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/*
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 * Realmedia RTSP protocol (RDT) support.
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 * Copyright (c) 2007 Ronald S. Bultje
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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/**
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 * @file rdt.c
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 * @brief Realmedia RTSP protocol (RDT) support
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 * @author Ronald S. Bultje <rbultje@ronald.bitfreak.net>
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 */
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#include "avformat.h"
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#include "libavutil/avstring.h"
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#include "rtp_internal.h"
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#include "rdt.h"
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#include "libavutil/base64.h"
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#include "libavutil/md5.h"
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#include "rm.h"
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#include "internal.h"
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struct RDTDemuxContext {
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    AVFormatContext *ic;
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    AVStream *st;
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    void *dynamic_protocol_context;
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    DynamicPayloadPacketHandlerProc parse_packet;
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    uint32_t prev_set_id, prev_timestamp;
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};
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RDTDemuxContext *
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ff_rdt_parse_open(AVFormatContext *ic, AVStream *st,
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                  void *priv_data, RTPDynamicProtocolHandler *handler)
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{
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    RDTDemuxContext *s = av_mallocz(sizeof(RDTDemuxContext));
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    if (!s)
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        return NULL;
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    s->ic = ic;
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    s->st = st;
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    s->prev_set_id    = -1;
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    s->prev_timestamp = -1;
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    s->parse_packet = handler->parse_packet;
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    s->dynamic_protocol_context = priv_data;
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    return s;
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}
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void
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ff_rdt_parse_close(RDTDemuxContext *s)
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{
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    av_free(s);
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}
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struct PayloadContext {
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    AVFormatContext *rmctx;
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    uint8_t *mlti_data;
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    unsigned int mlti_data_size;
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    char buffer[RTP_MAX_PACKET_LENGTH + FF_INPUT_BUFFER_PADDING_SIZE];
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};
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void
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ff_rdt_calc_response_and_checksum(char response[41], char chksum[9],
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                                  const char *challenge)
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{
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    int ch_len = strlen (challenge), i;
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    unsigned char zres[16],
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        buf[64] = { 0xa1, 0xe9, 0x14, 0x9d, 0x0e, 0x6b, 0x3b, 0x59 };
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#define XOR_TABLE_SIZE 37
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    const unsigned char xor_table[XOR_TABLE_SIZE] = {
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        0x05, 0x18, 0x74, 0xd0, 0x0d, 0x09, 0x02, 0x53,
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        0xc0, 0x01, 0x05, 0x05, 0x67, 0x03, 0x19, 0x70,
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        0x08, 0x27, 0x66, 0x10, 0x10, 0x72, 0x08, 0x09,
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        0x63, 0x11, 0x03, 0x71, 0x08, 0x08, 0x70, 0x02,
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        0x10, 0x57, 0x05, 0x18, 0x54 };
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    /* some (length) checks */
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    if (ch_len == 40) /* what a hack... */
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        ch_len = 32;
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    else if (ch_len > 56)
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        ch_len = 56;
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    memcpy(buf + 8, challenge, ch_len);
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    /* xor challenge bytewise with xor_table */
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    for (i = 0; i < XOR_TABLE_SIZE; i++)
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        buf[8 + i] ^= xor_table[i];
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    av_md5_sum(zres, buf, 64);
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    ff_data_to_hex(response, zres, 16);
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    for (i=0;i<32;i++) response[i] = tolower(response[i]);
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    /* add tail */
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    strcpy (response + 32, "01d0a8e3");
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    /* calculate checksum */
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    for (i = 0; i < 8; i++)
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        chksum[i] = response[i * 4];
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    chksum[8] = 0;
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}
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static int
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rdt_load_mdpr (PayloadContext *rdt, AVStream *st, int rule_nr)
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{
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    ByteIOContext *pb;
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    int size;
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    uint32_t tag;
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    /**
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     * Layout of the MLTI chunk:
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     * 4:MLTI
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     * 2:<number of streams>
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     * Then for each stream ([number_of_streams] times):
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     *     2:<mdpr index>
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     * 2:<number of mdpr chunks>
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     * Then for each mdpr chunk ([number_of_mdpr_chunks] times):
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     *     4:<size>
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     *     [size]:<data>
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     * we skip MDPR chunks until we reach the one of the stream
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     * we're interested in, and forward that ([size]+[data]) to
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     * the RM demuxer to parse the stream-specific header data.
