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fq/format/mpeg/mpeg_asc.go
2021-12-14 17:34:38 +01:00

56 lines
1.6 KiB
Go

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