add cut_bs.py script and correct path to it

#!/usr/bin/env python3

"""

   (C) 2022 IVAS codec Public Collaboration with portions copyright Dolby International AB, Ericsson AB,

   Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V., Huawei Technologies Co. LTD.,

   Koninklijke Philips N.V., Nippon Telegraph and Telephone Corporation, Nokia Technologies Oy, Orange,

   Panasonic Holdings Corporation, Qualcomm Technologies, Inc., VoiceAge Corporation, and other

   contributors to this repository. All Rights Reserved.

   This software is protected by copyright law and by international treaties.

   The IVAS codec Public Collaboration consisting of Dolby International AB, Ericsson AB,

   Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V., Huawei Technologies Co. LTD.,

   Koninklijke Philips N.V., Nippon Telegraph and Telephone Corporation, Nokia Technologies Oy, Orange,

   Panasonic Holdings Corporation, Qualcomm Technologies, Inc., VoiceAge Corporation, and other

   contributors to this repository retain full ownership rights in their respective contributions in

   the software. This notice grants no license of any kind, including but not limited to patent

   license, nor is any license granted by implication, estoppel or otherwise.

   Contributors are required to enter into the IVAS codec Public Collaboration agreement before making

   contributions.

   This software is provided "AS IS", without any express or implied warranties. The software is in the

   development stage. It is intended exclusively for experts who have experience with such software and

   solely for the purpose of inspection. All implied warranties of non-infringement, merchantability

   and fitness for a particular purpose are hereby disclaimed and excluded.

   Any dispute, controversy or claim arising under or in relation to providing this software shall be

   submitted to and settled by the final, binding jurisdiction of the courts of Munich, Germany in

   accordance with the laws of the Federal Republic of Germany excluding its conflict of law rules and

   the United Nations Convention on Contracts on the International Sales of Goods.

"""

import struct

import argparse

import os.path

import sys

SID_BITS = {35, 48, 88, 100}

SYNC_WORDS = {b"!k", b" k"}

def cut_bs(fp, fp_out, start_frame=0, start_with_sid=False):

    # cut until start frame

    fr_cnt = 0

    cut_cnt = 0

    for cur_frame in range(start_frame):

        sync_word = fp.read(2)

        if sync_word == b"":

            return (fr_cnt, cut_cnt)

        if sync_word not in SYNC_WORDS:

            raise ValueError("Bad Sync word!")

        n_bits = struct.unpack("h", fp.read(2))[0]

        fp.read(n_bits * 2)

        fr_cnt += 1

        cut_cnt += 1

    if start_with_sid:

        found = False

        while not found:

            sync_word = fp.read(2)

            if sync_word == b"":

                return (fr_cnt, cut_cnt)

            if sync_word not in SYNC_WORDS:

                raise ValueError("Bad Sync word!")

            n_bits_bs = fp.read(2)

            n_bits = struct.unpack("h", n_bits_bs)[0]

            if n_bits in SID_BITS:

                found = True

                fp_out.write(sync_word)

                fp_out.write(n_bits_bs)

                fp_out.write(fp.read(n_bits * 2))

            else:

                fp.read(n_bits * 2)

                cut_cnt += 1

            fr_cnt += 1

    # transfer remaining frames

    while True:

        sync_word = fp.read(2)

        if sync_word == b"":

            break

        if sync_word not in SYNC_WORDS:

            raise ValueError("Bad Sync word!")

        n_bits_bs = fp.read(2)

        n_bits = struct.unpack("h", n_bits_bs)[0]

        fp_out.write(sync_word)

        fp_out.write(n_bits_bs)

        fp_out.write(fp.read(n_bits * 2))

        fr_cnt += 1

    return (fr_cnt, cut_cnt)

if __name__ == "__main__":

    my_parser = argparse.ArgumentParser(

        description="Cut frames from the beginning of a G.192 bit stream file"

    )

    my_parser.add_argument(

        "--sid", "-s", help="Cut until the first SID frame", action="store_true"

    )

    my_parser.add_argument(

        "--frame", "-f", type=int, help="Number of frames to cut.", default=0

    )

    my_parser.add_argument("bs_in", type=str, help="G.192 bit stream file name to cut")

    my_parser.add_argument("bs_out", type=str, help="Cut G.192 bit stream file name")

    my_args = my_parser.parse_args()

    if not os.path.exists(os.path.realpath(my_args.bs_in)):

        print(f"\nInput file {my_args.bs_in} does not exist!")

        sys.exit(-1)

    if not os.path.exists(os.path.realpath(my_args.bs_out)):

        print(f"\nOutput file {my_args.bs_out} does not exist, creating it!")

    else:

        print(f"\nOutput file {my_args.bs_out} does exist, overwriting it!")

    with open(my_args.bs_in, "rb") as fp_in:

        with open(my_args.bs_out, "wb") as fp_out:

            fr_cnt, cut_cnt = cut_bs(

                fp_in, fp_out, start_frame=my_args.frame, start_with_sid=my_args.sid

            )

    if my_args.sid and (fr_cnt == cut_cnt):

        print("Warning! No SID frame found in bitstream!")

    print(f"Cut {cut_cnt} of {fr_cnt} frames from {my_args.bs_in}")

    if args["sidstart"]:

        sidstart_cmd = [

            os.path.join(constants.SCRIPTS_BASE_DIR, "tools", "cut_bs.py"),

            os.path.join(constants.SCRIPTS_BASE_DIR, "cut_bs.py"),

            "--sid",

            "{in_file}",

            "{out_file}",

    if args["sidstart"]:

        sidstart_cmd = [

            os.path.join(constants.SCRIPTS_BASE_DIR, "tools", "cut_bs.py"),

            os.path.join(constants.SCRIPTS_BASE_DIR, "cut_bs.py"),

            "--sid",

            "{in_file}",

            "{out_file}",