mirror of
https://github.com/wader/fq.git
synced 2024-12-24 22:05:31 +03:00
126 lines
3.6 KiB
Go
126 lines
3.6 KiB
Go
package vorbis
|
||
|
||
// https://xiph.org/vorbis/doc/Vorbis_I_spec.html
|
||
// TODO: setup? more audio?
|
||
// TODO: end padding? byte align?
|
||
|
||
import (
|
||
"github.com/wader/fq/format"
|
||
"github.com/wader/fq/pkg/decode"
|
||
"github.com/wader/fq/pkg/interp"
|
||
"github.com/wader/fq/pkg/scalar"
|
||
)
|
||
|
||
var vorbisComment decode.Group
|
||
|
||
func init() {
|
||
interp.RegisterFormat(decode.Format{
|
||
Name: format.VORBIS_PACKET,
|
||
Description: "Vorbis packet",
|
||
DecodeFn: vorbisDecode,
|
||
Dependencies: []decode.Dependency{
|
||
{Names: []string{format.VORBIS_COMMENT}, Group: &vorbisComment},
|
||
},
|
||
})
|
||
}
|
||
|
||
const (
|
||
packetTypeAudio = 0
|
||
packetTypeIdentification = 1
|
||
packetTypeComment = 3
|
||
packetTypeSetup = 5
|
||
)
|
||
|
||
var packetTypeNames = map[uint]string{
|
||
packetTypeAudio: "Audio",
|
||
packetTypeIdentification: "Identification",
|
||
packetTypeComment: "Comment",
|
||
packetTypeSetup: "Setup",
|
||
}
|
||
|
||
func vorbisDecode(d *decode.D, _ any) any {
|
||
d.Endian = decode.LittleEndian
|
||
|
||
packetType := d.FieldUScalarFn("packet_type", func(d *decode.D) scalar.S {
|
||
packetTypeName := "unknown"
|
||
t := d.U8()
|
||
// 4.2.1. Common header decode
|
||
// "these types are all odd as a packet with a leading single bit of ’0’ is an audio packet"
|
||
if t&1 == 0 {
|
||
t = packetTypeAudio
|
||
}
|
||
if n, ok := packetTypeNames[uint(t)]; ok {
|
||
packetTypeName = n
|
||
}
|
||
return scalar.S{Actual: t, Sym: packetTypeName}
|
||
})
|
||
|
||
switch packetType {
|
||
case packetTypeIdentification, packetTypeSetup, packetTypeComment:
|
||
d.FieldUTF8("magic", 6, d.AssertStr("vorbis"))
|
||
case packetTypeAudio:
|
||
default:
|
||
d.Fatalf("unknown packet type %d", packetType)
|
||
}
|
||
|
||
switch packetType {
|
||
case packetTypeAudio:
|
||
case packetTypeIdentification:
|
||
// 1 1) [vorbis_version] = read 32 bits as unsigned integer
|
||
// 2 2) [audio_channels] = read 8 bit integer as unsigned
|
||
// 3 3) [audio_sample_rate] = read 32 bits as unsigned integer
|
||
// 4 4) [bitrate_maximum] = read 32 bits as signed integer
|
||
// 5 5) [bitrate_nominal] = read 32 bits as signed integer
|
||
// 6 6) [bitrate_minimum] = read 32 bits as signed integer
|
||
// 7 7) [blocksize_0] = 2 exponent (read 4 bits as unsigned integer)
|
||
// 8 8) [blocksize_1] = 2 exponent (read 4 bits as unsigned integer)
|
||
// 9 9) [framing_flag] = read one bit
|
||
d.FieldU32("vorbis_version", d.ValidateU(0))
|
||
d.FieldU8("audio_channels")
|
||
d.FieldU32("audio_sample_rate")
|
||
d.FieldU32("bitrate_maximum")
|
||
d.FieldU32("bitrate_nominal")
|
||
d.FieldU32("bitrate_minimum")
|
||
// TODO: code/comment about 2.1.4. coding bits into byte sequences
|
||
d.FieldUFn("blocksize_1", func(d *decode.D) uint64 { return 1 << d.U4() })
|
||
d.FieldUFn("blocksize_0", func(d *decode.D) uint64 { return 1 << d.U4() })
|
||
// TODO: warning if blocksize0 > blocksize1
|
||
// TODO: warning if not 64-8192
|
||
d.FieldRawLen("padding0", 7, d.BitBufIsZero())
|
||
d.FieldU1("framing_flag", d.ValidateU(1))
|
||
case packetTypeSetup:
|
||
d.FieldUFn("vorbis_codebook_count", func(d *decode.D) uint64 { return d.U8() + 1 })
|
||
d.FieldU24("codecooke_sync", d.ValidateU(0x564342), scalar.ActualHex)
|
||
d.FieldU16("codebook_dimensions")
|
||
d.FieldU24("codebook_entries")
|
||
|
||
// d.SeekRel(7)
|
||
// ordered := d.FieldBool("ordered")
|
||
|
||
// if ordered {
|
||
|
||
// } else {
|
||
// d.SeekRel(-2)
|
||
// sparse := d.FieldBool("sparse")
|
||
// d.SeekRel(1)
|
||
|
||
// if sparse {
|
||
|
||
// } else {
|
||
// d.SeekRel(-7)
|
||
// d.FieldU5("length")
|
||
|
||
// }
|
||
// }
|
||
|
||
case packetTypeComment:
|
||
d.FieldFormat("comment", vorbisComment, nil)
|
||
|
||
// note this uses vorbis bitpacking convention, bits are added LSB first per byte
|
||
d.FieldRawLen("padding0", 7, d.BitBufIsZero())
|
||
d.FieldU1("frame_bit", d.ValidateU(1))
|
||
}
|
||
|
||
return nil
|
||
}
|