/*
  * 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 "bsf.h"

 #include "bytestream.h"

 #include "hevc.h"

 
 #define MIN_HEVCC_LENGTH 23
 
 typedef struct HEVCBSFContext {
     uint8_t  length_size;
     int      extradata_parsed;
 } HEVCBSFContext;
 

 static int hevc_extradata_to_annexb(AVBSFContext *ctx)

 {
     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, ctx->par_in->extradata, ctx->par_in->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 == HEVC_NAL_VPS || type == HEVC_NAL_SPS || type == HEVC_NAL_PPS ||
               type == HEVC_NAL_SEI_PREFIX || type == HEVC_NAL_SEI_SUFFIX)) {

             av_log(ctx, 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(&ctx->par_out->extradata);
     ctx->par_out->extradata      = new_extradata;
     ctx->par_out->extradata_size = new_extradata_size;

 
     if (!new_extradata_size)

         av_log(ctx, AV_LOG_WARNING, "No parameter sets in the extradata\n");

 
     return length_size;
 fail:
     av_freep(&new_extradata);
     return ret;
 }
 

 static int hevc_mp4toannexb_init(AVBSFContext *ctx)

 {

     HEVCBSFContext *s = ctx->priv_data;
     int ret;
 
     if (ctx->par_in->extradata_size < MIN_HEVCC_LENGTH ||
         AV_RB24(ctx->par_in->extradata) == 1           ||
         AV_RB32(ctx->par_in->extradata) == 1) {
         av_log(ctx, AV_LOG_VERBOSE,
                "The input looks like it is Annex B already\n");
     } else {
         ret = hevc_extradata_to_annexb(ctx);
         if (ret < 0)
             return ret;
         s->length_size      = ret;
         s->extradata_parsed = 1;
     }
 
     return 0;
 }
 
 static int hevc_mp4toannexb_filter(AVBSFContext *ctx, AVPacket *out)

 {

     HEVCBSFContext *s = ctx->priv_data;
     AVPacket *in;

     GetByteContext gb;
 
     int got_irap = 0;
     int i, ret = 0;
 

     ret = ff_bsf_get_packet(ctx, &in);
     if (ret < 0)
         return ret;

     if (!s->extradata_parsed) {
         av_packet_move_ref(out, in);
         av_packet_free(&in);
         return 0;

     }
 

     bytestream2_init(&gb, in->data, in->size);

 
     while (bytestream2_get_bytes_left(&gb)) {
         uint32_t nalu_size = 0;
         int      nalu_type;

         int is_irap, add_extradata, extra_size, prev_size;

         for (i = 0; i < s->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 * ctx->par_out->extradata_size;

         got_irap     |= is_irap;
 

         if (SIZE_MAX - nalu_size < 4 ||
             SIZE_MAX - 4 - nalu_size < extra_size) {

             ret = AVERROR_INVALIDDATA;
             goto fail;
         }
 

         prev_size = out->size;
 
         ret = av_grow_packet(out, 4 + nalu_size + extra_size);

         if (ret < 0)
             goto fail;
 
         if (add_extradata)

             memcpy(out->data + prev_size, ctx->par_out->extradata, extra_size);
         AV_WB32(out->data + prev_size + extra_size, 1);
         bytestream2_get_buffer(&gb, out->data + prev_size + 4 + extra_size, nalu_size);

     }
 

     ret = av_packet_copy_props(out, in);
     if (ret < 0)
         goto fail;

 
 fail:

     if (ret < 0)
         av_packet_unref(out);
     av_packet_free(&in);
 

     return ret;
 }
 

 static const enum AVCodecID codec_ids[] = {
     AV_CODEC_ID_HEVC, AV_CODEC_ID_NONE,
 };

 const AVBitStreamFilter ff_hevc_mp4toannexb_bsf = {
     .name           = "hevc_mp4toannexb",
     .priv_data_size = sizeof(HEVCBSFContext),
     .init           = hevc_mp4toannexb_init,
     .filter         = hevc_mp4toannexb_filter,
     .codec_ids      = codec_ids,

 };