Getting frames though a stream and display on screen

问题

I have a requirement of streaming from server and displaying the streamed content on the screen...Streaming is working fine using NSStream, and NSInputStream and NSOutputStream.How can I display it on the screen?

Stream used looks like @"http://191.168.143.41:1212/;

            if(stream == inputStream) {

            uint8_t buf[1024];
            unsigned int len = 0;

            len = [inputStream read:buf maxLength:1024];

            if(len > 0) {
                NSMutableData* datas=[[NSMutableData alloc] initWithLength:0];

                [datas appendBytes: (const void *)buf length:len];

                NSString *s = [[NSString alloc] initWithData:datas encoding:NSASCIIStringEncoding];

                [self readIn:s];
                NSLog(@"ss%@",s);
                 [self loadMovie:s]; //method for movie player 
            }

I tried to display this is in a movieplayer as below..

-(void_loadMovie:(NSString*)moviePrefix
   {
    NSString *path = [NSString stringWithFormat:@"%@.mjpg", moviePrefix];

    NSURL *url = [NSURL fileURLWithPath:path];
    if (url) {
        _moviePlayer = [[MPMoviePlayerController alloc] initWithContentURL:url];

       _moviePlayer.view.frame = CGRectMake(0, 70, 600, 450);
       _moviePlayer.controlStyle = MPMovieControlStyleNone;
        _moviePlayer.scalingMode = MPMovieScalingModeNone;
        [dic setObject:__moviePlayer forKey:path];
    }

}
[_moviePlayer prepareToPlay];
[self.view addSubview: _moviePlayer.view];
[self.view bringSubviewToFront:_moviePlayer.view];
[self.view addSubview: _moviePlayer.view];
[_moviePlayer play];  
}

Is NSString *path = [NSString stringWithFormat:@"%@.mjpg", moviePrefix]; correct way??

This displays a black screen.What is wrong? If this way is not correct,Is there any other way I can display those frames? Can anyone help me to solve this...

回答1:

MJPEG are only JPEG sent one after the other. I worked a few years ago on this. On a version of iOS (iOS5?), it was easily read with a UIWebView, but an update of iOS broke all this. This broke all my current work. Maybe a UIWebView could do the trick today again (fix).

Anyway, since it's just bunch of JPEG, you could just read the JPG (detect start/end of JPG file), create the JPG image and show it in a UIImageView.

A work around (not tested), but you should get the whole idea:

//Properties

@property (nonatomic, strong) NSMutableData *data;
@property (nonatomic, weak)   IBOutlet UIImageView *streamImageView;

//Initialize somewhere

_data = [[NSMutableData alloc] init];

//In the stream delegate method:

//Start JPG: FFD8 — End JPG: FFD9
UInt8 startJPEGBytes[2];
startJPEGBytes[0] = 0xFF;
startJPEGBytes[1] = 0xD8;
NSData *startData = [NSData dataWithBytes:&startJPEGBytes length:2];

UInt8 endJPEGBytes[2];
endJPEGBytes[0] = 0xFF;
endJPEGBytes[0] = 0xD9;
NSData *endData = [NSData dataWithBytes:&endJPEGBytes length:2];

[_data appendBytes: (const void *)buf length:len]; 
NSRange startRange = [_data rangeOfData:startData options:0 range:NSMakeRange(0, [_data length])];
if (startRange.location != NSNotFound) //We found the start of a JPEG
{
    NSRange endRange = [_data rangeOfData:endData options:0 range:NSMakeRange(startRange.location, [_data length]-startRange.location)];
    if (endRange.location != NSNotFound) //We found the end of a JPEG
    {
        NSRange imageRange = NSMakeRange(startRange.location, endRange.location+endRange.length-startRange.location);
        NSData *imageData = [_data subDataWithRange: imageRange];
        streamImage = [UIImage imageWithData:imageData];
        [_streamImageView setImage:streamImage];
        [_data replaceBytesInRange:NSMakeRange(0, imageRange.location+imageRange.length withBytes:NULL length:0]; //We remove the start till the end of JPEG frame. Start at 0, since there could be garbage at the start.
    }

}

回答2:

You are not adding moviePrefix to the string

NSString *path = [NSString stringWithFormat:@".mjpg", moviePrefix, @"movie"];

Change it to

NSString *path = [NSString stringWithFormat:@"%@.mjpg", moviePrefix, @"movie"];

回答3:

https://github.com/horsson/mjpeg-iphone/tree/55251a85e2c2489014036ddf5a491783f9b1962d

Used this to get the stream and display.It works

来源：https://stackoverflow.com/questions/30481563/getting-frames-though-a-stream-and-display-on-screen

标签

objective-c

iphone

http

mjpeg