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Preserve explicitly "undefined" language of MP4 tracks

This commit is contained in:
Martchus 2023-01-02 19:50:30 +01:00
parent 8d4c315611
commit 766e7657b5
1 changed files with 16 additions and 9 deletions
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25
mp4/mp4track.cpp
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@ -1335,29 +1335,36 @@ void Mp4Track::makeMedia(Diagnostics &diag)
writer().writeUInt32BE(static_cast<std::uint32_t>(timings.mdhdDuration));
}
// convert and write language
const std::string &language = m_locale.abbreviatedName(LocaleFormat::ISO_639_2_T, LocaleFormat::Unknown);
std::uint16_t codedLanguage = 0;
for (size_t charIndex = 0; charIndex != 3; ++charIndex) {
const char langChar = charIndex < language.size() ? language[charIndex] : 0;
// note: Not using m_locale.abbreviatedName() here to preserve "und" (explicitly undefined).
const auto *language = static_cast<const std::string *>(&LocaleDetail::getEmpty());
for (const auto &detail : m_locale) {
if (!detail.empty() && (detail.format == LocaleFormat::ISO_639_2_T || detail.format == LocaleFormat::Unknown)) {
language = &detail;
break;
}
}
auto codedLanguage = static_cast<std::uint16_t>(0u);
for (auto charIndex = static_cast<std::size_t>(0); charIndex != 3; ++charIndex) {
const char langChar = charIndex < language->size() ? (*language)[charIndex] : 0;
if (langChar >= 'a' && langChar <= 'z') {
codedLanguage |= static_cast<std::uint16_t>((langChar - 0x60) << (0xA - charIndex * 0x5));
continue;
}
// handle invalid characters
if (language.empty()) {
// preserve empty language field
if (language->empty()) {
// preserve null value (empty language field) which is not the same as "und" (explicitly undefined)
codedLanguage = 0;
break;
}
diag.emplace_back(
DiagLevel::Warning, "Assigned language \"" % language + "\" is of an invalid format. Setting language to undefined.", "making mdhd atom");
DiagLevel::Warning, "Assigned language \"" % *language + "\" is of an invalid format. Setting language to undefined.", "making mdhd atom");
codedLanguage = 0x55C4; // und(efined)
break;
}
if (language.size() > 3) {
if (language->size() > 3) {
diag.emplace_back(
DiagLevel::Warning, "Assigned language \"" % language + "\" is longer than 3 byte and hence will be truncated.", "making mdhd atom");
DiagLevel::Warning, "Assigned language \"" % *language + "\" is longer than 3 byte and hence will be truncated.", "making mdhd atom");
}
writer().writeUInt16BE(codedLanguage);
writer().writeUInt16BE(0); // pre defined