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96 lines
2.7 KiB
Go
96 lines
2.7 KiB
Go
package flac
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// https://xiph.org/flac/format.html
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// TODO: reuse samples buffer
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// TODO: mime audio/x-flac
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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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"fq/format"
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"fq/format/registry"
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"fq/internal/num"
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"fq/pkg/decode"
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)
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var flacMetadatablockFormat []*decode.Format
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var flacFrameFormat []*decode.Format
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func init() {
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registry.MustRegister(&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_METADATABLOCK}, Formats: &flacMetadatablockFormat},
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{Names: []string{format.FLAC_FRAME}, Formats: &flacFrameFormat},
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},
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})
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}
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func flacDecode(d *decode.D, in interface{}) interface{} {
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d.FieldValidateUTF8("magic", "fLaC")
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var streamInfo format.FlacMetadatablockStreamInfo
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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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d.FieldArrayFn("metadatablocks", func(d *decode.D) {
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for {
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_, v := d.FieldFormat("metadatablock", flacMetadatablockFormat)
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flacMetadatablockOut, ok := v.(format.FlacMetadatablockOut)
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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{StreamInfo: streamInfo}
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}
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if flacMetadatablockOut.IsLastBlock {
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return
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}
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}
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})
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md5Samples := md5.New()
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d.FieldArrayFn("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, decode.FormatOptions{InArg: 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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frameStreamSamplesBuf := ffo.SamplesBuf
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if streamTotalSamples > 0 {
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samplesInFrame := num.MinUInt64(streamTotalSamples-streamDecodedSamples, ffo.Samples)
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frameStreamSamplesBuf = frameStreamSamplesBuf[0 : samplesInFrame*uint64(ffo.Channels*ffo.BitsPerSample/8)]
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framesNDecodedSamples += ffo.Samples
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}
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decode.MustCopy(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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_ = streamInfo
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// if streamInfo.D != nil {
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// md5Value := streamInfo.D.FieldGet("md5")
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// d.FieldChecksumRange("md5_calculated", md5Value.Range.Start, md5Value.Range.Len, md5Samples.Sum(nil), decode.BigEndian)
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// }
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d.FieldValueBytes("md5_calculated", md5Samples.Sum(nil), "")
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d.FieldValueU("decoded_samples", framesNDecodedSamples, "")
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return nil
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}
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