FFmpeg/libavformat/rmdec.c

/*
 * "Real" compatible demuxer.
 * Copyright (c) 2000, 2001 Fabrice Bellard
 *
 * 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 <inttypes.h>

#include "libavutil/avassert.h"
#include "libavutil/avstring.h"
#include "libavutil/channel_layout.h"
#include "libavutil/internal.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/dict.h"
#include "avformat.h"
#include "avio_internal.h"
#include "internal.h"
#include "rmsipr.h"
#include "rm.h"

#define DEINT_ID_GENR MKTAG('g', 'e', 'n', 'r') ///< interleaving for Cooker/ATRAC
#define DEINT_ID_INT0 MKTAG('I', 'n', 't', '0') ///< no interleaving needed
#define DEINT_ID_INT4 MKTAG('I', 'n', 't', '4') ///< interleaving for 28.8
#define DEINT_ID_SIPR MKTAG('s', 'i', 'p', 'r') ///< interleaving for Sipro
#define DEINT_ID_VBRF MKTAG('v', 'b', 'r', 'f') ///< VBR case for AAC
#define DEINT_ID_VBRS MKTAG('v', 'b', 'r', 's') ///< VBR case for AAC

struct RMStream {
    AVPacket pkt;      ///< place to store merged video frame / reordered audio data
    int videobufsize;  ///< current assembled frame size
    int videobufpos;   ///< position for the next slice in the video buffer
    int curpic_num;    ///< picture number of current frame
    int cur_slice, slices;
    int64_t pktpos;    ///< first slice position in file
    /// Audio descrambling matrix parameters
    int64_t audiotimestamp; ///< Audio packet timestamp
    int sub_packet_cnt; // Subpacket counter, used while reading
    int sub_packet_size, sub_packet_h, coded_framesize; ///< Descrambling parameters from container
    int audio_framesize; /// Audio frame size from container
    int sub_packet_lengths[16]; /// Length of each subpacket
    int32_t deint_id;  ///< deinterleaver used in audio stream
};

typedef struct RMDemuxContext {
    int nb_packets;
    int old_format;
    int current_stream;
    int remaining_len;
    int audio_stream_num; ///< Stream number for audio packets
    int audio_pkt_cnt; ///< Output packet counter
    int data_end;
} RMDemuxContext;

static int rm_read_close(AVFormatContext *s);

static inline void get_strl(AVIOContext *pb, char *buf, int buf_size, int len)
{
    int i;
    char *q, r;

    q = buf;
    for(i=0;i<len;i++) {
        r = avio_r8(pb);
        if (i < buf_size - 1)
            *q++ = r;
    }
    if (buf_size > 0) *q = '\0';
}

static void get_str8(AVIOContext *pb, char *buf, int buf_size)
{
    get_strl(pb, buf, buf_size, avio_r8(pb));
}

static int rm_read_extradata(AVFormatContext *s, AVIOContext *pb, AVCodecParameters *par, unsigned size)
{
    if (size >= 1<<24) {
        av_log(s, AV_LOG_ERROR, "extradata size %u too large\n", size);
        return -1;
    }
    if (ff_get_extradata(s, par, pb, size) < 0)
        return AVERROR(ENOMEM);
    return 0;
}

static void rm_read_metadata(AVFormatContext *s, AVIOContext *pb, int wide)
{
    char buf[1024];
    int i;

    for (i=0; i<FF_ARRAY_ELEMS(ff_rm_metadata); i++) {
        int len = wide ? avio_rb16(pb) : avio_r8(pb);
        get_strl(pb, buf, sizeof(buf), len);
        av_dict_set(&s->metadata, ff_rm_metadata[i], buf, 0);
    }
}

RMStream *ff_rm_alloc_rmstream (void)
{
    RMStream *rms = av_mallocz(sizeof(RMStream));
    if (!rms)
        return NULL;
    rms->curpic_num = -1;
    return rms;
}

void ff_rm_free_rmstream (RMStream *rms)
{
    av_packet_unref(&rms->pkt);
}

static int rm_read_audio_stream_info(AVFormatContext *s, AVIOContext *pb,
                                     AVStream *st, RMStream *ast, int read_all)
{
    char buf[256];
    uint32_t version;
    int ret;

    /* ra type header */
    version = avio_rb16(pb); /* version */
    if (version == 3) {
        unsigned bytes_per_minute;
        int header_size = avio_rb16(pb);
        int64_t startpos = avio_tell(pb);
        avio_skip(pb, 8);
        bytes_per_minute = avio_rb16(pb);
        avio_skip(pb, 4);
        rm_read_metadata(s, pb, 0);
        if ((startpos + header_size) >= avio_tell(pb) + 2) {
            // fourcc (should always be "lpcJ")
            avio_r8(pb);
            get_str8(pb, buf, sizeof(buf));
        }
        // Skip extra header crap (this should never happen)
        if ((startpos + header_size) > avio_tell(pb))
            avio_skip(pb, header_size + startpos - avio_tell(pb));
        if (bytes_per_minute)
            st->codecpar->bit_rate = 8LL * bytes_per_minute / 60;
        st->codecpar->sample_rate = 8000;
        st->codecpar->channels = 1;
        st->codecpar->channel_layout = AV_CH_LAYOUT_MONO;
        st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
        st->codecpar->codec_id = AV_CODEC_ID_RA_144;
        ast->deint_id = DEINT_ID_INT0;
    } else {
        int flavor, sub_packet_h, coded_framesize, sub_packet_size;
        int codecdata_length;
        unsigned bytes_per_minute;
        /* old version (4) */
        avio_skip(pb, 2); /* unused */
        avio_rb32(pb); /* .ra4 */
        avio_rb32(pb); /* data size */
        avio_rb16(pb); /* version2 */
        avio_rb32(pb); /* header size */
        flavor= avio_rb16(pb); /* add codec info / flavor */
        ast->coded_framesize = coded_framesize = avio_rb32(pb); /* coded frame size */
        avio_rb32(pb); /* ??? */
        bytes_per_minute = avio_rb32(pb);
        if (version == 4) {
            if (bytes_per_minute)
                st->codecpar->bit_rate = 8LL * bytes_per_minute / 60;
        }
        avio_rb32(pb); /* ??? */
        ast->sub_packet_h = sub_packet_h = avio_rb16(pb); /* 1 */
        st->codecpar->block_align= avio_rb16(pb); /* frame size */
        ast->sub_packet_size = sub_packet_size = avio_rb16(pb); /* sub packet size */
        avio_rb16(pb); /* ??? */
        if (version == 5) {
            avio_rb16(pb); avio_rb16(pb); avio_rb16(pb);
        }
        st->codecpar->sample_rate = avio_rb16(pb);
        avio_rb32(pb);
        st->codecpar->channels = avio_rb16(pb);
        if (version == 5) {
            ast->deint_id = avio_rl32(pb);
            avio_read(pb, buf, 4);
            buf[4] = 0;
        } else {
            AV_WL32(buf, 0);
            get_str8(pb, buf, sizeof(buf)); /* desc */
            ast->deint_id = AV_RL32(buf);
            get_str8(pb, buf, sizeof(buf)); /* desc */
        }
        st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
        st->codecpar->codec_tag  = AV_RL32(buf);
        st->codecpar->codec_id   = ff_codec_get_id(ff_rm_codec_tags,
                                                   st->codecpar->codec_tag);

