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Known issues

1. A stream containing B-frames does not play or plays with artifacts (latencies, lags)

Symptoms:

• a stream sent by the RTMP encoder does not play or plays with latencies or lags
• warnings in the client log:

09:32:31,238 WARN 4BitstreamNormalizer - RTMP-pool-10-thread-5 It is B-frame!

Solution: change the encoder settings so, that B-frames were not used (lower encoding profile, specify in the command line etc).

2. AAC frames of type 0 are not supported by decoder and will be ignored while stream pulled playback

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Using RTMP connection timeouts

In some cases, if RTMP encoder does not support Keep Alive packets sending, or Keep Alives are disabled due to another reason with the following parameter

keep_alive.algorithm=NONE

it is necessary to control RTMP connection and close it when no data was transmitted for a long time. To do this, use the following parameters.

Read timeout

Read timeout is set with the following settings in flashphoner.properties file:

rtmp.server_read_socket_timeout=120

In this case RTMP connection will be closed if no data was received in last 120 seconds.

Write timeout

Write timeout is set with the following setting

rtmp.server_write_socket_timeout=120

In this case RTMP connection will be closed if no data was sent in last 120 seconds.

Read and write timeout

Read and write timeout is set with the following setting

rtmp.server_socket_timeout=120

In this case RTMP connection will be closed if no data was received and sent in last 120 seconds.

RTMP stream picture rotation

When publishing RTMP stream to WCS, stream picture can be rotated using RTMP metadata. It may be useful for picture handling from mobile publishers.

To turn a picture to a certain angle RTMP metadata containing ‘orientation’ field should be sent. The following orientations are supported:

A picture is rotated clockwise.

Set up

To enable stream rotation, set the following parameter in flashphoner.properties file:

video_filter_enable_rotate=true

Note that stream rotation works for transcoded streams only.

Testing

1. For test we use:

• WCS server with picture rotation enabled
• Flash Streaming application to publish and rotate the stream
• Player application to play the stream

2. Open Flash Streaming application. Set stream name test and desired stream publishing parameters:

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3. Click Login then Start. Stream publishing begins

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4. Open Player application in anoter tab or browser, play the stream named test

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5. In Flash Streaming application click 180 button in Rotate camera section. The stream rotated to 180 degrees clockwise will be displayed in Player application

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To developer

Stream orientation metadata sending is implemented in Flash Streaming application as follows:

code

			private function rotate(degree:Number):void {
			    var metaDataObj:Object = new Object();
			    switch(degree) {
                    case 0:
                        Logger.info("rotate camera to 0");
                        metaDataObj.orientation = 0;
                        break;
                    case 90:
                        Logger.info("rotate camera to 90");
                        metaDataObj.orientation = 1;
                        break;
                    case 180:
                        Logger.info("rotate camera to 180");
                        metaDataObj.orientation = 2;
                        break;
                    case 270:
                        Logger.info("rotate camera to 270");
                        metaDataObj.orientation = 3;
                        break;
                    default:
                        metaDataObj.orientation = 0;
                        break;
			    }
			    sendMetaData(metaDataObj);
			}

			private function sendMetaData(data:Object):void{
			    if (publishStream != null) {
			        publishStream.send("@setDataFrame", "onMetaData", data);
			    }
			}

Note that orientation value should be sent but not angle itself.

How to rotate stream published from ffmpeg

ffmpeg RTMP encoder allows to send orientation metadata to WCS server using command line switches:

10:13:06,815 WARN AAC - AudioProcessor-c6c22de8-a129-43b2-bf67-1f433a814ba9 Dropping AAC frame that starts with 0, 119056e500

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ffmpeg -i input.mp4 -metadata:s:v rotate=90 -vcodec copy -acodec copy -strict -2 -f flv rtmp://test1.flashphoner.com:1935/live/stream_ffmpeg

Note that ffmpeg sends orientattion value but not angle itself.

Known issues

4. Some RTMP functions does not supported and will be ignored:

• FCSubscribe
• FCPublish
• FCUnpublish
• onStatus
• onUpstreamBase
• releaseStream

45. Some RTMP-encoders does not support KeepAlive.

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keep_alive.enabled=websocket,rtmfp

7. When stream published with RTMP encoder is played as HLS, freezes may occur if GOP is not multiple of FPS of file published

Symptoms: freezes occur when RTMP stream is played as HLS

Solution: in RTMP encoder settings, assign GOP to value equal or multiple of FPS of file published. For example, when publishing file with FPS 25 set GOP to 50.