PeerStreamer

/*

 * "NUT" Container Format demuxer

 * Copyright (c) 2004-2006 Michael Niedermayer

 * Copyright (c) 2003 Alex Beregszaszi

 *

 * 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 <strings.h>

#include "libavutil/avstring.h"

#include "libavutil/bswap.h"

#include "libavutil/tree.h"

#include "nut.h"

#undef NDEBUG

#include <assert.h>

#if FF_API_MAX_STREAMS

#define NUT_MAX_STREAMS MAX_STREAMS

#else

#define NUT_MAX_STREAMS 256    /* arbitrary sanity check value */

#endif

static int get_str(AVIOContext *bc, char *string, unsigned int maxlen){

    unsigned int len= ff_get_v(bc);

    if(len && maxlen)

        avio_read(bc, string, FFMIN(len, maxlen));

    while(len > maxlen){

        avio_r8(bc);

        len--;

    }

    if(maxlen)

        string[FFMIN(len, maxlen-1)]= 0;

    if(maxlen == len)

        return -1;

    else

        return 0;

}

static int64_t get_s(AVIOContext *bc){

    int64_t v = ff_get_v(bc) + 1;

    if (v&1) return -(v>>1);

    else     return  (v>>1);

}

static uint64_t get_fourcc(AVIOContext *bc){

    unsigned int len= ff_get_v(bc);

    if     (len==2) return avio_rl16(bc);

    else if(len==4) return avio_rl32(bc);

    else            return -1;

}

#ifdef TRACE

static inline uint64_t get_v_trace(AVIOContext *bc, char *file, char *func, int line){

    uint64_t v= ff_get_v(bc);

    av_log(NULL, AV_LOG_DEBUG, "get_v %5"PRId64" / %"PRIX64" in %s %s:%d\n", v, v, file, func, line);

    return v;

}

static inline int64_t get_s_trace(AVIOContext *bc, char *file, char *func, int line){

    int64_t v= get_s(bc);

    av_log(NULL, AV_LOG_DEBUG, "get_s %5"PRId64" / %"PRIX64" in %s %s:%d\n", v, v, file, func, line);

    return v;

}

static inline uint64_t get_vb_trace(AVIOContext *bc, char *file, char *func, int line){

    uint64_t v= get_vb(bc);

    av_log(NULL, AV_LOG_DEBUG, "get_vb %5"PRId64" / %"PRIX64" in %s %s:%d\n", v, v, file, func, line);

    return v;

}

#define ff_get_v(bc)  get_v_trace(bc, __FILE__, __PRETTY_FUNCTION__, __LINE__)

#define get_s(bc)  get_s_trace(bc, __FILE__, __PRETTY_FUNCTION__, __LINE__)

#define get_vb(bc)  get_vb_trace(bc, __FILE__, __PRETTY_FUNCTION__, __LINE__)

#endif

static int get_packetheader(NUTContext *nut, AVIOContext *bc, int calculate_checksum, uint64_t startcode)

{

    int64_t size;

//    start= avio_tell(bc) - 8;

    startcode= av_be2ne64(startcode);

    startcode= ff_crc04C11DB7_update(0, (uint8_t*)&startcode, 8);

    init_checksum(bc, ff_crc04C11DB7_update, startcode);

    size= ff_get_v(bc);

    if(size > 4096)

        avio_rb32(bc);

    if(get_checksum(bc) && size > 4096)

        return -1;

    init_checksum(bc, calculate_checksum ? ff_crc04C11DB7_update : NULL, 0);

    return size;

}

static uint64_t find_any_startcode(AVIOContext *bc, int64_t pos){

    uint64_t state=0;

    if(pos >= 0)

        avio_seek(bc, pos, SEEK_SET); //note, this may fail if the stream is not seekable, but that should not matter, as in this case we simply start where we currently are

    while(!bc->eof_reached){

        state= (state<<8) | avio_r8(bc);

        if((state>>56) != 'N')

            continue;

        switch(state){

        case MAIN_STARTCODE:

        case STREAM_STARTCODE:

        case SYNCPOINT_STARTCODE:

        case INFO_STARTCODE:

        case INDEX_STARTCODE:

            return state;

        }

    }

    return 0;

}

/**

 * Find the given startcode.