        switch (st->codecpar->codec_id) {
        case AV_CODEC_ID_AC3:
            st->need_parsing = AVSTREAM_PARSE_FULL;
            break;
        case AV_CODEC_ID_RA_288:
            st->codecpar->extradata_size= 0;
            av_freep(&st->codecpar->extradata);
            ast->audio_framesize = st->codecpar->block_align;
            st->codecpar->block_align = coded_framesize;
            break;
        case AV_CODEC_ID_COOK:
            st->need_parsing = AVSTREAM_PARSE_HEADERS;
        case AV_CODEC_ID_ATRAC3:
        case AV_CODEC_ID_SIPR:
            if (read_all) {
                codecdata_length = 0;
            } else {
                avio_rb16(pb); avio_r8(pb);
                if (version == 5)
                    avio_r8(pb);
                codecdata_length = avio_rb32(pb);
                if(codecdata_length + AV_INPUT_BUFFER_PADDING_SIZE <= (unsigned)codecdata_length){
                    av_log(s, AV_LOG_ERROR, "codecdata_length too large\n");
                    return -1;
                }
            }

            ast->audio_framesize = st->codecpar->block_align;
            if (st->codecpar->codec_id == AV_CODEC_ID_SIPR) {
                if (flavor > 3) {
                    av_log(s, AV_LOG_ERROR, "bad SIPR file flavor %d\n",
                           flavor);
                    return -1;
                }
                st->codecpar->block_align = ff_sipr_subpk_size[flavor];
                st->need_parsing = AVSTREAM_PARSE_FULL_RAW;
            } else {
                if(sub_packet_size <= 0){
                    av_log(s, AV_LOG_ERROR, "sub_packet_size is invalid\n");
                    return -1;
                }
                st->codecpar->block_align = ast->sub_packet_size;
            }
            if ((ret = rm_read_extradata(s, pb, st->codecpar, codecdata_length)) < 0)
                return ret;

            break;
        case AV_CODEC_ID_AAC:
            avio_rb16(pb); avio_r8(pb);
            if (version == 5)
                avio_r8(pb);
            codecdata_length = avio_rb32(pb);
            if(codecdata_length + AV_INPUT_BUFFER_PADDING_SIZE <= (unsigned)codecdata_length){
                av_log(s, AV_LOG_ERROR, "codecdata_length too large\n");
                return -1;
            }
            if (codecdata_length >= 1) {
                avio_r8(pb);
                if ((ret = rm_read_extradata(s, pb, st->codecpar, codecdata_length - 1)) < 0)
                    return ret;
            }
            break;
        }
        switch (ast->deint_id) {
        case DEINT_ID_INT4:
            if (ast->coded_framesize > ast->audio_framesize ||
                sub_packet_h <= 1 ||
                ast->coded_framesize * sub_packet_h > (2 + (sub_packet_h & 1)) * ast->audio_framesize)
                return AVERROR_INVALIDDATA;
            if (ast->coded_framesize * sub_packet_h != 2*ast->audio_framesize) {
                avpriv_request_sample(s, "mismatching interleaver parameters");
                return AVERROR_INVALIDDATA;
            }
            break;
        case DEINT_ID_GENR:
            if (ast->sub_packet_size <= 0 ||
                ast->sub_packet_size > ast->audio_framesize)
                return AVERROR_INVALIDDATA;
            if (ast->audio_framesize % ast->sub_packet_size)
                return AVERROR_INVALIDDATA;
            break;
        case DEINT_ID_SIPR:
        case DEINT_ID_INT0:
        case DEINT_ID_VBRS:
        case DEINT_ID_VBRF:
            break;
        default:
            av_log(s, AV_LOG_ERROR ,"Unknown interleaver %"PRIX32"\n", ast->deint_id);
            return AVERROR_INVALIDDATA;
        }
        if (ast->deint_id == DEINT_ID_INT4 ||
            ast->deint_id == DEINT_ID_GENR ||
            ast->deint_id == DEINT_ID_SIPR) {
            if (st->codecpar->block_align <= 0 ||
                ast->audio_framesize * sub_packet_h > (unsigned)INT_MAX ||
                ast->audio_framesize * sub_packet_h < st->codecpar->block_align)
                return AVERROR_INVALIDDATA;
            if (av_new_packet(&ast->pkt, ast->audio_framesize * sub_packet_h) < 0)
                return AVERROR(ENOMEM);
        }

        if (read_all) {
            avio_r8(pb);
            avio_r8(pb);
            avio_r8(pb);
            rm_read_metadata(s, pb, 0);
        }
    }
    return 0;
}

int ff_rm_read_mdpr_codecdata(AVFormatContext *s, AVIOContext *pb,
                              AVStream *st, RMStream *rst,
                              unsigned int codec_data_size, const uint8_t *mime)
{
    unsigned int v;
    int size;
    int64_t codec_pos;
    int ret;

    if (codec_data_size > INT_MAX)
        return AVERROR_INVALIDDATA;
    if (codec_data_size == 0)
        return 0;

    avpriv_set_pts_info(st, 64, 1, 1000);
    codec_pos = avio_tell(pb);
    v = avio_rb32(pb);

    if (v == MKTAG(0xfd, 'a', 'r', '.')) {
        /* ra type header */
        if (rm_read_audio_stream_info(s, pb, st, rst, 0))
            return -1;
    } else if (v == MKBETAG('L', 'S', 'D', ':')) {
        avio_seek(pb, -4, SEEK_CUR);
        if ((ret = rm_read_extradata(s, pb, st->codecpar, codec_data_size)) < 0)
            return ret;

