1. A communication network unit comprising:
a memory configured to store, for each communication terminal of a plurality of first communication terminals which are each associated with a same user identification, information about communication capabilities of the respective communication terminals;
a determining unit configured to determine which communication capabilities are available for communicating with a user by reading from the memory the information about the communication capabilities of the plurality of first communication terminals associated with the user identification of the user; and
a first signaling unit configured to transmit to a second communication terminal a data message that indicates which communication capabilities, as determined by the determining unit, are available for communicating with the user,
wherein a communication connection is established between a first communication terminal of the plurality of first communication terminals and the second communication terminal, and the determining unit is further configured to determine which communication capabilities of the first communication terminal can be used for communicating with the second communication terminal and to determine which of the communication capabilities of the other communication terminals of the plurality of first communication terminals can be used for communicating with the second communication terminal, and
wherein the first signaling unit is further configured to signal to the second communication terminal the communication capabilities of the first communication terminal that can be used for communicating with the second communication terminal as being available and to signal the communication capabilities of the other communication terminals of the plurality of first communication terminals that can be used for communicating with the second communication terminal as being conditionally available, and
a second signaling unit configured to notify communication terminals of the plurality of first communication terminals about the communication connection between the first communication terminal of the plurality of first communication terminals and the second communication terminal,
wherein the second signaling unit is further configured to notify communication terminals of the plurality of first communication terminals that have communication capabilities that can be used for communication with the second communication terminal, about the communication connection between the first communication terminal of the plurality of first communication terminals and the second communication terminal, and
wherein at least one of the communication terminals of the communication terminals that are being notified about the communication connection comprises a reporting unit configured to inform the user about the communication connection.
2. The communication network unit according to claim 1, wherein the plurality of first communication terminals signal their communication capabilities to the communication network unit.
3. The communication network unit according to claim 1, wherein the reporting unit is further configured to inform the user about communication capabilities of the at least one other communication terminal that can be used for communicating with the second communication terminal.
4. The communication network unit according to claim 1, wherein the first signaling unit is further configured to signal the communication capabilities using a call control protocol.
5. The communication network unit according to claim 1, wherein at least one of the communication terminals signaling information about its communication capabilities uses a call control protocol.
6. The communication network unit according to claim 5, wherein at least one of the communication terminals uses another protocol for sending and receiving control information, and the communication network further comprises a converting unit configured to convert messages according to the other protocol to the call control protocol and configured to convert messages according to the call control protocol to the other protocol.
7. The communication network unit according to claim 1, wherein the first signaling unit is further configured to signal the communication capabilities using the SIP protocol.
8. The communication network unit according to claim 1, wherein at least one of the communication terminals signals information about its communication capabilities using the SIP protocol.
9. The communication network unit according to claim 8, wherein at least one of the communication terminals uses another protocol for sending and receiving control information, and the communication network further comprises a converting unit configured to convert messages according to the other protocol to the SIP protocol and configured to convert messages according to the SIP protocol to the other protocol.
10. A method for exchanging communication capabilities, comprising:
storing, for each communication terminal of a plurality of first communication terminals which are each associated with a same user identification, information about communication capabilities of the respective communication terminals;
determining which communication capabilities are available for communicating with a user based on the stored information about the communication capabilities of the plurality of first communication terminals associated with the user identification of the user;
transmitting to a second communication terminal a data message that indicates which communication capabilities are available for communicating with the user as determined based on the user identification;
establishing a communication connection between a first communication terminal of the plurality of first communication terminals and the second communication terminal;
determining which communication capabilities of the plurality of first communication terminals are available for communicating with the second communication terminal;
signaling to the second communication terminal the communication capabilities of the plurality of first communication terminals that can be used for communicating with the second communication terminal as being available;
notifying communication terminals of the plurality of first communication terminals about the communication connection;
notifying communication terminals of the plurality of first communication terminals that have communication capabilities that can be used for communication with the second communication terminal about the communication connection; and
informing the user about the communication connection on at least one of the communication terminals of the communication terminals that are being notified.
