Use the ISO639 Language Descriptor when available on the input #518
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When input is MPEG TS, the language information for audio streams could be available in PMT (ISO639 Language Descriptor). This commit extracts this information and uses it when needed. This code was submitted by the github user fpgamaster. All I did was create the pull request.
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@sammirata Thanks for working on it! I have left some comments, mostly on coding style. We generally follow Chromium C++ style guide (https://chromium.googlesource.com/chromium/src/+/master/styleguide/c++/c++.md), which is based on Google C++ style guide (https://google.github.io/styleguide/cppguide.html).
Let me know if you have any questions. Appreciated your help!
| @@ -80,11 +80,13 @@ static bool LookForSyncWord(const uint8_t* raw_es, | |||
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| EsParserAudio::EsParserAudio(uint32_t pid, | |||
| TsStreamType stream_type, | |||
| std::string lang, | |||
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Pass by reference, i.e. const std::string& lang
| @@ -29,6 +29,7 @@ class EsParserAudio : public EsParser { | |||
| public: | |||
| EsParserAudio(uint32_t pid, | |||
| TsStreamType stream_type, | |||
| std::string lang, | |||
| @@ -51,7 +51,7 @@ class Mp2tMediaParser : public MediaParser { | |||
| // Possible values for |media_type| are defined in: | |||
| // ISO-13818.1 / ITU H.222 Table 2.34 "Media type assignments". | |||
| // |pes_pid| is part of the Program Map Table refered by |pmt_pid|. | |||
| void RegisterPes(int pmt_pid, int pes_pid, int media_type); | |||
| void RegisterPes(int pmt_pid, int pes_pid, int media_type, std::string lang); | |||
| @@ -273,10 +273,12 @@ void Mp2tMediaParser::RegisterPmt(int program_number, int pmt_pid) { | |||
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| void Mp2tMediaParser::RegisterPes(int pmt_pid, | |||
| int pes_pid, | |||
| int stream_type) { | |||
| int stream_type, | |||
| std::string lang) { | |||
| RCHECK(bit_reader->ReadBits(8, &descriptor_tag)); | ||
| RCHECK(bit_reader->ReadBits(8, &descriptor_length)); | ||
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| if (descriptor_tag == 10) { |
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Define a constant for '10':
const int kISO639LanguageDescriptor = 10;| @@ -18,7 +18,7 @@ class TsSectionPmt : public TsSectionPsi { | |||
| // RegisterPesCb::Run(int pes_pid, int stream_type); | |||
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| } | ||
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| es_info_length -= 2 + descriptor_length; | ||
| } |
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Add instructions to validate that there are no corruptions in ES info descriptors and skip the additional data if there is.
RCHECK(es_info_length >= 0);
RCHECK(bit_reader->SkipBytes(es_info_length);| RCHECK(bit_reader->ReadBits(8, &lang[1])); | ||
| RCHECK(bit_reader->ReadBits(8, &lang[2])); | ||
| RCHECK(bit_reader->SkipBits(8)); // audio_type | ||
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Break to avoid unnecessary processing:
es_info_length -= 2 + 4;
break;| char lang[] = { 'u', 'n', 'd', '\0' }; | ||
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| while (es_info_length) { | ||
| RCHECK(bit_reader->ReadBits(8, &descriptor_tag)); |
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Please replace tab with spaces. Same elsewhere. We do not use tab in this project as it does not render consistently on different systems.
You can check the format using packager/tools/git/check_formatting.py:
$ packager/tools/git/check_formatting.py <base>| @@ -76,6 +76,7 @@ bool TsSectionPmt::ParsePsiSection(BitReader* bit_reader) { | |||
| // (4 bytes = size of the CRC). | |||
| int pid_map_end_marker = section_start_marker - section_length + 4; | |||
| std::map<int, int> pid_map; | |||
| std::map<int, std::string> pid_lang; | |||
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nit: I'd prefer defining a structure for it, for example PesCbInfo,
struct PesCbInfo {
int stream_type;
std::string lang;
};
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Closing due to lack of response. |
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When input is MPEG TS, the language information for audio streams could be available in PMT (ISO639 Language Descriptor).
This commit extracts this information and uses it when needed.
This code was submitted by the github user fpgamaster. All I did was create the pull request.