/*
  * MPEG1/2 muxer

  * Copyright (c) 2000, 2001, 2002 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 "libavutil/attributes.h"

 #include "libavutil/fifo.h"

 #include "libavutil/log.h"

 #include "libavutil/mathematics.h"

 #include "libavutil/opt.h"

 #include "libavcodec/put_bits.h"

 #include "avformat.h"

 #include "internal.h"

 #include "mpeg.h"
 
 #define MAX_PAYLOAD_SIZE 4096
 
 #undef NDEBUG
 #include <assert.h>
 
 typedef struct PacketDesc {
     int64_t pts;
     int64_t dts;
     int size;
     int unwritten_size;
     int flags;
     struct PacketDesc *next;
 } PacketDesc;
 
 typedef struct {

     AVFifoBuffer *fifo;

     uint8_t id;
     int max_buffer_size; /* in bytes */
     int buffer_index;
     PacketDesc *predecode_packet;
     PacketDesc *premux_packet;
     PacketDesc **next_packet;
     int packet_number;
     uint8_t lpcm_header[3];
     int lpcm_align;
     int bytes_to_iframe;
     int align_iframe;
     int64_t vobu_start_pts;
 } StreamInfo;
 
 typedef struct {

     const AVClass *class;

     int packet_size; /* required packet size */
     int packet_number;
     int pack_header_freq;     /* frequency (in packets^-1) at which we send pack headers */
     int system_header_freq;
     int system_header_size;

     int user_mux_rate; /* bitrate in units of bits/s */

     int mux_rate; /* bitrate in units of 50 bytes/s */
     /* stream info */
     int audio_bound;
     int video_bound;
     int is_mpeg2;
     int is_vcd;
     int is_svcd;
     int is_dvd;
     int64_t last_scr; /* current system clock */
 
     double vcd_padding_bitrate; //FIXME floats
     int64_t vcd_padding_bytes_written;
 

     int preload;

 } MpegMuxContext;
 

 extern AVOutputFormat ff_mpeg1vcd_muxer;
 extern AVOutputFormat ff_mpeg2dvd_muxer;
 extern AVOutputFormat ff_mpeg2svcd_muxer;
 extern AVOutputFormat ff_mpeg2vob_muxer;

 static int put_pack_header(AVFormatContext *ctx,
                            uint8_t *buf, int64_t timestamp)
 {
     MpegMuxContext *s = ctx->priv_data;
     PutBitContext pb;
 
     init_put_bits(&pb, buf, 128);
 

     put_bits32(&pb, PACK_START_CODE);

     if (s->is_mpeg2) {
         put_bits(&pb, 2, 0x1);
     } else {
         put_bits(&pb, 4, 0x2);
     }

     put_bits(&pb, 3,  (uint32_t)((timestamp >> 30) & 0x07));

     put_bits(&pb, 1, 1);
     put_bits(&pb, 15, (uint32_t)((timestamp >> 15) & 0x7fff));
     put_bits(&pb, 1, 1);

     put_bits(&pb, 15, (uint32_t)((timestamp      ) & 0x7fff));

     put_bits(&pb, 1, 1);
     if (s->is_mpeg2) {
         /* clock extension */
         put_bits(&pb, 9, 0);
     }
     put_bits(&pb, 1, 1);
     put_bits(&pb, 22, s->mux_rate);
     put_bits(&pb, 1, 1);
     if (s->is_mpeg2) {
         put_bits(&pb, 1, 1);
         put_bits(&pb, 5, 0x1f); /* reserved */
         put_bits(&pb, 3, 0); /* stuffing length */
     }
     flush_put_bits(&pb);

     return put_bits_ptr(&pb) - pb.buf;

 }
 
 static int put_system_header(AVFormatContext *ctx, uint8_t *buf,int only_for_stream_id)
 {
     MpegMuxContext *s = ctx->priv_data;
     int size, i, private_stream_coded, id;
     PutBitContext pb;
 
     init_put_bits(&pb, buf, 128);
 

     put_bits32(&pb, SYSTEM_HEADER_START_CODE);

     put_bits(&pb, 16, 0);
     put_bits(&pb, 1, 1);
 
