/* * H.264/HEVC common parsing code * * This file is part of Libav. * * Libav 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. * * Libav 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 Libav; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include <string.h> #include "config.h" #include "libavutil/intmath.h" #include "libavutil/intreadwrite.h" #include "libavutil/mem.h" #include "h2645_parse.h" int ff_h2645_extract_rbsp(const uint8_t *src, int length, H2645NAL *nal) { int i, si, di; uint8_t *dst; #define STARTCODE_TEST \ if (i + 2 < length && src[i + 1] == 0 && src[i + 2] <= 3) { \ if (src[i + 2] != 3) { \ /* startcode, so we must be past the end */ \ length = i; \ } \ break; \ } #if HAVE_FAST_UNALIGNED #define FIND_FIRST_ZERO \ if (i > 0 && !src[i]) \ i--; \ while (src[i]) \ i++ #if HAVE_FAST_64BIT for (i = 0; i + 1 < length; i += 9) { if (!((~AV_RN64A(src + i) & (AV_RN64A(src + i) - 0x0100010001000101ULL)) & 0x8000800080008080ULL)) continue; FIND_FIRST_ZERO; STARTCODE_TEST; i -= 7; } #else for (i = 0; i + 1 < length; i += 5) { if (!((~AV_RN32A(src + i) & (AV_RN32A(src + i) - 0x01000101U)) & 0x80008080U)) continue; FIND_FIRST_ZERO; STARTCODE_TEST; i -= 3; } #endif /* HAVE_FAST_64BIT */ #else for (i = 0; i + 1 < length; i += 2) { if (src[i]) continue; if (i > 0 && src[i - 1] == 0) i--; STARTCODE_TEST; } #endif /* HAVE_FAST_UNALIGNED */ if (i >= length - 1) { // no escaped 0 nal->data = nal->raw_data = src; nal->size = nal->raw_size = length; return length; } av_fast_malloc(&nal->rbsp_buffer, &nal->rbsp_buffer_size, length + AV_INPUT_BUFFER_PADDING_SIZE); if (!nal->rbsp_buffer) return AVERROR(ENOMEM); dst = nal->rbsp_buffer; memcpy(dst, src, i); si = di = i; while (si + 2 < length) { // remove escapes (very rare 1:2^22) if (src[si + 2] > 3) { dst[di++] = src[si++]; dst[di++] = src[si++]; } else if (src[si] == 0 && src[si + 1] == 0) { if (src[si + 2] == 3) { // escape dst[di++] = 0; dst[di++] = 0; si += 3; continue; } else // next start code goto nsc; } dst[di++] = src[si++]; } while (si < length) dst[di++] = src[si++]; nsc: memset(dst + di, 0, AV_INPUT_BUFFER_PADDING_SIZE); nal->data = dst; nal->size = di; nal->raw_data = src; nal->raw_size = si; return si; } static int get_bit_length(H2645NAL *nal, int skip_trailing_zeros) { int size = nal->size; int v; while (skip_trailing_zeros && size > 0 && nal->data[size - 1] == 0) size--; if (!size) return 0; v = nal->data[size - 1]; if (size > INT_MAX / 8) return AVERROR(ERANGE); size *= 8; /* remove the stop bit and following trailing zeros, * or nothing for damaged bitstreams */ if (v) size -= av_ctz(v) + 1; return size; } /** * @return AVERROR_INVALIDDATA if the packet is not a valid NAL unit, * 0 if the unit should be skipped, 1 otherwise */ static int hevc_parse_nal_header(H2645NAL *nal, void *logctx) { GetBitContext *gb = &nal->gb; int nuh_layer_id; if (get_bits1(gb) != 0) return AVERROR_INVALIDDATA; nal->type = get_bits(gb, 6); nuh_layer_id = get_bits(gb, 6); nal->temporal_id = get_bits(gb, 3) - 1; if (nal->temporal_id < 0) return AVERROR_INVALIDDATA; av_log(logctx, AV_LOG_DEBUG, "nal_unit_type: %d, nuh_layer_id: %dtemporal_id: %d\n", nal->type, nuh_layer_id, nal->temporal_id); return nuh_layer_id == 0; } static int h264_parse_nal_header(H2645NAL *nal, void *logctx) { GetBitContext *gb = &nal->gb; if (get_bits1(gb) != 