11. A communication network unit comprising:
a memory configured to store first information about the communication capabilities of a first communication terminal and to store information about the communication capabilities of a second communication terminal;
a processing unit configured to generate second information about the communication capabilities of the first communication terminal using the first information about the stored communication capabilities of the first communication terminal and taking into account the stored information about the communication capabilities of the second communication terminal;
a message generating unit configured to generate a message comprising the second information about the communication capabilities of the first communication terminal; a transmitting unit configured to transmit the message to the second communication terminal;
a connection unit configured to establish a communication connection between the first communication terminal and the second communication terminal;
a determining unit configured to determine which second information of the first communication terminal is available for communicating with the second communication terminal;
a signaling unit configured to signal to the second communication terminal the second information that can be used for communicating with the second communication terminal as being available;
a notifying unit configured to notify the first communication terminal about the communication connection and to notify communication terminal about the communication connection if mutual second information exists; and
a reporting unit configured to inform a user about the communication connection.
12. The communication network unit according to claim 11, wherein the second information specifies communication capabilities of the first communication terminal that can be used by the second communication terminal for communicating with the first communication terminal.
13. The communication network unit according to claim 8, wherein the message is generated according to a call control protocol.
14. The communication network unit according to claim 13, wherein the message is generated according to the SIP protocol.
15. A method for exchanging capability information, comprising:
storing first information about the communication capabilities of a first communication terminal and storing information about the communication capabilities of a second communication terminal;
generating second information about the communication capabilities of the first communication terminal using the stored first information about the communication capabilities of the first communication terminal and taking into account the stored information about the communication capabilities of the second communication terminal;
generating a message comprising the second information about the communication capabilities of the first communication terminal; transmitting the message to the second communication terminal;
establishing a communication connection between the first communication terminal and the second communication terminal;
determining which second information about the communication capabilities of the first communication terminal are available for communicating with the second communication terminal;
signaling to the second communication terminal second information about the communication capabilities of the first communication terminal that can be used for communicating with the second communication terminal as being available;
notifying the first communication terminal about the communication connection;
notifying the first communication terminal that has second information about communication capabilities that can be used for communication with the second communication terminal about the communication connection; and
informing a user about the communication connection on the first communication terminal.
16. The communication network unit according to claim 1, wherein the communication network is a home network and at least one of the plurality of first communication terminals is further configured to transmit the respective communication capabilities to a media router of the home network when the at least one of the plurality of first communication terminals is registered with the media router.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method of processing a request from a first communication apparatus connected through a communication network to a remote second communication apparatus, the method being implemented in the second apparatus, the method comprising the steps of:
receiving the request, wherein the request is for obtaining digital data of a compressed digital signal that comprises header data and a signal body comprising data packets;
determining whether or not at least one pointer marker, providing information for calculating the length of the part of the signal body preceding at least one data packet corresponding to the request, is absent in the header data via a test;
forming the at least one pointer marker in the compressed digital signal when the determining step determines that the at least one pointer marker providing information for calculating the length of the part of the signal body, is not present in the header data; and
processing the request including the step of determining a position, in the body of the compressed digital signal, of the at least one data packet corresponding to the request as a function of the length of the header data and of the at least one pointer marker present in the header data of the compressed digital signal.
2. The method according to claim 1, further comprising the step of determining the length of the part of the body of the compressed digital signal preceding the data packet under consideration comprising a preliminary step of determining the order of appearance of the data packet in the body of the compressed digital signal, according to parameters relating to structure and organization of the data in the compressed digital signal.
3. The method according to claim 1, wherein the compressed digital signal is partitioned into a number n of independently compressed regions ti =1 to n and n \u22671, the body of the compressed digital signal comprising, for each region, region header data and a region body containing data packets of the region under consideration.
4. The method according to claim 3, wherein the length of the part of the body of the compressed digital signal preceding the data packet under consideration is determined from:
at least one pointer marker PLT providing information for calculating the length of the data packet or packets preceding the data packet under consideration in the region where this packet is located,
the length of the header data of the region where the packet under consideration is located and, when one or more regions precede the region where the packet under consideration is located,
at least one pointer marker TLM providing information for calculating the length of the preceding region or regions.
5. The method according to claim 4, wherein a pointer marker TLM providing information for calculating the length of each region t, is present in the header data.
6. The method according to claim 4, wherein a pointer marker PLT providing information for calculating the length of the data packets in a region ti, is present in the header data of the region concerned.
7. The method according to claim 1, further comprising the steps of extracting and transmitting to the first communication apparatus the at least one data packet having a position that has been determined.
