/*
  * On2 VP8 parser for Ogg
  * Copyright (C) 2013 James Almer
  *
  * 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 "libavutil/intreadwrite.h"

 #include "avformat.h"
 #include "internal.h"
 #include "oggdec.h"
 
 #define VP8_HEADER_SIZE 26
 
 static int vp8_header(AVFormatContext *s, int idx)
 {
     struct ogg *ogg = s->priv_data;
     struct ogg_stream *os = ogg->streams + idx;
     uint8_t *p = os->buf + os->pstart;
     AVStream *st = s->streams[idx];
     AVRational framerate;
 
     if (os->psize < 7 || p[0] != 0x4f)
         return 0;
 
     switch (p[5]){
     case 0x01:
         if (os->psize < VP8_HEADER_SIZE) {
             av_log(s, AV_LOG_ERROR, "Invalid OggVP8 header packet");
             return AVERROR_INVALIDDATA;
         }
 
         if (p[6] != 1) {

             av_log(s, AV_LOG_WARNING,
                    "Unknown OggVP8 version %d.%d\n", p[6], p[7]);

             return AVERROR_INVALIDDATA;
         }
 

         st->codecpar->width         = AV_RB16(p +  8);
         st->codecpar->height        = AV_RB16(p + 10);

         st->sample_aspect_ratio.num = AV_RB24(p + 12);
         st->sample_aspect_ratio.den = AV_RB24(p + 15);

         framerate.num               = AV_RB32(p + 18);
         framerate.den               = AV_RB32(p + 22);

         avpriv_set_pts_info(st, 64, framerate.den, framerate.num);

         st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
         st->codecpar->codec_id   = AV_CODEC_ID_VP8;

         st->need_parsing      = AVSTREAM_PARSE_HEADERS;
         break;
     case 0x02:
         if (p[6] != 0x20)
             return AVERROR_INVALIDDATA;

         ff_vorbis_stream_comment(s, st, p + 7, os->psize - 7);

         break;
     default:
         av_log(s, AV_LOG_ERROR, "Unknown VP8 header type 0x%02X\n", p[5]);
         return AVERROR_INVALIDDATA;
     }
 
     return 1;
 }
 

 static uint64_t vp8_gptopts(AVFormatContext *s, int idx,
                             uint64_t granule, int64_t *dts)

 {
     struct ogg *ogg = s->priv_data;
     struct ogg_stream *os = ogg->streams + idx;
 

     int invcnt    = !((granule >> 30) & 3);
     // If page granule is that of an invisible vp8 frame, its pts will be

     // that of the end of the next visible frame. We subtract 1 for those

     // to prevent messing up pts calculations.
     uint64_t pts  = (granule >> 32) - invcnt;

     uint32_t dist = (granule >>  3) & 0x07ffffff;
 
     if (!dist)
         os->pflags |= AV_PKT_FLAG_KEY;
 
     if (dts)
         *dts = pts;
 
     return pts;
 }
 
 static int vp8_packet(AVFormatContext *s, int idx)
 {
     struct ogg *ogg = s->priv_data;
     struct ogg_stream *os = ogg->streams + idx;
     uint8_t *p = os->buf + os->pstart;
 

     if ((!os->lastpts || os->lastpts == AV_NOPTS_VALUE) &&
         !(os->flags & OGG_FLAG_EOS)) {

         int seg;
         int duration;
         uint8_t *last_pkt = p;
         uint8_t *next_pkt;
 
         seg = os->segp;
         duration = (last_pkt[0] >> 4) & 1;
         next_pkt = last_pkt += os->psize;
         for (; seg < os->nsegs; seg++) {
             if (os->segments[seg] < 255) {
                 duration += (last_pkt[0] >> 4) & 1;
                 last_pkt  = next_pkt + os->segments[seg];
             }
             next_pkt += os->segments[seg];
         }

         os->lastpts =
         os->lastdts = vp8_gptopts(s, idx, os->granule, NULL) - duration;

         if(s->streams[idx]->start_time == AV_NOPTS_VALUE) {
             s->streams[idx]->start_time = os->lastpts;

             if (s->streams[idx]->duration && s->streams[idx]->duration != AV_NOPTS_VALUE)

                 s->streams[idx]->duration -= s->streams[idx]->start_time;
         }
     }
 
     if (os->psize > 0)
         os->pduration = (p[0] >> 4) & 1;
 
     return 0;
 }
 
 const struct ogg_codec ff_vp8_codec = {
     .magic     = "OVP80",
     .magicsize = 5,
     .header    = vp8_header,
     .packet    = vp8_packet,
     .gptopts   = vp8_gptopts,
     .nb_header = 1,
 };