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     */
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    if (!rdt->mlti_data)
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        return -1;
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    url_open_buf(&pb, rdt->mlti_data, rdt->mlti_data_size, URL_RDONLY);
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    tag = get_le32(pb);
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    if (tag == MKTAG('M', 'L', 'T', 'I')) {
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        int num, chunk_nr;
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        /* read index of MDPR chunk numbers */
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        num = get_be16(pb);
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        if (rule_nr < 0 || rule_nr >= num)
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            return -1;
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        url_fskip(pb, rule_nr * 2);
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        chunk_nr = get_be16(pb);
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        url_fskip(pb, (num - 1 - rule_nr) * 2);
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        /* read MDPR chunks */
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        num = get_be16(pb);
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        if (chunk_nr >= num)
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            return -1;
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        while (chunk_nr--)
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            url_fskip(pb, get_be32(pb));
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        size = get_be32(pb);
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    } else {
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        size = rdt->mlti_data_size;
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        url_fseek(pb, 0, SEEK_SET);
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    }
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    rdt->rmctx->pb = pb;
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    if (ff_rm_read_mdpr_codecdata(rdt->rmctx, st, size) < 0)
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        return -1;
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    url_close_buf(pb);
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    return 0;
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}
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/**
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 * Actual data handling.
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 */
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int
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ff_rdt_parse_header(const uint8_t *buf, int len,
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                    int *set_id, int *seq_no, int *stream_id,
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                    int *is_keyframe, uint32_t *timestamp)
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{
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    int consumed = 10;
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    /* skip status packets */
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    while (len >= 5 && buf[1] == 0xFF /* status packet */) {
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        int pkt_len;
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        if (!(buf[0] & 0x80))
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            return -1; /* not followed by a data packet */
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        pkt_len = AV_RB16(buf+3);
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        buf += pkt_len;
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        len -= pkt_len;
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        consumed += pkt_len;
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    }
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    if (len < 10)
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        return -1;
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    /**
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     * Layout of the header (in bits):
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     * 1:  len_included
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     *     Flag indicating whether this header includes a length field;
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     *     this can be used to concatenate multiple RDT packets in a
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     *     single UDP/TCP data frame and is used to precede RDT data
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     *     by stream status packets
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     * 1:  need_reliable
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     *     Flag indicating whether this header includes a "reliable
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     *     sequence number"; these are apparently sequence numbers of
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     *     data packets alone. For data packets, this flag is always
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     *     set, according to the Real documentation [1]
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     * 5:  set_id
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     *     ID of a set of streams of identical content, possibly with
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     *     different codecs or bitrates
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     * 1:  is_reliable
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     *     Flag set for certain streams deemed less tolerable for packet
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     *     loss
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     * 16: seq_no
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     *     Packet sequence number; if >=0xFF00, this is a non-data packet
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     *     containing stream status info, the second byte indicates the
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     *     type of status packet (see wireshark docs / source code [2])
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     * if (len_included) {
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     *     16: packet_len
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     * } else {
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     *     packet_len = remainder of UDP/TCP frame
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     * }
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     * 1:  is_back_to_back
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     *     Back-to-Back flag; used for timing, set for one in every 10
