/*
  * MPEG-2/4 AAC ADTS to MPEG-4 Audio Specific Configuration bitstream filter
  * Copyright (c) 2009 Alex Converse <alex.converse@gmail.com>
  *
  * 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 "avcodec.h"

 #include "aacadtsdec.h"

 #include "put_bits.h"
 #include "get_bits.h"
 #include "mpeg4audio.h"
 #include "internal.h"
 
 typedef struct AACBSFContext {
     int first_frame_done;
 } AACBSFContext;
 
 /**
  * This filter creates an MPEG-4 AudioSpecificConfig from an MPEG-2/4
  * ADTS header and removes the ADTS header.
  */
 static int aac_adtstoasc_filter(AVBitStreamFilterContext *bsfc,
                                 AVCodecContext *avctx, const char *args,
                                 uint8_t  **poutbuf, int *poutbuf_size,
                                 const uint8_t *buf, int      buf_size,
                                 int keyframe)
 {
     GetBitContext gb;
     PutBitContext pb;
     AACADTSHeaderInfo hdr;
 
     AACBSFContext *ctx = bsfc->priv_data;
 
     init_get_bits(&gb, buf, AAC_ADTS_HEADER_SIZE*8);
 
     *poutbuf = (uint8_t*) buf;
     *poutbuf_size = buf_size;
 
     if (avctx->extradata)
         if (show_bits(&gb, 12) != 0xfff)
             return 0;
 

     if (avpriv_aac_parse_header(&gb, &hdr) < 0) {

         av_log(avctx, AV_LOG_ERROR, "Error parsing ADTS frame header!\n");
         return -1;
     }
 
     if (!hdr.crc_absent && hdr.num_aac_frames > 1) {

         av_log_missing_feature(avctx, "Multiple RDBs per frame with CRC is", 0);

         return -1;
     }
 
     buf      += AAC_ADTS_HEADER_SIZE + 2*!hdr.crc_absent;
     buf_size -= AAC_ADTS_HEADER_SIZE + 2*!hdr.crc_absent;
 
     if (!ctx->first_frame_done) {
         int            pce_size = 0;
         uint8_t        pce_data[MAX_PCE_SIZE];
         if (!hdr.chan_config) {

             init_get_bits(&gb, buf, buf_size * 8);

             if (get_bits(&gb, 3) != 5) {

                 av_log_missing_feature(avctx, "PCE based channel configuration, where the PCE is not the first syntax element is", 0);

                 return -1;
             }
             init_put_bits(&pb, pce_data, MAX_PCE_SIZE);

             pce_size = avpriv_copy_pce_data(&pb, &gb)/8;

             flush_put_bits(&pb);
             buf_size -= get_bits_count(&gb)/8;
             buf      += get_bits_count(&gb)/8;
         }
         avctx->extradata_size = 2 + pce_size;

         avctx->extradata = av_mallocz(avctx->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);

 
         init_put_bits(&pb, avctx->extradata, avctx->extradata_size);
         put_bits(&pb, 5, hdr.object_type);
         put_bits(&pb, 4, hdr.sampling_index);
         put_bits(&pb, 4, hdr.chan_config);
         put_bits(&pb, 1, 0); //frame length - 1024 samples
         put_bits(&pb, 1, 0); //does not depend on core coder
         put_bits(&pb, 1, 0); //is not extension
         flush_put_bits(&pb);
         if (pce_size) {
             memcpy(avctx->extradata + 2, pce_data, pce_size);
         }
 
         ctx->first_frame_done = 1;
     }
 
     *poutbuf = (uint8_t*) buf;
     *poutbuf_size = buf_size;
 
     return 0;
 }
 

 AVBitStreamFilter ff_aac_adtstoasc_bsf = {

     "aac_adtstoasc",
     sizeof(AACBSFContext),
     aac_adtstoasc_filter,
 };