8. The method according to claim 1, wherein the request for obtaining digital data specifies at least one data packet of the compressed digital signal.
9. The method according to claim 1, wherein the request for obtaining digital data specifies part of the compressed digital signal.
10. The method according to claim 9, wherein, subsequent to the request being received, the method comprises a step of identifying the data packet or packets necessary for the reconstruction of the specified part of the compressed digital signal.
11. A method of processing compressed digital data received by a first communication apparatus connected through a communication network to a remote second communication apparatus, the method being implemented in the first communication apparatus, the method comprising the steps of:
receiving only a portion of a compressed digital signal present in the second apparatus and comprising a body that comprises data packets, the received portion of the compressed digital signal comprising at least one data packet;
generating a derived compressed digital signal derived from the compressed digital signal present in the second apparatus in the form of a cache file, the derived compressed digital signal comprising header data and a body and capable of containing all or part of the body of the compressed digital signal present in the second apparatus;
filling the body of the derived compressed digital signal in the cache file with arbitrary data, so as to constitute a space of the same size as the body of the compressed digital signal present in the second apparatus;
determining a position at which the at least one data packet of the received portion of the compressed digital signal is to be inserted into the body of the derived compressed digital signal, the position being determined as a function of the length of the header data and of at least one pointer marker previously received and inserted into the header data of the derived compressed digital signal by the first apparatus, the at least one pointer marker providing information for calculating the length of the part of the body of the derived compressed digital signal preceding the at least one data packet of the received portion of the compressed digital signal;
inserting into the body of the derived compressed digital signal the at least one data packet of the received portion of the compressed digital signal at the determined position; and
a phase of converting the derived compressed digital signal into a valid signal comprising the steps of:
extracting from the derived compressed digital signal the header data and received data packets;
forming the header data of the valid signal from the header data extracted from the derived compressed digital signal;
concatenating the data packets extracted from the derived compressed digital signal in the body of the valid signal; and
when one or more data packets present in the body of an original compressed digital signal in the second apparatus, from which the derived compressed digital signal is derived, are not received by the first apparatus, concatenating respectively one or more empty packets in the body of the valid signal in the same order of appearance as that adopted in the derived compressed digital signal.
12. The method according to claim 11, wherein the compressed digital signal present in the second apparatus is an original compressed digital signal, said method further comprising the preliminary steps of:
receiving the header data from the original compressed digital signal present in the second apparatus, the received header data comprising at least one pointer marker TLM providing information for calculating the length of the body of the original compressed digital signal; and
forming, from the received header data, the derived compressed digital signal which thus comprises, as header data, the received header data and a signal body of length equal to that of the body of the original compressed digital signal, the body of the derived compressed digital signal representing a space initially filled with the arbitrary data and later containing the at least one data packet received from the second apparatus.
13. The method according to claim 11, wherein the derived compressed digital signal is partitioned into a number n of independently compressed regions ti, i =1 to n and n\u22671, the body of the signal of the derived compressed digital signal comprising, for each region, region header data and a region body containing data packets of the region under consideration.
14. The method according to claim 13, wherein the length of the part of the body of the derived compressed, digital signal preceding the data packet under consideration is determined from:
at least one pointer marker PLT providing information for calculating the length of the data packet or packets preceding the data packet under consideration in the region where this packet is located,
the length of the header data of the region where the packet under consideration is located, and,
when one or more regions precede the region where the packet under consideration is located, at least one pointer marker TLM provides information for calculating the length of the preceding region or regions.
15. The method according to claim 14, wherein a pointer marker providing information for calculating the length of each region t is present in the header data of the derived compressed digital signal.
16. The method according to claim 14, wherein a pointer marker providing information for calculating the length of the data packets in a region t, is present in the header data of the region under consideration.
17. The method according to claim 13, further comprising the steps of:
receiving region header data;
determining a position at which the received region header data is to be inserted into the body of the derived compressed digital signal, the position being determined according to the length of the header data of the derived compressed digital signal and, when one or more regions of the derived compressed digital signal precede the region header data according to one or more pointer markers TLM received previously, said method provides respectively the length of the preceding region or regions; and
inserting the received region header data at the determined position.
18. The method according to claim 11, further comprising the step of determining the length of the part of the body of the derived compressed digital signal preceding the at least one data packet comprising a preliminary step of determining the order of appearance of the at least one data packet in the body of the derived compressed digital signal according to parameters relating to structure and organization of the data in the derived compressed digital signal.
