PeerStreamer

/*

 * nut muxer

 * Copyright (c) 2004-2007 Michael Niedermayer

 *

 * 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 "libavutil/intreadwrite.h"

#include "libavutil/tree.h"

#include "libavcodec/mpegaudiodata.h"

#include "nut.h"

#include "internal.h"

static int find_expected_header(AVCodecContext *c, int size, int key_frame, uint8_t out[64]){

    int sample_rate= c->sample_rate;

    if(size>4096)

        return 0;

    AV_WB24(out, 1);

    if(c->codec_id == CODEC_ID_MPEG4){

        if(key_frame){

            return 3;

        }else{

            out[3]= 0xB6;

            return 4;

        }

    }else if(c->codec_id == CODEC_ID_MPEG1VIDEO || c->codec_id == CODEC_ID_MPEG2VIDEO){

        return 3;

    }else if(c->codec_id == CODEC_ID_H264){

        return 3;

    }else if(c->codec_id == CODEC_ID_MP3 || c->codec_id == CODEC_ID_MP2){

        int lsf, mpeg25, sample_rate_index, bitrate_index, frame_size;

        int layer= c->codec_id == CODEC_ID_MP3 ? 3 : 2;

        unsigned int header= 0xFFF00000;

        lsf     = sample_rate < (24000+32000)/2;

        mpeg25  = sample_rate < (12000+16000)/2;

        sample_rate <<= lsf + mpeg25;

        if     (sample_rate < (32000 + 44100)/2) sample_rate_index=2;

        else if(sample_rate < (44100 + 48000)/2) sample_rate_index=0;

        else                                     sample_rate_index=1;

        sample_rate= ff_mpa_freq_tab[sample_rate_index] >> (lsf + mpeg25);

        for(bitrate_index=2; bitrate_index<30; bitrate_index++){

            frame_size = ff_mpa_bitrate_tab[lsf][layer-1][bitrate_index>>1];

            frame_size = (frame_size * 144000) / (sample_rate << lsf) + (bitrate_index&1);

            if(frame_size == size)

                break;

        }

        header |= (!lsf)<<19;

        header |= (4-layer)<<17;

        header |= 1<<16; //no crc

        AV_WB32(out, header);

        if(size <= 0)

            return 2; //we guess there is no crc, if there is one the user clearly does not care about overhead

        if(bitrate_index == 30)

            return -1; //something is wrong ...

        header |= (bitrate_index>>1)<<12;

        header |= sample_rate_index<<10;

        header |= (bitrate_index&1)<<9;

        return 2; //FIXME actually put the needed ones in build_elision_headers()

        return 3; //we guess that the private bit is not set

//FIXME the above assumptions should be checked, if these turn out false too often something should be done

    }

    return 0;

}

static int find_header_idx(AVFormatContext *s, AVCodecContext *c, int size, int frame_type){

    NUTContext *nut = s->priv_data;

    uint8_t out[64];

    int i;

    int len= find_expected_header(c, size, frame_type, out);

//av_log(NULL, AV_LOG_ERROR, "expected_h len=%d size=%d codec_id=%d\n", len, size, c->codec_id);

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

        if(   len == nut->header_len[i]

           && !memcmp(out, nut->header[i], len)){

//    av_log(NULL, AV_LOG_ERROR, "found %d\n", i);

            return i;

        }

    }

//    av_log(NULL, AV_LOG_ERROR, "nothing found\n");

    return 0;

}

static void build_elision_headers(AVFormatContext *s){

    NUTContext *nut = s->priv_data;

    int i;

    //FIXME this is lame

    //FIXME write a 2pass mode to find the maximal headers

    static const uint8_t headers[][5]={

        {3, 0x00, 0x00, 0x01},

        {4, 0x00, 0x00, 0x01, 0xB6},

        {2, 0xFF, 0xFA}, //mp3+crc

        {2, 0xFF, 0xFB}, //mp3

        {2, 0xFF, 0xFC}, //mp2+crc

        {2, 0xFF, 0xFD}, //mp2

    };

    nut->header_count= 7;

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

        nut->header_len[i]=  headers[i-1][0];

        nut->header    [i]= &headers[i-1][1];

