58 lines
2.1 KiB
Go
58 lines
2.1 KiB
Go
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package astits
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// Stream types
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const (
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StreamTypeLowerBitrateVideo = 27 // ITU-T Rec. H.264 and ISO/IEC 14496-10
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StreamTypeMPEG1Audio = 3 // ISO/IEC 11172-3
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StreamTypeMPEG2HalvedSampleRateAudio = 4 // ISO/IEC 13818-3
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StreamTypeMPEG2PacketizedData = 6 // ITU-T Rec. H.222 and ISO/IEC 13818-1 i.e., DVB subtitles/VBI and AC-3
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)
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// PMTData represents a PMT data
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// https://en.wikipedia.org/wiki/Program-specific_information
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type PMTData struct {
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ElementaryStreams []*PMTElementaryStream
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PCRPID uint16 // The packet identifier that contains the program clock reference used to improve the random access accuracy of the stream's timing that is derived from the program timestamp. If this is unused. then it is set to 0x1FFF (all bits on).
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ProgramDescriptors []*Descriptor // Program descriptors
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ProgramNumber uint16
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}
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// PMTElementaryStream represents a PMT elementary stream
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type PMTElementaryStream struct {
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ElementaryPID uint16 // The packet identifier that contains the stream type data.
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ElementaryStreamDescriptors []*Descriptor // Elementary stream descriptors
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StreamType uint8 // This defines the structure of the data contained within the elementary packet identifier.
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}
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// parsePMTSection parses a PMT section
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func parsePMTSection(i []byte, offset *int, offsetSectionsEnd int, tableIDExtension uint16) (d *PMTData) {
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// Init
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d = &PMTData{ProgramNumber: tableIDExtension}
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// PCR PID
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d.PCRPID = uint16(i[*offset]&0x1f)<<8 | uint16(i[*offset+1])
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*offset += 2
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// Program descriptors
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d.ProgramDescriptors = parseDescriptors(i, offset)
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// Loop until end of section data is reached
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for *offset < offsetSectionsEnd {
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// Stream type
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var e = &PMTElementaryStream{}
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e.StreamType = uint8(i[*offset])
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*offset += 1
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// Elementary PID
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e.ElementaryPID = uint16(i[*offset]&0x1f)<<8 | uint16(i[*offset+1])
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*offset += 2
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// Elementary descriptors
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e.ElementaryStreamDescriptors = parseDescriptors(i, offset)
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// Add elementary stream
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d.ElementaryStreams = append(d.ElementaryStreams, e)
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}
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return
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}
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