Stu Leak
68df790d27
Major improvements to UnifiedPlayer: 1. GetFrameImage() now works when paused for responsive UI updates 2. Play() method properly starts FFmpeg process 3. Frame display loop runs continuously for smooth video display 4. Disabled audio temporarily to fix video playback fundamentals 5. Simplified FFmpeg command to focus on video stream only Player now: - Generates video frames correctly - Shows video when paused - Has responsive progress tracking - Starts playback properly Next steps: Re-enable audio playback once video is stable
150 lines
3.3 KiB
Go
150 lines
3.3 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package tiff
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// A tiff image file contains one or more images. The metadata
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// of each image is contained in an Image File Directory (IFD),
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// which contains entries of 12 bytes each and is described
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// on page 14-16 of the specification. An IFD entry consists of
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//
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// - a tag, which describes the signification of the entry,
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// - the data type and length of the entry,
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// - the data itself or a pointer to it if it is more than 4 bytes.
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//
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// The presence of a length means that each IFD is effectively an array.
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const (
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leHeader = "II\x2A\x00" // Header for little-endian files.
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beHeader = "MM\x00\x2A" // Header for big-endian files.
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ifdLen = 12 // Length of an IFD entry in bytes.
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)
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// Data types (p. 14-16 of the spec).
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const (
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dtByte = 1
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dtASCII = 2
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dtShort = 3
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dtLong = 4
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dtRational = 5
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)
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// The length of one instance of each data type in bytes.
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var lengths = [...]uint32{0, 1, 1, 2, 4, 8}
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// Tags (see p. 28-41 of the spec).
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const (
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tImageWidth = 256
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tImageLength = 257
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tBitsPerSample = 258
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tCompression = 259
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tPhotometricInterpretation = 262
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tFillOrder = 266
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tStripOffsets = 273
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tSamplesPerPixel = 277
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tRowsPerStrip = 278
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tStripByteCounts = 279
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tT4Options = 292 // CCITT Group 3 options, a set of 32 flag bits.
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tT6Options = 293 // CCITT Group 4 options, a set of 32 flag bits.
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tTileWidth = 322
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tTileLength = 323
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tTileOffsets = 324
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tTileByteCounts = 325
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tXResolution = 282
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tYResolution = 283
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tResolutionUnit = 296
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tPredictor = 317
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tColorMap = 320
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tExtraSamples = 338
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tSampleFormat = 339
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)
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// Compression types (defined in various places in the spec and supplements).
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const (
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cNone = 1
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cCCITT = 2
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cG3 = 3 // Group 3 Fax.
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cG4 = 4 // Group 4 Fax.
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cLZW = 5
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cJPEGOld = 6 // Superseded by cJPEG.
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cJPEG = 7
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cDeflate = 8 // zlib compression.
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cPackBits = 32773
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cDeflateOld = 32946 // Superseded by cDeflate.
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)
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// Photometric interpretation values (see p. 37 of the spec).
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const (
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pWhiteIsZero = 0
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pBlackIsZero = 1
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pRGB = 2
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pPaletted = 3
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pTransMask = 4 // transparency mask
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pCMYK = 5
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pYCbCr = 6
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pCIELab = 8
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)
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// Values for the tPredictor tag (page 64-65 of the spec).
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const (
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prNone = 1
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prHorizontal = 2
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)
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// Values for the tResolutionUnit tag (page 18).
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const (
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resNone = 1
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resPerInch = 2 // Dots per inch.
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resPerCM = 3 // Dots per centimeter.
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)
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// imageMode represents the mode of the image.
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type imageMode int
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const (
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mBilevel imageMode = iota
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mPaletted
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mGray
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mGrayInvert
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mRGB
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mRGBA
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mNRGBA
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mCMYK
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)
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// CompressionType describes the type of compression used in Options.
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type CompressionType int
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// Constants for supported compression types.
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const (
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Uncompressed CompressionType = iota
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Deflate
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LZW
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CCITTGroup3
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CCITTGroup4
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)
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// specValue returns the compression type constant from the TIFF spec that
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// is equivalent to c.
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func (c CompressionType) specValue() uint32 {
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switch c {
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case LZW:
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return cLZW
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case Deflate:
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return cDeflate
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case CCITTGroup3:
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return cG3
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case CCITTGroup4:
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return cG4
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}
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return cNone
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}
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