How to stream from VLC (linux) to iPod with web service (complete process)?

Question

I want to stream my webcam in linux with VLC to the iPod. From what I've seen on the web, the easiest way is to use a web server and then access to it from the iPod like this:

NSString *url = @"http://www.example.com/path/to/movie.mp4";
MPMoviePlayerController *moviePlayer = [[MPMoviePlayerController alloc] initWithContentURL:[NSURL URLWithString:url]];
[moviePlayer play];

I have never used web services before and would like to know how i can achieve this whole process. Thank you

EDIT: After setting up the linux/vlc/segmenter, this is what i get in the terminal after running the comment from Warren and exiting vlc:

VLC media player 1.1.4 The Luggage (revision exported)
Blocked: call to unsetenv("DBUS_ACTIVATION_ADDRESS")
Blocked: call to unsetenv("DBUS_ACTIVATION_BUS_TYPE")
[0x87bc914] main libvlc: Running vlc with the default interface. Use 'cvlc' to use vlc without interface.
Blocked: call to setlocale(6, "")
Blocked: call to sigaction(17, 0xb71840d4, 0xb7184048)
Warning: call to signal(13, 0x1)
Warning: call to signal(13, 0x1)
Warning: call to srand(1309581991)
Warning: call to rand()
Blocked: call to setlocale(6, "")

(process:4398): Gtk-WARNING **: Locale not supported by C library.
Using the fallback 'C' locale.
Warning: call to signal(13, 0x1)
Warning: call to signal(13, 0x1)
Blocked: call to setlocale(6, "")
Could not open input file, make sure it is an mpegts file: -1

Help me understanding all this? thks!

Answer 1

The URL you show assumes the video is prerecorded.

For live HTTP streaming to an iOS device, the URL will instead end in .m3u or .m3u8, which is a common playlist format type. (It is an extended version of the Icecast playlist format, documented in this IETF draft.) This playlist tells the iOS device how to find the other files it will retrieve, in series, in order to stream the video.

The first tricky bit is producing the video stream. Unlike all other iOS compatible media files, live HTTP streaming requires an MPEG-2 transport stream (.ts) container, rather than an MPEG-4 part 14 container (.mp4, .m4v). The video codec is still H.264 and the audio AAC, as you might expect.

A command something like this should work:

$ vlc /dev/camera –intf=dummy –sout-transcode-audio-sync –sout='#transcode{\
        vcodec=h264,venc=x264{\
            aud,profile=baseline,level=30,keyint=30,bframes=0,ref=1,nocabac\
        },\
        acodec=mp4a,ab=56,deinterlace\
    }:\
    duplicate{dst=std{access=file,mux=ts,dst=-}}' > test.ts

This is all one long command. I've just broken it up for clarity, and to work around SO's formatting style limits. You can remove the backslashes and whitespace to make it a single long line, if you prefer. See the VLC Streaming HOWTO for help on figuring out what all that means, and how to adjust it.

The /dev/camera bit will probably have to be adjusted, and you may want to fiddle with the A/V encoding parameters based on Apple's best practices tech note (#TN 2224) to suit your target iOS device capabilites.

The next tricky bit is producing this playlist file and the video segment files from the live video feed.

Apple offers a program called mediastreamsgementer which does this, but it's not open source, it only runs on OS X, and it isn't even freely downloadable. (It comes as part of Snow Leopard, but otherwise, you have to be in Apple's developer program to download a copy.)

Chase Douglas has produced a basic segmenter which builds against libavformat from ffmpeg. There is a newer variant here which has various improvments.

To combine this with the vlc camera capture and encoding command above, replace the > test.ts part with something like this:

| segmenter - 10 test test.m3u8 http://www.example.com/path/to/

This pipes VLC's video output through the segmenter, which breaks the TS up into 10 second chunks and maintains the test.m3u8 playlist file that tells the iOS device how to find the segment files. The - argument tells the segmenter that the video stream is being piped into its standard input, rather than coming from a file. The URL fragment at the end gets prepended onto the file names mentioned in the M3U file.

Having done all that, the only adjustment that should be needed for your Cocoa Touch code is that it should be accessing test.m3u8 instead of movie.mp4.