/*

  * AC-3 parser

  * Copyright (c) 2003 Fabrice Bellard
  * Copyright (c) 2003 Michael Niedermayer

  *
  * 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 "config.h"
 

 #include "libavutil/channel_layout.h"

 #include "parser.h"
 #include "ac3_parser.h"

 #include "ac3_parser_internal.h"

 #include "aac_ac3_parser.h"

 #include "get_bits.h"

 
 
 #define AC3_HEADER_SIZE 7
 

 #if CONFIG_AC3_PARSER

 
 static const uint8_t eac3_blocks[4] = {
     1, 2, 3, 6
 };
 

 /**
  * Table for center mix levels
  * reference: Section 5.4.2.4 cmixlev
  */
 static const uint8_t center_levels[4] = { 4, 5, 6, 5 };
 
 /**
  * Table for surround mix levels
  * reference: Section 5.4.2.5 surmixlev
  */
 static const uint8_t surround_levels[4] = { 4, 6, 7, 6 };
 

 int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)

 {

     int frame_size_code;

 
     memset(hdr, 0, sizeof(*hdr));
 

     hdr->sync_word = get_bits(gbc, 16);

     if(hdr->sync_word != 0x0B77)

         return AAC_AC3_PARSE_ERROR_SYNC;

     /* read ahead to bsid to distinguish between AC-3 and E-AC-3 */

     hdr->bitstream_id = show_bits_long(gbc, 29) & 0x1F;

     if(hdr->bitstream_id > 16)

         return AAC_AC3_PARSE_ERROR_BSID;

     hdr->num_blocks = 6;
 

     /* set default mix levels */

     hdr->center_mix_level   = 5;  // -4.5dB
     hdr->surround_mix_level = 6;  // -6.0dB

     /* set default dolby surround mode */
     hdr->dolby_surround_mode = AC3_DSURMOD_NOTINDICATED;
 

     if(hdr->bitstream_id <= 10) {

         /* Normal AC-3 */

         hdr->crc1 = get_bits(gbc, 16);
         hdr->sr_code = get_bits(gbc, 2);

         if(hdr->sr_code == 3)

             return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;

         frame_size_code = get_bits(gbc, 6);

         if(frame_size_code > 37)

             return AAC_AC3_PARSE_ERROR_FRAME_SIZE;

         skip_bits(gbc, 5); // skip bsid, already got it
 

         hdr->bitstream_mode = get_bits(gbc, 3);

         hdr->channel_mode = get_bits(gbc, 3);
 

         if(hdr->channel_mode == AC3_CHMODE_STEREO) {

             hdr->dolby_surround_mode = get_bits(gbc, 2);

         } else {
             if((hdr->channel_mode & 1) && hdr->channel_mode != AC3_CHMODE_MONO)

                 hdr->  center_mix_level =   center_levels[get_bits(gbc, 2)];

             if(hdr->channel_mode & 4)

                 hdr->surround_mix_level = surround_levels[get_bits(gbc, 2)];

         }

         hdr->lfe_on = get_bits1(gbc);

 
         hdr->sr_shift = FFMAX(hdr->bitstream_id, 8) - 8;
         hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code] >> hdr->sr_shift;
         hdr->bit_rate = (ff_ac3_bitrate_tab[frame_size_code>>1] * 1000) >> hdr->sr_shift;
         hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
         hdr->frame_size = ff_ac3_frame_size_tab[frame_size_code][hdr->sr_code] * 2;

         hdr->frame_type = EAC3_FRAME_TYPE_AC3_CONVERT; //EAC3_FRAME_TYPE_INDEPENDENT;

         hdr->substreamid = 0;

     } else {
         /* Enhanced AC-3 */
         hdr->crc1 = 0;

         hdr->frame_type = get_bits(gbc, 2);

         if(hdr->frame_type == EAC3_FRAME_TYPE_RESERVED)

             return AAC_AC3_PARSE_ERROR_FRAME_TYPE;

         hdr->substreamid = get_bits(gbc, 3);

         hdr->frame_size = (get_bits(gbc, 11) + 1) << 1;

         if(hdr->frame_size < AC3_HEADER_SIZE)

             return AAC_AC3_PARSE_ERROR_FRAME_SIZE;

         hdr->sr_code = get_bits(gbc, 2);

         if (hdr->sr_code == 3) {

             int sr_code2 = get_bits(gbc, 2);

             if(sr_code2 == 3)

                 return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;

             hdr->sample_rate = ff_ac3_sample_rate_tab[sr_code2] / 2;
             hdr->sr_shift = 1;
         } else {