     put_bits(&pb, 22, s->mux_rate); /* maximum bit rate of the multiplexed stream */
     put_bits(&pb, 1, 1); /* marker */
     if (s->is_vcd && only_for_stream_id==VIDEO_ID) {
         /* This header applies only to the video stream (see VCD standard p. IV-7)*/
         put_bits(&pb, 6, 0);
     } else
         put_bits(&pb, 6, s->audio_bound);
 
     if (s->is_vcd) {
         /* see VCD standard, p. IV-7*/
         put_bits(&pb, 1, 0);
         put_bits(&pb, 1, 1);
     } else {
         put_bits(&pb, 1, 0); /* variable bitrate*/
         put_bits(&pb, 1, 0); /* non constrainted bit stream */
     }
 
     if (s->is_vcd || s->is_dvd) {
         /* see VCD standard p IV-7 */
         put_bits(&pb, 1, 1); /* audio locked */
         put_bits(&pb, 1, 1); /* video locked */
     } else {
         put_bits(&pb, 1, 0); /* audio locked */
         put_bits(&pb, 1, 0); /* video locked */
     }
 
     put_bits(&pb, 1, 1); /* marker */
 

     if (s->is_vcd && (only_for_stream_id & 0xe0) == AUDIO_ID) {

         /* This header applies only to the audio stream (see VCD standard p. IV-7)*/
         put_bits(&pb, 5, 0);
     } else
         put_bits(&pb, 5, s->video_bound);
 
     if (s->is_dvd) {
         put_bits(&pb, 1, 0);    /* packet_rate_restriction_flag */
         put_bits(&pb, 7, 0x7f); /* reserved byte */
     } else
         put_bits(&pb, 8, 0xff); /* reserved byte */
 
     /* DVD-Video Stream_bound entries
     id (0xB9) video, maximum P-STD for stream 0xE0. (P-STD_buffer_bound_scale = 1)
     id (0xB8) audio, maximum P-STD for any MPEG audio (0xC0 to 0xC7) streams. If there are none set to 4096 (32x128). (P-STD_buffer_bound_scale = 0)
     id (0xBD) private stream 1 (audio other than MPEG and subpictures). (P-STD_buffer_bound_scale = 1)
     id (0xBF) private stream 2, NAV packs, set to 2x1024. */
     if (s->is_dvd) {
 
         int P_STD_max_video = 0;
         int P_STD_max_mpeg_audio = 0;
         int P_STD_max_mpeg_PS1 = 0;
 
         for(i=0;i<ctx->nb_streams;i++) {
             StreamInfo *stream = ctx->streams[i]->priv_data;
 
             id = stream->id;
             if (id == 0xbd && stream->max_buffer_size > P_STD_max_mpeg_PS1) {
                 P_STD_max_mpeg_PS1 = stream->max_buffer_size;
             } else if (id >= 0xc0 && id <= 0xc7 && stream->max_buffer_size > P_STD_max_mpeg_audio) {
                 P_STD_max_mpeg_audio = stream->max_buffer_size;
             } else if (id == 0xe0 && stream->max_buffer_size > P_STD_max_video) {
                 P_STD_max_video = stream->max_buffer_size;
             }
         }
 
         /* video */
         put_bits(&pb, 8, 0xb9); /* stream ID */
         put_bits(&pb, 2, 3);
         put_bits(&pb, 1, 1);
         put_bits(&pb, 13, P_STD_max_video / 1024);
 
         /* audio */
         if (P_STD_max_mpeg_audio == 0)
             P_STD_max_mpeg_audio = 4096;
         put_bits(&pb, 8, 0xb8); /* stream ID */
         put_bits(&pb, 2, 3);
         put_bits(&pb, 1, 0);
         put_bits(&pb, 13, P_STD_max_mpeg_audio / 128);
 
         /* private stream 1 */
         put_bits(&pb, 8, 0xbd); /* stream ID */
         put_bits(&pb, 2, 3);
         put_bits(&pb, 1, 0);
         put_bits(&pb, 13, P_STD_max_mpeg_PS1 / 128);
 
         /* private stream 2 */
         put_bits(&pb, 8, 0xbf); /* stream ID */
         put_bits(&pb, 2, 3);
         put_bits(&pb, 1, 1);
         put_bits(&pb, 13, 2);
     }
     else {
         /* audio stream info */
         private_stream_coded = 0;
         for(i=0;i<ctx->nb_streams;i++) {
             StreamInfo *stream = ctx->streams[i]->priv_data;
 