        st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
        st->codecpar->codec_tag  = AV_RL32(st->codecpar->extradata);
        st->codecpar->codec_id   = ff_codec_get_id(ff_rm_codec_tags,
                                                st->codecpar->codec_tag);
    } else if(mime && !strcmp(mime, "logical-fileinfo")){
        int stream_count, rule_count, property_count, i;
        ff_free_stream(s, st);
        if (avio_rb16(pb) != 0) {
            av_log(s, AV_LOG_WARNING, "Unsupported version\n");
            goto skip;
        }
        stream_count = avio_rb16(pb);
        avio_skip(pb, 6*stream_count);
        rule_count = avio_rb16(pb);
        avio_skip(pb, 2*rule_count);
        property_count = avio_rb16(pb);
        for(i=0; i<property_count; i++){
            uint8_t name[128], val[128];
            avio_rb32(pb);
            if (avio_rb16(pb) != 0) {
                av_log(s, AV_LOG_WARNING, "Unsupported Name value property version\n");
                goto skip; //FIXME skip just this one
            }
            get_str8(pb, name, sizeof(name));
            switch(avio_rb32(pb)) {
            case 2: get_strl(pb, val, sizeof(val), avio_rb16(pb));
                av_dict_set(&s->metadata, name, val, 0);
                break;
            default: avio_skip(pb, avio_rb16(pb));
            }
        }
    } else {
        int fps;
        if (avio_rl32(pb) != MKTAG('V', 'I', 'D', 'O')) {
        fail1:
            av_log(s, AV_LOG_WARNING, "Unsupported stream type %08x\n", v);
            goto skip;
        }
        st->codecpar->codec_tag = avio_rl32(pb);
        st->codecpar->codec_id  = ff_codec_get_id(ff_rm_codec_tags,
                                                  st->codecpar->codec_tag);
        av_log(s, AV_LOG_TRACE, "%"PRIX32" %X\n",
               st->codecpar->codec_tag, MKTAG('R', 'V', '2', '0'));
        if (st->codecpar->codec_id == AV_CODEC_ID_NONE)
            goto fail1;
        st->codecpar->width  = avio_rb16(pb);
        st->codecpar->height = avio_rb16(pb);
        avio_skip(pb, 2); // looks like bits per sample
        avio_skip(pb, 4); // always zero?
        st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
        st->need_parsing = AVSTREAM_PARSE_TIMESTAMPS;
        fps = avio_rb32(pb);

        if ((ret = rm_read_extradata(s, pb, st->codecpar, codec_data_size - (avio_tell(pb) - codec_pos))) < 0)
            return ret;

        if (fps > 0) {
            av_reduce(&st->avg_frame_rate.den, &st->avg_frame_rate.num,
                      0x10000, fps, (1 << 30) - 1);
#if FF_API_R_FRAME_RATE
            st->r_frame_rate = st->avg_frame_rate;
#endif
        } else if (s->error_recognition & AV_EF_EXPLODE) {
            av_log(s, AV_LOG_ERROR, "Invalid framerate\n");
            return AVERROR_INVALIDDATA;
        }
    }

skip:
    /* skip codec info */
    size = avio_tell(pb) - codec_pos;
    if (codec_data_size >= size) {
        avio_skip(pb, codec_data_size - size);
    } else {
        av_log(s, AV_LOG_WARNING, "codec_data_size %u < size %d\n", codec_data_size, size);
    }

    return 0;
}

/** this function assumes that the demuxer has already seeked to the start
 * of the INDX chunk, and will bail out if not. */
static int rm_read_index(AVFormatContext *s)
{
    AVIOContext *pb = s->pb;
    unsigned int size, n_pkts, str_id, next_off, n, pos, pts;
    AVStream *st;

    do {
        if (avio_rl32(pb) != MKTAG('I','N','D','X'))
            return -1;
        size     = avio_rb32(pb);
        if (size < 20)
            return -1;
        avio_skip(pb, 2);
        n_pkts   = avio_rb32(pb);
        str_id   = avio_rb16(pb);
        next_off = avio_rb32(pb);
        for (n = 0; n < s->nb_streams; n++)
            if (s->streams[n]->id == str_id) {
                st = s->streams[n];
                break;
            }
        if (n == s->nb_streams) {
            av_log(s, AV_LOG_ERROR,
                   "Invalid stream index %d for index at pos %"PRId64"\n",
                   str_id, avio_tell(pb));
            goto skip;
        } else if ((avio_size(pb) - avio_tell(pb)) / 14 < n_pkts) {
            av_log(s, AV_LOG_ERROR,
                   "Nr. of packets in packet index for stream index %d "
                   "exceeds filesize (%"PRId64" at %"PRId64" = %"PRId64")\n",
                   str_id, avio_size(pb), avio_tell(pb),
                   (avio_size(pb) - avio_tell(pb)) / 14);
            goto skip;
        }

        for (n = 0; n < n_pkts; n++) {
            avio_skip(pb, 2);
            pts = avio_rb32(pb);
            pos = avio_rb32(pb);
            avio_skip(pb, 4); /* packet no. */

            av_add_index_entry(st, pos, pts, 0, 0, AVINDEX_KEYFRAME);
        }

skip:
        if (next_off && avio_tell(pb) < next_off &&
            avio_seek(pb, next_off, SEEK_SET) < 0) {
            av_log(s, AV_LOG_ERROR,
                   "Non-linear index detected, not supported\n");
            return -1;
        }
    } while (next_off);

    return 0;
}

static int rm_read_header_old(AVFormatContext *s)
{
    RMDemuxContext *rm = s->priv_data;
    AVStream *st;

    rm->old_format = 1;
    st = avformat_new_stream(s, NULL);
    if (!st)
        return -1;
    st->priv_data = ff_rm_alloc_rmstream();
    if (!st->priv_data)
        return AVERROR(ENOMEM);
    return rm_read_audio_stream_info(s, s->pb, st, st->priv_data, 1);
}

