tc_append.py

import sys
import re
import os

def read_tc_v1(f, params):
    frame_count = None
    if "frame-count" in params:
        frame_count = int(params["frame-count"])

    parts = []
    default_fps = None
    for line in f:
        line = line.strip()
        if line.startswith("#"):
            if frame_count is None:
                m = re.match(r"^# vfr stats: .* (\d+) - total", line)
                if m:
                    frame_count = int(m.group(1))

            continue

        if not line:
            continue

        if line.lower().startswith("assume "):
            if default_fps:
                raise ValueError("Found multiple assume line")

            default_fps = float(line[7:].strip())
            continue

        if not default_fps:
            raise ValueError("Missing assume line")

        current_part = line.split(",")
        parts.append([
            int(current_part[0]), 
            int(current_part[1]), 
            float(current_part[2])])

    parts.sort(key=lambda x: x[0])

    if len(parts) == 0:
        raise ValueError("Timecode file is empty")

    if not frame_count:
        frame_count = parts[-1][1] + 1
        print("Warning: Frame count not specified, and this is not TIVTC-generated timecode file, using guessed frame count ({0})".format(frame_count))


    ret = []
    for i in range(frame_count):
        while True:
            if len(parts) == 0:
                current_fps = default_fps
                break
            elif i < parts[0][0]:
                current_fps = default_fps
                break
            elif i > parts[0][1]:
                parts.pop(0)
                continue
            else:
                current_fps = default_fps
                break

        ret.append(1000.0 / current_fps)

    return ret

def read_tc_v2(f, params):
    last_timestamp = None
    ret = []
    for line in f:
        line = line.strip()
        if not line or line.startswith("#"):
            continue

        current_timestamp = float(line)
        if last_timestamp is not None:
            ret.append(current_timestamp - last_timestamp)

        last_timestamp = current_timestamp

    if last_timestamp:
        if "default-fps" in params:
            ret.append(1000.0 / float(params["default-fps"]))
        else:
            ret.append(ret[-1])

    return ret

# !! returns duration for each frame
def read_tc(fn, params):
    try:
        with open(fn, "r") as f:
            while True:
                line = f.readline()
                if not line:
                    raise ValueError("File is empty")
                    sys.exit(1)

                line = line.strip()
                if not line:
                    continue
                
                if line.lower() == "# timecode format v1":
                    return read_tc_v1(f, params)
                elif line.lower() == "# timecode format v2":
                    return read_tc_v2(f, params)
                else:
                    raise ValueError("Invalid header")
    except ValueError as e:
        raise ValueError("Invalid timecode file {0}: {1}".format(fn, e.args))
                

def do_append(files, output):
    tc = []
    for f in files:
        tc += read_tc(f["name"], f["params"])

    with open(output, "w") as f:
        f.write("# timecode format v2\n")
        current_timestamp = 0.0
        for x in tc:
            f.write("{0:6f}".format(current_timestamp))
            f.write("\n")
            current_timestamp += x

def parse_options(options):
    files = []
    current_file = None
    
    options = list(options)
    while options:
        current_option = options.pop(0)
        if current_option.startswith("--"):
            current_file["params"][current_option[2:]] = options.pop(0)
            continue
        else:
            if current_file:
                files.append(current_file)

            current_file = {
                "name": current_option,
                "params": {},
            }

    if len(files) < 2:
        return None

    return {
        "files": files,
        "output": current_file["name"],
    }

def print_usage():
    script_name = os.path.basename(sys.argv[0])
    print("Usage:")
    print("{0} <input 1> <input 2> [<input N> ...] <output>" \
            .format(script_name))
    print("")
    print("Example:")
    print("{0} tcin_1.txt tcin_2.txt tcout.txt".format(script_name))
    print("")
    print("Timecode V1 files are supported, but if it isn't generated by TIVTC, you need to specify frame count like:")
    print("{0} tcv1.txt --frame-count 34567 tcv2.txt tcout.txt".format(script_name))

    pass

if __name__ == "__main__":
    options = parse_options(sys.argv[1:])
    if not options:
        print_usage()
        sys.exit(1)

    do_append(**options)