StreamingServerControl - Cronologia

VittorioPalmisano: /* The stream database */

2009-01-26T14:20:41Z

‎The stream database

VittorioPalmisano: /* The stream database */

2009-01-26T14:20:27Z

‎The stream database

VittorioPalmisano: /* The stream database */

2009-01-26T14:19:02Z

‎The stream database

Ldecicco: /* The stream database */

2007-12-04T14:54:05Z

‎The stream database

VittorioPalmisano il 14:47, 4 Dic 2007

2007-12-04T14:47:40Z

VittorioPalmisano il 14:45, 4 Dic 2007

2007-12-04T14:45:14Z

Ldecicco: /* Server Protocol */

2007-12-04T14:40:40Z

‎Server Protocol

VittorioPalmisano il 14:19, 4 Dic 2007

2007-12-04T14:19:29Z

VittorioPalmisano il 14:18, 4 Dic 2007

2007-12-04T14:18:44Z

VittorioPalmisano il 13:58, 4 Dic 2007

2007-12-04T13:58:12Z

@@ Riga 70: / Riga 70: @@
 and if the requested encoding rate '''enc_r''' is 432.94 KB/s, than level (10) is choosed because it has the maximum encoded rate lower than '''enc_r''' (378.95 KB/s).
-[[Immagine:rx-buffer-control.png|center|thumb|350px|]]
+[[Immagine:rx-buffer-control.png|center|thumb|600px|]]
 ==The encoding control==

@@ Riga 70: / Riga 70: @@
 and if the requested encoding rate '''enc_r''' is 432.94 KB/s, than level (10) is choosed because it has the maximum encoded rate lower than '''enc_r''' (378.95 KB/s).
-[[Immagine:rx-buffer-control.png]]
+[[Immagine:rx-buffer-control.png|center|thumb|350px|]]
 ==The encoding control==

←Older revision		Revisione 14:19, 26 Gen 2009
Riga 69:		Riga 69:

	and if the requested encoding rate '''enc_r''' is 432.94 KB/s, than level (10) is choosed because it has the maximum encoded rate lower than '''enc_r''' (378.95 KB/s).		and if the requested encoding rate '''enc_r''' is 432.94 KB/s, than level (10) is choosed because it has the maximum encoded rate lower than '''enc_r''' (378.95 KB/s).
		+
		+	[[Immagine:rx-buffer-control.png]]

	==The encoding control==		==The encoding control==

@@ Riga 32: / Riga 32: @@
 Each multimedia stream is stored into a SQLite database. This database has 4 tables: '''audio''', ''video''', '''audio_levels''' and '''video_levels'''.
-The '''audio''' and '''video''' table rows have this structure:
+The structure of both '''audio''' and '''video''' table rows is following:
    ---------------------------
@@ Riga 48: / Riga 48: @@
 where '''level''' is the encoding level (bit/s), '''size''' (bytes) and '''duration''' (seconds) are the total video size and duration encoded at this level.
-The '''StreamingServer''' can switch from one encoding level to another on fly in order to match the detected bandwidth and keep a desired buffer time on each client. When a new encoding rate request ('''enc_r''') is issued by the encoder control algorithm, the '''StreamingServer''' switches to the maximum encoding rate level lower than '''enc_r''' available on database.
+The '''StreamingServer''' can switch on the fly between two encoding levels in order to match the end-to-end bandwidth and to keep a desired buffer time on each client. When a new encoding rate request ('''enc_r''') is issued by the encoder control algorithm, the '''StreamingServer''' switches to the maximum encoding rate level which is lower than '''enc_r''' available on database.
 For example, if the database has the following encoding levels:

@@ Riga 90: / Riga 90: @@
 * '''STOPPED''': no video is currently playing
 * '''PAUSED''': the user has paused the video
-* '''PLAYING''': video is currently playing. The client reads from network and sends feedback reports when a new packet arrives on his own queue. If the client buffer becomes empty, the client switches to the '''BUFFERING''' state and the server doesn't change the current encoding level until '''queue_time''' doesn't reach again '''max_queue_t'''.
+* '''PLAYING''': video is currently playing. The client reads from network and sends feedback reports when a new packet arrives on his own queue. If the client buffer becomes empty, the client switches to the '''BUFFERING''' state and the server doesn't change the current encoding level as long as '''queue_time''' < '''max_queue_t'''.
 * '''BUFFERING''': video is currently paused, packets are read from the network and stored into the client buffer. When '''queue_time''' reach '''max_queue_t''', the client switches to the '''PLAYING''' state. In this state, the server doesn't change the current encoder rate.