    }

}

static void build_frame_code(AVFormatContext *s){

    NUTContext *nut = s->priv_data;

    int key_frame, index, pred, stream_id;

    int start=1;

    int end= 254;

    int keyframe_0_esc= s->nb_streams > 2;

    int pred_table[10];

    FrameCode *ft;

    ft= &nut->frame_code[start];

    ft->flags= FLAG_CODED;

    ft->size_mul=1;

    ft->pts_delta=1;

    start++;

    if(keyframe_0_esc){

        /* keyframe = 0 escape */

        FrameCode *ft= &nut->frame_code[start];

        ft->flags= FLAG_STREAM_ID | FLAG_SIZE_MSB | FLAG_CODED_PTS;

        ft->size_mul=1;

        start++;

    }

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

        int start2= start + (end-start)*stream_id / s->nb_streams;

        int end2  = start + (end-start)*(stream_id+1) / s->nb_streams;

        AVCodecContext *codec = s->streams[stream_id]->codec;

        int is_audio= codec->codec_type == AVMEDIA_TYPE_AUDIO;

        int intra_only= /*codec->intra_only || */is_audio;

        int pred_count;

        for(key_frame=0; key_frame<2; key_frame++){

            if(intra_only && keyframe_0_esc && key_frame==0)

                continue;

            {

                FrameCode *ft= &nut->frame_code[start2];

                ft->flags= FLAG_KEY*key_frame;

                ft->flags|= FLAG_SIZE_MSB | FLAG_CODED_PTS;

                ft->stream_id= stream_id;

                ft->size_mul=1;

                if(is_audio)

                    ft->header_idx= find_header_idx(s, codec, -1, key_frame);

                start2++;

            }

        }

        key_frame= intra_only;

#if 1

        if(is_audio){

            int frame_bytes= codec->frame_size*(int64_t)codec->bit_rate / (8*codec->sample_rate);

            int pts;

            for(pts=0; pts<2; pts++){

                for(pred=0; pred<2; pred++){

                    FrameCode *ft= &nut->frame_code[start2];

                    ft->flags= FLAG_KEY*key_frame;

                    ft->stream_id= stream_id;

                    ft->size_mul=frame_bytes + 2;

                    ft->size_lsb=frame_bytes + pred;

                    ft->pts_delta=pts;

                    ft->header_idx= find_header_idx(s, codec, frame_bytes + pred, key_frame);

                    start2++;

                }

            }

        }else{

            FrameCode *ft= &nut->frame_code[start2];

            ft->flags= FLAG_KEY | FLAG_SIZE_MSB;

            ft->stream_id= stream_id;

            ft->size_mul=1;

            ft->pts_delta=1;

            start2++;

        }

#endif

        if(codec->has_b_frames){

            pred_count=5;

            pred_table[0]=-2;

            pred_table[1]=-1;

            pred_table[2]=1;

            pred_table[3]=3;

            pred_table[4]=4;

        }else if(codec->codec_id == CODEC_ID_VORBIS){

            pred_count=3;

            pred_table[0]=2;

            pred_table[1]=9;

            pred_table[2]=16;

        }else{

            pred_count=1;

            pred_table[0]=1;

        }

        for(pred=0; pred<pred_count; pred++){

            int start3= start2 + (end2-start2)*pred / pred_count;

            int end3  = start2 + (end2-start2)*(pred+1) / pred_count;

            for(index=start3; index<end3; index++){

                FrameCode *ft= &nut->frame_code[index];

                ft->flags= FLAG_KEY*key_frame;

                ft->flags|= FLAG_SIZE_MSB;

                ft->stream_id= stream_id;

//FIXME use single byte size and pred from last

                ft->size_mul= end3-start3;

                ft->size_lsb= index - start3;

                ft->pts_delta= pred_table[pred];

                if(is_audio)

                    ft->header_idx= find_header_idx(s, codec, -1, key_frame);

            }

        }

    }

    memmove(&nut->frame_code['N'+1], &nut->frame_code['N'], sizeof(FrameCode)*(255-'N'));

    nut->frame_code[  0].flags=

    nut->frame_code[255].flags=

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

}

static void put_tt(NUTContext *nut, StreamContext *nus, ByteIOContext *bc, uint64_t val){

    val *= nut->time_base_count;

    val += nus->time_base - nut->time_base;

    ff_put_v(bc, val);

}

/**

 * Store a string as vb.