0) return AVERROR_INVALIDDATA; nal->ref_idc = get_bits(gb, 2); nal->type = get_bits(gb, 5); av_log(logctx, AV_LOG_DEBUG, "nal_unit_type: %d, nal_ref_idc: %d\n", nal->type, nal->ref_idc); return 1; } static int find_next_start_code(const uint8_t *buf, const uint8_t *next_avc) { int i = 0; if (buf + 3 >= next_avc) return next_avc - buf; while (buf + i + 3 < next_avc) { if (buf[i] == 0 && buf[i + 1] == 0 && buf[i + 2] == 1) break; i++; } return i + 3; } int ff_h2645_packet_split(H2645Packet *pkt, const uint8_t *buf, int length, void *logctx, int is_nalff, int nal_length_size, enum AVCodecID codec_id) { int consumed, ret = 0; const uint8_t *next_avc = buf + (is_nalff ? 0 : length); pkt->nb_nals = 0; while (length >= 4) { H2645NAL *nal; int extract_length = 0; int skip_trailing_zeros = 1; /* * Only parse an AVC1 length field if one is expected at the current * buffer position. There are unfortunately streams with multiple * NAL units covered by the length field. Those NAL units are delimited * by Annex B start code prefixes. ff_h2645_extract_rbsp() detects it * correctly and consumes only the first NAL unit. The additional NAL * units are handled here in the Annex B parsing code. */ if (buf == next_avc) { int i; for (i = 0; i < nal_length_size; i++) extract_length = (extract_length << 8) | buf[i]; if (extract_length > length) { av_log(logctx, AV_LOG_ERROR, "Invalid NAL unit size (%d > %d).\n", extract_length, length); return AVERROR_INVALIDDATA; } buf += nal_length_size; length -= nal_length_size; // keep track of the next AVC1 length field next_avc = buf + extract_length; } else { /* * expected to return immediately except for streams with mixed * NAL unit coding */ int buf_index = find_next_start_code(buf, next_avc); buf += buf_index; length -= buf_index; /* * break if an AVC1 length field is expected at the current buffer * position */ if (buf == next_avc) continue; if (length > 0) { extract_length = length; } else if (pkt->nb_nals == 0) { av_log(logctx, AV_LOG_ERROR, "No NAL unit found\n"); return AVERROR_INVALIDDATA; } else { break; } } if (pkt->nals_allocated < pkt->nb_nals + 1) { int new_size = pkt->nals_allocated + 1; H2645NAL *tmp = av_realloc_array(pkt->nals, new_size, sizeof(*tmp)); if (!tmp) return AVERROR(ENOMEM); pkt->nals = tmp; memset(pkt->nals + pkt->nals_allocated, 0, (new_size - pkt->nals_allocated) * sizeof(*tmp)); pkt->nals_allocated = new_size; } nal = &pkt->nals[pkt->nb_nals++]; consumed = ff_h2645_extract_rbsp(buf, extract_length, nal); if (consumed < 0) return consumed; /* see commit 3566042a0 */ if (consumed < length - 3 && buf[consumed] == 0x00 && buf[consumed + 1] == 0x00 && buf[consumed + 2] == 0x01 && buf[consumed + 3] == 0xE0) skip_trailing_zeros = 0; nal->size_bits = get_bit_length(nal, skip_trailing_zeros); ret = init_get_bits(&nal->gb, nal->data, nal->size_bits); if (ret < 0) return ret; if (codec_id == AV_CODEC_ID_HEVC) ret = hevc_parse_nal_header(nal, logctx); else ret = h264_parse_nal_header(nal, logctx); if (ret <= 0) { if (ret < 0) { av_log(logctx, AV_LOG_ERROR, "Invalid NAL unit %d, skipping.\n", nal->type); } pkt->nb_nals--; } buf += consumed; length -= consumed; } return 0; } void ff_h2645_packet_uninit(H2645Packet *pkt) { int i; for (i = 0; i < pkt->nals_allocated; i++) av_freep(&pkt->nals[i].rbsp_buffer); av_freep(&pkt->nals); pkt->nals_allocated = 0; }