 
             /* For VCDs, only include the stream info for the stream
             that the pack which contains this system belongs to.
             (see VCD standard p. IV-7) */
             if ( !s->is_vcd || stream->id==only_for_stream_id
                 || only_for_stream_id==0) {
 
                 id = stream->id;
                 if (id < 0xc0) {

                     /* special case for private streams (AC-3 uses that) */

                     if (private_stream_coded)
                         continue;
                     private_stream_coded = 1;
                     id = 0xbd;
                 }
                 put_bits(&pb, 8, id); /* stream ID */
                 put_bits(&pb, 2, 3);
                 if (id < 0xe0) {
                     /* audio */
                     put_bits(&pb, 1, 0);
                     put_bits(&pb, 13, stream->max_buffer_size / 128);
                 } else {
                     /* video */
                     put_bits(&pb, 1, 1);
                     put_bits(&pb, 13, stream->max_buffer_size / 1024);
                 }
             }
         }
     }
 
     flush_put_bits(&pb);

     size = put_bits_ptr(&pb) - pb.buf;

     /* patch packet size */

     AV_WB16(buf + 4, size - 6);

 
     return size;
 }
 
 static int get_system_header_size(AVFormatContext *ctx)
 {
     int buf_index, i, private_stream_coded;
     StreamInfo *stream;
     MpegMuxContext *s = ctx->priv_data;
 
     if (s->is_dvd)
        return 18; // DVD-Video system headers are 18 bytes fixed length.
 
     buf_index = 12;
     private_stream_coded = 0;
     for(i=0;i<ctx->nb_streams;i++) {
         stream = ctx->streams[i]->priv_data;
         if (stream->id < 0xc0) {
             if (private_stream_coded)
                 continue;
             private_stream_coded = 1;
         }
         buf_index += 3;
     }
     return buf_index;
 }
 

 static av_cold int mpeg_mux_init(AVFormatContext *ctx)

 {
     MpegMuxContext *s = ctx->priv_data;
     int bitrate, i, mpa_id, mpv_id, mps_id, ac3_id, dts_id, lpcm_id, j;
     AVStream *st;
     StreamInfo *stream;
     int audio_bitrate;
     int video_bitrate;
 
     s->packet_number = 0;

     s->is_vcd =    (CONFIG_MPEG1VCD_MUXER  && ctx->oformat == &ff_mpeg1vcd_muxer);
     s->is_svcd =   (CONFIG_MPEG2SVCD_MUXER && ctx->oformat == &ff_mpeg2svcd_muxer);
     s->is_mpeg2 = ((CONFIG_MPEG2VOB_MUXER  && ctx->oformat == &ff_mpeg2vob_muxer) ||
                    (CONFIG_MPEG2DVD_MUXER  && ctx->oformat == &ff_mpeg2dvd_muxer) ||
                    (CONFIG_MPEG2SVCD_MUXER && ctx->oformat == &ff_mpeg2svcd_muxer));
     s->is_dvd =    (CONFIG_MPEG2DVD_MUXER  && ctx->oformat == &ff_mpeg2dvd_muxer);

     if(ctx->packet_size) {
         if (ctx->packet_size < 20 || ctx->packet_size > (1 << 23) + 10) {
             av_log(ctx, AV_LOG_ERROR, "Invalid packet size %d\n",
                    ctx->packet_size);
             goto fail;
         }

         s->packet_size = ctx->packet_size;

     } else

         s->packet_size = 2048;

     if (ctx->max_delay < 0) /* Not set by the caller */

         ctx->max_delay = 0.7*AV_TIME_BASE;

 
     s->vcd_padding_bytes_written = 0;
     s->vcd_padding_bitrate=0;
 
     s->audio_bound = 0;
     s->video_bound = 0;
     mpa_id = AUDIO_ID;
     ac3_id = AC3_ID;
     dts_id = DTS_ID;
     mpv_id = VIDEO_ID;
     mps_id = SUB_ID;
     lpcm_id = LPCM_ID;
     for(i=0;i<ctx->nb_streams;i++) {
         st = ctx->streams[i];
         stream = av_mallocz(sizeof(StreamInfo));
         if (!stream)
             goto fail;
         st->priv_data = stream;
 

         avpriv_set_pts_info(st, 64, 1, 90000);

 
         switch(st->codec->codec_type) {

         case AVMEDIA_TYPE_AUDIO:

             if        (st->codec->codec_id == AV_CODEC_ID_AC3) {

                 stream->id = ac3_id++;

