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/*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdint.h>
#include "vaapi_encode_h26x.h"
int ff_vaapi_encode_h26x_nal_unit_to_byte_stream(uint8_t *dst, size_t *dst_bit_len,
uint8_t *src, size_t src_bit_len)
{
size_t dp, sp;
int zero_run = 0;
size_t dst_len = *dst_bit_len / 8;
size_t src_len = (src_bit_len + 7) / 8;
int trailing_zeroes = src_len * 8 - src_bit_len;
if (dst_len < src_len + 4) {
// Definitely doesn't fit.
goto fail;
}
// Start code.
dst[0] = dst[1] = dst[2] = 0;
dst[3] = 1;
dp = 4;
for (sp = 0; sp < src_len; sp++) {
if (dp >= dst_len)
goto fail;
if (zero_run < 2) {
if (src[sp] == 0)
++zero_run;
else
zero_run = 0;
} else {
if ((src[sp] & ~3) == 0) {
// emulation_prevention_three_byte
dst[dp++] = 3;
if (dp >= dst_len)
goto fail;
}
zero_run = src[sp] == 0;
}
dst[dp++] = src[sp];
}
*dst_bit_len = 8 * dp - trailing_zeroes;
return 0;
fail:
*dst_bit_len = 0;
return AVERROR(ENOSPC);
}
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