/*
  * Opus parser for Ogg
  * Copyright (c) 2012 Nicolas George
  *
  * 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 "avformat.h"
 #include "internal.h"
 #include "oggdec.h"
 
 struct oggopus_private {
     int need_comments;
     unsigned pre_skip;
     int64_t cur_dts;
 };
 

 #define OPUS_SEEK_PREROLL_MS 80

 #define OPUS_HEAD_SIZE 19
 
 static int opus_header(AVFormatContext *avf, int idx)
 {

     struct ogg *ogg              = avf->priv_data;
     struct ogg_stream *os        = &ogg->streams[idx];
     AVStream *st                 = avf->streams[idx];

     struct oggopus_private *priv = os->private;

     uint8_t *packet              = os->buf + os->pstart;

 
     if (!priv) {
         priv = os->private = av_mallocz(sizeof(*priv));
         if (!priv)
             return AVERROR(ENOMEM);
     }

     if (os->flags & OGG_FLAG_BOS) {
         if (os->psize < OPUS_HEAD_SIZE || (AV_RL8(packet + 8) & 0xF0) != 0)
             return AVERROR_INVALIDDATA;

         st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
         st->codecpar->codec_id   = AV_CODEC_ID_OPUS;
         st->codecpar->channels   = AV_RL8(packet + 9);

         priv->pre_skip        = AV_RL16(packet + 10);

         st->codecpar->initial_padding = priv->pre_skip;

         /*orig_sample_rate    = AV_RL32(packet + 12);*/
         /*gain                = AV_RL16(packet + 16);*/
         /*channel_map         = AV_RL8 (packet + 18);*/

         av_freep(&st->codecpar->extradata);

         if (ff_alloc_extradata(st->codecpar, os->psize))

             return AVERROR(ENOMEM);

         memcpy(st->codecpar->extradata, packet, os->psize);

         st->codecpar->sample_rate = 48000;

         st->codecpar->seek_preroll = av_rescale(OPUS_SEEK_PREROLL_MS,
                                                 st->codecpar->sample_rate, 1000);

         avpriv_set_pts_info(st, 64, 1, 48000);
         priv->need_comments = 1;
         return 1;
     }
 
     if (priv->need_comments) {
         if (os->psize < 8 || memcmp(packet, "OpusTags", 8))
             return AVERROR_INVALIDDATA;

         ff_vorbis_stream_comment(avf, st, packet + 8, os->psize - 8);

         priv->need_comments--;
         return 1;
     }

     return 0;
 }
 

 static int opus_duration(uint8_t *src, int size)
 {
     unsigned nb_frames  = 1;
     unsigned toc        = src[0];
     unsigned toc_config = toc >> 3;
     unsigned toc_count  = toc & 3;
     unsigned frame_size = toc_config < 12 ? FFMAX(480, 960 * (toc_config & 3)) :
                           toc_config < 16 ? 480 << (toc_config & 1) :
                                             120 << (toc_config & 3);
     if (toc_count == 3) {
         if (size<2)
             return AVERROR_INVALIDDATA;
         nb_frames = src[1] & 0x3F;
     } else if (toc_count) {
         nb_frames = 2;
     }
 
     return frame_size * nb_frames;
 }
 

 static int opus_packet(AVFormatContext *avf, int idx)
 {

     struct ogg *ogg              = avf->priv_data;
     struct ogg_stream *os        = &ogg->streams[idx];
     AVStream *st                 = avf->streams[idx];

     struct oggopus_private *priv = os->private;

     uint8_t *packet              = os->buf + os->pstart;

     int ret;

 
     if (!os->psize)
         return AVERROR_INVALIDDATA;

     if (os->granule > (1LL << 62)) {

         av_log(avf, AV_LOG_ERROR, "Unsupported huge granule pos %"PRId64 "\n", os->granule);
         return AVERROR_INVALIDDATA;
     }

     if ((!os->lastpts || os->lastpts == AV_NOPTS_VALUE) && !(os->flags & OGG_FLAG_EOS)) {
         int seg, d;
         int duration;
         uint8_t *last_pkt  = os->buf + os->pstart;
         uint8_t *next_pkt  = last_pkt;
 
         duration = 0;
         seg = os->segp;
         d = opus_duration(last_pkt, os->psize);
         if (d < 0) {
             os->pflags |= AV_PKT_FLAG_CORRUPT;
             return 0;
         }
         duration += d;
         last_pkt = next_pkt =  next_pkt + os->psize;
         for (; seg < os->nsegs; seg++) {
             next_pkt += os->segments[seg];

             if (os->segments[seg] < 255 && next_pkt != last_pkt) {
                 int d = opus_duration(last_pkt, next_pkt - last_pkt);
                 if (d > 0)
                     duration += d;
                 last_pkt = next_pkt;
             }

         }
         os->lastpts                 =
         os->lastdts                 = os->granule - duration;
     }

     if ((ret = opus_duration(packet, os->psize)) < 0)
         return ret;
 
     os->pduration = ret;

     if (os->lastpts != AV_NOPTS_VALUE) {
         if (st->start_time == AV_NOPTS_VALUE)
             st->start_time = os->lastpts;
         priv->cur_dts = os->lastdts = os->lastpts -= priv->pre_skip;
     }

     priv->cur_dts += os->pduration;
     if ((os->flags & OGG_FLAG_EOS)) {
         int64_t skip = priv->cur_dts - os->granule + priv->pre_skip;
         skip = FFMIN(skip, os->pduration);
         if (skip > 0) {
             os->pduration = skip < os->pduration ? os->pduration - skip : 1;

             os->end_trimming = skip;

             av_log(avf, AV_LOG_DEBUG,
                    "Last packet was truncated to %d due to end trimming.\n",

                    os->pduration);
         }
     }

     return 0;
 }
 
 const struct ogg_codec ff_opus_codec = {

     .name             = "Opus",
     .magic            = "OpusHead",
     .magicsize        = 8,
     .header           = opus_header,
     .packet           = opus_packet,

     .nb_header        = 1,

 };