sei-kf.awk

#!/bin/awk -f
#
# Parses the ffmpeg trace_headers output and displays timestamp SEI (MISB ST 0604)
# contents in a readable format:
#
# ${ts.identifier}: ${datetime.of.timestamp}: ${timestamp.value}
# cf848278-ee23-306c-9265-e8fef22fb8b8: Fri Nov 24 09:40:48 UTC 2023 : 1700818848602427904
#
# Expects the H.265 SEI i.e. nano precision timestamps. For the H.264 (microseconds precision)
# update the timestamp dividing and identifier dump.
#
# Example:
#
# ffmpeg -i udp://127.0.0.1:5050 -c:v copy -bsf:v trace_headers -f null - 2>&1 | ./sei.awk
#

function timestamp_to_date(timestamp) {
    command = "date -d @" timestamp;
    command | getline date_string;
    close(command);
    return date_string;
}

BEGIN {
    user_data_line = 64
    key_frame = 0
}

user_data_line < 64 {
    user_data_line++
}

$4 == "User" && $5 == "Data" && $6 == "Unregistered" && key_frame == 1 {
    user_data_line = 0
    identifier = ""
    timestamp = "0x"
}

$4 == "Packet:" && $7 == "key" {
    key_frame = 1
}

user_data_line > 0 && user_data_line < 17 {
    char = sprintf("%02x", $8)
    identifier = identifier char
    if (user_data_line == 4 || user_data_line == 6 || user_data_line == 8 || user_data_line == 10) {
        identifier = identifier "-"
    }
}

user_data_line > 17 && user_data_line < 29 && user_data_line != 20 && user_data_line != 23 && user_data_line != 26 {
    char = sprintf("%02x", $8)
    timestamp = timestamp char
}

user_data_line == 28 {
    timestamp = strtonum(timestamp)
    ts = int(timestamp / 1000000000)
    print identifier ": " timestamp_to_date(ts) " : " timestamp
    key_frame = 0
}