177 lines
4.6 KiB
C
177 lines
4.6 KiB
C
/**************************************************************************
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*
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* Copyright 2013 Advanced Micro Devices, Inc.
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* All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sub license, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice (including the
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* next paragraph) shall be included in all copies or substantial portions
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* of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
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* IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR
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* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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**************************************************************************/
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/*
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* Authors:
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* Christian König <christian.koenig@amd.com>
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*
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*/
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/*
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* Functions for reading the raw byte sequence payload of H.264
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*/
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#ifndef vl_rbsp_h
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#define vl_rbsp_h
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#include "util/vl_vlc.h"
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struct vl_rbsp {
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struct vl_vlc nal;
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unsigned escaped;
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};
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/**
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* Initialize the RBSP object
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*/
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static inline void vl_rbsp_init(struct vl_rbsp *rbsp, struct vl_vlc *nal, unsigned num_bits)
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{
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unsigned valid, bits_left = vl_vlc_bits_left(nal);
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int i;
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/* copy the position */
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rbsp->nal = *nal;
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/* search for the end of the NAL unit */
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while (vl_vlc_search_byte(nal, num_bits, 0x00)) {
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if (vl_vlc_peekbits(nal, 24) == 0x000001 ||
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vl_vlc_peekbits(nal, 32) == 0x00000001) {
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vl_vlc_limit(&rbsp->nal, bits_left - vl_vlc_bits_left(nal));
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break;
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}
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vl_vlc_eatbits(nal, 8);
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}
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valid = vl_vlc_valid_bits(&rbsp->nal);
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/* search for the emulation prevention three byte */
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for (i = 24; i <= valid; i += 8) {
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if ((vl_vlc_peekbits(&rbsp->nal, i) & 0xffffff) == 0x3) {
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vl_vlc_removebits(&rbsp->nal, i - 8, 8);
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i += 8;
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}
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}
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valid = vl_vlc_valid_bits(&rbsp->nal);
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rbsp->escaped = (valid >= 16) ? 16 : ((valid >= 8) ? 8 : 0);
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}
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/**
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* Make at least 16 more bits available
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*/
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static inline void vl_rbsp_fillbits(struct vl_rbsp *rbsp)
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{
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unsigned valid = vl_vlc_valid_bits(&rbsp->nal);
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unsigned i, bits;
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/* abort if we still have enough bits */
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if (valid >= 32)
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return;
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vl_vlc_fillbits(&rbsp->nal);
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/* abort if we have less than 24 bits left in this nal */
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if (vl_vlc_bits_left(&rbsp->nal) < 24)
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return;
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/* check that we have enough bits left from the last fillbits */
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assert(valid >= rbsp->escaped);
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/* handle the already escaped bits */
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valid -= rbsp->escaped;
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/* search for the emulation prevention three byte */
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rbsp->escaped = 16;
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bits = vl_vlc_valid_bits(&rbsp->nal);
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for (i = valid + 24; i <= bits; i += 8) {
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if ((vl_vlc_peekbits(&rbsp->nal, i) & 0xffffff) == 0x3) {
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vl_vlc_removebits(&rbsp->nal, i - 8, 8);
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rbsp->escaped = bits - i;
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bits -= 8;
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i += 8;
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}
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}
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}
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/**
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* Return an unsigned integer from the first n bits
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*/
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static inline unsigned vl_rbsp_u(struct vl_rbsp *rbsp, unsigned n)
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{
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if (n == 0)
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return 0;
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vl_rbsp_fillbits(rbsp);
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return vl_vlc_get_uimsbf(&rbsp->nal, n);
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}
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/**
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* Return an unsigned exponential Golomb encoded integer
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*/
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static inline unsigned vl_rbsp_ue(struct vl_rbsp *rbsp)
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{
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unsigned bits = 0;
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vl_rbsp_fillbits(rbsp);
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while (!vl_vlc_get_uimsbf(&rbsp->nal, 1))
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++bits;
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return (1 << bits) - 1 + vl_rbsp_u(rbsp, bits);
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}
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/**
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* Return an signed exponential Golomb encoded integer
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*/
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static inline signed vl_rbsp_se(struct vl_rbsp *rbsp)
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{
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signed codeNum = vl_rbsp_ue(rbsp);
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if (codeNum & 1)
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return (codeNum + 1) >> 1;
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else
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return -(codeNum >> 1);
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}
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/**
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* Are more data available in the RBSP ?
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*/
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static inline bool vl_rbsp_more_data(struct vl_rbsp *rbsp)
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{
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unsigned bits, value;
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if (vl_vlc_bits_left(&rbsp->nal) > 8)
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return true;
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bits = vl_vlc_valid_bits(&rbsp->nal);
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value = vl_vlc_peekbits(&rbsp->nal, bits);
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if (value == 0 || value == (1 << (bits - 1)))
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return false;
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return true;
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}
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#endif /* vl_rbsp_h */
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