 */

static void put_str(ByteIOContext *bc, const char *string){

    int len= strlen(string);

    ff_put_v(bc, len);

    put_buffer(bc, string, len);

}

static void put_s(ByteIOContext *bc, int64_t val){

    ff_put_v(bc, 2*FFABS(val) - (val>0));

}

#ifdef TRACE

static inline void ff_put_v_trace(ByteIOContext *bc, uint64_t v, char *file, char *func, int line){

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

    ff_put_v(bc, v);

}

static inline void put_s_trace(ByteIOContext *bc, int64_t v, char *file, char *func, int line){

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

    put_s(bc, v);

}

#define ff_put_v(bc, v)  ff_put_v_trace(bc, v, __FILE__, __PRETTY_FUNCTION__, __LINE__)

#define put_s(bc, v)  put_s_trace(bc, v, __FILE__, __PRETTY_FUNCTION__, __LINE__)

#endif

//FIXME remove calculate_checksum

static void put_packet(NUTContext *nut, ByteIOContext *bc, ByteIOContext *dyn_bc, int calculate_checksum, uint64_t startcode){

    uint8_t *dyn_buf=NULL;

    int dyn_size= url_close_dyn_buf(dyn_bc, &dyn_buf);

    int forw_ptr= dyn_size + 4*calculate_checksum;

    if(forw_ptr > 4096)

        init_checksum(bc, ff_crc04C11DB7_update, 0);

    put_be64(bc, startcode);

    ff_put_v(bc, forw_ptr);

    if(forw_ptr > 4096)

        put_le32(bc, get_checksum(bc));

    if(calculate_checksum)

        init_checksum(bc, ff_crc04C11DB7_update, 0);

    put_buffer(bc, dyn_buf, dyn_size);

    if(calculate_checksum)

        put_le32(bc, get_checksum(bc));

    av_free(dyn_buf);

}

static void write_mainheader(NUTContext *nut, ByteIOContext *bc){

    int i, j, tmp_pts, tmp_flags, tmp_stream, tmp_mul, tmp_size, tmp_fields, tmp_head_idx;

    int64_t tmp_match;

    ff_put_v(bc, 3); /* version */

    ff_put_v(bc, nut->avf->nb_streams);

    ff_put_v(bc, nut->max_distance);

    ff_put_v(bc, nut->time_base_count);

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

        ff_put_v(bc, nut->time_base[i].num);

        ff_put_v(bc, nut->time_base[i].den);

    }

    tmp_pts=0;

    tmp_mul=1;

    tmp_stream=0;

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

    tmp_head_idx= 0;

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

        tmp_fields=0;

        tmp_size=0;

//        tmp_res=0;

        if(tmp_pts    != nut->frame_code[i].pts_delta) tmp_fields=1;

        if(tmp_mul    != nut->frame_code[i].size_mul ) tmp_fields=2;

        if(tmp_stream != nut->frame_code[i].stream_id) tmp_fields=3;

        if(tmp_size   != nut->frame_code[i].size_lsb ) tmp_fields=4;

//        if(tmp_res    != nut->frame_code[i].res            ) tmp_fields=5;

        if(tmp_head_idx!=nut->frame_code[i].header_idx)tmp_fields=8;

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

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

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

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

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

//        tmp_res   = nut->frame_code[i].res;

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

        for(j=0; i<256; j++,i++){

            if(i == 'N'){

                j--;

                continue;

            }

            if(nut->frame_code[i].pts_delta != tmp_pts   ) break;

            if(nut->frame_code[i].flags     != tmp_flags ) break;

            if(nut->frame_code[i].stream_id != tmp_stream) break;

            if(nut->frame_code[i].size_mul  != tmp_mul   ) break;

            if(nut->frame_code[i].size_lsb  != tmp_size+j) break;

//            if(nut->frame_code[i].res       != tmp_res   ) break;

            if(nut->frame_code[i].header_idx!= tmp_head_idx) break;

