mirror of https://bitbucket.org/ausocean/av.git
468 lines
12 KiB
Go
468 lines
12 KiB
Go
/*
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DESCRIPTION
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jpeg.go contains code ported from FFmpeg's C implementation of an RTP
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JPEG-compressed Video Depacketizer following RFC 2435. See
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https://ffmpeg.org/doxygen/2.6/rtpdec__jpeg_8c_source.html and
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https://tools.ietf.org/html/rfc2435).
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This code can be used to build JPEG images from an RTP/JPEG stream.
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AUTHOR
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Saxon Nelson-Milton <saxon@ausocean.org>
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LICENSE
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Copyright (c) 2012 Samuel Pitoiset.
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This file is part of FFmpeg.
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FFmpeg is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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FFmpeg is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with FFmpeg; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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package mjpeg
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import (
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"encoding/binary"
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"errors"
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"fmt"
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"io"
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)
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const maxJPEG = 1000000 // 1 MB (arbitrary)
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// JPEG marker codes.
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const (
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codeSOI = 0xd8 // Start of image.
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codeDRI = 0xdd // Define restart interval.
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codeDQT = 0xdb // Define quantization tables.
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codeDHT = 0xc4 // Define huffman tables.
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codeSOS = 0xda // Start of scan.
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codeAPP0 = 0xe0 // TODO: find out what this is.
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codeSOF0 = 0xc0 // Baseline
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codeEOI = 0xd9 // End of image.
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)
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// Density units.
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const (
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unitNone = iota
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unitPxIN // Pixels per inch.
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unitPxCM // Pixels per centimeter.
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)
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// JFIF header fields.
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const (
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jfifLabel = "JFIF\000"
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jfifVer = 0x0201
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jfifDensityUnit = unitNone // Units for pixel density fields.
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jfifXDensity = 1 // Horizontal pixel desnity.
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jfifYDensity = 1 // Vertical pixel density.
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jfifXThumbCnt = 0 // Horizontal pixel count of embedded thumbnail.
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jfifYThumbCnt = 0 // Vertical pixel count of embedded thumbnail.
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jfifHeadLen = 16 // Length of JFIF header segment excluding APP0 marker.
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)
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// SOF0 (start of frame) header fields.
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const (
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sofLen = 17 // Length of SOF0 segment excluding marker.
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sofPrecision = 8 // Data precision in bits/sample.
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sofNoOfComponents = 3 // Number of components (1 = grey scaled, 3 = color YcbCr or YIQ 4 = color CMYK)
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)
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// SOS (start of scan) header fields.
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const (
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sosLen = 12 // Length of SOS segment excluding marker.
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sosComponentsInScan = 3 // Number of components in scan.
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)
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var (
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errNoQTable = errors.New("no quantization table")
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errReservedQ = errors.New("q value is reserved")
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)
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// Slices used in the creation of huffman tables.
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var (
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bitsDCLum = []byte{0, 0, 1, 5, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}
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bitsDCChr = []byte{0, 0, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0}
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bitsACLum = []byte{0, 0, 2, 1, 3, 3, 2, 4, 3, 5, 5, 4, 4, 0, 0, 1, 0x7d}
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bitsACChr = []byte{0, 0, 2, 1, 2, 4, 4, 3, 4, 7, 5, 4, 4, 0, 1, 2, 0x77}
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valDC = []byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}
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valACLum = []byte{
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0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12,
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0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07,
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0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xa1, 0x08,
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0x23, 0x42, 0xb1, 0xc1, 0x15, 0x52, 0xd1, 0xf0,
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0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0a, 0x16,
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0x17, 0x18, 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28,
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0x29, 0x2a, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
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0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
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0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,
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0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
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0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,
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0x7a, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,
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0x8a, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98,
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0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
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0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6,
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0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5,
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0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4,
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0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xe1, 0xe2,
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0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea,
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0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
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0xf9, 0xfa,
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}
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valACChr = []byte{
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0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21,
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0x31, 0x06, 0x12, 0x41, 0x51, 0x07, 0x61, 0x71,
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0x13, 0x22, 0x32, 0x81, 0x08, 0x14, 0x42, 0x91,
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0xa1, 0xb1, 0xc1, 0x09, 0x23, 0x33, 0x52, 0xf0,
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0x15, 0x62, 0x72, 0xd1, 0x0a, 0x16, 0x24, 0x34,
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0xe1, 0x25, 0xf1, 0x17, 0x18, 0x19, 0x1a, 0x26,
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0x27, 0x28, 0x29, 0x2a, 0x35, 0x36, 0x37, 0x38,
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0x39, 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
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0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,
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0x59, 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,
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0x69, 0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,
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0x79, 0x7a, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
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0x88, 0x89, 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96,
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0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5,
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0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4,
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0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3,
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0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2,
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0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda,
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0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9,
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0xea, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
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0xf9, 0xfa,
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}
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)
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var defaultQuantisers = []byte{
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// Luma table.
