C++ program to strip out ID3v2 tag from beginning of a file.

id3strip.cc

#include <iostream>
#include <fstream>
#include <cstdint>
#include <cstring>
#include <boost/program_options.hpp>

uint32_t get_ID3v2_size(uint8_t rawhdr[10]) {
    if(memcmp(rawhdr, "ID3", 3) != 0)
        throw "ID3v2 magic numbers not found!";
    
    return rawhdr[6] << 21 |
           rawhdr[7] << 14 |
           rawhdr[8] << 7  |
           rawhdr[9]; }

int main(int argc, char** argv) {
    boost::program_options::options_description prog_argp("strips down ID3v2 tags from any file");
    boost::program_options::variables_map       prog_opts;

    prog_argp.add_options()
        ("help,h", "show this help message")
        ("input,i", boost::program_options::value<std::string>(), "input file containing ID3v2 tag")
        ("output,o", boost::program_options::value<std::string>(), "output file to put remaining data");
    
    boost::program_options::store(boost::program_options::parse_command_line(argc, argv, prog_argp), prog_opts);
    boost::program_options::notify(prog_opts);

    if(prog_opts.count("help") || argc < 2)
        std::cerr << prog_argp << std::endl;

    
    /* iostreams for input and output files */
    std::fstream in_id3v2    (prog_opts["input"] .as<std::string>(), std::ios::in  | std::ios::binary);
    std::fstream out_stripped(prog_opts["output"].as<std::string>(), std::ios::out | std::ios::binary);

    struct {
        uint8_t            raw[10];
        uint32_            size;
    } id3v2_header;

    in_id3v2.read(reinterpret_cast<char*>(id3v2_header.raw), 10);
    try { id3v2_header.size = get_ID3v2_size(id3v2_header.raw); }
    catch(const char* id3v2_err) { std::cerr << id3v2_err << std::endl; }

    /* write all non ID3v2 data to the output file by
       using a chunk of 16384 bytes for reading and writing. */
    in_id3v2.seekg(in_id3v2.tellg() + id3v2_header.size);
    out_stripped << in_id3v2.rdbuf();
}

Dependencies

• libboost
• libstdc++

Building

# linux / mingw / cygwin
$ g++ -o id3strip id3strip.cc -lboost_program_options