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56 lines
1.5 KiB
Go
56 lines
1.5 KiB
Go
package mpeg
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// https://wiki.multimedia.cx/index.php/MPEG-4_Audio
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import (
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"github.com/wader/fq/format"
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"github.com/wader/fq/format/registry"
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"github.com/wader/fq/pkg/decode"
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"github.com/wader/fq/pkg/scalar"
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)
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func init() {
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registry.MustRegister(decode.Format{
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Name: format.MPEG_ASC,
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Description: "MPEG-4 Audio Specific Config",
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DecodeFn: ascDecoder,
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})
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}
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var frequencyIndexHzMap = scalar.UToSymU{
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0x0: 96000,
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0x1: 88200,
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0x2: 64000,
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0x3: 48000,
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0x4: 44100,
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0x5: 32000,
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0x6: 24000,
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0x7: 22050,
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0x8: 16000,
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0x9: 12000,
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0xa: 11025,
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0xb: 8000,
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0xc: 7350,
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}
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var channelConfigurationNames = scalar.UToDescription{
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0: "defined in AOT Specifc Config",
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1: "front-center",
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2: "front-left, front-right",
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3: "front-center, front-left, front-right",
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4: "front-center, front-left, front-right, back-center",
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5: "front-center, front-left, front-right, back-left, back-right",
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6: "front-center, front-left, front-right, back-left, back-right, LFE-channel",
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7: "front-center, front-left, front-right, side-left, side-right, back-left, back-right, LFE-channel",
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}
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func ascDecoder(d *decode.D, in interface{}) interface{} {
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objectType := d.FieldUFn("object_type", decodeEscapeValueCarryFn(5, 6, 0), format.MPEGAudioObjectTypeNames)
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d.FieldUFn("sampling_frequency", decodeEscapeValueAbsFn(4, 24, 0), frequencyIndexHzMap)
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d.FieldU4("channel_configuration", channelConfigurationNames)
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// TODO: GASpecificConfig etc
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d.FieldRawLen("var_aot_or_byte_align", d.BitsLeft())
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return format.MPEGASCOut{ObjectType: int(objectType)}
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}
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