        }

        if(j != tmp_mul - tmp_size) tmp_fields=6;

        ff_put_v(bc, tmp_flags);

        ff_put_v(bc, tmp_fields);

        if(tmp_fields>0) put_s(bc, tmp_pts);

        if(tmp_fields>1) ff_put_v(bc, tmp_mul);

        if(tmp_fields>2) ff_put_v(bc, tmp_stream);

        if(tmp_fields>3) ff_put_v(bc, tmp_size);

        if(tmp_fields>4) ff_put_v(bc, 0 /*tmp_res*/);

        if(tmp_fields>5) ff_put_v(bc, j);

        if(tmp_fields>6) ff_put_v(bc, tmp_match);

        if(tmp_fields>7) ff_put_v(bc, tmp_head_idx);

    }

    ff_put_v(bc, nut->header_count-1);

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

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

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

    }

}

static int write_streamheader(AVFormatContext *avctx, ByteIOContext *bc, AVStream *st, int i){

    NUTContext *nut = avctx->priv_data;

    AVCodecContext *codec = st->codec;

    ff_put_v(bc, i);

    switch(codec->codec_type){

    case AVMEDIA_TYPE_VIDEO: ff_put_v(bc, 0); break;

    case AVMEDIA_TYPE_AUDIO: ff_put_v(bc, 1); break;

    case AVMEDIA_TYPE_SUBTITLE: ff_put_v(bc, 2); break;

    default              : ff_put_v(bc, 3); break;

    }

    ff_put_v(bc, 4);

    if (codec->codec_tag){

        put_le32(bc, codec->codec_tag);

    } else {

        av_log(avctx, AV_LOG_ERROR, "No codec tag defined for stream %d\n", i);

        return AVERROR(EINVAL);

    }

    ff_put_v(bc, nut->stream[i].time_base - nut->time_base);

    ff_put_v(bc, nut->stream[i].msb_pts_shift);

    ff_put_v(bc, nut->stream[i].max_pts_distance);

    ff_put_v(bc, codec->has_b_frames);

    put_byte(bc, 0); /* flags: 0x1 - fixed_fps, 0x2 - index_present */

    ff_put_v(bc, codec->extradata_size);

    put_buffer(bc, codec->extradata, codec->extradata_size);

    switch(codec->codec_type){

    case AVMEDIA_TYPE_AUDIO:

        ff_put_v(bc, codec->sample_rate);

        ff_put_v(bc, 1);

        ff_put_v(bc, codec->channels);

        break;

    case AVMEDIA_TYPE_VIDEO:

        ff_put_v(bc, codec->width);

        ff_put_v(bc, codec->height);

        if(st->sample_aspect_ratio.num<=0 || st->sample_aspect_ratio.den<=0){

            ff_put_v(bc, 0);

            ff_put_v(bc, 0);

        }else{

            ff_put_v(bc, st->sample_aspect_ratio.num);

            ff_put_v(bc, st->sample_aspect_ratio.den);

        }

        ff_put_v(bc, 0); /* csp type -- unknown */

        break;

    default:

        break;

    }

    return 0;

}

static int add_info(ByteIOContext *bc, const char *type, const char *value){

    put_str(bc, type);

    put_s(bc, -1);

    put_str(bc, value);

    return 1;

}

static int write_globalinfo(NUTContext *nut, ByteIOContext *bc){

    AVFormatContext *s= nut->avf;

    AVMetadataTag *t = NULL;

    ByteIOContext *dyn_bc;

    uint8_t *dyn_buf=NULL;

    int count=0, dyn_size;

    int ret = url_open_dyn_buf(&dyn_bc);

    if(ret < 0)

        return ret;

    while ((t = av_metadata_get(s->metadata, "", t, AV_METADATA_IGNORE_SUFFIX)))

        count += add_info(dyn_bc, t->key, t->value);

    ff_put_v(bc, 0); //stream_if_plus1

    ff_put_v(bc, 0); //chapter_id

    ff_put_v(bc, 0); //timestamp_start

    ff_put_v(bc, 0); //length

    ff_put_v(bc, count);

    dyn_size= url_close_dyn_buf(dyn_bc, &dyn_buf);

    put_buffer(bc, dyn_buf, dyn_size);

    av_free(dyn_buf);

    return 0;