19. The method according to claim 12, further comprising a phase of converting the derived compressed digital signal into a valid signal comprising the steps of:
extracting from the derived compressed digital signal the header data and received data packets;
forming the header data of the valid signal from the header data extracted from the derived compressed digital signal;
concatenating the data packets extracted from the derived compressed digital signal in the body of the valid signal; and
when one or more data packets present in the body of the original compressed digital signal are not received by the first apparatus, concatenating respectively one or more empty packets in the body of the valid signal in the same order of appearance as that adopted in the derived compressed digital signal.
20. The method according to claim 12, further comprising the steps of:
going through the data contained in the body of the derived compressed digital signal;
converting, when the data gone through does not correspond to a data packet received from the second apparatus, the space filled by the data concerned into an empty packet; and
shifting in an adapted manner the data comprising the remainder of the body of the derived compressed digital signal.
21. The method according to claim 11, wherein the data received by the first apparatus comprises the reply to a request previously transmitted from the first apparatus to the second apparatus.
22. A device for processing a request coming from a first communication apparatus connected through a communication network to a remote second communication apparatus, the device being implemented in the second apparatus, the device comprising:
a receiver that receives the request, wherein the request is for obtaining digital data of a compressed digital signal that comprises header data and a signal body comprising data packets;
a determining device that determines whether or not at least one pointer marker, providing information for calculating the length of the part of the signal body preceding at least one data packet corresponding to the request, is absent in the header data via a test;
a forming device that forms the at least one pointer marker in the compressed digital signal when the determining device determines that the at least one pointer marker providing information for calculating the length of the part of the signal body, is not present in the header data; and
a processor that processes the request and determines a position, in the body of the compressed digital signal, of the at least one data packet corresponding to the request as a function of the length of the header data and of the at least one pointer marker present in the header data of the compressed digital signal.
23. The device according to claim 22, further comprising a length determining device that determines the length of the part of the body of the compressed digital signal preceding the data packet under consideration and determines the order of appearance of the data packet in the body of the compressed digital signal according to parameters relating to structure and organization of the data in the compressed digital signal.
24. The device according to claim 22, wherein the compressed digital signal is partitioned into a number n of independently compressed regions ti, i =1 to n and n\u22671, the body of the compressed digital signal comprising, for each region, region header data and a region body containing data packets of the region under consideration.
25. The device according to claim 24, wherein the length of the part of the body of the compressed digital signal preceding the data packet under consideration is determined from:
at least one pointer marker PLT providing information for calculating the length of the data packet or packets preceding the data packet under consideration in the region where this packet is located,
the length of the header data of the region where the packet under consideration is located,
and, when one or more regions precede the region where the packet under consideration is located, at least one pointer marker TLM providing information for calculating the length of the preceding region or regions.
26. The device according to claim 22, further comprising an extractor that extracts and transmits to the first communication apparatus the at least one data packet having a position that has been determined.
27. A device for processing compressed digital data received by a first communication apparatus connected through a communication network to a remote second communication apparatus, the device being implemented in the first communication apparatus, the device comprising:
a receiver that receives only a portion of a compressed digital signal present in the second apparatus and comprising a body that comprises data packets, the received portion of the compressed digital signal comprising at least one data packet;
a generating device that generates a derived compressed digital signal derived from the compressed digital signal present in the second apparatus in the form of a cache file, the derived compressed digital signal comprising header data and a body and capable of containing all or part of the body of the compressed digital signal present in the second apparatus;
a filling device that fills the body of the derived compressed digital signal in the cache file with arbitrary data, so as to constitute a space of the same size as the body of the compressed digital signal present in the second apparatus;
a processor that determines a position at which the at least one data packet of the received portion of the compressed digital signal is to be inserted into the body of the derived compressed digital signal, the position being determined as a function of the length of the header data and of at least one pointer marker previously received and inserted into the header data of the derived compressed digital signal by the first apparatus, the at least one pointer marker providing information for calculating the length of the part of the body of the derived compressed digital signal preceding the at least one data packet of the received portion of the compressed digital signal;
an inserting device that inserts, into the body of the derived compressed digital signal, the at least one data packet of the received portion of the compressed digital signal at the determined position; and
a converter that converts the derived compressed digital signal into a valid signal which comprises:
an extractor that extracts from the derived compressed digital signal header data and received data packets;
a forming device that forms the header data of the valid signal from the header data extracted from the derived compressed digital signal; and
a concatenating device that concatenates the data packets extracted from the derived compressed digital signal in the body of the valid signal and, when one or more data packets present in the body of an original compressed digital signal in the second apparatus, from which the derived compressed digital signal is derived, are not received by the first apparatus, concatenating respectively one or more empty packets in the body of the valid signal in the same order of appearance as that adopted in the derived compressed digital signal.
