/*

  * VP9 compatible video decoder
  *
  * Copyright (C) 2013 Ronald S. Bultje <rsbultje gmail com>
  * Copyright (C) 2013 Clément Bœsch <u pkh me>

  *
  * 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 "libavcodec/get_bits.h"

 #include "parser.h"
 
 typedef struct VP9ParseContext {
     int n_frames; // 1-8
     int size[8];

     int marker_size;

     int64_t pts;

 } VP9ParseContext;
 

 static int parse_frame(AVCodecParserContext *ctx, const uint8_t *buf, int size)

 {

     VP9ParseContext *s = ctx->priv_data;

     GetBitContext gb;
     int res, profile, keyframe, invisible;

     if ((res = init_get_bits8(&gb, buf, size)) < 0)
         return res;
     get_bits(&gb, 2); // frame marker
     profile  = get_bits1(&gb);
     profile |= get_bits1(&gb) << 1;
     if (profile == 3) profile += get_bits1(&gb);
 
     if (get_bits1(&gb)) {
         keyframe = 0;
         invisible = 0;
     } else {
         keyframe  = !get_bits1(&gb);
         invisible = !get_bits1(&gb);
     }
 
     if (!keyframe) {

         ctx->pict_type = AV_PICTURE_TYPE_P;
         ctx->key_frame = 0;
     } else {
         ctx->pict_type = AV_PICTURE_TYPE_I;
         ctx->key_frame = 1;
     }

     if (!invisible) {

         if (ctx->pts == AV_NOPTS_VALUE)
             ctx->pts = s->pts;
         s->pts = AV_NOPTS_VALUE;

     } else if (ctx->pts != AV_NOPTS_VALUE) {

         s->pts = ctx->pts;
         ctx->pts = AV_NOPTS_VALUE;
     }

 
     return 0;

 }
 
 static int parse(AVCodecParserContext *ctx,
                  AVCodecContext *avctx,
                  const uint8_t **out_data, int *out_size,
                  const uint8_t *data, int size)
 {
     VP9ParseContext *s = ctx->priv_data;

     int full_size = size;

     int marker;
 

     if (size <= 0) {
         *out_size = 0;
         *out_data = data;
 
         return 0;
     }
 

     if (s->n_frames > 0) {

         int i;
         int size_sum = 0;
 
         for (i = 0; i < s->n_frames ;i++)
             size_sum += s->size[i];
         size_sum += s->marker_size;
 
         if (size_sum != size) {
             av_log(avctx, AV_LOG_ERROR, "Inconsistent input frame sizes %d %d\n",
                    size_sum, size);
             s->n_frames = 0;
         }
     }
 
     if (s->n_frames > 0) {

         *out_data = data;
         *out_size = s->size[--s->n_frames];
         parse_frame(ctx, *out_data, *out_size);
 
         return s->n_frames > 0 ? *out_size : size /* i.e. include idx tail */;
     }
 
     marker = data[size - 1];
     if ((marker & 0xe0) == 0xc0) {
         int nbytes = 1 + ((marker >> 3) & 0x3);
         int n_frames = 1 + (marker & 0x7), idx_sz = 2 + n_frames * nbytes;
 
         if (size >= idx_sz && data[size - idx_sz] == marker) {
             const uint8_t *idx = data + size + 1 - idx_sz;
             int first = 1;
 
             switch (nbytes) {
 #define case_n(a, rd) \
             case a: \
                 while (n_frames--) { \

                     unsigned sz = rd; \

                     idx += a; \

                     if (sz == 0 || sz > size) { \

                         s->n_frames = 0; \

                         *out_size = size; \

                         *out_data = data; \

                         av_log(avctx, AV_LOG_ERROR, \

                                "Invalid superframe packet size: %u frame size: %d\n", \

                                sz, size); \

                         return full_size; \

                     } \
                     if (first) { \
                         first = 0; \
                         *out_data = data; \
                         *out_size = sz; \
                         s->n_frames = n_frames; \
                     } else { \
                         s->size[n_frames] = sz; \
                     } \
                     data += sz; \
                     size -= sz; \
                 } \

                 s->marker_size = size; \

                 parse_frame(ctx, *out_data, *out_size); \

                 return s->n_frames > 0 ? *out_size : full_size

 
                 case_n(1, *idx);
                 case_n(2, AV_RL16(idx));
                 case_n(3, AV_RL24(idx));
                 case_n(4, AV_RL32(idx));
             }
         }
     }
 
     *out_data = data;
     *out_size = size;
     parse_frame(ctx, data, size);
 
     return size;
 }
 
 AVCodecParser ff_vp9_parser = {
     .codec_ids      = { AV_CODEC_ID_VP9 },
     .priv_data_size = sizeof(VP9ParseContext),
     .parser_parse   = parse,
 };