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const zlib = require('zlib') |
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2
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const ID3FrameHeader = require('./ID3FrameHeader') |
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3
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const ID3Frames = require('./ID3Frames') |
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4
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const ID3Util = require('./ID3Util') |
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5
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6
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class ID3Frame { |
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constructor(identifier, value, flags = {}) { |
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this.identifier = identifier |
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this.value = value |
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10
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this.dataLengthIndicator = 0 |
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this.flags = flags |
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} |
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14
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static createFromBuffer(frameBuffer, version) { |
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const frameHeaderSize = ID3FrameHeader.getSizeByVersion(version) |
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// Specification requirement |
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if(frameBuffer < frameHeaderSize + 1) { |
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return null |
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} |
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const frameHeaderBuffer = frameBuffer.subarray(0, frameHeaderSize) |
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const frameHeader = ID3FrameHeader.createFromBuffer(frameHeaderBuffer, version) |
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22
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if(frameHeader.flags.encryption) { |
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return null |
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24
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} |
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25
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26
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const frameBodyOffset = frameHeader.flags.dataLengthIndicator ? 4 : 0 |
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27
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const frameBodyStart = frameHeaderSize + frameBodyOffset |
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28
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let frameBody = frameBuffer.subarray(frameBodyStart, frameBodyStart + frameHeader.frameSize - frameBodyOffset) |
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29
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if(frameHeader.flags.unsynchronisation) { |
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30
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// This method should stay in ID3Util for now because it's also used in the Tag's header which we don't have a class for. |
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31
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frameBody = ID3Util.processUnsynchronisedBuffer(frameBody) |
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32
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} |
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33
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if(frameHeader.flags.dataLengthIndicator) { |
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34
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this.dataLengthIndicator = frameBuffer.readInt32BE(frameHeaderSize) |
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35
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} |
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36
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if(frameHeader.flags.compression) { |
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37
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const uncompressedFrameBody = this.decompressBodyBuffer(frameBody, this.dataLengthIndicator) |
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38
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if(!uncompressedFrameBody) { |
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39
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return null |
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40
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} |
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41
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frameBody = uncompressedFrameBody |
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42
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} |
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43
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44
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let value = null |
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45
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if(ID3Frames[frameHeader.identifier]) { |
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46
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value = ID3Frames[frameHeader.identifier].read(frameBody, version) |
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47
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} else if(frameHeader.identifier.startsWith('T')) { |
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48
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value = ID3Frames.GENERIC_TEXT.read(frameBody, version) |
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49
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} else if(frameHeader.identifier.startsWith('W')) { |
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50
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value = ID3Frames.GENERIC_URL.read(frameBody, version) |
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51
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} else { |
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52
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// Unknown frames are not supported currently. |
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53
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return null |
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54
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} |
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55
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56
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return new ID3Frame(frameHeader.identifier, value, frameHeader.flags) |
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57
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} |
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58
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59
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getBuffer() { |
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60
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if(ID3Frames[this.identifier]) { |
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61
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return ID3Frames[this.identifier].create(this.value) |
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62
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} |
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63
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if(this.identifier.startsWith('T')) { |
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64
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return ID3Frames.GENERIC_TEXT.create(this.value) |
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65
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} |
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66
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if(this.identifier.startsWith('W')) { |
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67
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return ID3Frames.GENERIC_URL.create(this.value) |
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68
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} |
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69
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70
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return null |
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71
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} |
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72
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73
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getValue() { |
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74
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return this.value |
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75
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} |
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76
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77
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static decompressBodyBuffer(bodyBuffer, dataLengthIndicator) { |
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78
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if(bodyBuffer.length < 5 || dataLengthIndicator === undefined) { |
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79
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return null |
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80
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} |
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81
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82
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/* |
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83
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* ID3 spec defines that compression is stored in ZLIB format, but doesn't specify if header is present or not. |
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84
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* ZLIB has a 2-byte header. |
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85
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* 1. try if header + body decompression |
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86
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* 2. else try if header is not stored (assume that all content is deflated "body") |
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87
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* 3. else try if inflation works if the header is omitted (implementation dependent) |
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88
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* */ |
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89
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let decompressedBody |
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90
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try { |
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91
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decompressedBody = zlib.inflateSync(bodyBuffer) |
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92
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} catch (e) { |
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93
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try { |
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94
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decompressedBody = zlib.inflateRawSync(bodyBuffer) |
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95
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} catch (e) { |
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96
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try { |
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97
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decompressedBody = zlib.inflateRawSync(bodyBuffer.subarray(2)) |
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98
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} catch (e) { |
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99
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return null |
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100
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} |
|
101
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} |
|
102
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} |
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103
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if(decompressedBody.length !== dataLengthIndicator) { |
|
104
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return null |
|
105
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} |
|
106
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return decompressedBody |
|
107
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} |
|
108
|
|
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} |
|
109
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110
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module.exports = ID3Frame |
Zazama /
node-id3
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