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4.5.1 Sequencing During Playback

If the user drags the seek bar to a new position, the following sequence occurs.

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Figure 6: Sequencing during playback--new position of seek bar

  1. The client sends the LinkViewerToMacStopPlaying message, followed by a LinkViewerToMacLogging message.

  2. The server confirms with a LinkMacToViewerReportEndOfStream message.

  3. The client sends a LinkViewerToMacStreamSwitch message.

  4. The server responds with a LinkMacToViewerReportStreamSwitch message.

  5. The client sends a LinkViewerToMacStartPlaying message that contains the new playback position.

  6. The server responds with a LinkMacToViewerReportStartedPlaying message while also streaming data to the client.

If the user presses and holds the fast forward or rewind button, the following sequence occurs.

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Figure 7: Sequencing during playback--fast forward and rewind buttons

  1. The client sends the LinkViewerToMacStopPlaying message followed by a LinkViewerToMacLogging message.

  2. The server confirms with a LinkMacToViewerReportEndOfStream message.

  3. The client sends a LinkViewerToMacStreamSwitch message.

  4. The server responds with a LinkMacToViewerReportStreamSwitch message.

  5. The client sends a LinkViewerToMacStartStriding message that contains the new playback position.

  6. The server responds with a LinkMacToViewerReportStartStriding message while also streaming data to the client.

When a server changes streams as part of a server-side playlist, the following sequence occurs.

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Figure 8: Sequencing during playback--server changes streams

  1. The server sends a LinkMacToViewerReportStreamChange message between two consecutive items in the playlist.

  2. The client sends a LinkViewerToMacReadBlock message to retrieve the ASF header for the new stream.

  3. The server responds with a LinkMacToViewerReportReadBlock message and sends the ASF file header as a Data packet on the streaming channel.

  4. The client sends a LinkViewerToMacLogging message, and then sends a LinkViewerToMacStartPlaying message.

  5. The server responds with a LinkMacToViewerReportStartedPlaying message while also streaming data to the client.

Every time a stream stops playing, for any reason, the client sends a LinkViewerToMacLogging message.

If the control connection is lost, the client may attempt to reconnect by sending a new connection request. In response, the server re-establishes the streaming media connection with the client and seeks the playback position where the connection was interrupted.

MMS uses TCP port 1755 for command communication between the client and server. If UDP is used, the client may occasionally request that the server resend lost Data packets. These requests are sent on UDP port 1755.

When streaming ASF data packets using the MMS Protocol, for performance reasons it is recommended that ASF data packets not include padding.

 
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