             } else if (st->codec->codec_id == AV_CODEC_ID_DTS) {

                 stream->id = dts_id++;

             } else if (st->codec->codec_id == AV_CODEC_ID_PCM_S16BE) {

                 stream->id = lpcm_id++;
                 for(j = 0; j < 4; j++) {
                     if (lpcm_freq_tab[j] == st->codec->sample_rate)
                         break;
                 }
                 if (j == 4)
                     goto fail;
                 if (st->codec->channels > 8)
                     return -1;
                 stream->lpcm_header[0] = 0x0c;
                 stream->lpcm_header[1] = (st->codec->channels - 1) | (j << 4);
                 stream->lpcm_header[2] = 0x80;
                 stream->lpcm_align = st->codec->channels * 2;
             } else {
                 stream->id = mpa_id++;
             }
 
             /* This value HAS to be used for VCD (see VCD standard, p. IV-7).
                Right now it is also used for everything else.*/
             stream->max_buffer_size = 4 * 1024;
             s->audio_bound++;
             break;

         case AVMEDIA_TYPE_VIDEO:

             stream->id = mpv_id++;
             if (st->codec->rc_buffer_size)
                 stream->max_buffer_size = 6*1024 + st->codec->rc_buffer_size/8;

             else {

                 av_log(ctx, AV_LOG_WARNING, "VBV buffer size not set, muxing may fail\n");

                 stream->max_buffer_size = 230*1024; //FIXME this is probably too small as default

             }

             if (stream->max_buffer_size > 1024 * 8191) {
                 av_log(ctx, AV_LOG_WARNING, "buffer size %d, too large\n", stream->max_buffer_size);
                 stream->max_buffer_size = 1024 * 8191;
             }

             s->video_bound++;
             break;

         case AVMEDIA_TYPE_SUBTITLE:

             stream->id = mps_id++;
             stream->max_buffer_size = 16 * 1024;
             break;
         default:
             return -1;
         }

         stream->fifo= av_fifo_alloc(16);

         if (!stream->fifo)
             goto fail;

     }
     bitrate = 0;
     audio_bitrate = 0;
     video_bitrate = 0;
     for(i=0;i<ctx->nb_streams;i++) {
         int codec_rate;
         st = ctx->streams[i];
         stream = (StreamInfo*) st->priv_data;
 
         if(st->codec->rc_max_rate || stream->id==VIDEO_ID)
             codec_rate= st->codec->rc_max_rate;
         else
             codec_rate= st->codec->bit_rate;
 
         if(!codec_rate)
             codec_rate= (1<<21)*8*50/ctx->nb_streams;
 
         bitrate += codec_rate;
 

         if ((stream->id & 0xe0) == AUDIO_ID)

             audio_bitrate += codec_rate;
         else if (stream->id==VIDEO_ID)
             video_bitrate += codec_rate;
     }
 

     if (s->user_mux_rate) {
         s->mux_rate = (s->user_mux_rate + (8 * 50) - 1) / (8 * 50);
     } else {

         /* we increase slightly the bitrate to take into account the
            headers. XXX: compute it exactly */

         bitrate += bitrate / 20;

         bitrate += 10000;
         s->mux_rate = (bitrate + (8 * 50) - 1) / (8 * 50);

         if (s->mux_rate >= (1<<22)) {
             av_log(ctx, AV_LOG_WARNING, "mux rate %d is too large\n", s->mux_rate);
             s->mux_rate = (1<<22) - 1;
         }

     }
 
     if (s->is_vcd) {
         double overhead_rate;
 
         /* The VCD standard mandates that the mux_rate field is 3528
            (see standard p. IV-6).
            The value is actually "wrong", i.e. if you calculate
            it using the normal formula and the 75 sectors per second transfer
            rate you get a different value because the real pack size is 2324,
            not 2352. But the standard explicitly specifies that the mux_rate
            field in the header must have this value.*/
 //        s->mux_rate=2352 * 75 / 50;    /* = 3528*/
 
         /* The VCD standard states that the muxed stream must be
            exactly 75 packs / second (the data rate of a single speed cdrom).
            Since the video bitrate (probably 1150000 bits/sec) will be below
            the theoretical maximum we have to add some padding packets
            to make up for the lower data rate.
            (cf. VCD standard p. IV-6 )*/
 
