/*
  * Copyright (c) 2013-2014 Mozilla Corporation
  *

  * 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
  */
 
 /**
  * @file
  * Opus parser
  *
  * Determines the duration for each packet.
  */
 
 #include "avcodec.h"

 #include "bytestream.h"

 #include "opus.h"

 #include "parser.h"

 
 typedef struct OpusParseContext {

     ParseContext pc;

     OpusContext ctx;
     OpusPacket pkt;
     int extradata_parsed;

     int ts_framing;

 } OpusParseContext;
 

 static const uint8_t *parse_opus_ts_header(const uint8_t *start, int *payload_len, int buf_len)
 {
     const uint8_t *buf = start + 1;
     int start_trim_flag, end_trim_flag, control_extension_flag, control_extension_length;
     uint8_t flags;
 
     GetByteContext gb;
     bytestream2_init(&gb, buf, buf_len);
 
     flags = bytestream2_get_byte(&gb);
     start_trim_flag        = (flags >> 4) & 1;
     end_trim_flag          = (flags >> 3) & 1;
     control_extension_flag = (flags >> 2) & 1;
 
     *payload_len = 0;
     while (bytestream2_peek_byte(&gb) == 0xff)
         *payload_len += bytestream2_get_byte(&gb);
 
     *payload_len += bytestream2_get_byte(&gb);
 
     if (start_trim_flag)
         bytestream2_skip(&gb, 2);
     if (end_trim_flag)
         bytestream2_skip(&gb, 2);
     if (control_extension_flag) {
         control_extension_length = bytestream2_get_byte(&gb);
         bytestream2_skip(&gb, control_extension_length);
     }
 
     return buf + bytestream2_tell(&gb);
 }
 
 /**
  * Find the end of the current frame in the bitstream.
  * @return the position of the first byte of the next frame, or -1
  */
 static int opus_find_frame_end(AVCodecParserContext *ctx, AVCodecContext *avctx,
                                const uint8_t *buf, int buf_size, int *header_len)

 {
     OpusParseContext *s = ctx->priv_data;

     ParseContext *pc    = &s->pc;
     int ret, start_found, i = 0, payload_len = 0;
     const uint8_t *payload;
     uint32_t state;
     uint16_t hdr;
     *header_len = 0;

 
     if (!buf_size)
         return 0;
 

     start_found = pc->frame_start_found;
     state = pc->state;
     payload = buf;
 
     /* Check if we're using Opus in MPEG-TS framing */
     if (!s->ts_framing && buf_size > 2) {
         hdr = AV_RB16(buf);
         if ((hdr & OPUS_TS_MASK) == OPUS_TS_HEADER)
             s->ts_framing = 1;
     }
 
     if (s->ts_framing && !start_found) {
         for (i = 0; i < buf_size-2; i++) {
             state = (state << 8) | payload[i];
             if ((state & OPUS_TS_MASK) == OPUS_TS_HEADER) {
                 payload = parse_opus_ts_header(payload, &payload_len, buf_size - i);
                 *header_len = payload - buf;
                 start_found = 1;
                 break;
             }
         }
     }
 
     if (!s->ts_framing)
         payload_len = buf_size;
 

     if (avctx->extradata && !s->extradata_parsed) {
         ret = ff_opus_parse_extradata(avctx, &s->ctx);
         if (ret < 0) {
             av_log(avctx, AV_LOG_ERROR, "Error parsing Ogg extradata.\n");

             return AVERROR_INVALIDDATA;

         }
         av_freep(&s->ctx.channel_maps);
         s->extradata_parsed = 1;
     }
 

     if (payload_len <= buf_size && (!s->ts_framing || start_found)) {
         ret = ff_opus_parse_packet(&s->pkt, payload, payload_len, s->ctx.nb_streams > 1);
         if (ret < 0) {
             av_log(avctx, AV_LOG_ERROR, "Error parsing Opus packet header.\n");
             pc->frame_start_found = 0;
             return AVERROR_INVALIDDATA;
         }
 
         ctx->duration = s->pkt.frame_count * s->pkt.frame_duration;

     }
 

     if (s->ts_framing) {
         if (start_found) {
             if (payload_len + *header_len <= buf_size) {
                 pc->frame_start_found = 0;
                 pc->state             = -1;
                 return payload_len + *header_len;
             }
         }
 
         pc->frame_start_found = start_found;
         pc->state = state;
         return END_NOT_FOUND;
     }

 
     return buf_size;
 }
 

 static int opus_parse(AVCodecParserContext *ctx, AVCodecContext *avctx,
                        const uint8_t **poutbuf, int *poutbuf_size,
                        const uint8_t *buf, int buf_size)
 {
     OpusParseContext *s = ctx->priv_data;
     ParseContext *pc    = &s->pc;
     int next, header_len;
 
     next = opus_find_frame_end(ctx, avctx, buf, buf_size, &header_len);
 
     if (s->ts_framing && next != AVERROR_INVALIDDATA &&
         ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
         *poutbuf      = NULL;
         *poutbuf_size = 0;
         return buf_size;
     }
 
     if (next == AVERROR_INVALIDDATA){
         *poutbuf      = NULL;
         *poutbuf_size = 0;
         return buf_size;
     }
 
     *poutbuf      = buf + header_len;
     *poutbuf_size = buf_size - header_len;
     return next;
 }
 

 AVCodecParser ff_opus_parser = {
     .codec_ids      = { AV_CODEC_ID_OPUS },
     .priv_data_size = sizeof(OpusParseContext),
     .parser_parse   = opus_parse,

     .parser_close   = ff_parse_close

 };