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86 lines
2.5 KiB
Go
86 lines
2.5 KiB
Go
package flac
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// https://xiph.org/flac/format.html
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// https://wiki.hydrogenaud.io/index.php?title=FLAC_decoder_testbench
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import (
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"bytes"
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"crypto/md5"
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"fmt"
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"github.com/wader/fq/format"
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"github.com/wader/fq/internal/mathex"
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"github.com/wader/fq/pkg/bitio"
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"github.com/wader/fq/pkg/decode"
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"github.com/wader/fq/pkg/interp"
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"github.com/wader/fq/pkg/scalar"
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)
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var flacMetadatablocksFormat decode.Group
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var flacFrameFormat decode.Group
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func init() {
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interp.RegisterFormat(decode.Format{
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Name: format.FLAC,
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Description: "Free Lossless Audio Codec file",
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Groups: []string{format.PROBE},
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DecodeFn: flacDecode,
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Dependencies: []decode.Dependency{
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{Names: []string{format.FLAC_METADATABLOCKS}, Group: &flacMetadatablocksFormat},
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{Names: []string{format.FLAC_FRAME}, Group: &flacFrameFormat},
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},
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})
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}
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func flacDecode(d *decode.D, _ any) any {
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d.FieldUTF8("magic", 4, d.AssertStr("fLaC"))
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var streamInfo format.FlacStreamInfo
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var flacFrameIn format.FlacFrameIn
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var framesNDecodedSamples uint64
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var streamTotalSamples uint64
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var streamDecodedSamples uint64
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_, v := d.FieldFormat("metadatablocks", flacMetadatablocksFormat, nil)
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flacMetadatablockOut, ok := v.(format.FlacMetadatablocksOut)
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if !ok {
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panic(fmt.Sprintf("expected FlacMetadatablockOut got %#+v", v))
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}
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if flacMetadatablockOut.HasStreamInfo {
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streamInfo = flacMetadatablockOut.StreamInfo
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streamTotalSamples = streamInfo.TotalSamplesInStream
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flacFrameIn = format.FlacFrameIn{BitsPerSample: int(streamInfo.BitsPerSample)}
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}
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md5Samples := md5.New()
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d.FieldArray("frames", func(d *decode.D) {
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for d.NotEnd() {
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// flac frame might need some fields from stream info to decode
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_, v := d.FieldFormat("frame", flacFrameFormat, flacFrameIn)
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ffo, ok := v.(format.FlacFrameOut)
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if !ok {
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panic(fmt.Sprintf("expected FlacFrameOut got %#+v", v))
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}
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samplesInFrame := ffo.Samples
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if streamTotalSamples > 0 {
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samplesInFrame = mathex.Min(streamTotalSamples-streamDecodedSamples, ffo.Samples)
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}
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frameStreamSamplesBuf := ffo.SamplesBuf[0 : samplesInFrame*uint64(ffo.Channels*ffo.BitsPerSample/8)]
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framesNDecodedSamples += ffo.Samples
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d.Copy(md5Samples, bytes.NewReader(frameStreamSamplesBuf))
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streamDecodedSamples += ffo.Samples
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// reuse buffer if possible
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flacFrameIn.SamplesBuf = ffo.SamplesBuf
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}
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})
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md5CalcValue := d.FieldRootBitBuf("md5_calculated", bitio.NewBitReader(md5Samples.Sum(nil), -1))
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_ = md5CalcValue.TryScalarFn(d.ValidateBitBuf(streamInfo.MD5), scalar.RawHex)
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d.FieldValueU("decoded_samples", framesNDecodedSamples)
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return nil
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}
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