static int rm_read_multi(AVFormatContext *s, AVIOContext *pb,
                         AVStream *st, char *mime)
{
    int number_of_streams = avio_rb16(pb);
    int number_of_mdpr;
    int i, ret;
    unsigned size2;
    for (i = 0; i<number_of_streams; i++)
        avio_rb16(pb);
    number_of_mdpr = avio_rb16(pb);
    if (number_of_mdpr != 1) {
        avpriv_request_sample(s, "MLTI with multiple (%d) MDPR", number_of_mdpr);
    }
    for (i = 0; i < number_of_mdpr; i++) {
        AVStream *st2;
        if (i > 0) {
            st2 = avformat_new_stream(s, NULL);
            if (!st2) {
                ret = AVERROR(ENOMEM);
                return ret;
            }
            st2->id = st->id + (i<<16);
            st2->codecpar->bit_rate = st->codecpar->bit_rate;
            st2->start_time = st->start_time;
            st2->duration   = st->duration;
            st2->codecpar->codec_type = AVMEDIA_TYPE_DATA;
            st2->priv_data = ff_rm_alloc_rmstream();
            if (!st2->priv_data)
                return AVERROR(ENOMEM);
        } else
            st2 = st;

        size2 = avio_rb32(pb);
        ret = ff_rm_read_mdpr_codecdata(s, s->pb, st2, st2->priv_data,
                                        size2, mime);
        if (ret < 0)
            return ret;
    }
    return 0;
}

static int rm_read_header(AVFormatContext *s)
{
    RMDemuxContext *rm = s->priv_data;
    AVStream *st;
    AVIOContext *pb = s->pb;
    unsigned int tag;
    int tag_size;
    unsigned int start_time, duration;
    unsigned int data_off = 0, indx_off = 0;
    char buf[128], mime[128];
    int flags = 0;
    int ret = -1;
    unsigned size, v;
    int64_t codec_pos;

    tag = avio_rl32(pb);
    if (tag == MKTAG('.', 'r', 'a', 0xfd)) {
        /* very old .ra format */
        return rm_read_header_old(s);
    } else if (tag != MKTAG('.', 'R', 'M', 'F')) {
        return AVERROR(EIO);
    }

    tag_size = avio_rb32(pb);
    avio_skip(pb, tag_size - 8);

    for(;;) {
        if (avio_feof(pb))
            goto fail;
        tag = avio_rl32(pb);
        tag_size = avio_rb32(pb);
        avio_rb16(pb);
        av_log(s, AV_LOG_TRACE, "tag=%s size=%d\n",
               av_fourcc2str(tag), tag_size);
        if (tag_size < 10 && tag != MKTAG('D', 'A', 'T', 'A'))
            goto fail;
        switch(tag) {
        case MKTAG('P', 'R', 'O', 'P'):
            /* file header */
            avio_rb32(pb); /* max bit rate */
            avio_rb32(pb); /* avg bit rate */
            avio_rb32(pb); /* max packet size */
            avio_rb32(pb); /* avg packet size */
            avio_rb32(pb); /* nb packets */
            duration = avio_rb32(pb); /* duration */
            s->duration = av_rescale(duration, AV_TIME_BASE, 1000);
            avio_rb32(pb); /* preroll */
            indx_off = avio_rb32(pb); /* index offset */
            data_off = avio_rb32(pb); /* data offset */
            avio_rb16(pb); /* nb streams */
            flags = avio_rb16(pb); /* flags */
            break;
        case MKTAG('C', 'O', 'N', 'T'):
            rm_read_metadata(s, pb, 1);
            break;
        case MKTAG('M', 'D', 'P', 'R'):
            st = avformat_new_stream(s, NULL);
            if (!st) {
                ret = AVERROR(ENOMEM);
                goto fail;
            }
            st->id = avio_rb16(pb);
            avio_rb32(pb); /* max bit rate */
            st->codecpar->bit_rate = avio_rb32(pb); /* bit rate */
            avio_rb32(pb); /* max packet size */
            avio_rb32(pb); /* avg packet size */
            start_time = avio_rb32(pb); /* start time */
            avio_rb32(pb); /* preroll */
            duration = avio_rb32(pb); /* duration */
            st->start_time = start_time;
            st->duration = duration;
            if(duration>0)
                s->duration = AV_NOPTS_VALUE;
            get_str8(pb, buf, sizeof(buf)); /* desc */
            get_str8(pb, mime, sizeof(mime)); /* mimetype */
            st->codecpar->codec_type = AVMEDIA_TYPE_DATA;
            st->priv_data = ff_rm_alloc_rmstream();
            if (!st->priv_data)
                return AVERROR(ENOMEM);

            size = avio_rb32(pb);
            codec_pos = avio_tell(pb);

            ffio_ensure_seekback(pb, 4);
            v = avio_rb32(pb);
            if (v == MKBETAG('M', 'L', 'T', 'I')) {
                ret = rm_read_multi(s, s->pb, st, mime);
                if (ret < 0)
                    goto fail;
                avio_seek(pb, codec_pos + size, SEEK_SET);
            } else {
                avio_skip(pb, -4);
                if (ff_rm_read_mdpr_codecdata(s, s->pb, st, st->priv_data,
                                              size, mime) < 0)
                    goto fail;
            }

            break;
        case MKTAG('D', 'A', 'T', 'A'):
            goto header_end;
        default:
            /* unknown tag: skip it */
            avio_skip(pb, tag_size - 10);
            break;
        }
    }
 header_end:
    rm->nb_packets = avio_rb32(pb); /* number of packets */
    if (!rm->nb_packets && (flags & 4))
        rm->nb_packets = 3600 * 25;
    avio_rb32(pb); /* next data header */

    if (!data_off)
        data_off = avio_tell(pb) - 18;
    if (indx_off && (pb->seekable & AVIO_SEEKABLE_NORMAL) &&
        !(s->flags & AVFMT_FLAG_IGNIDX) &&
        avio_seek(pb, indx_off, SEEK_SET) >= 0) {
        rm_read_index(s);
        avio_seek(pb, data_off + 18, SEEK_SET);
    }

    return 0;

fail:
    rm_read_close(s);
    return ret;
}

static int get_num(AVIOContext *pb, int *len)
{
    int n, n1;

    n = avio_rb16(pb);
    (*len)-=2;
    n &= 0x7FFF;
    if (n >= 0x4000) {
        return n - 0x4000;
    } else {
        n1 = avio_rb16(pb);
        (*len)-=2;
        return (n << 16) | n1;
    }
}

