/*

  * H.264/HEVC common parsing code

  *

  * 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 <string.h>
 
 #include "config.h"
 

 #include "libavutil/intmath.h"

 #include "libavutil/intreadwrite.h"
 #include "libavutil/mem.h"
 

 #include "bytestream.h"

 #include "hevc.h"

 #include "h264.h"

 #include "h2645_parse.h"

 int ff_h2645_extract_rbsp(const uint8_t *src, int length,

                           H2645RBSP *rbsp, H2645NAL *nal, int small_padding)

 {
     int i, si, di;
     uint8_t *dst;
 

     nal->skipped_bytes = 0;

 #define STARTCODE_TEST                                                  \
         if (i + 2 < length && src[i + 1] == 0 && src[i + 2] <= 3) {     \

             if (src[i + 2] != 3 && src[i + 2] != 0) {                   \

                 /* 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_RN64(src + i) &
                (AV_RN64(src + i) - 0x0100010001000101ULL)) &

               0x8000800080008080ULL))
             continue;
         FIND_FIRST_ZERO;
         STARTCODE_TEST;
         i -= 7;
     }
 #else
     for (i = 0; i + 1 < length; i += 5) {

         if (!((~AV_RN32(src + i) &
                (AV_RN32(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 && small_padding) { // no escaped 0

         nal->data     =
         nal->raw_data = src;
         nal->size     =
         nal->raw_size = length;
         return length;

     } else if (i > length)
         i = length;

     nal->rbsp_buffer = &rbsp->rbsp_buffer[rbsp->rbsp_buffer_size];

     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 && src[si + 2] != 0) {

             if (src[si + 2] == 3) { // escape
                 dst[di++] = 0;
                 dst[di++] = 0;
                 si       += 3;
 

                 if (nal->skipped_bytes_pos) {

                     nal->skipped_bytes++;
                     if (nal->skipped_bytes_pos_size < nal->skipped_bytes) {
                         nal->skipped_bytes_pos_size *= 2;
                         av_assert0(nal->skipped_bytes_pos_size >= nal->skipped_bytes);
                         av_reallocp_array(&nal->skipped_bytes_pos,
                                 nal->skipped_bytes_pos_size,
                                 sizeof(*nal->skipped_bytes_pos));
                         if (!nal->skipped_bytes_pos) {
                             nal->skipped_bytes_pos_size = 0;
                             return AVERROR(ENOMEM);

                         }

                     }
                     if (nal->skipped_bytes_pos)
                         nal->skipped_bytes_pos[nal->skipped_bytes-1] = di - 1;

                 }

                 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;

     rbsp->rbsp_buffer_size += si;
 

     return si;
 }

 static const char *hevc_nal_type_name[64] = {
     "TRAIL_N", // HEVC_NAL_TRAIL_N
     "TRAIL_R", // HEVC_NAL_TRAIL_R
     "TSA_N", // HEVC_NAL_TSA_N
     "TSA_R", // HEVC_NAL_TSA_R
     "STSA_N", // HEVC_NAL_STSA_N
     "STSA_R", // HEVC_NAL_STSA_R
     "RADL_N", // HEVC_NAL_RADL_N
     "RADL_R", // HEVC_NAL_RADL_R
     "RASL_N", // HEVC_NAL_RASL_N
     "RASL_R", // HEVC_NAL_RASL_R
     "RSV_VCL_N10", // HEVC_NAL_VCL_N10
     "RSV_VCL_R11", // HEVC_NAL_VCL_R11
     "RSV_VCL_N12", // HEVC_NAL_VCL_N12
     "RSV_VLC_R13", // HEVC_NAL_VCL_R13
     "RSV_VCL_N14", // HEVC_NAL_VCL_N14
     "RSV_VCL_R15", // HEVC_NAL_VCL_R15
     "BLA_W_LP", // HEVC_NAL_BLA_W_LP
     "BLA_W_RADL", // HEVC_NAL_BLA_W_RADL
     "BLA_N_LP", // HEVC_NAL_BLA_N_LP
     "IDR_W_RADL", // HEVC_NAL_IDR_W_RADL
     "IDR_N_LP", // HEVC_NAL_IDR_N_LP
     "CRA_NUT", // HEVC_NAL_CRA_NUT

