/*
  * 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 "libavutil/dict.h"

 #include "libavcodec/mpegaudiodata.h"

 #include "nut.h"

 #include "internal.h"

 #include "avio_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, AVRational *time_base, AVIOContext *bc, uint64_t val){

     val *= nut->time_base_count;

     val += time_base - nut->time_base;

     ff_put_v(bc, val);

 }
 

 /**

  * Store a string as vb.

  */

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

     int len= strlen(string);
 

     ff_put_v(bc, len);

     avio_write(bc, string, len);

 }
 

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

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

 }
 
 #ifdef TRACE

 static inline void ff_put_v_trace(AVIOContext *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(AVIOContext *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, AVIOContext *bc, AVIOContext *dyn_bc, int calculate_checksum, uint64_t startcode){

     uint8_t *dyn_buf=NULL;

     int dyn_size= avio_close_dyn_buf(dyn_bc, &dyn_buf);

     int forw_ptr= dyn_size + 4*calculate_checksum;
 
     if(forw_ptr > 4096)

         ffio_init_checksum(bc, ff_crc04C11DB7_update, 0);

     avio_wb64(bc, startcode);

     ff_put_v(bc, forw_ptr);

     if(forw_ptr > 4096)

         avio_wl32(bc, ffio_get_checksum(bc));

 
     if(calculate_checksum)

         ffio_init_checksum(bc, ff_crc04C11DB7_update, 0);

     avio_write(bc, dyn_buf, dyn_size);

     if(calculate_checksum)

         avio_wl32(bc, ffio_get_checksum(bc));

     av_free(dyn_buf);

 }
 

 static void write_mainheader(NUTContext *nut, AVIOContext *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]);

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

     }

 }

 static int write_streamheader(AVFormatContext *avctx, AVIOContext *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){

         avio_wl32(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);

     avio_w8(bc, 0); /* flags: 0x1 - fixed_fps, 0x2 - index_present */

     ff_put_v(bc, codec->extradata_size);

     avio_write(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(AVIOContext *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, AVIOContext *bc){

     AVFormatContext *s= nut->avf;

     AVDictionaryEntry *t = NULL;

     AVIOContext *dyn_bc;

     uint8_t *dyn_buf=NULL;
     int count=0, dyn_size;

     int ret = avio_open_dyn_buf(&dyn_bc);

     if(ret < 0)
         return ret;

     while ((t = av_dict_get(s->metadata, "", t, AV_DICT_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= avio_close_dyn_buf(dyn_bc, &dyn_buf);

     avio_write(bc, dyn_buf, dyn_size);

     av_free(dyn_buf);

     return 0;

 }
 

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

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

     AVIOContext *dyn_bc;

     uint8_t *dyn_buf=NULL;
     int count=0, dyn_size, i;

     int ret = avio_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 = avio_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);

         avio_write(bc, dyn_buf, dyn_size);

     }
 
     av_free(dyn_buf);
     return count;
 }
 

 static int write_chapter(NUTContext *nut, AVIOContext *bc, int id)
 {
     AVIOContext *dyn_bc;
     uint8_t *dyn_buf = NULL;

     AVDictionaryEntry *t = NULL;

     AVChapter *ch    = nut->avf->chapters[id];
     int ret, dyn_size, count = 0;
 

     ret = avio_open_dyn_buf(&dyn_bc);

     if (ret < 0)
         return ret;
 
     ff_put_v(bc, 0);                                        // stream_id_plus1
     put_s(bc, id + 1);                                      // chapter_id
     put_tt(nut, nut->chapter[id].time_base, bc, ch->start); // chapter_start
     ff_put_v(bc, ch->end - ch->start);                      // chapter_len
 

     while ((t = av_dict_get(ch->metadata, "", t, AV_DICT_IGNORE_SUFFIX)))

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

     dyn_size = avio_close_dyn_buf(dyn_bc, &dyn_buf);

     avio_write(bc, dyn_buf, dyn_size);
     av_freep(&dyn_buf);
     return 0;
 }
 

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

     NUTContext *nut = avctx->priv_data;

     AVIOContext *dyn_bc;

     int i, ret;

     ff_metadata_conv_ctx(avctx, ff_nut_metadata_conv, NULL);
 

     ret = avio_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 = avio_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 = avio_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 = avio_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;

             avio_close_dyn_buf(dyn_bc, &buf);

             av_free(buf);
         }
     }
 

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

         ret = avio_open_dyn_buf(&dyn_bc);

         if (ret < 0)
             return ret;
         ret = write_chapter(nut, dyn_bc, i);
         if (ret < 0) {
             uint8_t *buf;

             avio_close_dyn_buf(dyn_bc, &buf);

             av_freep(&buf);
             return ret;
         }
         put_packet(nut, bc, dyn_bc, 1, INFO_STARTCODE);
     }
 

     nut->last_syncpoint_pos= INT_MIN;
     nut->header_count++;

     return 0;

 }
 

 static int write_header(AVFormatContext *s){
     NUTContext *nut = s->priv_data;

     AVIOContext *bc = s->pb;

     int i, j, ret;

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

     nut->chapter  = av_mallocz(sizeof(ChapterContext)*s->nb_chapters);
     nut->time_base= av_mallocz(sizeof(AVRational   )*(s->nb_streams +
                                                       s->nb_chapters));

     if (!nut->stream || !nut->chapter || !nut->time_base) {

         av_freep(&nut->stream);
         av_freep(&nut->chapter);
         av_freep(&nut->time_base);
         return AVERROR(ENOMEM);
     }

 
     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(INT64_C(1000) * time_base.num >= time_base.den)

             nut->stream[i].msb_pts_shift = 7;
         else
             nut->stream[i].msb_pts_shift = 14;

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

     }
 

     for (i = 0; i < s->nb_chapters; i++) {
         AVChapter *ch = s->chapters[i];
 
         for (j = 0; j < nut->time_base_count; j++) {
             if (!memcmp(&ch->time_base, &nut->time_base[j], sizeof(AVRational)))
                 break;
         }
 
         nut->time_base[j] = ch->time_base;
         nut->chapter[i].time_base = &nut->time_base[j];
         if(j == nut->time_base_count)
             nut->time_base_count++;
     }
 

     nut->max_distance = MAX_DISTANCE;

     build_elision_headers(s);

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

     avio_write(bc, ID_STRING, strlen(ID_STRING));
     avio_w8(bc, 0);

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

     avio_flush(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];

     AVIOContext *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) <= avio_tell(bc))

         write_headers(s, bc);

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

         store_sp= 1;
 

     if(pkt->size + 30/*FIXME check*/ + avio_tell(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= avio_tell(bc);

         ret = avio_open_dyn_buf(&dyn_bc);

         if(ret < 0)
             return ret;

         put_tt(nut, nus->time_base, 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;

     ffio_init_checksum(bc, ff_crc04C11DB7_update, 0);

     avio_w8(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)   avio_wl32(bc, ffio_get_checksum(bc));
     else                        ffio_get_checksum(bc);

     avio_write(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;

     AVIOContext *bc= s->pb;

     while(nut->header_count<3)

         write_headers(s, bc);

     avio_flush(bc);

     ff_nut_free_sp(nut);

     av_freep(&nut->stream);

     av_freep(&nut->chapter);

     av_freep(&nut->time_base);

 
     return 0;
 }
 

 AVOutputFormat ff_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 },

 };