}

static int write_streaminfo(NUTContext *nut, ByteIOContext *bc, int stream_id){

    AVFormatContext *s= nut->avf;

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

    ByteIOContext *dyn_bc;

    uint8_t *dyn_buf=NULL;

    int count=0, dyn_size, i;

    int ret = url_open_dyn_buf(&dyn_bc);

    if(ret < 0)

        return ret;

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

        if (st->disposition & ff_nut_dispositions[i].flag)

            count += add_info(dyn_bc, "Disposition", ff_nut_dispositions[i].str);

    }

    dyn_size = url_close_dyn_buf(dyn_bc, &dyn_buf);

    if (count) {

        ff_put_v(bc, stream_id + 1); //stream_id_plus1

        ff_put_v(bc, 0); //chapter_id

        ff_put_v(bc, 0); //timestamp_start

        ff_put_v(bc, 0); //length

        ff_put_v(bc, count);

        put_buffer(bc, dyn_buf, dyn_size);

    }

    av_free(dyn_buf);

    return count;

}

static int write_headers(AVFormatContext *avctx, ByteIOContext *bc){

    NUTContext *nut = avctx->priv_data;

    ByteIOContext *dyn_bc;

    int i, ret;

    ret = url_open_dyn_buf(&dyn_bc);

    if(ret < 0)

        return ret;

    write_mainheader(nut, dyn_bc);

    put_packet(nut, bc, dyn_bc, 1, MAIN_STARTCODE);

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

        ret = url_open_dyn_buf(&dyn_bc);

        if(ret < 0)

            return ret;

        if ((ret = write_streamheader(avctx, dyn_bc, nut->avf->streams[i], i)) < 0)

            return ret;

        put_packet(nut, bc, dyn_bc, 1, STREAM_STARTCODE);

    }

    ret = url_open_dyn_buf(&dyn_bc);

    if(ret < 0)

        return ret;

    write_globalinfo(nut, dyn_bc);

    put_packet(nut, bc, dyn_bc, 1, INFO_STARTCODE);

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

        ret = url_open_dyn_buf(&dyn_bc);

        if(ret < 0)

            return ret;

        ret = write_streaminfo(nut, dyn_bc, i);

        if (ret < 0)

            return ret;

        if (ret > 0)

            put_packet(nut, bc, dyn_bc, 1, INFO_STARTCODE);

        else {

            uint8_t* buf;

            url_close_dyn_buf(dyn_bc, &buf);

            av_free(buf);

        }

    }

    nut->last_syncpoint_pos= INT_MIN;

    nut->header_count++;

    return 0;

}

static int write_header(AVFormatContext *s){

    NUTContext *nut = s->priv_data;

    ByteIOContext *bc = s->pb;

    int i, j, ret;

    nut->avf= s;

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

    nut->time_base= av_mallocz(sizeof(AVRational   )*s->nb_streams);

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

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

        int ssize;

        AVRational time_base;

        ff_parse_specific_params(st->codec, &time_base.den, &ssize, &time_base.num);

        av_set_pts_info(st, 64, time_base.num, time_base.den);

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

            if(!memcmp(&time_base, &nut->time_base[j], sizeof(AVRational))){

                break;

            }

        }

        nut->time_base[j]= time_base;

        nut->stream[i].time_base= &nut->time_base[j];

        if(j==nut->time_base_count)

            nut->time_base_count++;

        if(av_q2d(time_base) >= 0.001)

            nut->stream[i].msb_pts_shift = 7;

        else

            nut->stream[i].msb_pts_shift = 14;

        nut->stream[i].max_pts_distance= FFMAX(1/av_q2d(time_base), 1);

    }

    nut->max_distance = MAX_DISTANCE;

    build_elision_headers(s);

    build_frame_code(s);

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

    put_buffer(bc, ID_STRING, strlen(ID_STRING));

    put_byte(bc, 0);

    if ((ret = write_headers(s, bc)) < 0)

        return ret;

    put_flush_packet(bc);

    //FIXME index

    return 0;

