3.4. Can you explain the details of Custom Timestamp?#
The following times are recorded in the RTP packet for each mode:
ID |
|
|
|
explain |
|---|---|---|---|---|
0 |
0 |
- |
- |
Custom timestamp disabled (General RTP header Time is recorded) |
1 |
1 |
0 |
1 |
Custom timestamp enabled, records the start time of RTP packet generation |
2 |
1 |
0 |
0 |
Custom timestamp enabled, records the end time of RTP packet generation |
3 |
1 |
1 |
- |
Custom timestamp enabled, records the time when the fsync trigger is output from the GMSL2-10GbEthernet board to the camera (≒ Time of start camera shutter) |
The custom timestamp is constructed as follows: 96 bits possible in total:
48b - MSBs from [95:48] for seconds representation
32b - [47:16] for nanoseconds representation
16b - [15:0] for fractions of nanoseconds representation
Thus the RTP header will contain the following set of data when used with custom_timestamp:
RTP header’s timestamp - 32b all for the 32b of MSBs from the seconds-related portion of the timestamp array
RTP header’s SSRC_ID - 32b - 16b - MSBs [31:16] for low part of the seconds on 16b, and the rest for the high part of the nanoseconds representation
Additional RTP header’s CSRC_ID (only one in this case by using a CSRC count == 1 and a first CSRC field with 32b added to the packet - resulting a larger packet dimension) - 16b for the low part of the nanoseconds and 16b for the fractions of nanoseconds representation