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16, 11, 12, 14, 12, 10, 16, 14,
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13, 14, 18, 17, 16, 19, 24, 40,
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26, 24, 22, 22, 24, 49, 35, 37,
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29, 40, 58, 51, 61, 60, 57, 51,
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56, 55, 64, 72, 92, 78, 64, 68,
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87, 69, 55, 56, 80, 109, 81, 87,
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95, 98, 103, 104, 103, 62, 77, 113,
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121, 112, 100, 120, 92, 101, 103, 99,
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/* chroma table */
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17, 18, 18, 24, 21, 24, 47, 26,
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26, 47, 99, 66, 56, 66, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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}
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// Context describes a RTP/JPEG parsing context that will keep track of the current
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// JPEG (held by p), and the state of the quantization tables.
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type Context struct {
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qTables [128][128]byte
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qTablesLen [128]byte
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buf []byte
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blen int
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dst io.Writer
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}
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// NewContext will return a new Context with destination d.
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func NewContext(d io.Writer) *Context {
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return &Context{
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dst: d,
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buf: make([]byte, maxJPEG),
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}
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}
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// ParsePayload will parse an RTP/JPEG payload and append to current image.
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func (c *Context) ParsePayload(p []byte, m bool) error {
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idx := 1 // Ignore type-specific flag (skip to index 1).
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off := get24(p[idx:]) // Fragment offset (3 bytes).
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t := int(p[idx+3]) // Type (1 byte).
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q := p[idx+4] // Quantization value (1 byte).
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width := p[idx+5] // Picture width (1 byte).
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height := p[idx+6] // Picture height (1 byte).
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idx += 7
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var dri int // Restart interval.
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if t&0x40 != 0 {
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dri = int(binary.BigEndian.Uint16(p[idx:]))
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idx += 4 // Ignore restart count (2 bytes).
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t &= ^0x40
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}
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if t > 1 {
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panic("unimplemented RTP/JPEG type")
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}
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// Parse quantization table if our offset is 0.
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if off == 0 {
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var qTable []byte
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var qLen int
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if q > 127 {
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idx++
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prec := p[idx] // The size of coefficients (1 byte).
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qLen = int(binary.BigEndian.Uint16(p[idx+1:])) // The length of the quantization table (2 bytes).
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idx += 3
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if prec != 0 {
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panic("unsupported precision")
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}
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if qLen > 0 {
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qTable = p[idx : idx+qLen]
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idx += qLen
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if q < 255 && c.qTablesLen[q-128] == 0 && qLen <= 128 {
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copy(c.qTables[q-128][:], qTable)
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c.qTablesLen[q-128] = byte(qLen)
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}
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} else {
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if q == 255 {
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return errNoQTable
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}
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if c.qTablesLen[q-128] == 0 {
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return fmt.Errorf("no quantization tables known for q %d yet", q)
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}
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qTable = c.qTables[q-128][:]
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qLen = int(c.qTablesLen[q-128])
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}
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} else { // q <= 127
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if q == 0 || q > 99 {
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return errReservedQ
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}
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qTable = defaultQTable(int(q))
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qLen = len(qTable)
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}
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c.blen = writeHeader(c.buf[c.blen:], int(t), int(width), int(height), qLen/64, dri, qTable)
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}
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if c.blen == 0 {
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// Must have missed start of frame? So ignore and wait for start.
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return nil
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}
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// TODO: check that timestamp is consistent
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// This will need expansion to RTP package to create Timestamp parsing func.
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// TODO: could also check offset with how many bytes we currently have
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// to determine if there are missing frames.
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// Write frame data
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rem := len(p)
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f := p[idx:rem]
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copy(c.buf[c.blen:], f)
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c.blen += len(f)
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idx += rem
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if m {
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// End of image marker.
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binary.BigEndian.PutUint16(c.buf[c.blen:], 0xff00|codeEOI)
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c.blen += 2
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n, err := c.dst.Write(c.buf[0:c.blen])
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if err != nil {
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return fmt.Errorf("could not write JPEG to dst: %w", err)
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}
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c.blen -= n
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}
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return nil
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}
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func get24(p []byte) int {
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return int(p[0]<<16) | int(p[1]<<8) | int(p[2])
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}
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// writeHeader writes a JPEG header to the writer w.
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func writeHeader(p []byte, _type, width, height, nbqTab, dri int, qtable []byte) int {
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width <<= 3
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height <<= 3
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// Indicate start of image.
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idx := 0
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binary.BigEndian.PutUint16(p[idx:], 0xff00|codeSOI)
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idx += 2
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// Write JFIF header.
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binary.BigEndian.PutUint16(p[idx:], 0xff00|codeAPP0)
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binary.BigEndian.PutUint16(p[idx+2:], jfifHeadLen)
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idx += 4
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src := []byte(jfifLabel)
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copy(p[idx:], src)
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idx += len(src)
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binary.BigEndian.PutUint16(p[idx:], jfifVer)
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p[idx+2] = jfifDensityUnit
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binary.BigEndian.PutUint16(p[idx+3:], jfifXDensity)
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binary.BigEndian.PutUint16(p[idx+5:], jfifYDensity)
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p[idx+7] = jfifXThumbCnt
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p[idx+8] = jfifYThumbCnt
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idx += 9
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// If we want to define restart interval then write that.