@@ Riga 8: / Riga 8: @@
 The client->server supported messages are the following:
 * '''GET <filename>''': initial client request
-* '''q=<value>''': the client queued time (ns)
+* '''q:<value>''': the client queued time (ns)
-* '''r=<value>''': the client receiving rate (bytes/s)
+* '''r:<value>''': the client receiving rate (bytes/s)
-* '''b=<value>''': the last queued buffer duration (ns)
+* '''b:<value>''': the last queued buffer duration (ns)
-* '''max_queue_t=<value>''': the client maximum queue time (ns)
+* '''max_queue_t:<value>''': the client maximum queue time (ns)
-* '''target_t=<value>''': the client target queue time (ns)
+* '''target_t:<value>''': the client target queue time (ns)
-* '''stop:control:''': the server encoder control should be stopped
+* '''s:''': the client status
 The server->client packet structure is:
@@ Riga 90: / Riga 90: @@
 * '''STOPPED''': no video is currently playing
 * '''PAUSED''': the user has paused the video
-* '''PLAYING''': video is currently playing. The client reads from network and sends feedback reports when a new packet arrives on his own queue. If the client buffer becomes empty, the client switches to the '''BUFFERING''' state and sends the '''stop_control''' command to the server.
+* '''PLAYING''': video is currently playing. The client reads from network and sends feedback reports when a new packet arrives on his own queue. If the client buffer becomes empty, the client switches to the '''BUFFERING''' state and the server doesn't change the current encoding level until '''queue_time''' doesn't reach again '''max_queue_t'''.
 * '''BUFFERING''': video is currently paused, packets are read from the network and stored into the client buffer. When '''queue_time''' reach '''max_queue_t''', the client switches to the '''PLAYING''' state. In this state, the server doesn't change the current encoder rate.

@@ Riga 3: / Riga 3: @@
 ==Server Protocol ==
-The '''StreamingServer''' module implements is a custom server developed using [http://twistedmatrix.com Twisted] libraries.
+The '''StreamingServer''' module is a custom server developed using [http://twistedmatrix.com Twisted] libraries.
-It listens on TCP port 1234 and it uses a custom line-based protocol based on SDP.
+It listens on TCP port 1234 and employs a custom line-based protocol based on SDP which is described in the following.
 The client->server supported messages are the following:
@@ Riga 15: / Riga 15: @@
 * '''stop:control:''': the server encoder control should be stopped
-The server->client packet structure is the following:
+The server->client packet structure is:
    ------------------------------------------------------------------------------
@@ Riga 26: / Riga 26: @@
 When a new packet is sent over the network, the server adds the packet buffer duration to the variable ('''outstandings''').
-When a new packet is received, the client reports back to the server the queued time (q), the receiving rate (r) and the current received buffer duration (b).
+When a new packet is received, the client feeds back to the server the queued time (q), the receiving rate (r) and the current received buffer duration (b).
 The server subtracts '''b''' from the '''outstandings''' variable.

@@ Riga 88: / Riga 88: @@
 The client has the following states:
-* STOPPED: no video is currently playing
+* '''STOPPED''': no video is currently playing
-* PAUSED: the user has paused the video
+* '''PAUSED''': the user has paused the video
-* PLAYING: video is currently playing. The client reads from network and sends feedback reports when a new packet arrives on his own queue. If the client buffer becomes empty, the client switches to the BUFFERING state and sends the '''stop_control''' command to the server.
+* '''PLAYING''': video is currently playing. The client reads from network and sends feedback reports when a new packet arrives on his own queue. If the client buffer becomes empty, the client switches to the '''BUFFERING''' state and sends the '''stop_control''' command to the server.
-* BUFFERING: video is currently paused, packets are read from the network and stored into the client buffer. When '''queue_time''' reach '''max_queue_t''', the client switches to the PLAYING state. In this state, the server doesn't change the current encoder rate.
+* '''BUFFERING''': video is currently paused, packets are read from the network and stored into the client buffer. When '''queue_time''' reach '''max_queue_t''', the client switches to the '''PLAYING''' state. In this state, the server doesn't change the current encoder rate.