| /* |
| * 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); |
| } |