     "RSV_IRAP_VCL22", // HEVC_NAL_RSV_IRAP_VCL22
     "RSV_IRAP_VCL23", // HEVC_NAL_RSV_IRAP_VCL23

     "RSV_VCL24", // HEVC_NAL_RSV_VCL24
     "RSV_VCL25", // HEVC_NAL_RSV_VCL25
     "RSV_VCL26", // HEVC_NAL_RSV_VCL26
     "RSV_VCL27", // HEVC_NAL_RSV_VCL27
     "RSV_VCL28", // HEVC_NAL_RSV_VCL28
     "RSV_VCL29", // HEVC_NAL_RSV_VCL29
     "RSV_VCL30", // HEVC_NAL_RSV_VCL30
     "RSV_VCL31", // HEVC_NAL_RSV_VCL31
     "VPS", // HEVC_NAL_VPS
     "SPS", // HEVC_NAL_SPS
     "PPS", // HEVC_NAL_PPS
     "AUD", // HEVC_NAL_AUD
     "EOS_NUT", // HEVC_NAL_EOS_NUT
     "EOB_NUT", // HEVC_NAL_EOB_NUT
     "FD_NUT", // HEVC_NAL_FD_NUT
     "SEI_PREFIX", // HEVC_NAL_SEI_PREFIX
     "SEI_SUFFIX", // HEVC_NAL_SEI_SUFFIX
     "RSV_NVCL41", // HEVC_NAL_RSV_NVCL41
     "RSV_NVCL42", // HEVC_NAL_RSV_NVCL42
     "RSV_NVCL43", // HEVC_NAL_RSV_NVCL43
     "RSV_NVCL44", // HEVC_NAL_RSV_NVCL44
     "RSV_NVCL45", // HEVC_NAL_RSV_NVCL45
     "RSV_NVCL46", // HEVC_NAL_RSV_NVCL46
     "RSV_NVCL47", // HEVC_NAL_RSV_NVCL47
     "UNSPEC48", // HEVC_NAL_UNSPEC48
     "UNSPEC49", // HEVC_NAL_UNSPEC49
     "UNSPEC50", // HEVC_NAL_UNSPEC50
     "UNSPEC51", // HEVC_NAL_UNSPEC51
     "UNSPEC52", // HEVC_NAL_UNSPEC52
     "UNSPEC53", // HEVC_NAL_UNSPEC53
     "UNSPEC54", // HEVC_NAL_UNSPEC54
     "UNSPEC55", // HEVC_NAL_UNSPEC55
     "UNSPEC56", // HEVC_NAL_UNSPEC56
     "UNSPEC57", // HEVC_NAL_UNSPEC57
     "UNSPEC58", // HEVC_NAL_UNSPEC58
     "UNSPEC59", // HEVC_NAL_UNSPEC59
     "UNSPEC60", // HEVC_NAL_UNSPEC60
     "UNSPEC61", // HEVC_NAL_UNSPEC61
     "UNSPEC62", // HEVC_NAL_UNSPEC62
     "UNSPEC63", // HEVC_NAL_UNSPEC63
 };
 

 static const char *hevc_nal_unit_name(int nal_type)

 {

     av_assert0(nal_type >= 0 && nal_type < 64);
     return hevc_nal_type_name[nal_type];

 }
 

 static const char *h264_nal_type_name[32] = {
     "Unspecified 0", //H264_NAL_UNSPECIFIED
     "Coded slice of a non-IDR picture", // H264_NAL_SLICE
     "Coded slice data partition A", // H264_NAL_DPA
     "Coded slice data partition B", // H264_NAL_DPB
     "Coded slice data partition C", // H264_NAL_DPC
     "IDR", // H264_NAL_IDR_SLICE
     "SEI", // H264_NAL_SEI
     "SPS", // H264_NAL_SPS
     "PPS", // H264_NAL_PPS
     "AUD", // H264_NAL_AUD
     "End of sequence", // H264_NAL_END_SEQUENCE
     "End of stream", // H264_NAL_END_STREAM
     "Filler data", // H264_NAL_FILLER_DATA
     "SPS extension", // H264_NAL_SPS_EXT
     "Prefix", // H264_NAL_PREFIX
     "Subset SPS", // H264_NAL_SUB_SPS
     "Depth parameter set", // H264_NAL_DPS
     "Reserved 17", // H264_NAL_RESERVED17
     "Reserved 18", // H264_NAL_RESERVED18
     "Auxiliary coded picture without partitioning", // H264_NAL_AUXILIARY_SLICE
     "Slice extension", // H264_NAL_EXTEN_SLICE
     "Slice extension for a depth view or a 3D-AVC texture view", // H264_NAL_DEPTH_EXTEN_SLICE
     "Reserved 22", // H264_NAL_RESERVED22
     "Reserved 23", // H264_NAL_RESERVED23
     "Unspecified 24", // H264_NAL_UNSPECIFIED24
     "Unspecified 25", // H264_NAL_UNSPECIFIED25
     "Unspecified 26", // H264_NAL_UNSPECIFIED26
     "Unspecified 27", // H264_NAL_UNSPECIFIED27
     "Unspecified 28", // H264_NAL_UNSPECIFIED28
     "Unspecified 29", // H264_NAL_UNSPECIFIED29
     "Unspecified 30", // H264_NAL_UNSPECIFIED30
     "Unspecified 31", // H264_NAL_UNSPECIFIED31
 };
 
