's designed such that each time slice can be encoded at any number of bitrates, and none of them is canonical.
In theory, there might be a way to collect all the slices for a particular bitrate and re-encode them into a single video. But Apple's playback APIs are not going to give you that opportunity.
Instead of HTTP Live Streaming, consider progressive download. Just serve the original video file (transcode it to something the iPhone likes if necessary). If your server is configured properly, the playback APIs will do small requests to get particular chunks of the file, rather than the whole thing in one go, and it's a close second to proper streaming. I wish I could find where I read about this so I could give the proper name for it. Amazon S3 is set up to serve this way, if you need a quick solution.
But beware, Apple's docs say,
If your app delivers video over
cellular networks, and the video
exceeds either 10 minutes duration or
5 MB of data in a five minute period,
you are required to use HTTP Live
Streaming. (Progressive download may
be used for smaller clips.)
I'd like to get real-time video from the iPhone to another device (either desktop browser or another iPhone, e.g. point-to-point).
NOTE: It's not one-to-many, just one-to-one at the moment. Audio can be part of stream or via telephone call on iphone.
There are four ways I can think of...
Capture frames on iPhone, send
frames to mediaserver, have
mediaserver publish realtime video
using host webserver.
Capture frames on iPhone, convert to
images, send to httpserver, have
javascript/AJAX in browser reload
images from server as fast as
possible.
Run httpServer on iPhone, Capture 1 second duration movies on
iPhone, create M3U8 files on iPhone, have the other
user connect directly to httpServer on iPhone for
liveStreaming.
Capture 1 second duration movies on
iPhone, create M3U8 files on iPhone,
send to httpServer, have the other
user connected to the httpServer
for liveStreaming. This is a good answer, has anyone gotten it to work?
Is there a better, more efficient option?
What's the fastest way to get data off the iPhone? Is it ASIHTTPRequest?
Thanks, everyone.
Sending raw frames or individual images will never work well enough for you (because of the amount of data and number of frames). Nor can you reasonably serve anything from the phone (WWAN networks have all sorts of firewalls). You'll need to encode the video, and stream it to a server, most likely over a standard streaming format (RTSP, RTMP). There is an H.264 encoder chip on the iPhone >= 3GS. The problem is that it is not stream oriented. That is, it outputs the metadata required to parse the video last. This leaves you with a few options.
Get the raw data and use FFmpeg to encode on the phone (will use a ton of CPU and battery).
Write your own parser for the H.264/AAC output (very hard)
Record and process in chunks (will add latency equal to the length of the chunks, and drop around 1/4 second of video between each chunk as you start and stop the sessions).
"Record and process in chunks (will add latency equal to the length of the chunks, and drop around 1/4 second of video between each chunk as you start and stop the sessions)."
I have just wrote such a code, but it is quite possible to eliminate such a gap by overlapping two AVAssetWriters. Since it uses the hardware encoder, I strongly recommend this approach.
We have similar needs; to be more specific, we want to implement streaming video & audio between an iOS device and a web UI. The goal is to enable high-quality video discussions between participants using these platforms. We did some research on how to implement this:
We decided to use OpenTok and managed to pretty quickly implement a proof-of-concept style video chat between an iPad and a website using the OpenTok getting started guide. There's also a PhoneGap plugin for OpenTok, which is handy for us as we are not doing native iOS.
Liblinphone also seemed to be a potential solution, but we didn't investigate further.
iDoubs also came up, but again, we felt OpenTok was the most promising one for our needs and thus didn't look at iDoubs in more detail.
I want to be able to (live) stream the frames/video FROM the iPhone camera to the internet. I've seen in a Thread (streaming video FROM an iPhone) that it's possible using AVCaptureSession's beginConfiguration and commitConfiguration. But I don't know how to start designing this task. There are already a lot of tutorials about how to stream video TO the iPhone, and it is not actually what I am searching for.
Could you guys give me any ideas which could help me further?
That's a tricky one. You should be able to do it, but it won't be easy.
One way that wouldn't be live (not answering your need, but worth mentioning) is to capture from the camera and save it to a video file. see the AV Foundation Guide on how to do that. Once saved you can then use the HTTP Live Streaming segmenter to generate the proper segments. Apple has applications for Mac OSX, but there's an open source version as well that you could adapt for iOS. On top of that, you'd also have to run an http server to serve those segments. Lots of http servers out there you could adapt.
But to do it live, first as you have already found, you need to collect frames from the camera. Once you have those you want to convert them to h.264. For that you want ffmpeg. Basically you shove the images to ffmpeg's AVPicture, making a stream. Then you'd need to manage that stream so that the live streaming segmenter recognized it as a live streaming h.264 device. I'm not sure how to do that, and it sounds like some serious work. Once you've done that, then you need to have an http server, serving that stream.
What might actually be easier would be to use an RTP/RTSP based stream instead. That approach is covered by open source versions of RTP and ffmpeg supports that fully. It's not http live streaming, but it will work well enough.
Using FFMPEG, Live555, JSON
Not sure how it works but if you look at the source files at http://github.com/dropcam/dropcam_for_iphone you can see that they are using a combination of open source projects like FFMPEG, Live555, JSON etc. Using Wireshark to sniff the packets sent from one of the public cameras that's available to view with the free "Dropcam For Iphone App" at the App Store, I was able to confirm that the iphone was receiving H264 video via RTP/RTSP/RTCP and even RTMPT which looks like maybe some of the stream is tunneled?
Maybe someone could take a look at the open source files and explain how they got RTSP to work on the iphone.
Thanks for the info TinC0ils. After digging a little deeper I'v read that they have modified the Axis camera with custom firmware to limit the streaming to just a single 320x240 H264 feed, to better provide a consistent quality video over different networks and, as you point out, be less of a draw on the phone's hardware etc. My interest was driven by a desire to use my iphone to view live video and audio from a couple of IP cameras that I own without the jerkiness of MJPEG or the inherent latency that is involved with "http live streaming". I think Dropcam have done an excellent job with their hardware/software combo, I just don't need any new hardware at the moment.
Oh yeah, I almost forgot the reason of this post RTSP PROTOCOL DOES WORK ON THE IPHONE!
They are using open source projects to receive the frames and decoding in software instead of using hardware decoders. This will work, however, this runs counter to Apple's requirement that you use their HTTP Streaming. It will also require greater CPU resources such that it doesn't decode video at the desired fps/resolution on older devices and/or decrease battery life compared to HTTP streaming.