 * @param code the startcode

 * @param pos the start position of the search, or -1 if the current position

 * @return the position of the startcode or -1 if not found

 */

static int64_t find_startcode(AVIOContext *bc, uint64_t code, int64_t pos){

    for(;;){

        uint64_t startcode= find_any_startcode(bc, pos);

        if(startcode == code)

            return avio_tell(bc) - 8;

        else if(startcode == 0)

            return -1;

        pos=-1;

    }

}

static int nut_probe(AVProbeData *p){

    int i;

    uint64_t code= 0;

    for (i = 0; i < p->buf_size; i++) {

        code = (code << 8) | p->buf[i];

        if (code == MAIN_STARTCODE)

            return AVPROBE_SCORE_MAX;

    }

    return 0;

}

#define GET_V(dst, check) \

    tmp= ff_get_v(bc);\

    if(!(check)){\

        av_log(s, AV_LOG_ERROR, "Error " #dst " is (%"PRId64")\n", tmp);\

        return -1;\

    }\

    dst= tmp;

static int skip_reserved(AVIOContext *bc, int64_t pos){

    pos -= avio_tell(bc);

    if(pos<0){

        avio_seek(bc, pos, SEEK_CUR);

        return -1;

    }else{

        while(pos--)

            avio_r8(bc);

        return 0;

    }

}

static int decode_main_header(NUTContext *nut){

    AVFormatContext *s= nut->avf;

    AVIOContext *bc = s->pb;

    uint64_t tmp, end;

    unsigned int stream_count;

    int i, j, tmp_stream, tmp_mul, tmp_pts, tmp_size, count, tmp_res, tmp_head_idx;

    int64_t tmp_match;

    end= get_packetheader(nut, bc, 1, MAIN_STARTCODE);

    end += avio_tell(bc);

    GET_V(tmp              , tmp >=2 && tmp <= 3)

    GET_V(stream_count     , tmp > 0 && tmp <= NUT_MAX_STREAMS)

    nut->max_distance = ff_get_v(bc);

    if(nut->max_distance > 65536){

        av_log(s, AV_LOG_DEBUG, "max_distance %d\n", nut->max_distance);

        nut->max_distance= 65536;

    }

    GET_V(nut->time_base_count, tmp>0 && tmp<INT_MAX / sizeof(AVRational))

    nut->time_base= av_malloc(nut->time_base_count * sizeof(AVRational));

    for(i=0; i<nut->time_base_count; i++){

        GET_V(nut->time_base[i].num, tmp>0 && tmp<(1ULL<<31))

        GET_V(nut->time_base[i].den, tmp>0 && tmp<(1ULL<<31))

        if(av_gcd(nut->time_base[i].num, nut->time_base[i].den) != 1){

            av_log(s, AV_LOG_ERROR, "time base invalid\n");

            return AVERROR_INVALIDDATA;

        }

    }

    tmp_pts=0;

    tmp_mul=1;

    tmp_stream=0;

    tmp_match= 1-(1LL<<62);

    tmp_head_idx= 0;

    for(i=0; i<256;){

        int tmp_flags = ff_get_v(bc);

        int tmp_fields= ff_get_v(bc);

        if(tmp_fields>0) tmp_pts   = get_s(bc);

        if(tmp_fields>1) tmp_mul   = ff_get_v(bc);

        if(tmp_fields>2) tmp_stream= ff_get_v(bc);

        if(tmp_fields>3) tmp_size  = ff_get_v(bc);

        else             tmp_size  = 0;

        if(tmp_fields>4) tmp_res   = ff_get_v(bc);

        else             tmp_res   = 0;

        if(tmp_fields>5) count     = ff_get_v(bc);

        else             count     = tmp_mul - tmp_size;

        if(tmp_fields>6) tmp_match = get_s(bc);

        if(tmp_fields>7) tmp_head_idx= ff_get_v(bc);

        while(tmp_fields-- > 8)

           ff_get_v(bc);

        if(count == 0 || i+count > 256){

            av_log(s, AV_LOG_ERROR, "illegal count %d at %d\n", count, i);

            return AVERROR_INVALIDDATA;

        }

        if(tmp_stream >= stream_count){

            av_log(s, AV_LOG_ERROR, "illegal stream number\n");

            return AVERROR_INVALIDDATA;

        }

        for(j=0; j<count; j++,i++){

            if (i == 'N') {

                nut->frame_code[i].flags= FLAG_INVALID;

                j--;

                continue;