 static const char *h264_nal_unit_name(int nal_type)
 {
     av_assert0(nal_type >= 0 && nal_type < 32);
     return h264_nal_type_name[nal_type];
 }
 

 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 -= ff_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;
 
     if (get_bits1(gb) != 0)
         return AVERROR_INVALIDDATA;
 
     nal->type = get_bits(gb, 6);
 

     nal->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(%s), nuh_layer_id: %d, temporal_id: %d\n",

            nal->type, hevc_nal_unit_name(nal->type), nal->nuh_layer_id, nal->temporal_id);

     return 1;

 }
 

 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(%s), nal_ref_idc: %d\n",
            nal->type, h264_nal_unit_name(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;
 }
 

 static void alloc_rbsp_buffer(H2645RBSP *rbsp, unsigned int size, int use_ref)
 {

     int min_size = size;
 

     if (size > INT_MAX - AV_INPUT_BUFFER_PADDING_SIZE)
         goto fail;
     size += AV_INPUT_BUFFER_PADDING_SIZE;
 
     if (rbsp->rbsp_buffer_alloc_size >= size &&

         (!rbsp->rbsp_buffer_ref || av_buffer_is_writable(rbsp->rbsp_buffer_ref))) {
         av_assert0(rbsp->rbsp_buffer);
         memset(rbsp->rbsp_buffer + min_size, 0, AV_INPUT_BUFFER_PADDING_SIZE);

         return;

     }

 
     size = FFMIN(size + size / 16 + 32, INT_MAX);
 
     if (rbsp->rbsp_buffer_ref)
         av_buffer_unref(&rbsp->rbsp_buffer_ref);
     else
         av_free(rbsp->rbsp_buffer);
 

     rbsp->rbsp_buffer = av_mallocz(size);

     if (!rbsp->rbsp_buffer)
         goto fail;
     rbsp->rbsp_buffer_alloc_size = size;
 
     if (use_ref) {
         rbsp->rbsp_buffer_ref = av_buffer_create(rbsp->rbsp_buffer, size,
                                                  NULL, NULL, 0);
         if (!rbsp->rbsp_buffer_ref)
             goto fail;
     }
 
     return;
 
 fail:
     rbsp->rbsp_buffer_alloc_size = 0;
     if (rbsp->rbsp_buffer_ref) {
         av_buffer_unref(&rbsp->rbsp_buffer_ref);
         rbsp->rbsp_buffer = NULL;
     } else
         av_freep(&rbsp->rbsp_buffer);
 
     return;
 }
 

 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 small_padding, int use_ref)

 {

     GetByteContext bc;

     int consumed, ret = 0;

     int next_avc = is_nalff ? 0 : length;

     int64_t padding = small_padding ? 0 : MAX_MBPAIR_SIZE;

 
     bytestream2_init(&bc, buf, length);

     alloc_rbsp_buffer(&pkt->rbsp, length + padding, use_ref);
 

     if (!pkt->rbsp.rbsp_buffer)
         return AVERROR(ENOMEM);

     pkt->rbsp.rbsp_buffer_size = 0;

     pkt->nb_nals = 0;

     while (bytestream2_get_bytes_left(&bc) >= 4) {

         H2645NAL *nal;

         int extract_length = 0;

         int skip_trailing_zeros = 1;

         if (bytestream2_tell(&bc) == next_avc) {

             int i = 0;
             extract_length = get_nalsize(nal_length_size,

                                          bc.buffer, bytestream2_get_bytes_left(&bc), &i, logctx);

             if (extract_length < 0)
                 return extract_length;
 

             bytestream2_skip(&bc, nal_length_size);

             next_avc = bytestream2_tell(&bc) + extract_length;