/* multiple of 20 bytes for ra144 (ugly) */
#define RAW_PACKET_SIZE 1000

static int rm_sync(AVFormatContext *s, int64_t *timestamp, int *flags, int *stream_index, int64_t *pos){
    RMDemuxContext *rm = s->priv_data;
    AVIOContext *pb = s->pb;
    AVStream *st;
    uint32_t state=0xFFFFFFFF;

    while(!avio_feof(pb)){
        int len, num, i;
        int mlti_id;
        *pos= avio_tell(pb) - 3;
        if(rm->remaining_len > 0){
            num= rm->current_stream;
            mlti_id = 0;
            len= rm->remaining_len;
            *timestamp = AV_NOPTS_VALUE;
            *flags= 0;
        }else{
            state= (state<<8) + avio_r8(pb);

            if(state == MKBETAG('I', 'N', 'D', 'X')){
                int n_pkts, expected_len;
                len = avio_rb32(pb);
                avio_skip(pb, 2);
                n_pkts = avio_rb32(pb);
                expected_len = 20 + n_pkts * 14;
                if (len == 20)
                    /* some files don't add index entries to chunk size... */
                    len = expected_len;
                else if (len != expected_len)
                    av_log(s, AV_LOG_WARNING,
                           "Index size %d (%d pkts) is wrong, should be %d.\n",
                           len, n_pkts, expected_len);
                len -= 14; // we already read part of the index header
                if(len<0)
                    continue;
                goto skip;
            } else if (state == MKBETAG('D','A','T','A')) {
                av_log(s, AV_LOG_WARNING,
                       "DATA tag in middle of chunk, file may be broken.\n");
            }

            if(state > (unsigned)0xFFFF || state <= 12)
                continue;
            len=state - 12;
            state= 0xFFFFFFFF;

            num = avio_rb16(pb);
            *timestamp = avio_rb32(pb);
            mlti_id = (avio_r8(pb)>>1)-1<<16;
            mlti_id = FFMAX(mlti_id, 0);
            *flags = avio_r8(pb); /* flags */
        }
        for(i=0;i<s->nb_streams;i++) {
            st = s->streams[i];
            if (mlti_id + num == st->id)
                break;
        }
        if (i == s->nb_streams) {
skip:
            /* skip packet if unknown number */
            avio_skip(pb, len);
            rm->remaining_len = 0;
            continue;
        }
        *stream_index= i;

        return len;
    }
    return -1;
}

static int rm_assemble_video_frame(AVFormatContext *s, AVIOContext *pb,
                                   RMDemuxContext *rm, RMStream *vst,
                                   AVPacket *pkt, int len, int *pseq,
                                   int64_t *timestamp)
{
    int hdr;
    int seq = 0, pic_num = 0, len2 = 0, pos = 0; //init to silence compiler warning
    int type;
    int ret;

    hdr = avio_r8(pb); len--;
    type = hdr >> 6;

    if(type != 3){  // not frame as a part of packet
        seq = avio_r8(pb); len--;
    }
    if(type != 1){  // not whole frame
        len2 = get_num(pb, &len);
        pos  = get_num(pb, &len);
        pic_num = avio_r8(pb); len--;
    }
    if(len<0) {
        av_log(s, AV_LOG_ERROR, "Insufficient data\n");
        return -1;
    }
    rm->remaining_len = len;
    if(type&1){     // frame, not slice
        if(type == 3){  // frame as a part of packet
            len= len2;
            *timestamp = pos;
        }
        if(rm->remaining_len < len) {
            av_log(s, AV_LOG_ERROR, "Insufficient remaining len\n");
            return -1;
        }
        rm->remaining_len -= len;
        if(av_new_packet(pkt, len + 9) < 0)
            return AVERROR(EIO);
        pkt->data[0] = 0;
        AV_WL32(pkt->data + 1, 1);
        AV_WL32(pkt->data + 5, 0);
        if ((ret = avio_read(pb, pkt->data + 9, len)) != len) {
            av_packet_unref(pkt);
            av_log(s, AV_LOG_ERROR, "Failed to read %d bytes\n", len);
            return ret < 0 ? ret : AVERROR(EIO);
        }
        return 0;
    }
    //now we have to deal with single slice

    *pseq = seq;
    if((seq & 0x7F) == 1 || vst->curpic_num != pic_num){
        if (len2 > ffio_limit(pb, len2)) {
            av_log(s, AV_LOG_ERROR, "Impossibly sized packet\n");
            return AVERROR_INVALIDDATA;
        }
        vst->slices = ((hdr & 0x3F) << 1) + 1;
        vst->videobufsize = len2 + 8*vst->slices + 1;
        av_packet_unref(&vst->pkt); //FIXME this should be output.
        if(av_new_packet(&vst->pkt, vst->videobufsize) < 0)
            return AVERROR(ENOMEM);
        memset(vst->pkt.data, 0, vst->pkt.size);
        vst->videobufpos = 8*vst->slices + 1;
        vst->cur_slice = 0;
        vst->curpic_num = pic_num;
        vst->pktpos = avio_tell(pb);
    }
    if(type == 2)
        len = FFMIN(len, pos);

    if(++vst->cur_slice > vst->slices) {
        av_log(s, AV_LOG_ERROR, "cur slice %d, too large\n", vst->cur_slice);
        return 1;
    }
    if(!vst->pkt.data)
        return AVERROR(ENOMEM);
    AV_WL32(vst->pkt.data - 7 + 8*vst->cur_slice, 1);
    AV_WL32(vst->pkt.data - 3 + 8*vst->cur_slice, vst->videobufpos - 8*vst->slices - 1);
    if(vst->videobufpos + len > vst->videobufsize) {
        av_log(s, AV_LOG_ERROR, "outside videobufsize\n");
        return 1;
    }
    if (avio_read(pb, vst->pkt.data + vst->videobufpos, len) != len)
        return AVERROR(EIO);
    vst->videobufpos += len;
    rm->remaining_len-= len;

    if (type == 2 || vst->videobufpos == vst->videobufsize) {
        vst->pkt.data[0] = vst->cur_slice-1;
        *pkt= vst->pkt;
        vst->pkt.data= NULL;
        vst->pkt.size= 0;
        vst->pkt.buf = NULL;
        if(vst->slices != vst->cur_slice) //FIXME find out how to set slices correct from the begin
            memmove(pkt->data + 1 + 8*vst->cur_slice, pkt->data + 1 + 8*vst->slices,
                vst->videobufpos - 1 - 8*vst->slices);
        pkt->size = vst->videobufpos + 8*(vst->cur_slice - vst->slices);
        pkt->pts = AV_NOPTS_VALUE;
        pkt->pos = vst->pktpos;
        vst->slices = 0;
        return 0;
    }