            }

            nut->frame_code[i].flags           = tmp_flags ;

            nut->frame_code[i].pts_delta       = tmp_pts   ;

            nut->frame_code[i].stream_id       = tmp_stream;

            nut->frame_code[i].size_mul        = tmp_mul   ;

            nut->frame_code[i].size_lsb        = tmp_size+j;

            nut->frame_code[i].reserved_count  = tmp_res   ;

            nut->frame_code[i].header_idx      = tmp_head_idx;

        }

    }

    assert(nut->frame_code['N'].flags == FLAG_INVALID);

    if(end > avio_tell(bc) + 4){

        int rem= 1024;

        GET_V(nut->header_count, tmp<128U)

        nut->header_count++;

        for(i=1; i<nut->header_count; i++){

            GET_V(nut->header_len[i], tmp>0 && tmp<256);

            rem -= nut->header_len[i];

            if(rem < 0){

                av_log(s, AV_LOG_ERROR, "invalid elision header\n");

                return AVERROR_INVALIDDATA;

            }

            nut->header[i]= av_malloc(nut->header_len[i]);

            avio_read(bc, nut->header[i], nut->header_len[i]);

        }

        assert(nut->header_len[0]==0);

    }

    if(skip_reserved(bc, end) || get_checksum(bc)){

        av_log(s, AV_LOG_ERROR, "main header checksum mismatch\n");

        return AVERROR_INVALIDDATA;

    }

    nut->stream = av_mallocz(sizeof(StreamContext)*stream_count);

    for(i=0; i<stream_count; i++){

        av_new_stream(s, i);

    }

    return 0;

}

static int decode_stream_header(NUTContext *nut){

    AVFormatContext *s= nut->avf;

    AVIOContext *bc = s->pb;

    StreamContext *stc;

    int class, stream_id;

    uint64_t tmp, end;

    AVStream *st;

    end= get_packetheader(nut, bc, 1, STREAM_STARTCODE);

    end += avio_tell(bc);

    GET_V(stream_id, tmp < s->nb_streams && !nut->stream[tmp].time_base);

    stc= &nut->stream[stream_id];

    st = s->streams[stream_id];

    if (!st)

        return AVERROR(ENOMEM);

    class = ff_get_v(bc);

    tmp = get_fourcc(bc);

    st->codec->codec_tag= tmp;

    switch(class)

    {

        case 0:

            st->codec->codec_type = AVMEDIA_TYPE_VIDEO;

            st->codec->codec_id = av_codec_get_id(

                (const AVCodecTag * const []) { ff_codec_bmp_tags, ff_nut_video_tags, 0 },

                tmp);

            break;

        case 1:

            st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

            st->codec->codec_id = ff_codec_get_id(ff_codec_wav_tags, tmp);

            break;

        case 2:

            st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;

            st->codec->codec_id = ff_codec_get_id(ff_nut_subtitle_tags, tmp);

            break;

        case 3:

            st->codec->codec_type = AVMEDIA_TYPE_DATA;

            break;

        default:

            av_log(s, AV_LOG_ERROR, "unknown stream class (%d)\n", class);

            return -1;

    }

    if(class<3 && st->codec->codec_id == CODEC_ID_NONE)

        av_log(s, AV_LOG_ERROR, "Unknown codec tag '0x%04x' for stream number %d\n",

               (unsigned int)tmp, stream_id);

    GET_V(stc->time_base_id    , tmp < nut->time_base_count);

    GET_V(stc->msb_pts_shift   , tmp < 16);

    stc->max_pts_distance= ff_get_v(bc);

    GET_V(stc->decode_delay    , tmp < 1000); //sanity limit, raise this if Moore's law is true

    st->codec->has_b_frames= stc->decode_delay;

    ff_get_v(bc); //stream flags

    GET_V(st->codec->extradata_size, tmp < (1<<30));

    if(st->codec->extradata_size){

        st->codec->extradata= av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);

        avio_read(bc, st->codec->extradata, st->codec->extradata_size);

    }

    if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO){

        GET_V(st->codec->width , tmp > 0)

        GET_V(st->codec->height, tmp > 0)

        st->sample_aspect_ratio.num= ff_get_v(bc);

        st->sample_aspect_ratio.den= ff_get_v(bc);

        if((!st->sample_aspect_ratio.num) != (!st->sample_aspect_ratio.den)){

            av_log(s, AV_LOG_ERROR, "invalid aspect ratio %d/%d\n", st->sample_aspect_ratio.num, st->sample_aspect_ratio.den);

            return -1;