         } else {

             int buf_index;
 
             if (bytestream2_tell(&bc) > next_avc)

                 av_log(logctx, AV_LOG_WARNING, "Exceeded next NALFF position, re-syncing.\n");
 

             /* search start code */

             buf_index = find_next_start_code(bc.buffer, buf + next_avc);

             bytestream2_skip(&bc, buf_index);

             if (!bytestream2_get_bytes_left(&bc)) {
                 if (pkt->nb_nals > 0) {
                     // No more start codes: we discarded some irrelevant
                     // bytes at the end of the packet.
                     return 0;
                 } else {
                     av_log(logctx, AV_LOG_ERROR, "No start code is found.\n");
                     return AVERROR_INVALIDDATA;
                 }

             }
 

             extract_length = FFMIN(bytestream2_get_bytes_left(&bc), next_avc - bytestream2_tell(&bc));

             if (bytestream2_tell(&bc) >= next_avc) {

                 /* skip to the start of the next NAL */

                 bytestream2_skip(&bc, next_avc - bytestream2_tell(&bc));

                 continue;
             }

         }
 
         if (pkt->nals_allocated < pkt->nb_nals + 1) {
             int new_size = pkt->nals_allocated + 1;

             void *tmp;

             if (new_size >= INT_MAX / sizeof(*pkt->nals))
                 return AVERROR(ENOMEM);
 
             tmp = av_fast_realloc(pkt->nals, &pkt->nal_buffer_size, new_size * sizeof(*pkt->nals));

             if (!tmp)
                 return AVERROR(ENOMEM);
 
             pkt->nals = tmp;

             memset(pkt->nals + pkt->nals_allocated, 0, sizeof(*pkt->nals));

             nal = &pkt->nals[pkt->nb_nals];

             nal->skipped_bytes_pos_size = 1024; // initial buffer size
             nal->skipped_bytes_pos = av_malloc_array(nal->skipped_bytes_pos_size, sizeof(*nal->skipped_bytes_pos));
             if (!nal->skipped_bytes_pos)

                 return AVERROR(ENOMEM);
 

             pkt->nals_allocated = new_size;
         }

         nal = &pkt->nals[pkt->nb_nals];

         consumed = ff_h2645_extract_rbsp(bc.buffer, extract_length, &pkt->rbsp, nal, small_padding);

         if (consumed < 0)
             return consumed;
 

         if (is_nalff && (extract_length != consumed) && extract_length)
             av_log(logctx, AV_LOG_DEBUG,
                    "NALFF: Consumed only %d bytes instead of %d\n",
                    consumed, extract_length);
 

         pkt->nb_nals++;

         bytestream2_skip(&bc, consumed);
 

         /* see commit 3566042a0 */

         if (bytestream2_get_bytes_left(&bc) >= 4 &&
             bytestream2_peek_be32(&bc) == 0x000001E0)

             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 || nal->size <= 0 || nal->size_bits <= 0) {

             if (ret < 0) {

                 av_log(logctx, AV_LOG_WARNING, "Invalid NAL unit %d, skipping.\n",

                        nal->type);
             }
             pkt->nb_nals--;
         }
     }
 
     return 0;
 }

 void ff_h2645_packet_uninit(H2645Packet *pkt)
 {
     int i;

     for (i = 0; i < pkt->nals_allocated; i++) {
         av_freep(&pkt->nals[i].skipped_bytes_pos);
     }

     av_freep(&pkt->nals);

     pkt->nals_allocated = pkt->nal_buffer_size = 0;

     if (pkt->rbsp.rbsp_buffer_ref) {
         av_buffer_unref(&pkt->rbsp.rbsp_buffer_ref);
         pkt->rbsp.rbsp_buffer = NULL;
     } else
         av_freep(&pkt->rbsp.rbsp_buffer);

     pkt->rbsp.rbsp_buffer_alloc_size = pkt->rbsp.rbsp_buffer_size = 0;

 }