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if dri != 0 {
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binary.BigEndian.PutUint16(p[idx:], 0xff00|codeDRI)
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binary.BigEndian.PutUint16(p[idx+2:], 4)
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binary.BigEndian.PutUint16(p[idx+4:], uint16(dri))
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idx += 6
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}
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// Define quantization tables.
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binary.BigEndian.PutUint16(p[idx:], 0xff00|codeDQT)
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idx += 2
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// Calculate table size and create slice for table.
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ts := 2 + nbqTab*(1+64)
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binary.BigEndian.PutUint16(p[idx:], uint16(ts))
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idx += 2
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for i := 0; i < nbqTab; i++ {
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p[idx] = byte(i)
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idx++
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src := qtable[64*i : (64*i)+64]
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copy(p[idx:], src)
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idx += len(src)
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}
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// Define huffman table.
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binary.BigEndian.PutUint16(p[idx:], 0xff00|codeDHT)
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idx += 2
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lenIdx := idx
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binary.BigEndian.PutUint16(p[idx:], 0)
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idx += 2
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idx += writeHuffman(p[idx:], 0, 0, bitsDCLum, valDC)
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idx += writeHuffman(p[idx:], 0, 1, bitsDCChr, valDC)
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idx += writeHuffman(p[idx:], 1, 0, bitsACLum, valACLum)
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idx += writeHuffman(p[idx:], 1, 1, bitsACChr, valACChr)
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binary.BigEndian.PutUint16(p[lenIdx:], uint16(idx-lenIdx))
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// Start of frame.
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binary.BigEndian.PutUint16(p[idx:], 0xff00|codeSOF0)
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idx += 2
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// Derive sample type.
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sample := 1
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if _type != 0 {
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sample = 2
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}
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// Derive matrix number.
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mtxNo := 0
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if nbqTab == 2 {
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mtxNo = 1
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}
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binary.BigEndian.PutUint16(p[idx:], sofLen)
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p[idx+2] = byte(sofPrecision)
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binary.BigEndian.PutUint16(p[idx+3:], uint16(height))
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binary.BigEndian.PutUint16(p[idx+5:], uint16(width))
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p[idx+7] = byte(sofNoOfComponents)
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idx += 8
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// TODO: find meaning of these fields.
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p[idx] = 1
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p[idx+1] = uint8((2 << 4) | sample)
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p[idx+2] = 0
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p[idx+3] = 2
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p[idx+4] = 1<<4 | 1
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p[idx+5] = uint8(mtxNo)
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p[idx+6] = 3
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p[idx+7] = 1<<4 | 1
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p[idx+8] = uint8(mtxNo)
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idx += 9
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// Write start of scan.
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binary.BigEndian.PutUint16(p[idx:], 0xff00|codeSOS)
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binary.BigEndian.PutUint16(p[idx+2:], sosLen)
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p[idx+4] = sosComponentsInScan
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idx += 5
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// TODO: find out what remaining fields are.
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p[idx] = 1
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p[idx+1] = 0
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p[idx+2] = 2
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p[idx+3] = 17
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p[idx+4] = 3
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p[idx+5] = 17
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p[idx+6] = 0
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p[idx+7] = 63
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p[idx+8] = 0
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idx += 9
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return idx
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}
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// writeHuffman write a JPEG huffman table to w.
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func writeHuffman(p []byte, class, id int, bits, values []byte) int {
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idx := 0
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p[idx] = uint8(class<<4 | id)
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idx++
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var n int
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for i := 1; i <= 16; i++ {
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n += int(bits[i])
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}
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src := bits[1:17]
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copy(p[idx:], src)
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idx += len(src)
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src = values[0:n]
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copy(p[idx:], src)
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idx += len(src)
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return idx
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}
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// defaultQTable returns a default quantization table.
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func defaultQTable(q int) []byte {
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f := clip(q, q, 99)
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const tabLen = 128
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tab := make([]byte, tabLen)
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if q < 50 {
|
|
q = 5000 / f
|
|
} else {
|
|
q = 200 - f*2
|
|
}
|
|
|
|
for i := 0; i < tabLen; i++ {
|
|
v := (int(defaultQuantisers[i])*q + 50) / 100
|
|
v = clip(v, 1, 255)
|
|
tab[i] = byte(v)
|
|
}
|
|
return tab
|
|
}
|
|
|
|
// clip clips the value v to the bounds defined by min and max.
|
|
func clip(v, min, max int) int {
|
|
if v < min {
|
|
return min
|
|
}
|
|
|
|
if v > max {
|
|
return max
|
|
}
|
|
|
|
return v
|
|
}
|