encoder: Improve custom options parsing drastically
Splits the parsing into two steps, one for quotes and escaping, the other for actual option parsing. This drastically lowers the chances of messing up, and makes the entire thing much safer than a really complex monolithic loop.
This commit is contained in:
Michael Fabian 'Xaymar' Dirks
+124
-81
@@ -946,87 +946,7 @@ bool obsffmpeg::encoder::update(obs_data_t* settings)
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const char* opts = obs_data_get_string(settings, ST_FFMPEG_CUSTOMSETTINGS);
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size_t opts_len = strnlen(opts, 65535);
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// Parses options like FFmpeg's command line would:
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// '-key=value -key=value -key=value'
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std::stack<char> quote_stack;
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bool have_param = false;
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bool have_key = false;
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bool have_value = false;
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bool value_is_quoted = false;
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size_t p_key = 0;
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size_t p_value = 0;
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std::string key;
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std::string value;
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for (size_t p = 0; p <= opts_len; p++) {
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char here = opts[p];
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if (!have_param) {
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if (here == '-') {
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have_param = true;
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p_key = p + 1;
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}
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} else if (!have_key) {
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if (here == '=') {
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have_key = true;
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key = std::string(&opts[p_key], &opts[p]);
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p_value = p + 1;
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while (quote_stack.size() > 0)
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quote_stack.pop();
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} else if (p == opts_len) {
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PLOG_WARNING("Option '%s' has no value, ignoring.", &opts[p_key]);
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}
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} else {
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// To support quotes, some interesting stuff needs to be done.
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// First we need to parse \ as escaping the next character, and just jump over it.
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if (here == '\\') {
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p++;
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} else {
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if ((here == '"') || (here == '\'')) {
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// Dealing with quotes is only possible with a stack.
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if ((quote_stack.size() > 0) && (quote_stack.top() == here)) {
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quote_stack.pop();
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} else {
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quote_stack.push(here);
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value_is_quoted = true;
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}
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} else if ((here == ' ') || (p == opts_len)) {
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if (quote_stack.size() == 0) {
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have_value = true;
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} else if (p == opts_len) {
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PLOG_WARNING(
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"Option '%.*s' has mismatched quotations, ignoring.",
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p_value - p_key, &opts[p_key]);
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}
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}
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if (have_value) {
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if (value_is_quoted) {
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value = std::string(&opts[p_value + 1], &opts[p - 1]);
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} else {
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value = std::string(&opts[p_value], &opts[p]);
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}
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int res = av_opt_set(_context, key.c_str(), value.c_str(),
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AV_OPT_SEARCH_CHILDREN);
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if (res < 0) {
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PLOG_WARNING(
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"Failed setting option '%s' to '%s' due to error: %s",
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key.c_str(), value.c_str(),
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ffmpeg::tools::get_error_description(res));
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}
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have_param = false;
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have_key = false;
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have_value = false;
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value_is_quoted = false;
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}
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}
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}
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}
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parse_ffmpeg_commandline(std::string{opts, opts + opts_len});
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}
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if (_handler)
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@@ -1358,3 +1278,126 @@ const AVCodecContext* obsffmpeg::encoder::get_avcodeccontext()
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{
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return _context;
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}
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void obsffmpeg::encoder::parse_ffmpeg_commandline(std::string text)
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{
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// Steps to properly parse a command line:
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// 1. Split by space and package by quotes.
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// 2. Parse each resulting option individually.
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// First, we split by space and of course respect quotes while doing so.
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// That means that "-foo= bar" is stored as std::string("-foo= bar"),
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// and things like -foo="bar" is stored as std::string("-foo=\"bar\"").
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// However "-foo"=bar" -foo2=bar" is stored as std::string("-foo=bar -foo2=bar")
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// because the quote was not escaped.
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std::list<std::string> opts;
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std::stringstream opt_stream{std::ios_base::in | std::ios_base::out | std::ios_base::binary};
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std::stack<char> quote_stack;
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for (size_t p = 0; p <= text.size(); p++) {
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char here = p < text.size() ? text.at(p) : 0;
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if (here == '\\') {
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size_t p2 = p + 1;
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if (p2 < text.size()) {
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char here2 = text.at(p2);
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if (isdigit(here2)) { // Octal
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// Not supported yet.
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p++;
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} else if (here2 == 'x') { // Hexadecimal
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// Not supported yet.
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p += 3;
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} else if (here2 == 'u') { // 4 or 8 wide Unicode.
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// Not supported yet.
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} else if (here2 == 'a') {
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opt_stream << '\a';
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p++;
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} else if (here2 == 'b') {
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opt_stream << '\b';
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p++;
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} else if (here2 == 'e') {
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opt_stream << '\e';
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p++;
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} else if (here2 == 'f') {
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opt_stream << '\f';
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p++;
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} else if (here2 == 'n') {
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opt_stream << '\n';
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p++;
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} else if (here2 == 'r') {
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opt_stream << '\r';
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p++;
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} else if (here2 == 't') {
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opt_stream << '\t';
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p++;
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} else if (here2 == 'v') {
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opt_stream << '\v';
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p++;
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} else if (here2 == '\\') {
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opt_stream << '\\';
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p++;
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} else if (here2 == '\'') {
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opt_stream << '\'';
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p++;
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} else if (here2 == '"') {
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opt_stream << '"';
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p++;
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} else if (here2 == '?') {
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opt_stream << '\?';
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p++;
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}
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}
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} else if ((here == '\'') || (here == '"')) {
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if (quote_stack.size() > 1) {
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opt_stream << here;
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}
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if (quote_stack.size() == 0) {
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quote_stack.push(here);
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} else if (quote_stack.top() == here) {
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quote_stack.pop();
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} else {
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quote_stack.push(here);
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}
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} else if ((here == 0) || ((here == ' ') && (quote_stack.size() == 0))) {
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std::string ropt = opt_stream.str();
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if (ropt.size() > 0) {
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opts.push_back(ropt);
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opt_stream.clear();
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}
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} else {
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opt_stream << here;
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}
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}
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// Now that we have a list of parameters as neatly grouped strings, and
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// have also dealt with escaping for the most part. We want to parse
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// an FFmpeg commandline option set here, so the first character in
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// the string must be a '-'.
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for (std::string& opt : opts) {
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// Skip empty options.
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if (opt.size() == 0)
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continue;
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// Skip options that don't start with a '-'.
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if (opt.at(0) != '-') {
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PLOG_WARNING("Option '%s' is malformed, must start with a '-'.", opt.c_str());
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continue;
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}
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// Skip options that don't contain a '='.
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const char* cstr = opt.c_str();
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const char* eq_at = strchr(cstr, '=');
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if (eq_at == nullptr) {
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PLOG_WARNING("Option '%s' is malformed, must contain a '='.", opt.c_str());
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continue;
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}
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std::string key{&opt.at(1), opt.at(eq_at - cstr)};
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std::string value{&opt.at(eq_at - cstr + 1), &opt.at(opt.size())};
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int res = av_opt_set(_context, key.c_str(), value.c_str(), AV_OPT_SEARCH_CHILDREN);
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if (res < 0) {
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PLOG_WARNING("Option '%s' could not be set to '%s' due to error: %s", key.c_str(),
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value.c_str(), ffmpeg::tools::get_error_description(res));
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}
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}
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}
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@@ -158,5 +158,7 @@ namespace obsffmpeg {
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const AVCodec* get_avcodec();
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const AVCodecContext* get_avcodeccontext();
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void parse_ffmpeg_commandline(std::string text);
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};
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} // namespace obsffmpeg
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