28. The device according to claim 27, wherein the compressed digital signal present in the second apparatus is an original compressed digital signal, said device further comprising:
a header-data receiver that receives the header data from the original compressed digital signal present in the second apparatus, the received header data comprising at least one pointer marker TLM providing information for calculating the length of the body of the original compressed digital signal; and
a forming device that forms the derived compressed digital signal from the received header data and which thus comprises, as header data, the received header data and a signal body of length equal to that of the body of the original compressed digital signal, the body of the derived compressed digital signal representing a space initially filled with the arbitrary data and later containing the at least one data packet received from the second apparatus.
29. The device according to claim 27, wherein the compressed digital signal is partitioned into a number n of independently compressed regions ti, =1 to n and n\u22671, the body of the signal of the derived compressed digital signal comprising, for each region, region header data and a region body containing data packets of the region under consideration.
30. The device according to claim 29, wherein the length of the part of the body of the derived compressed digital signal preceding the data packet under consideration is determined from:
at least one pointer marker PLT providing information for calculating the length of the data packet or packets preceding the data packet under consideration in the region where this packet is located,
the length of the header data of the region where the packet under consideration is located, and,
when one or more regions precede the region where the packet under consideration is located, at least one pointer marker TLM provides information for calculating the length of the preceding region or regions.
31. The device according to claim 29, further comprising:
a region-header-data receiver that receives region header data;
a determining device that determines a position at which the received region header data is to be inserted into the body of the derived compressed digital signal, the position being determined according to the length of the header data of the derived compressed digital signal and, when one or more regions of the derived compressed digital signal precede the region header data, also according to one or more pointer markers TLM received previously, said device provides respectively the length of the preceding region or regions; and
a received-region-header-data inserting device that inserts the received region header data at the determined position.
32. The device according to claim 27, further comprising a length determining device that determines the length of the part of the body of the derived compressed digital signal preceding the at least one data packet and that determines the order of appearance of the at least one data packet in the body of the derived compressed digital signal according to parameters relating to structure and organization of the data in the derived compressed digital signal.
33. The device according to claim 28, further comprising a converter that converts the derived compressed digital signal into a valid signal which comprises:
an extractor that extracts from the derived compressed digital signal header data and received data packets;
a forming device that forms the header data of the valid signal from the header data extracted from the derived compressed digital signal; and
a concatenating device that concatenates the data packets extracted from the derived compressed digital signal in the body of the valid signal and, when one or more data packets present in the body of the original compressed digital signal are not received by the first apparatus, concatenating respectively one or more empty packets in the body of the valid signal in the same order of appearance as that adopted in the derived compressed digital signal.
34. The device according to claim 28, further comprising:
an examining device that examines the data contained in the body of the derived compressed digital signal;
a converter that converts , when the examined data does not correspond to a data packet received from the second apparatus, the space filled by the data concerned into an empty packet; and
a shifting device that shifts in an adapted manner the data comprising the remainder of the body of the derived compressed digital signal.
35. A non-transitory information storage device readable by a computer or a microprocessor comprising code instructions of a computer program for executing the steps of the method of processing a request according to claim 1.
36. A non-transitory information storage device readable by a computer or a microprocessor comprising code instructions of a computer program for executing the steps of the method of processing data according to claim 11.
37. A computer program stored in a non-transitory computer-readable medium for loading into a programmable apparatus, comprising sequences of instructions or portions of software code for implementing the steps of the method of processing a request according to claim 1, when the computer program is loaded and executed by the programmable apparatus.
38. A computer program stored in a non-transitory computer-readable medium for loading into a programmable apparatus, comprising sequences of instructions or portions of software code for implementing the steps of the method of processing data according to claim 11, when the computer program is loaded and executed by the programmable apparatus.