             hdr->num_blocks = eac3_blocks[get_bits(gbc, 2)];

             hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code];
             hdr->sr_shift = 0;
         }
 

         hdr->channel_mode = get_bits(gbc, 3);
         hdr->lfe_on = get_bits1(gbc);

         hdr->bit_rate = 8LL * hdr->frame_size * hdr->sample_rate /
                         (hdr->num_blocks * 256);

         hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
     }

     hdr->channel_layout = avpriv_ac3_channel_layout_tab[hdr->channel_mode];

     if (hdr->lfe_on)

         hdr->channel_layout |= AV_CH_LOW_FREQUENCY;

 
     return 0;
 }
 

 // TODO: Better way to pass AC3HeaderInfo fields to mov muxer.
 int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const uint8_t *buf,
                             size_t size)
 {
     GetBitContext gb;
     AC3HeaderInfo *hdr;
     int err;
 
     if (!*phdr)
         *phdr = av_mallocz(sizeof(AC3HeaderInfo));
     if (!*phdr)
         return AVERROR(ENOMEM);
     hdr = *phdr;
 
     init_get_bits8(&gb, buf, size);
     err = ff_ac3_parse_header(&gb, hdr);
     if (err < 0)
         return AVERROR_INVALIDDATA;
 
     return get_bits_count(&gb);
 }
 

 int av_ac3_parse_header(const uint8_t *buf, size_t size,
                         uint8_t *bitstream_id, uint16_t *frame_size)
 {
     GetBitContext gb;
     AC3HeaderInfo hdr;
     int err;
 
     init_get_bits8(&gb, buf, size);
     err = ff_ac3_parse_header(&gb, &hdr);
     if (err < 0)
         return AVERROR_INVALIDDATA;
 
     *bitstream_id = hdr.bitstream_id;
     *frame_size   = hdr.frame_size;
 
     return 0;
 }
 

 static int ac3_sync(uint64_t state, AACAC3ParseContext *hdr_info,
         int *need_next_header, int *new_frame_start)

 {
     int err;

     union {
         uint64_t u64;

         uint8_t  u8[8 + AV_INPUT_BUFFER_PADDING_SIZE];

     } tmp = { av_be2ne64(state) };

     AC3HeaderInfo hdr;

     GetBitContext gbc;

     init_get_bits(&gbc, tmp.u8+8-AC3_HEADER_SIZE, 54);

     err = ff_ac3_parse_header(&gbc, &hdr);

     if(err < 0)

         return 0;
 

     hdr_info->sample_rate = hdr.sample_rate;
     hdr_info->bit_rate = hdr.bit_rate;
     hdr_info->channels = hdr.channels;

     hdr_info->channel_layout = hdr.channel_layout;

     hdr_info->samples = hdr.num_blocks * 256;

     hdr_info->service_type = hdr.bitstream_mode;
     if (hdr.bitstream_mode == 0x7 && hdr.channels > 1)
         hdr_info->service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;

     if(hdr.bitstream_id>10)

         hdr_info->codec_id = AV_CODEC_ID_EAC3;
     else if (hdr_info->codec_id == AV_CODEC_ID_NONE)
         hdr_info->codec_id = AV_CODEC_ID_AC3;

     *need_next_header = (hdr.frame_type != EAC3_FRAME_TYPE_AC3_CONVERT);
     *new_frame_start  = (hdr.frame_type != EAC3_FRAME_TYPE_DEPENDENT);

     return hdr.frame_size;

 }
 

 static av_cold int ac3_parse_init(AVCodecParserContext *s1)

 {

     AACAC3ParseContext *s = s1->priv_data;

     s->header_size = AC3_HEADER_SIZE;
     s->sync = ac3_sync;
     return 0;
 }
 
 

 AVCodecParser ff_ac3_parser = {

     .codec_ids      = { AV_CODEC_ID_AC3, AV_CODEC_ID_EAC3 },

     .priv_data_size = sizeof(AACAC3ParseContext),
     .parser_init    = ac3_parse_init,
     .parser_parse   = ff_aac_ac3_parse,
     .parser_close   = ff_parse_close,

 };

 
 #else
 

 int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const uint8_t *buf,
                             size_t size)
 {
     return AVERROR(ENOSYS);
 }
 

 int av_ac3_parse_header(const uint8_t *buf, size_t size,
                         uint8_t *bitstream_id, uint16_t *frame_size)
 {
     return AVERROR(ENOSYS);
 }
 #endif