/*
  * HEVC MP4 to Annex B byte stream format filter
  * copyright (c) 2015 Anton Khirnov
  *

  * 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 "libavutil/intreadwrite.h"
 #include "libavutil/mem.h"
 
 #include "avcodec.h"
 #include "bytestream.h"
 #include "hevc.h"
 
 #define MIN_HEVCC_LENGTH 23
 
 typedef struct HEVCBSFContext {
     uint8_t  length_size;
     int      extradata_parsed;
 
     int logged_nonmp4_warning;
 } HEVCBSFContext;
 
 static int hevc_extradata_to_annexb(AVCodecContext *avctx)
 {
     GetByteContext gb;
     int length_size, num_arrays, i, j;
     int ret = 0;
 
     uint8_t *new_extradata = NULL;
     size_t   new_extradata_size = 0;;
 
     bytestream2_init(&gb, avctx->extradata, avctx->extradata_size);
 
     bytestream2_skip(&gb, 21);
     length_size = (bytestream2_get_byte(&gb) & 3) + 1;
     num_arrays  = bytestream2_get_byte(&gb);
 
     for (i = 0; i < num_arrays; i++) {
         int type = bytestream2_get_byte(&gb) & 0x3f;
         int cnt  = bytestream2_get_be16(&gb);
 
         if (!(type == NAL_VPS || type == NAL_SPS || type == NAL_PPS ||
               type == NAL_SEI_PREFIX || type == NAL_SEI_SUFFIX)) {
             av_log(avctx, AV_LOG_ERROR, "Invalid NAL unit type in extradata: %d\n",
                    type);
             ret = AVERROR_INVALIDDATA;
             goto fail;
         }
 
         for (j = 0; j < cnt; j++) {
             int nalu_len = bytestream2_get_be16(&gb);
 

             if (4 + AV_INPUT_BUFFER_PADDING_SIZE + nalu_len > SIZE_MAX - new_extradata_size) {

                 ret = AVERROR_INVALIDDATA;
                 goto fail;
             }

             ret = av_reallocp(&new_extradata, new_extradata_size + nalu_len + 4 + AV_INPUT_BUFFER_PADDING_SIZE);

             if (ret < 0)
                 goto fail;
 
             AV_WB32(new_extradata + new_extradata_size, 1); // add the startcode
             bytestream2_get_buffer(&gb, new_extradata + new_extradata_size + 4, nalu_len);
             new_extradata_size += 4 + nalu_len;

             memset(new_extradata + new_extradata_size, 0, AV_INPUT_BUFFER_PADDING_SIZE);

         }
     }
 
     av_freep(&avctx->extradata);
     avctx->extradata      = new_extradata;
     avctx->extradata_size = new_extradata_size;
 
     if (!new_extradata_size)
         av_log(avctx, AV_LOG_WARNING, "No parameter sets in the extradata\n");
 
     return length_size;
 fail:
     av_freep(&new_extradata);
     return ret;
 }
 
 static int hevc_mp4toannexb_filter(AVBitStreamFilterContext *bsfc,
                                    AVCodecContext *avctx, const char *args,
                                    uint8_t **poutbuf, int *poutbuf_size,
                                    const uint8_t *buf, int buf_size,
                                    int keyframe)
 {
     HEVCBSFContext *ctx = bsfc->priv_data;
     GetByteContext gb;
 
     uint8_t *out = NULL;
     size_t   out_size = 0;
     int got_irap = 0;
     int i, ret = 0;
 
     if (!ctx->extradata_parsed) {
         if (avctx->extradata_size < MIN_HEVCC_LENGTH ||
             AV_RB24(avctx->extradata) == 1           ||
             AV_RB32(avctx->extradata) == 1) {
             if (!ctx->logged_nonmp4_warning) {
                 av_log(avctx, AV_LOG_VERBOSE,
                        "The input looks like it is Annex B already\n");
                 ctx->logged_nonmp4_warning = 1;
             }
             *poutbuf      = buf;
             *poutbuf_size = buf_size;
             return 0;
         }
 
         ret = hevc_extradata_to_annexb(avctx);
         if (ret < 0)
             return ret;
         ctx->length_size      = ret;
         ctx->extradata_parsed = 1;
     }
 
     *poutbuf_size = 0;
     *poutbuf      = NULL;
 
     bytestream2_init(&gb, buf, buf_size);
 
     while (bytestream2_get_bytes_left(&gb)) {
         uint32_t nalu_size = 0;
         int      nalu_type;
         int is_irap, add_extradata, extra_size;
 
         for (i = 0; i < ctx->length_size; i++)
             nalu_size = (nalu_size << 8) | bytestream2_get_byte(&gb);
 
         nalu_type = (bytestream2_peek_byte(&gb) >> 1) & 0x3f;
 
         /* prepend extradata to IRAP frames */
         is_irap       = nalu_type >= 16 && nalu_type <= 23;
         add_extradata = is_irap && !got_irap;
         extra_size    = add_extradata * avctx->extradata_size;
         got_irap     |= is_irap;
 
         if (SIZE_MAX - out_size < 4             ||
             SIZE_MAX - out_size - 4 < nalu_size ||
             SIZE_MAX - out_size - 4 - nalu_size < extra_size) {
             ret = AVERROR_INVALIDDATA;
             goto fail;
         }
 
         ret = av_reallocp(&out, out_size + 4 + nalu_size + extra_size);
         if (ret < 0)
             goto fail;
 
         if (add_extradata)
             memcpy(out + out_size, avctx->extradata, extra_size);
         AV_WB32(out + out_size + extra_size, 1);
         bytestream2_get_buffer(&gb, out + out_size + 4 + extra_size, nalu_size);
         out_size += 4 + nalu_size + extra_size;
     }
 
     *poutbuf      = out;
     *poutbuf_size = out_size;
 
     return 1;
 
 fail:
     av_freep(&out);
     return ret;
 }
 
 AVBitStreamFilter ff_hevc_mp4toannexb_bsf = {
     "hevc_mp4toannexb",
     sizeof(HEVCBSFContext),
     hevc_mp4toannexb_filter,
 };