        }

        ff_get_v(bc); /* csp type */

    }else if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO){

        GET_V(st->codec->sample_rate , tmp > 0)

        ff_get_v(bc); // samplerate_den

        GET_V(st->codec->channels, tmp > 0)

    }

    if(skip_reserved(bc, end) || get_checksum(bc)){

        av_log(s, AV_LOG_ERROR, "stream header %d checksum mismatch\n", stream_id);

        return -1;

    }

    stc->time_base= &nut->time_base[stc->time_base_id];

    av_set_pts_info(s->streams[stream_id], 63, stc->time_base->num, stc->time_base->den);

    return 0;

}

static void set_disposition_bits(AVFormatContext* avf, char* value, int stream_id){

    int flag = 0, i;

    for (i=0; ff_nut_dispositions[i].flag; ++i) {

        if (!strcmp(ff_nut_dispositions[i].str, value))

            flag = ff_nut_dispositions[i].flag;

    }

    if (!flag)

        av_log(avf, AV_LOG_INFO, "unknown disposition type '%s'\n", value);

    for (i = 0; i < avf->nb_streams; ++i)

        if (stream_id == i || stream_id == -1)

            avf->streams[i]->disposition |= flag;

}

static int decode_info_header(NUTContext *nut){

    AVFormatContext *s= nut->avf;

    AVIOContext *bc = s->pb;

    uint64_t tmp, chapter_start, chapter_len;

    unsigned int stream_id_plus1, count;

    int chapter_id, i;

    int64_t value, end;

    char name[256], str_value[1024], type_str[256];

    const char *type;

    AVChapter *chapter= NULL;

    AVStream *st= NULL;

    AVMetadata **metadata = NULL;

    end= get_packetheader(nut, bc, 1, INFO_STARTCODE);

    end += avio_tell(bc);

    GET_V(stream_id_plus1, tmp <= s->nb_streams)

    chapter_id   = get_s(bc);

    chapter_start= ff_get_v(bc);

    chapter_len  = ff_get_v(bc);

    count        = ff_get_v(bc);

    if(chapter_id && !stream_id_plus1){

        int64_t start= chapter_start / nut->time_base_count;

        chapter= ff_new_chapter(s, chapter_id,

                                nut->time_base[chapter_start % nut->time_base_count],

                                start, start + chapter_len, NULL);

        metadata = &chapter->metadata;

    } else if(stream_id_plus1) {

        st= s->streams[stream_id_plus1 - 1];

        metadata = &st->metadata;

    } else

        metadata = &s->metadata;

    for(i=0; i<count; i++){

        get_str(bc, name, sizeof(name));

        value= get_s(bc);

        if(value == -1){

            type= "UTF-8";

            get_str(bc, str_value, sizeof(str_value));

        }else if(value == -2){

            get_str(bc, type_str, sizeof(type_str));

            type= type_str;

            get_str(bc, str_value, sizeof(str_value));

        }else if(value == -3){

            type= "s";

            value= get_s(bc);

        }else if(value == -4){

            type= "t";

            value= ff_get_v(bc);

        }else if(value < -4){

            type= "r";

            get_s(bc);

        }else{

            type= "v";

        }

        if (stream_id_plus1 > s->nb_streams) {

            av_log(s, AV_LOG_ERROR, "invalid stream id for info packet\n");

            continue;

        }

        if(!strcmp(type, "UTF-8")){

            if(chapter_id==0 && !strcmp(name, "Disposition")) {

                set_disposition_bits(s, str_value, stream_id_plus1 - 1);

                continue;

            }

            if(metadata && strcasecmp(name,"Uses")

               && strcasecmp(name,"Depends") && strcasecmp(name,"Replaces"))

                av_metadata_set2(metadata, name, str_value, 0);

        }

    }

    if(skip_reserved(bc, end) || get_checksum(bc)){

        av_log(s, AV_LOG_ERROR, "info header checksum mismatch\n");

        return -1;

    }

    return 0;

}

static int decode_syncpoint(NUTContext *nut, int64_t *ts, int64_t *back_ptr){

    AVFormatContext *s= nut->avf;

    AVIOContext *bc = s->pb;

    int64_t end, tmp;

    nut->last_syncpoint_pos= avio_tell(bc)-8;

    end= get_packetheader(nut, bc, 1, SYNCPOINT_STARTCODE);

    end += avio_tell(bc);

    tmp= ff_get_v(bc);