    return 1;
}

static inline void
rm_ac3_swap_bytes (AVStream *st, AVPacket *pkt)
{
    uint8_t *ptr;
    int j;

    if (st->codecpar->codec_id == AV_CODEC_ID_AC3) {
        ptr = pkt->data;
        for (j=0;j<pkt->size;j+=2) {
            FFSWAP(int, ptr[0], ptr[1]);
            ptr += 2;
        }
    }
}

static int readfull(AVFormatContext *s, AVIOContext *pb, uint8_t *dst, int n) {
    int ret = avio_read(pb, dst, n);
    if (ret != n) {
        if (ret >= 0) memset(dst + ret, 0, n - ret);
        else          memset(dst      , 0, n);
        av_log(s, AV_LOG_ERROR, "Failed to fully read block\n");
    }
    return ret;
}

int
ff_rm_parse_packet (AVFormatContext *s, AVIOContext *pb,
                    AVStream *st, RMStream *ast, int len, AVPacket *pkt,
                    int *seq, int flags, int64_t timestamp)
{
    RMDemuxContext *rm = s->priv_data;
    int ret;

    if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
        rm->current_stream= st->id;
        ret = rm_assemble_video_frame(s, pb, rm, ast, pkt, len, seq, &timestamp);
        if(ret)
            return ret < 0 ? ret : -1; //got partial frame or error
    } else if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
        if ((ast->deint_id == DEINT_ID_GENR) ||
            (ast->deint_id == DEINT_ID_INT4) ||
            (ast->deint_id == DEINT_ID_SIPR)) {
            int x;
            int sps = ast->sub_packet_size;
            int cfs = ast->coded_framesize;
            int h = ast->sub_packet_h;
            int y = ast->sub_packet_cnt;
            int w = ast->audio_framesize;

            if (flags & 2)
                y = ast->sub_packet_cnt = 0;
            if (!y)
                ast->audiotimestamp = timestamp;

            switch (ast->deint_id) {
                case DEINT_ID_INT4:
                    for (x = 0; x < h/2; x++)
                        readfull(s, pb, ast->pkt.data+x*2*w+y*cfs, cfs);
                    break;
                case DEINT_ID_GENR:
                    for (x = 0; x < w/sps; x++)
                        readfull(s, pb, ast->pkt.data+sps*(h*x+((h+1)/2)*(y&1)+(y>>1)), sps);
                    break;
                case DEINT_ID_SIPR:
                    readfull(s, pb, ast->pkt.data + y * w, w);
                    break;
            }

            if (++(ast->sub_packet_cnt) < h)
                return -1;
            if (ast->deint_id == DEINT_ID_SIPR)
                ff_rm_reorder_sipr_data(ast->pkt.data, h, w);

             ast->sub_packet_cnt = 0;
             rm->audio_stream_num = st->index;
            if (st->codecpar->block_align <= 0) {
                av_log(s, AV_LOG_ERROR, "Invalid block alignment %d\n", st->codecpar->block_align);
                return AVERROR_INVALIDDATA;
            }
             rm->audio_pkt_cnt = h * w / st->codecpar->block_align;
        } else if ((ast->deint_id == DEINT_ID_VBRF) ||
                   (ast->deint_id == DEINT_ID_VBRS)) {
            int x;
            rm->audio_stream_num = st->index;
            ast->sub_packet_cnt = (avio_rb16(pb) & 0xf0) >> 4;
            if (ast->sub_packet_cnt) {
                for (x = 0; x < ast->sub_packet_cnt; x++)
                    ast->sub_packet_lengths[x] = avio_rb16(pb);
                rm->audio_pkt_cnt = ast->sub_packet_cnt;
                ast->audiotimestamp = timestamp;
            } else
                return -1;
        } else {
            ret = av_get_packet(pb, pkt, len);
            if (ret < 0)
                return ret;
            rm_ac3_swap_bytes(st, pkt);
        }
    } else {
        ret = av_get_packet(pb, pkt, len);
        if (ret < 0)
            return ret;
    }

    pkt->stream_index = st->index;

    pkt->pts = timestamp;
    if (flags & 2)
        pkt->flags |= AV_PKT_FLAG_KEY;

    return st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO ? rm->audio_pkt_cnt : 0;
}

int
ff_rm_retrieve_cache (AVFormatContext *s, AVIOContext *pb,
                      AVStream *st, RMStream *ast, AVPacket *pkt)
{
    RMDemuxContext *rm = s->priv_data;
    int ret;

    av_assert0 (rm->audio_pkt_cnt > 0);

    if (ast->deint_id == DEINT_ID_VBRF ||
        ast->deint_id == DEINT_ID_VBRS) {
        ret = av_get_packet(pb, pkt, ast->sub_packet_lengths[ast->sub_packet_cnt - rm->audio_pkt_cnt]);
        if (ret < 0)
            return ret;
    } else {
        ret = av_new_packet(pkt, st->codecpar->block_align);
        if (ret < 0)
            return ret;
        memcpy(pkt->data, ast->pkt.data + st->codecpar->block_align * //FIXME avoid this
               (ast->sub_packet_h * ast->audio_framesize / st->codecpar->block_align - rm->audio_pkt_cnt),
               st->codecpar->block_align);
    }
    rm->audio_pkt_cnt--;
    if ((pkt->pts = ast->audiotimestamp) != AV_NOPTS_VALUE) {
        ast->audiotimestamp = AV_NOPTS_VALUE;
        pkt->flags = AV_PKT_FLAG_KEY;
    } else
        pkt->flags = 0;
    pkt->stream_index = st->index;

    return rm->audio_pkt_cnt;
}

static int rm_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    RMDemuxContext *rm = s->priv_data;
    AVStream *st = NULL; // init to silence compiler warning
    int i, len, res, seq = 1;
    int64_t timestamp, pos;
    int flags;

    for (;;) {
        if (rm->audio_pkt_cnt) {
            // If there are queued audio packet return them first
            st = s->streams[rm->audio_stream_num];
            res = ff_rm_retrieve_cache(s, s->pb, st, st->priv_data, pkt);
            if(res < 0)
                return res;
            flags = 0;
        } else {
            if (rm->old_format) {
                RMStream *ast;