}

static int get_needed_flags(NUTContext *nut, StreamContext *nus, FrameCode *fc, AVPacket *pkt){

    int flags= 0;

    if(pkt->flags & AV_PKT_FLAG_KEY             ) flags |= FLAG_KEY;

    if(pkt->stream_index != fc->stream_id       ) flags |= FLAG_STREAM_ID;

    if(pkt->size / fc->size_mul                 ) flags |= FLAG_SIZE_MSB;

    if(pkt->pts - nus->last_pts != fc->pts_delta) flags |= FLAG_CODED_PTS;

    if(pkt->size > 2*nut->max_distance          ) flags |= FLAG_CHECKSUM;

    if(FFABS(pkt->pts - nus->last_pts)

                         > nus->max_pts_distance) flags |= FLAG_CHECKSUM;

    if(   pkt->size < nut->header_len[fc->header_idx]

       || (pkt->size > 4096 && fc->header_idx)

       || memcmp(pkt->data, nut->header[fc->header_idx], nut->header_len[fc->header_idx]))

                                                  flags |= FLAG_HEADER_IDX;

    return flags | (fc->flags & FLAG_CODED);

}

static int find_best_header_idx(NUTContext *nut, AVPacket *pkt){

    int i;

    int best_i  = 0;

    int best_len= 0;

    if(pkt->size > 4096)

        return 0;

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

        if(   pkt->size >= nut->header_len[i]

           &&  nut->header_len[i] > best_len

           && !memcmp(pkt->data, nut->header[i], nut->header_len[i])){

            best_i= i;

            best_len= nut->header_len[i];

        }

    }

    return best_i;

}

static int write_packet(AVFormatContext *s, AVPacket *pkt){

    NUTContext *nut = s->priv_data;

    StreamContext *nus= &nut->stream[pkt->stream_index];

    ByteIOContext *bc = s->pb, *dyn_bc;

    FrameCode *fc;

    int64_t coded_pts;

    int best_length, frame_code, flags, needed_flags, i, header_idx, best_header_idx;

    int key_frame = !!(pkt->flags & AV_PKT_FLAG_KEY);

    int store_sp=0;

    int ret;

    if(pkt->pts < 0)

        return -1;

    if(1LL<<(20+3*nut->header_count) <= url_ftell(bc))

        write_headers(s, bc);

    if(key_frame && !(nus->last_flags & FLAG_KEY))

        store_sp= 1;

    if(pkt->size + 30/*FIXME check*/ + url_ftell(bc) >= nut->last_syncpoint_pos + nut->max_distance)

        store_sp= 1;

//FIXME: Ensure store_sp is 1 in the first place.

    if(store_sp){

        Syncpoint *sp, dummy= {.pos= INT64_MAX};

        ff_nut_reset_ts(nut, *nus->time_base, pkt->dts);

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

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

            int64_t dts_tb = av_rescale_rnd(pkt->dts,

                nus->time_base->num * (int64_t)nut->stream[i].time_base->den,

                nus->time_base->den * (int64_t)nut->stream[i].time_base->num,

                AV_ROUND_DOWN);

            int index= av_index_search_timestamp(st, dts_tb, AVSEEK_FLAG_BACKWARD);

            if(index>=0) dummy.pos= FFMIN(dummy.pos, st->index_entries[index].pos);

        }

        if(dummy.pos == INT64_MAX)

            dummy.pos= 0;

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

                         NULL);

        nut->last_syncpoint_pos= url_ftell(bc);

        ret = url_open_dyn_buf(&dyn_bc);

        if(ret < 0)

            return ret;

        put_tt(nut, nus, dyn_bc, pkt->dts);

        ff_put_v(dyn_bc, sp ? (nut->last_syncpoint_pos - sp->pos)>>4 : 0);

        put_packet(nut, bc, dyn_bc, 1, SYNCPOINT_STARTCODE);

        ff_nut_add_sp(nut, nut->last_syncpoint_pos, 0/*unused*/, pkt->dts);