    *back_ptr= nut->last_syncpoint_pos - 16*ff_get_v(bc);

    if(*back_ptr < 0)

        return -1;

    ff_nut_reset_ts(nut, nut->time_base[tmp % nut->time_base_count], tmp / nut->time_base_count);

    if(skip_reserved(bc, end) || get_checksum(bc)){

        av_log(s, AV_LOG_ERROR, "sync point checksum mismatch\n");

        return -1;

    }

    *ts= tmp / s->nb_streams * av_q2d(nut->time_base[tmp % s->nb_streams])*AV_TIME_BASE;

    ff_nut_add_sp(nut, nut->last_syncpoint_pos, *back_ptr, *ts);

    return 0;

}

static int find_and_decode_index(NUTContext *nut){

    AVFormatContext *s= nut->avf;

    AVIOContext *bc = s->pb;

    uint64_t tmp, end;

    int i, j, syncpoint_count;

    int64_t filesize= avio_size(bc);

    int64_t *syncpoints;

    int8_t *has_keyframe;

    int ret= -1;

    avio_seek(bc, filesize-12, SEEK_SET);

    avio_seek(bc, filesize-avio_rb64(bc), SEEK_SET);

    if(avio_rb64(bc) != INDEX_STARTCODE){

        av_log(s, AV_LOG_ERROR, "no index at the end\n");

        return -1;

    }

    end= get_packetheader(nut, bc, 1, INDEX_STARTCODE);

    end += avio_tell(bc);

    ff_get_v(bc); //max_pts

    GET_V(syncpoint_count, tmp < INT_MAX/8 && tmp > 0)

    syncpoints= av_malloc(sizeof(int64_t)*syncpoint_count);

    has_keyframe= av_malloc(sizeof(int8_t)*(syncpoint_count+1));

    for(i=0; i<syncpoint_count; i++){

        syncpoints[i] = ff_get_v(bc);

        if(syncpoints[i] <= 0)

            goto fail;

        if(i)

            syncpoints[i] += syncpoints[i-1];

    }

    for(i=0; i<s->nb_streams; i++){

        int64_t last_pts= -1;

        for(j=0; j<syncpoint_count;){

            uint64_t x= ff_get_v(bc);

            int type= x&1;

            int n= j;

            x>>=1;

            if(type){

                int flag= x&1;

                x>>=1;

                if(n+x >= syncpoint_count + 1){

                    av_log(s, AV_LOG_ERROR, "index overflow A\n");

                    goto fail;

                }

                while(x--)

                    has_keyframe[n++]= flag;

                has_keyframe[n++]= !flag;

            }else{

                while(x != 1){

                    if(n>=syncpoint_count + 1){

                        av_log(s, AV_LOG_ERROR, "index overflow B\n");

                        goto fail;

                    }

                    has_keyframe[n++]= x&1;

                    x>>=1;

                }

            }

            if(has_keyframe[0]){

                av_log(s, AV_LOG_ERROR, "keyframe before first syncpoint in index\n");

                goto fail;

            }

            assert(n<=syncpoint_count+1);

            for(; j<n && j<syncpoint_count; j++){

                if(has_keyframe[j]){

                    uint64_t B, A= ff_get_v(bc);

                    if(!A){

                        A= ff_get_v(bc);

                        B= ff_get_v(bc);

                        //eor_pts[j][i] = last_pts + A + B

                    }else

                        B= 0;

                    av_add_index_entry(

                        s->streams[i],

                        16*syncpoints[j-1],

                        last_pts + A,

                        0,

                        0,

                        AVINDEX_KEYFRAME);

                    last_pts += A + B;

                }

            }

        }

    }

    if(skip_reserved(bc, end) || get_checksum(bc)){

        av_log(s, AV_LOG_ERROR, "index checksum mismatch\n");

        goto fail;

    }

    ret= 0;

fail:

    av_free(syncpoints);

    av_free(has_keyframe);

    return ret;

}

static int nut_read_header(AVFormatContext *s, AVFormatParameters *ap)

{

    NUTContext *nut = s->priv_data;

    AVIOContext *bc = s->pb;

    int64_t pos;

    int initialized_stream_count;

    nut->avf= s;

    /* main header */

    pos=0;

    do{

        pos= find_startcode(bc, MAIN_STARTCODE, pos)+1;

        if (pos<0+1){

            av_log(s, AV_LOG_ERROR, "No main startcode found.\n");

            return AVERROR_INVALIDDATA;