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     *     packets, according to the Real documentation [1]
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     * 1:  is_slow_data
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     *     Slow-data flag; currently unused, according to Real docs [1]
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     * 5:  stream_id
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     *     ID of the stream within this particular set of streams
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     * 1:  is_no_keyframe
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     *     Non-keyframe flag (unset if packet belongs to a keyframe)
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     * 32: timestamp (PTS)
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     * if (set_id == 0x1F) {
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     *     16: set_id (extended set-of-streams ID; see set_id)
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     * }
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     * if (need_reliable) {
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     *     16: reliable_seq_no
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     *         Reliable sequence number (see need_reliable)
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     * }
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     * if (stream_id == 0x3F) {
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     *     16: stream_id (extended stream ID; see stream_id)
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     * }
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     * [1] https://protocol.helixcommunity.org/files/2005/devdocs/RDT_Feature_Level_20.txt
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     * [2] http://www.wireshark.org/docs/dfref/r/rdt.html and
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     *     http://anonsvn.wireshark.org/viewvc/trunk/epan/dissectors/packet-rdt.c
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     */
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    if (set_id)      *set_id      = (buf[0]>>1) & 0x1f;
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    if (seq_no)      *seq_no      = AV_RB16(buf+1);
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    if (timestamp)   *timestamp   = AV_RB32(buf+4);
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    if (stream_id)   *stream_id   = (buf[3]>>1) & 0x1f;
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    if (is_keyframe) *is_keyframe = !(buf[3] & 0x1);
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    return consumed;
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}
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/**< return 0 on packet, no more left, 1 on packet, 1 on partial packet... */
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static int
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rdt_parse_packet (PayloadContext *rdt, AVStream *st,
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                  AVPacket *pkt, uint32_t *timestamp,
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                  const uint8_t *buf, int len, int flags)
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{
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    int seq = 1, res;
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    ByteIOContext *pb = rdt->rmctx->pb;
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    RMContext *rm = rdt->rmctx->priv_data;
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    if (rm->audio_pkt_cnt == 0) {
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        int pos;
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        url_open_buf (&pb, buf, len, URL_RDONLY);
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        flags = (flags & PKT_FLAG_KEY) ? 2 : 0;
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        rdt->rmctx->pb = pb;
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        res = ff_rm_parse_packet (rdt->rmctx, st, len, pkt,
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                                  &seq, &flags, timestamp);
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        pos = url_ftell(pb);
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        url_close_buf (pb);
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        if (res < 0)
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            return res;
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        if (rm->audio_pkt_cnt > 0 &&
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            st->codec->codec_id == CODEC_ID_AAC) {
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            memcpy (rdt->buffer, buf + pos, len - pos);
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            url_open_buf (&pb, rdt->buffer, len - pos, URL_RDONLY);
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            rdt->rmctx->pb = pb;
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        }
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    } else {
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        ff_rm_retrieve_cache (rdt->rmctx, st, pkt);
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        if (rm->audio_pkt_cnt == 0 &&
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            st->codec->codec_id == CODEC_ID_AAC)
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            url_close_buf (pb);
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    }
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    pkt->stream_index = st->index;
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    pkt->pts = *timestamp;
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    return rm->audio_pkt_cnt > 0;
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}
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int
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ff_rdt_parse_packet(RDTDemuxContext *s, AVPacket *pkt,
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                    const uint8_t *buf, int len)
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{
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    int seq_no, flags = 0, stream_id, set_id, is_keyframe;
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    uint32_t timestamp;
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    int rv= 0;
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    if (!s->parse_packet)
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        return -1;
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    if (!buf) {
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        /* return the next packets, if any */
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        timestamp= 0; ///< Should not be used if buf is NULL, but should be set to the timestamp of the packet returned....