39. The method according to claim 11, further comprising a preliminary step of forming the derived compressed digital signal which thus comprises the header data and the body, the body of the derived compressed digital signal having a length equal to that of the body of the compressed digital signal present in the second apparatus, the body of the derived compressed digital signal representing a space initially filled with the arbitrary data and later containing the at least one data packet of the portion received from the second apparatus.
40. The method according to claim 39, wherein the insertion into the body of the derived compressed digital signal of the at least one data packet leads to overwriting part of the space initially filled with the arbitrary data.
41. The method according to claim 12, wherein the insertion into the body of the derived compressed digital signal of the at least one data packet leads to overwriting part of the space initially filled with the arbitrary data.
42. The device according to claim 27, further comprising a forming device that forms the derived compressed digital signal which thus comprises the header data and the body, the body of the derived compressed digital signal having a length equal to that of the body of the compressed digital signal present in the second apparatus, the body of the derived compressed digital signal representing a space initially filled with the arbitrary data and later containing the at least one data packet of the portion of the compressed digital signal received from the second apparatus.
43. The device according to claim 42, wherein the inserting device overwrites part of the space initially filled with the arbitrary data.
44. The device according to claim 28, wherein the inserting device overwrites part of the space initially filled with the arbitrary data.
45. A method of processing compressed digital data received by a first communication apparatus connected through a communication network to a remote second communication apparatus, the method being implemented in the first communication apparatus, the method comprising the steps of:
receiving only a portion of a compressed digital signal present in the second apparatus and comprising a body that comprises data packets, the received portion of the compressed digital signal comprising at least one data packet;
generating a derived compressed digital signal derived from the compressed digital signal present in the second apparatus in the form of a cache file, the derived compressed digital signal comprising header data and a body and capable of containing all or part of the body of the compressed digital signal present in the second apparatus;
filling the body of the derived compressed digital signal in the cache file with arbitrary data, so as to constitute a space of the same size as the body of the compressed digital signal present in the second apparatus;
determining a position at which the at least one data packet of the received portion of the compressed digital signal is to be inserted into the body of the derived compressed digital signal the position being determined as a function of the length of the header data and of at least one pointer marker previously received and inserted into the header data of the derived compressed digital signal by the first apparatus, the at least one pointer marker providing information for calculating the length of the part of the body of the derived compressed digital signal preceding the at least one data packet of the received portion of the compressed digital signal;
inserting into the body of the derived compressed digital signal the at least one data packet of the received portion of the compressed digital signal at the determined position;
going through the data contained in the body of the derived compressed digital signal;
converting, when the data gone through does not correspond to a data packet received from the second apparatus, the space filled by the data concerned into an empty packet; and
shifting in an adapted manner the data comprising the remainder of the body of the derived compressed digital signal.
46. A device for processing compressed digital data received by a first communication apparatus connected through a communication network to a remote second communication apparatus, the device being implemented in the first communication apparatus, the device comprising:
a receiver that receives only a portion of a compressed digital signal present in the second apparatus and comprising a body that comprises data packets, the received portion of the compressed digital signal comprising at least one data packet;
a generating device that generates a derived compressed digital signal derived from the compressed digital signal present in the second apparatus in the form of a cache file, the derived compressed digital signal comprising header data and a body and capable of containing all or part of the body of the compressed digital signal present in the second apparatus;
a filling device that fills the body of the derived compressed digital signal in the cache file with arbitrary data, so as to constitute a space of the same size as the body of the compressed digital signal present in the second apparatus;
a processor that determines a position at which the at least one data packet of the received portion of the compressed digital signal is to be inserted into the body of the derived compressed digital signal, the position being determined as a function of the length of the header data and of at least one pointer marker previously received and inserted into the header data of the derived compressed digital signal by the first apparatus, the at least one pointer marker providing information for calculating the length of the part of the body of the derived compressed digital signal preceding the at least one data packet of the received portion of the compressed digital signal;
an inserting device that inserts, into the body of the derived compressed digital signal, the at least one data packet of the received portion of the compressed digital signal at the determined position;
an examining device that examines the data contained in the body of the derived compressed digital signal;
a converter that converts, when the examined data does not correspond to a data packet received from the second apparatus, the space filled by the data concerned into an empty packet; and
a shifting device that shifts in an adapted manner the data comprising the remainder of the body of the derived compressed digital signal.