iphone AVVideoAverageBitRateKey

NSDictionary *videoCompressionProps = [NSDictionary dictionaryWithObjectsAndKeys:

                                                                  [NSNumber numberWithDouble:128.0*1024.0], AVVideoAverageBitRateKey, nil ];

NSMutableDictionary *d=[[NSMutableDictionary alloc] init];

[d setValue: AVVideoCodecH264 forKey: AVVideoCodecKey];

[d setValue:[NSNumber numberWithInt:192] forKey:AVVideoWidthKey];

[d setValue:[NSNumber numberWithInt:144] forKey:AVVideoHeightKey];

[d setValue:videoCompressionProps forKey:AVVideoCompressionPropertiesKey];