/*

 * 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 "libavutil/mem.h"

#include "avcodec.h"

#include "bytestream.h"

#include "opus.h"

#include "parse.h"

#include "parser.h"

typedef struct OpusParserContext {

    ParseContext pc;

    OpusParseContext ctx;

    OpusPacket pkt;

    int extradata_parsed;

    int ts_framing;

} OpusParserContext;

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;

    uint64_t payload_len_tmp;

    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_tmp = *payload_len = 0;

    while (bytestream2_peek_byte(&gb) == 0xff)

        payload_len_tmp += bytestream2_get_byte(&gb);

    payload_len_tmp += 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);

    }

    if (bytestream2_tell(&gb) + payload_len_tmp > buf_len)

        return NULL;

    *payload_len = payload_len_tmp;

    return buf + bytestream2_tell(&gb);

}

static int set_frame_duration(AVCodecParserContext *ctx, AVCodecContext *avctx,

                              const uint8_t *buf, int buf_size)

{

    OpusParserContext *s = ctx->priv_data;

    if (ff_opus_parse_packet(&s->pkt, buf, buf_size, s->ctx.nb_streams > 1) < 0) {

        av_log(avctx, AV_LOG_ERROR, "Error parsing Opus packet header.\n");

        return AVERROR_INVALIDDATA;

    }

    ctx->duration = s->pkt.frame_count * s->pkt.frame_duration;

    return 0;

}

/**

 * 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)

{

    OpusParserContext *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);

                if (!payload) {

                    av_log(avctx, AV_LOG_ERROR, "Error parsing Ogg TS header.\n");

                    return AVERROR_INVALIDDATA;

                }

                *header_len = payload - buf;

                start_found = 1;

                break;

            }

        }

    }

    if (!s->ts_framing)

        payload_len = buf_size;

    if (payload_len <= buf_size && (!s->ts_framing || start_found)) {

        ret = set_frame_duration(ctx, avctx, payload, payload_len);

        if (ret < 0) {

            pc->frame_start_found = 0;

            return AVERROR_INVALIDDATA;

        }

    }

    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)

{

    OpusParserContext *s = ctx->priv_data;

    ParseContext *pc    = &s->pc;

    int next, header_len = 0;

    avctx->sample_rate = 48000;

    if (avctx->extradata && !s->extradata_parsed) {

        if (ff_opus_parse_extradata(avctx, &s->ctx) < 0) {

            av_log(avctx, AV_LOG_ERROR, "Error parsing Ogg extradata.\n");

            goto fail;

        }

        av_freep(&s->ctx.channel_maps);

        s->extradata_parsed = 1;

    }

    if (ctx->flags & PARSER_FLAG_COMPLETE_FRAMES) {

        next = buf_size;

        if (set_frame_duration(ctx, avctx, buf, buf_size) < 0)

            goto fail;

    } else {

        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) {

            goto fail;

        }

        if (next == AVERROR_INVALIDDATA){

            goto fail;

        }

    }

    *poutbuf      = buf + header_len;

    *poutbuf_size = buf_size - header_len;

    return next;

fail:

    *poutbuf      = NULL;

    *poutbuf_size = 0;

    return buf_size;

}

const AVCodecParser ff_opus_parser = {

    .codec_ids      = { AV_CODEC_ID_OPUS },

    .priv_data_size = sizeof(OpusParserContext),

    .parser_parse   = opus_parse,

    .parser_close   = ff_parse_close

};