                st = s->streams[0];
                ast = st->priv_data;
                timestamp = AV_NOPTS_VALUE;
                len = !ast->audio_framesize ? RAW_PACKET_SIZE :
                    ast->coded_framesize * ast->sub_packet_h / 2;
                flags = (seq++ == 1) ? 2 : 0;
                pos = avio_tell(s->pb);
            } else {
                len = rm_sync(s, &timestamp, &flags, &i, &pos);
                if (len > 0)
                    st = s->streams[i];
            }

            if (avio_feof(s->pb))
                return AVERROR_EOF;
            if (len <= 0)
                return AVERROR(EIO);

            res = ff_rm_parse_packet (s, s->pb, st, st->priv_data, len, pkt,
                                      &seq, flags, timestamp);
            if (res < -1)
                return res;
            if((flags&2) && (seq&0x7F) == 1)
                av_add_index_entry(st, pos, timestamp, 0, 0, AVINDEX_KEYFRAME);
            if (res)
                continue;
        }

        if(  (st->discard >= AVDISCARD_NONKEY && !(flags&2))
           || st->discard >= AVDISCARD_ALL){
            av_packet_unref(pkt);
        } else
            break;
    }

    return 0;
}

static int rm_read_close(AVFormatContext *s)
{
    int i;

    for (i=0;i<s->nb_streams;i++)
        ff_rm_free_rmstream(s->streams[i]->priv_data);

    return 0;
}

static int rm_probe(AVProbeData *p)
{
    /* check file header */
    if ((p->buf[0] == '.' && p->buf[1] == 'R' &&
         p->buf[2] == 'M' && p->buf[3] == 'F' &&
         p->buf[4] == 0 && p->buf[5] == 0) ||
        (p->buf[0] == '.' && p->buf[1] == 'r' &&
         p->buf[2] == 'a' && p->buf[3] == 0xfd))
        return AVPROBE_SCORE_MAX;
    else
        return 0;
}

static int64_t rm_read_dts(AVFormatContext *s, int stream_index,
                               int64_t *ppos, int64_t pos_limit)
{
    RMDemuxContext *rm = s->priv_data;
    int64_t pos, dts;
    int stream_index2, flags, len, h;

    pos = *ppos;

    if(rm->old_format)
        return AV_NOPTS_VALUE;

    if (avio_seek(s->pb, pos, SEEK_SET) < 0)
        return AV_NOPTS_VALUE;

    rm->remaining_len=0;
    for(;;){
        int seq=1;
        AVStream *st;

        len = rm_sync(s, &dts, &flags, &stream_index2, &pos);
        if(len<0)
            return AV_NOPTS_VALUE;

        st = s->streams[stream_index2];
        if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
            h= avio_r8(s->pb); len--;
            if(!(h & 0x40)){
                seq = avio_r8(s->pb); len--;
            }
        }

        if((flags&2) && (seq&0x7F) == 1){
            av_log(s, AV_LOG_TRACE, "%d %d-%d %"PRId64" %d\n",
                    flags, stream_index2, stream_index, dts, seq);
            av_add_index_entry(st, pos, dts, 0, 0, AVINDEX_KEYFRAME);
            if(stream_index2 == stream_index)
                break;
        }

        avio_skip(s->pb, len);
    }
    *ppos = pos;
    return dts;
}

static int rm_read_seek(AVFormatContext *s, int stream_index,
                        int64_t pts, int flags)
{
    RMDemuxContext *rm = s->priv_data;

    if (ff_seek_frame_binary(s, stream_index, pts, flags) < 0)
        return -1;
    rm->audio_pkt_cnt = 0;
    return 0;
}


AVInputFormat ff_rm_demuxer = {
    .name           = "rm",
    .long_name      = NULL_IF_CONFIG_SMALL("RealMedia"),
    .priv_data_size = sizeof(RMDemuxContext),
    .read_probe     = rm_probe,
    .read_header    = rm_read_header,
    .read_packet    = rm_read_packet,
    .read_close     = rm_read_close,
    .read_timestamp = rm_read_dts,
    .read_seek      = rm_read_seek,
};

AVInputFormat ff_rdt_demuxer = {
    .name           = "rdt",
    .long_name      = NULL_IF_CONFIG_SMALL("RDT demuxer"),
    .priv_data_size = sizeof(RMDemuxContext),
    .read_close     = rm_read_close,
    .flags          = AVFMT_NOFILE,
};

static int ivr_probe(AVProbeData *p)
{
    if (memcmp(p->buf, ".R1M\x0\x1\x1", 7) &&
        memcmp(p->buf, ".REC", 4))
        return 0;

    return AVPROBE_SCORE_MAX;
}

static int ivr_read_header(AVFormatContext *s)
{
    unsigned tag, type, len, tlen, value;
    int i, j, n, count, nb_streams = 0, ret;
    uint8_t key[256], val[256];
    AVIOContext *pb = s->pb;
    AVStream *st;
    int64_t pos, offset, temp;

    pos = avio_tell(pb);
    tag = avio_rl32(pb);
    if (tag == MKTAG('.','R','1','M')) {
        if (avio_rb16(pb) != 1)
            return AVERROR_INVALIDDATA;
        if (avio_r8(pb) != 1)
            return AVERROR_INVALIDDATA;
        len = avio_rb32(pb);
        avio_skip(pb, len);
        avio_skip(pb, 5);
        temp = avio_rb64(pb);
        while (!avio_feof(pb) && temp) {
            offset = temp;
            temp = avio_rb64(pb);
        }
        avio_skip(pb, offset - avio_tell(pb));
        if (avio_r8(pb) != 1)
            return AVERROR_INVALIDDATA;
        len = avio_rb32(pb);
        avio_skip(pb, len);
        if (avio_r8(pb) != 2)
            return AVERROR_INVALIDDATA;
        avio_skip(pb, 16);
        pos = avio_tell(pb);
        tag = avio_rl32(pb);
    }

    if (tag != MKTAG('.','R','E','C'))
        return AVERROR_INVALIDDATA;

    if (avio_r8(pb) != 0)
        return AVERROR_INVALIDDATA;
    count = avio_rb32(pb);
    for (i = 0; i < count; i++) {
        if (avio_feof(pb))
            return AVERROR_INVALIDDATA;