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        rv= s->parse_packet(s->dynamic_protocol_context,
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                            s->st, pkt, &timestamp, NULL, 0, flags);
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        return rv;
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    }
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    if (len < 12)
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        return -1;
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    rv = ff_rdt_parse_header(buf, len, &set_id, &seq_no, &stream_id, &is_keyframe, &timestamp);
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    if (rv < 0)
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        return rv;
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    if (is_keyframe && (set_id != s->prev_set_id || timestamp != s->prev_timestamp)) {
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        flags |= PKT_FLAG_KEY;
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        s->prev_set_id    = set_id;
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        s->prev_timestamp = timestamp;
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    }
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    buf += rv;
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    len -= rv;
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    rv = s->parse_packet(s->dynamic_protocol_context,
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                         s->st, pkt, &timestamp, buf, len, flags);
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    return rv;
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}
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void
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ff_rdt_subscribe_rule (char *cmd, int size,
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                       int stream_nr, int rule_nr)
336
{
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    av_strlcatf(cmd, size, "stream=%d;rule=%d,stream=%d;rule=%d",
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                stream_nr, rule_nr * 2, stream_nr, rule_nr * 2 + 1);
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}
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void
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ff_rdt_subscribe_rule2 (RDTDemuxContext *s, char *cmd, int size,
343
                        int stream_nr, int rule_nr)
344
{
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    PayloadContext *rdt = s->dynamic_protocol_context;
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    rdt_load_mdpr(rdt, s->st, rule_nr * 2);
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}
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static unsigned char *
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rdt_parse_b64buf (unsigned int *target_len, const char *p)
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{
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    unsigned char *target;
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    int len = strlen(p);
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    if (*p == '\"') {
356
        p++;
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        len -= 2; /* skip embracing " at start/end */
358
    }
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    *target_len = len * 3 / 4;
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    target = av_mallocz(*target_len + FF_INPUT_BUFFER_PADDING_SIZE);
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    av_base64_decode(target, p, *target_len);
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    return target;
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}
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static int
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rdt_parse_sdp_line (AVStream *stream, PayloadContext *rdt, const char *line)
367
{
368
    const char *p = line;
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370
    if (av_strstart(p, "OpaqueData:buffer;", &p)) {
371
        rdt->mlti_data = rdt_parse_b64buf(&rdt->mlti_data_size, p);
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    } else if (av_strstart(p, "StartTime:integer;", &p))
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        stream->first_dts = atoi(p);
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    return 0;
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}
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static PayloadContext *
379
rdt_new_extradata (void)
380
{
381
    PayloadContext *rdt = av_mallocz(sizeof(PayloadContext));
382

    
383
    av_open_input_stream(&rdt->rmctx, NULL, "", &rdt_demuxer, NULL);
384

    
385
    return rdt;
386
}
387

    
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static void
389
rdt_free_extradata (PayloadContext *rdt)
390
{
391
    if (rdt->rmctx)
392
        av_close_input_stream(rdt->rmctx);
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    av_freep(&rdt->mlti_data);
394
    av_free(rdt);
395
}
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397
#define RDT_HANDLER(n, s, t) \
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static RTPDynamicProtocolHandler ff_rdt_ ## n ## _handler = { \
399
    s, \
400
    t, \
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    CODEC_ID_NONE, \
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    rdt_parse_sdp_line, \
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    rdt_new_extradata, \
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    rdt_free_extradata, \
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    rdt_parse_packet \
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};
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408
RDT_HANDLER(live_video, "x-pn-multirate-realvideo-live", CODEC_TYPE_VIDEO);
409
RDT_HANDLER(live_audio, "x-pn-multirate-realaudio-live", CODEC_TYPE_AUDIO);
410
RDT_HANDLER(video,      "x-pn-realvideo",                CODEC_TYPE_VIDEO);
411
RDT_HANDLER(audio,      "x-pn-realaudio",                CODEC_TYPE_AUDIO);
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413
void av_register_rdt_dynamic_payload_handlers(void)
414
{
415
    ff_register_dynamic_payload_handler(&ff_rdt_video_handler);
416
    ff_register_dynamic_payload_handler(&ff_rdt_audio_handler);
417
    ff_register_dynamic_payload_handler(&ff_rdt_live_video_handler);
418
    ff_register_dynamic_payload_handler(&ff_rdt_live_audio_handler);
419
}