Methods and systems for codec detection in video streams
Method and apparatus for carrying out the method receiving packets, each of the packets comprising a header and a payload. For a particular packet among the packets, the method includes processing at least the header of the particular packet to determine a flow associated with the particular packet; attempting to determine a payload structure based on the flow, the payload structure associated with transport of coded video data in the payload of the particular packet; and if the attempting is successful, repackaging coded video data contained in the payload of the particular packet into a new packet and forwarding the new packet to an external system or storing the new packet in memory.
1 . A processor-implemented method, comprising:
receiving a plurality of packets, each belonging to one of a plurality of flows, each packet comprising a header and a payload;
responsive to receipt of each of the packets:
searching in a memory for a record associated with the flow to which the packet belongs;
in case the searching finds no record in the memory, allocating a portion of the memory to a record associated with the flow to which the packet belongs;
attempting codec identification by processing at least part of the payload of the packet;
in case the attempting successfully identifies a particular codec, storing information regarding the particular codec in the record associated with the flow to which the packet belongs;
in case the attempting is unsuccessful and a certain condition has been reached since the portion of the memory has been allocated, freeing up the portion of the memory.
2 . The method defined in claim 1 , wherein the certain condition comprises a period of time having elapsed.
3 . The method defined in claim 1 , the packet being a current packet, wherein the certain condition is defined by a predetermined number of previously received packets associated with said flow.
4 . A non-transitory computer-readable medium storing computer-readable instructions which, when executed by a processor, cause the processor to carry out a method that comprises:
receiving a plurality of packets, each belonging to one of a plurality of flows, each packet comprising a header and a payload;
responsive to receipt of each of the packets:
searching in a memory for a record associated with the flow to which the packet belongs;
in case the searching finds no record in the memory, allocating a portion of the memory to a record associated with the flow to which the packet belongs;
attempting codec identification by processing at least part of the payload of the packet;
in case the attempting successfully identifies a particular codec, storing information regarding the particular codec in the record associated with the flow to which the packet belongs;
in case the attempting is unsuccessful and a certain condition has been reached since the portion of the memory has been allocated, freeing up the portion of the memory.
5 . The computer-readable medium defined in claim 4 , wherein the certain condition comprises a predetermined amount of time having elapsed.
6 . The computer-readable medium defined in claim 4 , the packet being a current packet, wherein the certain condition is defined by a predetermined number of previously received packets associated with said flow.
7 . The method defined in claim 1 , wherein searching in the memory for the record associated with the flow to which the packet belongs comprises determining if the flow of the packet corresponds to contents in a flow field of the record.
8 . The method defined in claim 7 , wherein the flow field comprises a source IP sub-field, a source port sub-field, a destination IP sub-field, and a destination port sub-field.
9 . The method defined in claim 1 , wherein the information stored in the record comprises at least one of a corresponding payload structure, the particular codec, and a current time.
10 . The method defined in claim 1 , wherein the record associated with the flow is included in a memory container.
11 . The method defined in claim 10 , wherein the memory container is stored as a global variable.
12 . The method defined in claim 10 , the method further comprising:
obtaining a current time; and
for each record of a plurality of records in the memory container, comparing the current time with a value in a timestamp field of the record to compute a respective difference.
13 . The method defined in claim 12 , the method further comprising:
in case the respective computed difference for a given record is greater than a threshold, deallocating a memory space formerly taken up by the given record.
14 . The method defined in claim 1 , wherein the method is performed by a surveillance module.
15 . The computer-readable medium defined in claim 4 , wherein searching in the memory for the record associated with the flow to which the packet belongs comprises determining if the flow of the packet corresponds to contents in a flow field of the record.
16 . The computer-readable medium defined in claim 15 , wherein the flow field comprises a source IP sub-field, a source port sub-field, a destination IP sub-field, and a destination port sub-field.
17 . The computer-readable medium defined in claim 4 , wherein the information stored in the record comprises at least one of a corresponding payload structure, the particular codec, and a current time.
18 . The computer-readable medium defined in claim 4 , wherein the record associated with the flow is included in a memory container.
19 . The computer-readable medium defined in claim 18 , wherein the memory container is stored as a global variable.
20 . The computer-readable medium defined in claim 18 , wherein the method further comprises:
obtaining a current time; and
for each record of a plurality of records in the memory container, comparing the current time with a value in a timestamp field of the record to compute a respective difference.
21 . The computer-readable medium defined in claim 20 , wherein the method further comprises:
in case the respective computed difference for a given record is greater than a threshold, deallocating a memory space formerly taken up by the given record.
22 . A system comprising:
a processor; and
a memory accessible by the processor, the memory storing instructions that, when executed by the processor, cause the processor to:
receive a plurality of packets, each belonging to one of a plurality of flows, each packet comprising a header and a payload;
responsive to receipt of each of the packets:
search in the memory for a record associated with the flow to which the packet belongs;
in case the search finds no record in the memory associated with the flow to which the packet belongs, allocate a portion of the memory to a record associated with the flow to which the packet belongs;
attempt codec identification by processing at least part of the payload of the packet;
in case the attempt successfully identifies a particular codec, store information regarding the particular codec in the record associated with the flow to which the packet belongs;
in case the attempt is unsuccessful and a certain condition has been reached since the portion of the memory has been allocated, free up the portion of the memory.