blob: 87a7f33d8c2a35931efbad5bbdb72a18c90f0db4
| 1 | /* ***** BEGIN LICENSE BLOCK ***** |
| 2 | * Source last modified: $Id: envelope.c,v 1.6 2005/04/27 19:20:50 hubbe Exp $ |
| 3 | * |
| 4 | * REALNETWORKS CONFIDENTIAL--NOT FOR DISTRIBUTION IN SOURCE CODE FORM |
| 5 | * Portions Copyright (c) 1995-2002 RealNetworks, Inc. |
| 6 | * All Rights Reserved. |
| 7 | * |
| 8 | * The contents of this file, and the files included with this file, |
| 9 | * are subject to the current version of the Real Format Source Code |
| 10 | * Porting and Optimization License, available at |
| 11 | * https://helixcommunity.org/2005/license/realformatsource (unless |
| 12 | * RealNetworks otherwise expressly agrees in writing that you are |
| 13 | * subject to a different license). You may also obtain the license |
| 14 | * terms directly from RealNetworks. You may not use this file except |
| 15 | * in compliance with the Real Format Source Code Porting and |
| 16 | * Optimization License. There are no redistribution rights for the |
| 17 | * source code of this file. Please see the Real Format Source Code |
| 18 | * Porting and Optimization License for the rights, obligations and |
| 19 | * limitations governing use of the contents of the file. |
| 20 | * |
| 21 | * RealNetworks is the developer of the Original Code and owns the |
| 22 | * copyrights in the portions it created. |
| 23 | * |
| 24 | * This file, and the files included with this file, is distributed and |
| 25 | * made available on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, |
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| 27 | * SUCH WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF |
| 28 | * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT |
| 29 | * OR NON-INFRINGEMENT. |
| 30 | * |
| 31 | * Technology Compatibility Kit Test Suite(s) Location: |
| 32 | * https://rarvcode-tck.helixcommunity.org |
| 33 | * |
| 34 | * Contributor(s): |
| 35 | * |
| 36 | * ***** END LICENSE BLOCK ***** */ |
| 37 | |
| 38 | /************************************************************************************** |
| 39 | * Fixed-point RealAudio 8 decoder |
| 40 | * Jon Recker (jrecker@real.com), Ken Cooke (kenc@real.com) |
| 41 | * October 2003 |
| 42 | * |
| 43 | * envelope.c - power envelope reconstruction |
| 44 | **************************************************************************************/ |
| 45 | |
| 46 | #include "coder.h" |
| 47 | |
| 48 | /* coding params for rms[0] */ |
| 49 | #define RMS0BITS 6 /* bits for env[0] */ |
| 50 | #define RMS0MIN -6 /* arbitrary! */ |
| 51 | #define CODE2RMS(i) ((i)+(RMS0MIN)) |
| 52 | |
| 53 | /************************************************************************************** |
| 54 | * Function: DecodeEnvelope |
| 55 | * |
| 56 | * Description: decode the power envelope |
| 57 | * |
| 58 | * Inputs: pointer to initialized Gecko2Info struct |
| 59 | * number of bits remaining in bitstream for this frame |
| 60 | * index of current channel |
| 61 | * |
| 62 | * Outputs: rmsIndex[0, ..., cregsions-1] has power index for each region |
| 63 | * updated rmsMax with largest value of rmsImdex for this channel |
| 64 | * |
| 65 | * Return: number of bits remaining in bitstream, -1 if out-of-bits |
| 66 | **************************************************************************************/ |
| 67 | int DecodeEnvelope(Gecko2Info *gi, int availbits, int ch) |
| 68 | { |
| 69 | int r, code, nbits, rprime, cache, rmsMax; |
| 70 | int *rmsIndex = gi->db.rmsIndex; |
| 71 | BitStreamInfo *bsi = &(gi->bsi); |
| 72 | |
| 73 | if (availbits < RMS0BITS) { |
| 74 | return -1; |
| 75 | } |
| 76 | |
| 77 | /* unpack first index */ |
| 78 | code = GetBits(bsi, RMS0BITS, 1); |
| 79 | availbits -= RMS0BITS; |
| 80 | rmsIndex[0] = CODE2RMS(code); |
| 81 | |
| 82 | /* check for escape code */ |
| 83 | /* ASSERT(rmsIndex[0] != 0); */ |
| 84 | |
| 85 | rmsMax = rmsIndex[0]; |
| 86 | for (r = 1; r < gi->cRegions; r++) { |
| 87 | |
| 88 | /* for interleaved regions, choose a reasonable table */ |
| 89 | if (r < 2 * gi->cplStart) { |
| 90 | rprime = r >> 1; |
| 91 | if (rprime < 1) { |
| 92 | rprime = 1; |
| 93 | } |
| 94 | } else { |
| 95 | rprime = r - gi->cplStart; |
| 96 | } |
| 97 | |
| 98 | /* above NUM_POWTABLES, always use the same Huffman table */ |
| 99 | if (rprime > NUM_POWTABLES) { |
| 100 | rprime = NUM_POWTABLES; |
| 101 | } |
| 102 | |
| 103 | cache = GetBits(bsi, MAX_HUFF_BITS, 0); |
| 104 | nbits = DecodeHuffmanScalar(huffTabPower, &huffTabPowerInfo[rprime - 1], cache, &code); |
| 105 | |
| 106 | /* ran out of bits coding power envelope - should not happen (encoder spec) */ |
| 107 | if (nbits > availbits) { |
| 108 | return -1; |
| 109 | } |
| 110 | |
| 111 | availbits -= nbits; |
| 112 | AdvanceBitstream(bsi, nbits); |
| 113 | |
| 114 | /* encoder uses differential coding with differences constrained to the range [-12, 11] */ |
| 115 | rmsIndex[r] = rmsIndex[r - 1] + (code - 12); |
| 116 | if (rmsIndex[r] > rmsMax) { |
| 117 | rmsMax = rmsIndex[r]; |
| 118 | } |
| 119 | } |
| 120 | gi->rmsMax[ch] = rmsMax; |
| 121 | |
| 122 | return availbits; |
| 123 | } |
| 124 |