mirror of
https://github.com/FFmpeg/FFmpeg.git
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130 lines
3.9 KiB
C
130 lines
3.9 KiB
C
/*
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* HEVC common code
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*
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* This file is part of Libav.
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*
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* Libav 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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*
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* Libav 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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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; 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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#include <string.h>
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#include "config.h"
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#include "libavutil/intreadwrite.h"
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#include "libavutil/mem.h"
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#include "hevc.h"
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/* FIXME: This is adapted from ff_h264_decode_nal, avoiding duplication
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* between these functions would be nice. */
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int ff_hevc_extract_rbsp(const uint8_t *src, int length,
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HEVCNAL *nal)
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{
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int i, si, di;
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uint8_t *dst;
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#define STARTCODE_TEST \
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if (i + 2 < length && src[i + 1] == 0 && src[i + 2] <= 3) { \
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if (src[i + 2] != 3) { \
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/* startcode, so we must be past the end */ \
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length = i; \
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} \
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break; \
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}
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#if HAVE_FAST_UNALIGNED
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#define FIND_FIRST_ZERO \
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if (i > 0 && !src[i]) \
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i--; \
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while (src[i]) \
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i++
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#if HAVE_FAST_64BIT
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for (i = 0; i + 1 < length; i += 9) {
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if (!((~AV_RN64A(src + i) &
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(AV_RN64A(src + i) - 0x0100010001000101ULL)) &
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0x8000800080008080ULL))
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continue;
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FIND_FIRST_ZERO;
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STARTCODE_TEST;
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i -= 7;
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}
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#else
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for (i = 0; i + 1 < length; i += 5) {
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if (!((~AV_RN32A(src + i) &
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(AV_RN32A(src + i) - 0x01000101U)) &
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0x80008080U))
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continue;
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FIND_FIRST_ZERO;
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STARTCODE_TEST;
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i -= 3;
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}
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#endif /* HAVE_FAST_64BIT */
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#else
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for (i = 0; i + 1 < length; i += 2) {
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if (src[i])
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continue;
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if (i > 0 && src[i - 1] == 0)
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i--;
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STARTCODE_TEST;
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}
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#endif /* HAVE_FAST_UNALIGNED */
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if (i >= length - 1) { // no escaped 0
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nal->data =
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nal->raw_data = src;
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nal->size =
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nal->raw_size = length;
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return length;
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}
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av_fast_malloc(&nal->rbsp_buffer, &nal->rbsp_buffer_size,
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length + FF_INPUT_BUFFER_PADDING_SIZE);
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if (!nal->rbsp_buffer)
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return AVERROR(ENOMEM);
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dst = nal->rbsp_buffer;
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memcpy(dst, src, i);
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si = di = i;
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while (si + 2 < length) {
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// remove escapes (very rare 1:2^22)
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if (src[si + 2] > 3) {
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dst[di++] = src[si++];
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dst[di++] = src[si++];
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} else if (src[si] == 0 && src[si + 1] == 0) {
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if (src[si + 2] == 3) { // escape
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dst[di++] = 0;
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dst[di++] = 0;
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si += 3;
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continue;
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} else // next start code
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goto nsc;
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}
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dst[di++] = src[si++];
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}
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while (si < length)
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dst[di++] = src[si++];
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nsc:
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memset(dst + di, 0, FF_INPUT_BUFFER_PADDING_SIZE);
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nal->data = dst;
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nal->size = di;
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nal->raw_data = src;
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nal->raw_size = si;
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return si;
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}
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