        }

    }while(decode_main_header(nut) < 0);

    /* stream headers */

    pos=0;

    for(initialized_stream_count=0; initialized_stream_count < s->nb_streams;){

        pos= find_startcode(bc, STREAM_STARTCODE, pos)+1;

        if (pos<0+1){

            av_log(s, AV_LOG_ERROR, "Not all stream headers found.\n");

            return AVERROR_INVALIDDATA;

        }

        if(decode_stream_header(nut) >= 0)

            initialized_stream_count++;

    }

    /* info headers */

    pos=0;

    for(;;){

        uint64_t startcode= find_any_startcode(bc, pos);

        pos= avio_tell(bc);

        if(startcode==0){

            av_log(s, AV_LOG_ERROR, "EOF before video frames\n");

            return AVERROR_INVALIDDATA;

        }else if(startcode == SYNCPOINT_STARTCODE){

            nut->next_startcode= startcode;

            break;

        }else if(startcode != INFO_STARTCODE){

            continue;

        }

        decode_info_header(nut);

    }

    s->data_offset= pos-8;

    if(!url_is_streamed(bc)){

        int64_t orig_pos= avio_tell(bc);

        find_and_decode_index(nut);

        avio_seek(bc, orig_pos, SEEK_SET);

    }

    assert(nut->next_startcode == SYNCPOINT_STARTCODE);

    ff_metadata_conv_ctx(s, NULL, ff_nut_metadata_conv);

    return 0;

}

static int decode_frame_header(NUTContext *nut, int64_t *pts, int *stream_id, uint8_t *header_idx, int frame_code){

    AVFormatContext *s= nut->avf;

    AVIOContext *bc = s->pb;

    StreamContext *stc;

    int size, flags, size_mul, pts_delta, i, reserved_count;

    uint64_t tmp;

    if(avio_tell(bc) > nut->last_syncpoint_pos + nut->max_distance){

        av_log(s, AV_LOG_ERROR, "Last frame must have been damaged %"PRId64" > %"PRId64" + %d\n", avio_tell(bc), nut->last_syncpoint_pos, nut->max_distance);

        return AVERROR_INVALIDDATA;

    }

    flags          = nut->frame_code[frame_code].flags;

    size_mul       = nut->frame_code[frame_code].size_mul;

    size           = nut->frame_code[frame_code].size_lsb;

    *stream_id     = nut->frame_code[frame_code].stream_id;

    pts_delta      = nut->frame_code[frame_code].pts_delta;

    reserved_count = nut->frame_code[frame_code].reserved_count;

    *header_idx    = nut->frame_code[frame_code].header_idx;

    if(flags & FLAG_INVALID)

        return AVERROR_INVALIDDATA;

    if(flags & FLAG_CODED)

        flags ^= ff_get_v(bc);

    if(flags & FLAG_STREAM_ID){

        GET_V(*stream_id, tmp < s->nb_streams)

    }

    stc= &nut->stream[*stream_id];

    if(flags&FLAG_CODED_PTS){

        int coded_pts= ff_get_v(bc);

//FIXME check last_pts validity?

        if(coded_pts < (1<<stc->msb_pts_shift)){

            *pts=ff_lsb2full(stc, coded_pts);

        }else

            *pts=coded_pts - (1<<stc->msb_pts_shift);

    }else

        *pts= stc->last_pts + pts_delta;

    if(flags&FLAG_SIZE_MSB){

        size += size_mul*ff_get_v(bc);

    }

    if(flags&FLAG_MATCH_TIME)

        get_s(bc);

    if(flags&FLAG_HEADER_IDX)

        *header_idx= ff_get_v(bc);

    if(flags&FLAG_RESERVED)

        reserved_count= ff_get_v(bc);

    for(i=0; i<reserved_count; i++)

        ff_get_v(bc);

    if(*header_idx >= (unsigned)nut->header_count){

        av_log(s, AV_LOG_ERROR, "header_idx invalid\n");

        return AVERROR_INVALIDDATA;

    }

    if(size > 4096)

        *header_idx=0;

    size -= nut->header_len[*header_idx];

    if(flags&FLAG_CHECKSUM){

        avio_rb32(bc); //FIXME check this

    }else if(size > 2*nut->max_distance || FFABS(stc->last_pts - *pts) > stc->max_pts_distance){

        av_log(s, AV_LOG_ERROR, "frame size > 2max_distance and no checksum\n");

        return AVERROR_INVALIDDATA;