         /* Add the header overhead to the data rate.
            2279 data bytes per audio pack, 2294 data bytes per video pack*/

         overhead_rate  = ((audio_bitrate / 8.0) / 2279) * (2324 - 2279);

         overhead_rate += ((video_bitrate / 8.0) / 2294) * (2324 - 2294);
         overhead_rate *= 8;
 
         /* Add padding so that the full bitrate is 2324*75 bytes/sec */
         s->vcd_padding_bitrate = 2324 * 75 * 8 - (bitrate + overhead_rate);
     }
 
     if (s->is_vcd || s->is_mpeg2)
         /* every packet */
         s->pack_header_freq = 1;
     else
         /* every 2 seconds */
         s->pack_header_freq = 2 * bitrate / s->packet_size / 8;
 
     /* the above seems to make pack_header_freq zero sometimes */
     if (s->pack_header_freq == 0)
        s->pack_header_freq = 1;
 
     if (s->is_mpeg2)
         /* every 200 packets. Need to look at the spec.  */
         s->system_header_freq = s->pack_header_freq * 40;
     else if (s->is_vcd)
         /* the standard mandates that there are only two system headers
            in the whole file: one in the first packet of each stream.
            (see standard p. IV-7 and IV-8) */
         s->system_header_freq = 0x7fffffff;
     else
         s->system_header_freq = s->pack_header_freq * 5;
 
     for(i=0;i<ctx->nb_streams;i++) {
         stream = ctx->streams[i]->priv_data;
         stream->packet_number = 0;
     }
     s->system_header_size = get_system_header_size(ctx);

     s->last_scr = AV_NOPTS_VALUE;

     return 0;
  fail:
     for(i=0;i<ctx->nb_streams;i++) {
         av_free(ctx->streams[i]->priv_data);
     }
     return AVERROR(ENOMEM);
 }
 

 static inline void put_timestamp(AVIOContext *pb, int id, int64_t timestamp)

 {

     avio_w8(pb,

              (id << 4) |
              (((timestamp >> 30) & 0x07) << 1) |
              1);

     avio_wb16(pb, (uint16_t)((((timestamp >> 15) & 0x7fff) << 1) | 1));
     avio_wb16(pb, (uint16_t)((((timestamp      ) & 0x7fff) << 1) | 1));

 }
 
 
 /* return the number of padding bytes that should be inserted into
    the multiplexed stream.*/
 static int get_vcd_padding_size(AVFormatContext *ctx, int64_t pts)
 {
     MpegMuxContext *s = ctx->priv_data;
     int pad_bytes = 0;
 
     if (s->vcd_padding_bitrate > 0 && pts!=AV_NOPTS_VALUE)
     {
         int64_t full_pad_bytes;
 
         full_pad_bytes = (int64_t)((s->vcd_padding_bitrate * (pts / 90000.0)) / 8.0); //FIXME this is wrong
         pad_bytes = (int) (full_pad_bytes - s->vcd_padding_bytes_written);
 
         if (pad_bytes<0)
             /* might happen if we have already padded to a later timestamp. This
                can occur if another stream has already advanced further.*/
             pad_bytes=0;
     }
 
     return pad_bytes;
 }
 
 
 /* Write an MPEG padding packet header. */

 static void put_padding_packet(AVFormatContext *ctx, AVIOContext *pb,int packet_bytes)

 {
     MpegMuxContext *s = ctx->priv_data;
     int i;
 

     avio_wb32(pb, PADDING_STREAM);
     avio_wb16(pb, packet_bytes - 6);

     if (!s->is_mpeg2) {

         avio_w8(pb, 0x0f);

         packet_bytes -= 7;
     } else
         packet_bytes -= 6;
 
     for(i=0;i<packet_bytes;i++)

         avio_w8(pb, 0xff);

