mirror of
https://github.com/wader/fq.git
synced 2024-12-23 21:31:33 +03:00
60 lines
1.7 KiB
Go
60 lines
1.7 KiB
Go
package vorbis
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import (
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"encoding/base64"
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"io"
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"strings"
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"github.com/wader/fq/format"
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"github.com/wader/fq/pkg/decode"
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"github.com/wader/fq/pkg/interp"
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)
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var flacPicture decode.Group
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func init() {
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interp.RegisterFormat(decode.Format{
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Name: format.VORBIS_COMMENT,
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Description: "Vorbis comment",
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DecodeFn: commentDecode,
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Dependencies: []decode.Dependency{
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{Names: []string{format.FLAC_PICTURE}, Group: &flacPicture},
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},
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})
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}
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func commentDecode(d *decode.D, _ any) any {
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d.Endian = decode.LittleEndian
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vendorLen := d.FieldU32("vendor_length")
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d.FieldUTF8("vendor", int(vendorLen))
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userCommentListLength := d.FieldU32("user_comment_list_length")
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i := uint64(0)
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d.FieldStructArrayLoop("user_comments", "user_comment", func() bool { return i < userCommentListLength }, func(d *decode.D) {
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userCommentLength := d.FieldU32("length")
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userCommentStart := d.Pos()
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userComment := d.FieldUTF8("comment", int(userCommentLength))
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var metadataBlockPicturePrefix = "METADATA_BLOCK_PICTURE="
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var metadataBlockPicturePrefixLower = "metadata_block_picture="
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if strings.HasPrefix(userComment, metadataBlockPicturePrefix) ||
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strings.HasPrefix(userComment, metadataBlockPicturePrefixLower) {
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base64Offset := int64(len(metadataBlockPicturePrefix)) * 8
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base64Len := int64(len(userComment))*8 - base64Offset
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_, base64Br, dv, _, _ := d.TryFieldReaderRangeFormat(
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"picture",
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userCommentStart+base64Offset, base64Len,
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func(r io.Reader) io.Reader { return base64.NewDecoder(base64.StdEncoding, r) },
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flacPicture, nil,
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)
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if dv == nil && base64Br != nil {
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d.FieldRootBitBuf("picture", base64Br)
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}
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}
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i++
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})
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return nil
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}
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