    }

    stc->last_pts= *pts;

    stc->last_flags= flags;

    return size;

}

static int decode_frame(NUTContext *nut, AVPacket *pkt, int frame_code){

    AVFormatContext *s= nut->avf;

    AVIOContext *bc = s->pb;

    int size, stream_id, discard;

    int64_t pts, last_IP_pts;

    StreamContext *stc;

    uint8_t header_idx;

    size= decode_frame_header(nut, &pts, &stream_id, &header_idx, frame_code);

    if(size < 0)

        return size;

    stc= &nut->stream[stream_id];

    if (stc->last_flags & FLAG_KEY)

        stc->skip_until_key_frame=0;

    discard= s->streams[ stream_id ]->discard;

    last_IP_pts= s->streams[ stream_id ]->last_IP_pts;

    if(  (discard >= AVDISCARD_NONKEY && !(stc->last_flags & FLAG_KEY))

       ||(discard >= AVDISCARD_BIDIR && last_IP_pts != AV_NOPTS_VALUE && last_IP_pts > pts)

       || discard >= AVDISCARD_ALL

       || stc->skip_until_key_frame){

        avio_seek(bc, size, SEEK_CUR);

        return 1;

    }

    av_new_packet(pkt, size + nut->header_len[header_idx]);

    memcpy(pkt->data, nut->header[header_idx], nut->header_len[header_idx]);

    pkt->pos= avio_tell(bc); //FIXME

    avio_read(bc, pkt->data + nut->header_len[header_idx], size);

    pkt->stream_index = stream_id;

    if (stc->last_flags & FLAG_KEY)

        pkt->flags |= AV_PKT_FLAG_KEY;

    pkt->pts = pts;

    return 0;

}

static int nut_read_packet(AVFormatContext *s, AVPacket *pkt)

{

    NUTContext *nut = s->priv_data;

    AVIOContext *bc = s->pb;

    int i, frame_code=0, ret, skip;

    int64_t ts, back_ptr;

    for(;;){

        int64_t pos= avio_tell(bc);

        uint64_t tmp= nut->next_startcode;

        nut->next_startcode=0;

        if(tmp){

            pos-=8;

        }else{

            frame_code = avio_r8(bc);

            if(bc->eof_reached)

                return -1;

            if(frame_code == 'N'){

                tmp= frame_code;

                for(i=1; i<8; i++)

                    tmp = (tmp<<8) + avio_r8(bc);

            }

        }

        switch(tmp){

        case MAIN_STARTCODE:

        case STREAM_STARTCODE:

        case INDEX_STARTCODE:

            skip= get_packetheader(nut, bc, 0, tmp);

            avio_seek(bc, skip, SEEK_CUR);

            break;

        case INFO_STARTCODE:

            if(decode_info_header(nut)<0)

                goto resync;

            break;

        case SYNCPOINT_STARTCODE:

            if(decode_syncpoint(nut, &ts, &back_ptr)<0)

                goto resync;

            frame_code = avio_r8(bc);

        case 0:

            ret= decode_frame(nut, pkt, frame_code);

            if(ret==0)

                return 0;

            else if(ret==1) //ok but discard packet

                break;

        default:

resync:

av_log(s, AV_LOG_DEBUG, "syncing from %"PRId64"\n", pos);

            tmp= find_any_startcode(bc, nut->last_syncpoint_pos+1);

            if(tmp==0)

                return AVERROR_INVALIDDATA;

av_log(s, AV_LOG_DEBUG, "sync\n");

            nut->next_startcode= tmp;

        }

    }

}

static int64_t nut_read_timestamp(AVFormatContext *s, int stream_index, int64_t *pos_arg, int64_t pos_limit){

    NUTContext *nut = s->priv_data;

    AVIOContext *bc = s->pb;

    int64_t pos, pts, back_ptr;

av_log(s, AV_LOG_DEBUG, "read_timestamp(X,%d,%"PRId64",%"PRId64")\n", stream_index, *pos_arg, pos_limit);

    pos= *pos_arg;

    do{

        pos= find_startcode(bc, SYNCPOINT_STARTCODE, pos)+1;

        if(pos < 1){

            assert(nut->next_startcode == 0);

            av_log(s, AV_LOG_ERROR, "read_timestamp failed.\n");

            return AV_NOPTS_VALUE;

