blob: d806f9b52b354fdf55070f3d0acc44c79948df94
| 1 | /* |
| 2 | * This file is part of FFmpeg. |
| 3 | * |
| 4 | * FFmpeg is free software; you can redistribute it and/or |
| 5 | * modify it under the terms of the GNU Lesser General Public |
| 6 | * License as published by the Free Software Foundation; either |
| 7 | * version 2.1 of the License, or (at your option) any later version. |
| 8 | * |
| 9 | * FFmpeg is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 12 | * Lesser General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU Lesser General Public |
| 15 | * License along with FFmpeg; if not, write to the Free Software |
| 16 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 17 | */ |
| 18 | |
| 19 | #include <stdint.h> |
| 20 | |
| 21 | #include "vaapi_encode_h26x.h" |
| 22 | |
| 23 | int ff_vaapi_encode_h26x_nal_unit_to_byte_stream(uint8_t *dst, size_t *dst_bit_len, |
| 24 | uint8_t *src, size_t src_bit_len) |
| 25 | { |
| 26 | size_t dp, sp; |
| 27 | int zero_run = 0; |
| 28 | size_t dst_len = *dst_bit_len / 8; |
| 29 | size_t src_len = (src_bit_len + 7) / 8; |
| 30 | int trailing_zeroes = src_len * 8 - src_bit_len; |
| 31 | |
| 32 | if (dst_len < src_len + 4) { |
| 33 | // Definitely doesn't fit. |
| 34 | goto fail; |
| 35 | } |
| 36 | |
| 37 | // Start code. |
| 38 | dst[0] = dst[1] = dst[2] = 0; |
| 39 | dst[3] = 1; |
| 40 | dp = 4; |
| 41 | |
| 42 | for (sp = 0; sp < src_len; sp++) { |
| 43 | if (dp >= dst_len) |
| 44 | goto fail; |
| 45 | if (zero_run < 2) { |
| 46 | if (src[sp] == 0) |
| 47 | ++zero_run; |
| 48 | else |
| 49 | zero_run = 0; |
| 50 | } else { |
| 51 | if ((src[sp] & ~3) == 0) { |
| 52 | // emulation_prevention_three_byte |
| 53 | dst[dp++] = 3; |
| 54 | if (dp >= dst_len) |
| 55 | goto fail; |
| 56 | } |
| 57 | zero_run = src[sp] == 0; |
| 58 | } |
| 59 | dst[dp++] = src[sp]; |
| 60 | } |
| 61 | |
| 62 | *dst_bit_len = 8 * dp - trailing_zeroes; |
| 63 | return 0; |
| 64 | |
| 65 | fail: |
| 66 | *dst_bit_len = 0; |
| 67 | return AVERROR(ENOSPC); |
| 68 | } |
| 69 |