        type = avio_r8(pb);
        tlen = avio_rb32(pb);
        avio_get_str(pb, tlen, key, sizeof(key));
        len = avio_rb32(pb);
        if (type == 5) {
            avio_get_str(pb, len, val, sizeof(val));
            av_log(s, AV_LOG_DEBUG, "%s = '%s'\n", key, val);
        } else if (type == 4) {
            av_log(s, AV_LOG_DEBUG, "%s = '0x", key);
            for (j = 0; j < len; j++) {
                if (avio_feof(pb))
                    return AVERROR_INVALIDDATA;
                av_log(s, AV_LOG_DEBUG, "%X", avio_r8(pb));
            }
            av_log(s, AV_LOG_DEBUG, "'\n");
        } else if (len == 4 && type == 3 && !strncmp(key, "StreamCount", tlen)) {
            nb_streams = value = avio_rb32(pb);
        } else if (len == 4 && type == 3) {
            value = avio_rb32(pb);
            av_log(s, AV_LOG_DEBUG, "%s = %d\n", key, value);
        } else {
            av_log(s, AV_LOG_DEBUG, "Skipping unsupported key: %s\n", key);
            avio_skip(pb, len);
        }
    }

    for (n = 0; n < nb_streams; n++) {
        st = avformat_new_stream(s, NULL);
        if (!st)
            return AVERROR(ENOMEM);
        st->priv_data = ff_rm_alloc_rmstream();
        if (!st->priv_data)
            return AVERROR(ENOMEM);

        if (avio_r8(pb) != 1)
            return AVERROR_INVALIDDATA;

        count = avio_rb32(pb);
        for (i = 0; i < count; i++) {
            if (avio_feof(pb))
                return AVERROR_INVALIDDATA;

            type = avio_r8(pb);
            tlen  = avio_rb32(pb);
            avio_get_str(pb, tlen, key, sizeof(key));
            len  = avio_rb32(pb);
            if (type == 5) {
                avio_get_str(pb, len, val, sizeof(val));
                av_log(s, AV_LOG_DEBUG, "%s = '%s'\n", key, val);
            } else if (type == 4 && !strncmp(key, "OpaqueData", tlen)) {
                ret = ffio_ensure_seekback(pb, 4);
                if (ret < 0)
                    return ret;
                if (avio_rb32(pb) == MKBETAG('M', 'L', 'T', 'I')) {
                    ret = rm_read_multi(s, pb, st, NULL);
                } else {
                    avio_seek(pb, -4, SEEK_CUR);
                    ret = ff_rm_read_mdpr_codecdata(s, pb, st, st->priv_data, len, NULL);
                }

                if (ret < 0)
                    return ret;
            } else if (type == 4) {
                int j;

                av_log(s, AV_LOG_DEBUG, "%s = '0x", key);
                for (j = 0; j < len; j++)
                    av_log(s, AV_LOG_DEBUG, "%X", avio_r8(pb));
                av_log(s, AV_LOG_DEBUG, "'\n");
            } else if (len == 4 && type == 3 && !strncmp(key, "Duration", tlen)) {
                st->duration = avio_rb32(pb);
            } else if (len == 4 && type == 3) {
                value = avio_rb32(pb);
                av_log(s, AV_LOG_DEBUG, "%s = %d\n", key, value);
            } else {
                av_log(s, AV_LOG_DEBUG, "Skipping unsupported key: %s\n", key);
                avio_skip(pb, len);
            }
        }
    }

    if (avio_r8(pb) != 6)
        return AVERROR_INVALIDDATA;
    avio_skip(pb, 12);
    avio_skip(pb, avio_rb64(pb) + pos - avio_tell(s->pb));
    if (avio_r8(pb) != 8)
        return AVERROR_INVALIDDATA;
    avio_skip(pb, 8);

    return 0;
}

static int ivr_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    RMDemuxContext *rm = s->priv_data;
    int ret = AVERROR_EOF, opcode;
    AVIOContext *pb = s->pb;
    unsigned size, index;
    int64_t pos, pts;

    if (avio_feof(pb) || rm->data_end)
        return AVERROR_EOF;

    pos = avio_tell(pb);

    for (;;) {
        if (rm->audio_pkt_cnt) {
            // If there are queued audio packet return them first
            AVStream *st;

            st = s->streams[rm->audio_stream_num];
            ret = ff_rm_retrieve_cache(s, pb, st, st->priv_data, pkt);
            if (ret < 0) {
                return ret;
            }
        } else {
            if (rm->remaining_len) {
                avio_skip(pb, rm->remaining_len);
                rm->remaining_len = 0;
            }

            if (avio_feof(pb))
                return AVERROR_EOF;

            opcode = avio_r8(pb);
            if (opcode == 2) {
                AVStream *st;
                int seq = 1;

                pts = avio_rb32(pb);
                index = avio_rb16(pb);
                if (index >= s->nb_streams)
                    return AVERROR_INVALIDDATA;

                avio_skip(pb, 4);
                size = avio_rb32(pb);
                avio_skip(pb, 4);

                if (size < 1 || size > INT_MAX/4) {
                    av_log(s, AV_LOG_ERROR, "size %u is invalid\n", size);
                    return AVERROR_INVALIDDATA;
                }

                st = s->streams[index];
                ret = ff_rm_parse_packet(s, pb, st, st->priv_data, size, pkt,
                                         &seq, 0, pts);
                if (ret < -1) {
                    return ret;
                } else if (ret) {
                    continue;
                }

                pkt->pos = pos;
                pkt->pts = pts;
                pkt->stream_index = index;
            } else if (opcode == 7) {
                pos = avio_rb64(pb);
                if (!pos) {
                    rm->data_end = 1;
                    return AVERROR_EOF;
                }
            } else {
                av_log(s, AV_LOG_ERROR, "Unsupported opcode=%d at %"PRIX64"\n", opcode, avio_tell(pb) - 1);
                return AVERROR(EIO);
            }
        }

        break;
    }

    return ret;
}

AVInputFormat ff_ivr_demuxer = {
    .name           = "ivr",
    .long_name      = NULL_IF_CONFIG_SMALL("IVR (Internet Video Recording)"),
    .priv_data_size = sizeof(RMDemuxContext),
    .read_probe     = ivr_probe,
    .read_header    = ivr_read_header,
    .read_packet    = ivr_read_packet,
    .read_close     = rm_read_close,
    .extensions     = "ivr",
};