        }

    }while(decode_syncpoint(nut, &pts, &back_ptr) < 0);

    *pos_arg = pos-1;

    assert(nut->last_syncpoint_pos == *pos_arg);

    av_log(s, AV_LOG_DEBUG, "return %"PRId64" %"PRId64"\n", pts,back_ptr );

    if     (stream_index == -1) return pts;

    else if(stream_index == -2) return back_ptr;

assert(0);

}

static int read_seek(AVFormatContext *s, int stream_index, int64_t pts, int flags){

    NUTContext *nut = s->priv_data;

    AVStream *st= s->streams[stream_index];

    Syncpoint dummy={.ts= pts*av_q2d(st->time_base)*AV_TIME_BASE};

    Syncpoint nopts_sp= {.ts= AV_NOPTS_VALUE, .back_ptr= AV_NOPTS_VALUE};

    Syncpoint *sp, *next_node[2]= {&nopts_sp, &nopts_sp};

    int64_t pos, pos2, ts;

    int i;

    if(st->index_entries){

        int index= av_index_search_timestamp(st, pts, flags);

        if(index<0)

            return -1;

        pos2= st->index_entries[index].pos;

        ts  = st->index_entries[index].timestamp;

    }else{

        av_tree_find(nut->syncpoints, &dummy, (void *) ff_nut_sp_pts_cmp,

                     (void **) next_node);

        av_log(s, AV_LOG_DEBUG, "%"PRIu64"-%"PRIu64" %"PRId64"-%"PRId64"\n", next_node[0]->pos, next_node[1]->pos,

                                                    next_node[0]->ts , next_node[1]->ts);

        pos= av_gen_search(s, -1, dummy.ts, next_node[0]->pos, next_node[1]->pos, next_node[1]->pos,

                                            next_node[0]->ts , next_node[1]->ts, AVSEEK_FLAG_BACKWARD, &ts, nut_read_timestamp);

        if(!(flags & AVSEEK_FLAG_BACKWARD)){

            dummy.pos= pos+16;

            next_node[1]= &nopts_sp;

            av_tree_find(nut->syncpoints, &dummy, (void *) ff_nut_sp_pos_cmp,

                         (void **) next_node);

            pos2= av_gen_search(s, -2, dummy.pos, next_node[0]->pos     , next_node[1]->pos, next_node[1]->pos,

                                                next_node[0]->back_ptr, next_node[1]->back_ptr, flags, &ts, nut_read_timestamp);

            if(pos2>=0)

                pos= pos2;

            //FIXME dir but I think it does not matter

        }

        dummy.pos= pos;

        sp= av_tree_find(nut->syncpoints, &dummy, (void *) ff_nut_sp_pos_cmp,

                         NULL);

        assert(sp);

        pos2= sp->back_ptr  - 15;

    }

    av_log(NULL, AV_LOG_DEBUG, "SEEKTO: %"PRId64"\n", pos2);

    pos= find_startcode(s->pb, SYNCPOINT_STARTCODE, pos2);

    avio_seek(s->pb, pos, SEEK_SET);

    av_log(NULL, AV_LOG_DEBUG, "SP: %"PRId64"\n", pos);

    if(pos2 > pos || pos2 + 15 < pos){

        av_log(NULL, AV_LOG_ERROR, "no syncpoint at backptr pos\n");

    }

    for(i=0; i<s->nb_streams; i++)

        nut->stream[i].skip_until_key_frame=1;

    return 0;

}

static int nut_read_close(AVFormatContext *s)

{

    NUTContext *nut = s->priv_data;

    int i;

    av_freep(&nut->time_base);

    av_freep(&nut->stream);

    ff_nut_free_sp(nut);

    for(i = 1; i < nut->header_count; i++)

        av_freep(&nut->header[i]);

    return 0;

}

#if CONFIG_NUT_DEMUXER

AVInputFormat ff_nut_demuxer = {

    "nut",

    NULL_IF_CONFIG_SMALL("NUT format"),

    sizeof(NUTContext),

    nut_probe,

    nut_read_header,

    nut_read_packet,

    nut_read_close,

    read_seek,

    .extensions = "nut",

    .codec_tag = (const AVCodecTag * const []) { ff_codec_bmp_tags, ff_nut_video_tags, ff_codec_wav_tags, ff_nut_subtitle_tags, 0 },

};

#endif