Remote server recorder

This class acts as a recorder that receives media from a camera and records it to the network. E.g. the server can be configured to receive video from a FFmpeg player and send it to the network where a client player plays the video.

exception cpl_media.remote.server.EndConnection

Bases: Exception

Raised when the connection is closed.

class cpl_media.remote.server.RemoteData

Bases: object

Provides methods to send and receive messages from a socket.

decode_data(msg_buff, msg_len)

Decodes buffer data received from the network.

Parameters

• msg_buff – The bytes data received so far.

• msg_len – The expected size of the message as tuple - The size of the message and any associated binary data.

Returns

A tuple of the message name and value, or (None, None) if we haven’t read the full message.

read_msg(sock, msg_len, msg_buff)

Reads the message and decodes it once we read the full message.

Parameters

• sock – The socket.

• msg_len – The tuple of the message length and associated data. If empty, the start of the next message will provide this information.

• msg_buff – The message buffer.

Returns

A 4-tuple of (msg_len, msg_buff, msg, value). Where msg_len, msg_buff are similar to the input, and (msg, value) is the message and its value if we read a full message, otherwise they are None.

send_msg(sock, msg, value)

Sends message to the server.

Parameters

• sock – The socket

• msg – The message name string (e.g. image).

• value – The message value.

Returns

class cpl_media.remote.server.RemoteRecordSettingsWidget(recorder=None, **kwargs)

Bases: BoxLayout

Settings widget for RemoteVideoRecorder.

recorder: RemoteVideoRecorder = None

The recorder.

class cpl_media.remote.server.RemoteVideoRecorder(**kwargs)

Bases: BaseRecorder, RemoteData

A server recorder that takes images from a player and sends it to a client player over a socket.

The server is intended to be started before anything else can be processed. Once the server is run, we can start recording (whether a client is connected or not). If the client is not playing, we don’t send frames and just skip them.

A client should accept these messages: exception, started_recording, stopped_recording, or image. Server accepts messages from client: started_playing, stopped_playing.

We send started_recording in response to started_playing request. Either immediately if we were already recording, or later when we start. We send stopped_recording in response to stopping recording, if the client was between started_playing and stopped_playing (i.e. it expected to get images). We send images if between started_playing and stopped_playing requests and if we are recording.

We only accept started_playing either before any started_playing message or after a stopped_playing message (i.e. no duplicates).

_config_props_: Tuple[str] = ('server', 'port', 'timeout', 'max_images_buffered')

A list of configurable property names of the class that is set/read by the configuration API.

Each sub/super-class can define this and the properties are accumulated across all the sub/super-classes.

from_kivy_queue = None

The queue that receives messages from Kivy.

This queue can receive these messages: eof, image, started_recording, or stopped_recording.

max_images_buffered

How many images the server should buffer before it starts dropping images, rather than queuing them to be sent to the client.

port

The server port on which to broadcast the data.

process_in_kivy_thread(*largs)

Processes messages from the server in the kivy thread.

record(*largs, **kwargs)

Starts recording from the provided player and sets the record_state to starting.

May be called from main kivy thread only.

May only be called when record_state is none, otherwise an exception is raised. Similarly, only when the player’s play state is playing. The players metadata_play_used, must also have been set to the value it’s using.

Recorders need to eventually call complete_start() to finish starting recording.

record_thread_run(*largs)

The method that runs in the internal record thread.

send_image_to_client(image)

Sends a image (tuple of image, metadata) to the client through the server.

send_message_to_client(msg, value)

Sends the message to the client through the server.

Parameters

• msg – The message name string.

• value – The message value.

server

The server address on which to broadcast the data.

server_active

Whether the server is currently running.

server_run(from_kivy_queue, to_kivy_queue)

Server method, that is executed in the internal server thread.

server_thread = None

The server thread instance.

start_server()

Starts the server, so that we can record().

stop(*largs, join=False)

Stops recording from the player, if it is recording and sets the record_state to stopping.

Recorders need to eventually call complete_stop() to finish stopping recording.

Parameters

join – whether to block the thread until the internal record thread has exited.

Returns

Whether we stopped recording (True) or were already stop(ping/ed) recording.

stop_all(join=False)

Causes all internal threads to stop and exit.

Parameters

join – Whether to wait and block the calling thread until the internal threads exit.

stop_server(join=False)

Stops the server and also stops recording if we were recording.

timeout

How long to wait before timing out when reading data before checking the queue for other requests.

to_kivy_queue = None

The queue that sends messages to Kivy.