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mirror of https://github.com/wader/fq.git synced 2024-12-25 14:23:18 +03:00
fq/format/flac/flac.go
Mattias Wadman 2fc0a71a47 decode: Refactor scalar usage
Move scalar into own package.
Split scalar code into decode related scalar code (that reads etc) and
scalar code that just transform the scalar value.
Use a scalar.Mapper interface instead of just a function.
Make mappers, assert and validat impement the interface.
2021-12-02 17:39:26 +01:00

89 lines
2.7 KiB
Go

package flac
// https://xiph.org/flac/format.html
// https://wiki.hydrogenaud.io/index.php?title=FLAC_decoder_testbench
// TODO:
// 16 - Part 6 of Ladybug Castle (partition order 8 with escape codes)
// 32 - Part 5 of The Four of Us Are Dying (partition order 8 with escape codes)
import (
"bytes"
"crypto/md5"
"fmt"
"github.com/wader/fq/format"
"github.com/wader/fq/format/registry"
"github.com/wader/fq/internal/num"
"github.com/wader/fq/pkg/bitio"
"github.com/wader/fq/pkg/decode"
"github.com/wader/fq/pkg/scalar"
)
var flacMetadatablocksFormat decode.Group
var flacFrameFormat decode.Group
func init() {
registry.MustRegister(decode.Format{
Name: format.FLAC,
Description: "Free Lossless Audio Codec file",
Groups: []string{format.PROBE},
DecodeFn: flacDecode,
Dependencies: []decode.Dependency{
{Names: []string{format.FLAC_METADATABLOCKS}, Group: &flacMetadatablocksFormat},
{Names: []string{format.FLAC_FRAME}, Group: &flacFrameFormat},
},
})
}
func flacDecode(d *decode.D, in interface{}) interface{} {
d.FieldUTF8("magic", 4, d.AssertStr("fLaC"))
var streamInfo format.FlacStreamInfo
var flacFrameIn format.FlacFrameIn
var framesNDecodedSamples uint64
var streamTotalSamples uint64
var streamDecodedSamples uint64
_, v := d.FieldFormat("metadatablocks", flacMetadatablocksFormat, nil)
flacMetadatablockOut, ok := v.(format.FlacMetadatablocksOut)
if !ok {
panic(fmt.Sprintf("expected FlacMetadatablockOut got %#+v", v))
}
if flacMetadatablockOut.HasStreamInfo {
streamInfo = flacMetadatablockOut.StreamInfo
streamTotalSamples = streamInfo.TotalSamplesInStream
flacFrameIn = format.FlacFrameIn{StreamInfo: streamInfo}
}
md5Samples := md5.New()
d.FieldArray("frames", func(d *decode.D) {
for d.NotEnd() {
// flac frame might need some fields from stream info to decode
_, v := d.FieldFormat("frame", flacFrameFormat, flacFrameIn)
ffo, ok := v.(format.FlacFrameOut)
if !ok {
panic(fmt.Sprintf("expected FlacFrameOut got %#+v", v))
}
samplesInFrame := ffo.Samples
if streamTotalSamples > 0 {
samplesInFrame = num.MinUInt64(streamTotalSamples-streamDecodedSamples, ffo.Samples)
}
frameStreamSamplesBuf := ffo.SamplesBuf[0 : samplesInFrame*uint64(ffo.Channels*ffo.BitsPerSample/8)]
framesNDecodedSamples += ffo.Samples
d.MustCopy(md5Samples, bytes.NewReader(frameStreamSamplesBuf))
streamDecodedSamples += ffo.Samples
// reuse buffer if possible
flacFrameIn.SamplesBuf = ffo.SamplesBuf
}
})
md5CalcValue := d.FieldRootBitBuf("md5_calculated", bitio.NewBufferFromBytes(md5Samples.Sum(nil), -1))
_ = md5CalcValue.TryScalarFn(d.ValidateBitBuf(streamInfo.MD5), scalar.RawHex)
d.FieldValueU("decoded_samples", framesNDecodedSamples)
return nil
}