    }

    assert(nus->last_pts != AV_NOPTS_VALUE);

    coded_pts = pkt->pts & ((1<<nus->msb_pts_shift)-1);

    if(ff_lsb2full(nus, coded_pts) != pkt->pts)

        coded_pts= pkt->pts + (1<<nus->msb_pts_shift);

    best_header_idx= find_best_header_idx(nut, pkt);

    best_length=INT_MAX;

    frame_code= -1;

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

        int length= 0;

        FrameCode *fc= &nut->frame_code[i];

        int flags= fc->flags;

        if(flags & FLAG_INVALID)

            continue;

        needed_flags= get_needed_flags(nut, nus, fc, pkt);

        if(flags & FLAG_CODED){

            length++;

            flags = needed_flags;

        }

        if((flags & needed_flags) != needed_flags)

            continue;

        if((flags ^ needed_flags) & FLAG_KEY)

            continue;

        if(flags & FLAG_STREAM_ID)

            length+= ff_get_v_length(pkt->stream_index);

        if(pkt->size % fc->size_mul != fc->size_lsb)

            continue;

        if(flags & FLAG_SIZE_MSB)

            length += ff_get_v_length(pkt->size / fc->size_mul);

        if(flags & FLAG_CHECKSUM)

            length+=4;

        if(flags & FLAG_CODED_PTS)

            length += ff_get_v_length(coded_pts);

        if(   (flags & FLAG_CODED)

           && nut->header_len[best_header_idx] > nut->header_len[fc->header_idx]+1){

            flags |= FLAG_HEADER_IDX;

        }

        if(flags & FLAG_HEADER_IDX){

            length += 1 - nut->header_len[best_header_idx];

        }else{

            length -= nut->header_len[fc->header_idx];

        }

        length*=4;

        length+= !(flags & FLAG_CODED_PTS);

        length+= !(flags & FLAG_CHECKSUM);

        if(length < best_length){

            best_length= length;

            frame_code=i;

        }

    }

    assert(frame_code != -1);

    fc= &nut->frame_code[frame_code];

    flags= fc->flags;

    needed_flags= get_needed_flags(nut, nus, fc, pkt);

    header_idx= fc->header_idx;

    init_checksum(bc, ff_crc04C11DB7_update, 0);

    put_byte(bc, frame_code);

    if(flags & FLAG_CODED){

        ff_put_v(bc, (flags^needed_flags) & ~(FLAG_CODED));

        flags = needed_flags;

    }

    if(flags & FLAG_STREAM_ID)  ff_put_v(bc, pkt->stream_index);

    if(flags & FLAG_CODED_PTS)  ff_put_v(bc, coded_pts);

    if(flags & FLAG_SIZE_MSB)   ff_put_v(bc, pkt->size / fc->size_mul);

    if(flags & FLAG_HEADER_IDX) ff_put_v(bc, header_idx= best_header_idx);

    if(flags & FLAG_CHECKSUM)   put_le32(bc, get_checksum(bc));

    else                        get_checksum(bc);

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

    nus->last_flags= flags;

    nus->last_pts= pkt->pts;

    //FIXME just store one per syncpoint

    if(flags & FLAG_KEY)

        av_add_index_entry(

            s->streams[pkt->stream_index],

            nut->last_syncpoint_pos,

            pkt->pts,

            0,

            0,

            AVINDEX_KEYFRAME);

    return 0;

}

static int write_trailer(AVFormatContext *s){

    NUTContext *nut= s->priv_data;

    ByteIOContext *bc= s->pb;

    while(nut->header_count<3)

        write_headers(s, bc);

    put_flush_packet(bc);

    ff_nut_free_sp(nut);

    av_freep(&nut->stream);

    av_freep(&nut->time_base);

    return 0;

}

AVOutputFormat nut_muxer = {

    "nut",

    NULL_IF_CONFIG_SMALL("NUT format"),

    "video/x-nut",

    "nut",

    sizeof(NUTContext),

#if   CONFIG_LIBVORBIS

    CODEC_ID_VORBIS,

#elif CONFIG_LIBMP3LAME

    CODEC_ID_MP3,

#else

    CODEC_ID_MP2,

#endif

    CODEC_ID_MPEG4,

    write_header,

    write_packet,

    write_trailer,

    .flags = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS,

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

    .metadata_conv = ff_nut_metadata_conv,

};