 }
 
 static int get_nb_frames(AVFormatContext *ctx, StreamInfo *stream, int len){
     int nb_frames=0;
     PacketDesc *pkt_desc= stream->premux_packet;
 
     while(len>0){
         if(pkt_desc->size == pkt_desc->unwritten_size)
             nb_frames++;
         len -= pkt_desc->unwritten_size;
         pkt_desc= pkt_desc->next;
     }
 
     return nb_frames;
 }
 
 /* flush the packet on stream stream_index */
 static int flush_packet(AVFormatContext *ctx, int stream_index,
                          int64_t pts, int64_t dts, int64_t scr, int trailer_size)
 {
     MpegMuxContext *s = ctx->priv_data;
     StreamInfo *stream = ctx->streams[stream_index]->priv_data;
     uint8_t *buf_ptr;
     int size, payload_size, startcode, id, stuffing_size, i, header_len;
     int packet_size;
     uint8_t buffer[128];
     int zero_trail_bytes = 0;
     int pad_packet_bytes = 0;
     int pes_flags;
     int general_pack = 0;  /*"general" pack without data specific to one stream?*/
     int nb_frames;
 
     id = stream->id;
 

     av_dlog(ctx, "packet ID=%2x PTS=%0.3f\n", id, pts / 90000.0);

 
     buf_ptr = buffer;
 
     if ((s->packet_number % s->pack_header_freq) == 0 || s->last_scr != scr) {
         /* output pack and systems header if needed */
         size = put_pack_header(ctx, buf_ptr, scr);
         buf_ptr += size;
         s->last_scr= scr;
 
         if (s->is_vcd) {
             /* there is exactly one system header for each stream in a VCD MPEG,
                One in the very first video packet and one in the very first
                audio packet (see VCD standard p. IV-7 and IV-8).*/
 
             if (stream->packet_number==0) {
                 size = put_system_header(ctx, buf_ptr, id);
                 buf_ptr += size;
             }
         } else if (s->is_dvd) {
             if (stream->align_iframe || s->packet_number == 0){
                 int PES_bytes_to_fill = s->packet_size - size - 10;
 
                 if (pts != AV_NOPTS_VALUE) {
                     if (dts != pts)
                         PES_bytes_to_fill -= 5 + 5;
                     else
                         PES_bytes_to_fill -= 5;
                 }
 
                 if (stream->bytes_to_iframe == 0 || s->packet_number == 0) {
                     size = put_system_header(ctx, buf_ptr, 0);
                     buf_ptr += size;
                     size = buf_ptr - buffer;

                     avio_write(ctx->pb, buffer, size);

                     avio_wb32(ctx->pb, PRIVATE_STREAM_2);
                     avio_wb16(ctx->pb, 0x03d4);         // length
                     avio_w8(ctx->pb, 0x00);           // substream ID, 00=PCI

                     for (i = 0; i < 979; i++)

                         avio_w8(ctx->pb, 0x00);

                     avio_wb32(ctx->pb, PRIVATE_STREAM_2);
                     avio_wb16(ctx->pb, 0x03fa);         // length
                     avio_w8(ctx->pb, 0x01);           // substream ID, 01=DSI

                     for (i = 0; i < 1017; i++)

                         avio_w8(ctx->pb, 0x00);

 
                     memset(buffer, 0, 128);
                     buf_ptr = buffer;
                     s->packet_number++;
                     stream->align_iframe = 0;
                     scr += s->packet_size*90000LL / (s->mux_rate*50LL); //FIXME rounding and first few bytes of each packet
                     size = put_pack_header(ctx, buf_ptr, scr);
                     s->last_scr= scr;
                     buf_ptr += size;
                     /* GOP Start */
                 } else if (stream->bytes_to_iframe < PES_bytes_to_fill) {
                     pad_packet_bytes = PES_bytes_to_fill - stream->bytes_to_iframe;
                 }
             }
         } else {
             if ((s->packet_number % s->system_header_freq) == 0) {
                 size = put_system_header(ctx, buf_ptr, 0);
                 buf_ptr += size;
             }
         }
     }
     size = buf_ptr - buffer;

     avio_write(ctx->pb, buffer, size);

 
     packet_size = s->packet_size - size;
 

     if (s->is_vcd && (id & 0xe0) == AUDIO_ID)

         /* The VCD standard demands that 20 zero bytes follow
            each audio pack (see standard p. IV-8).*/
         zero_trail_bytes += 20;
 
     if ((s->is_vcd && stream->packet_number==0)
         || (s->is_svcd && s->packet_number==0)) {
         /* for VCD the first pack of each stream contains only the pack header,
            the system header and lots of padding (see VCD standard p. IV-6).
            In the case of an audio pack, 20 zero bytes are also added at
            the end.*/
         /* For SVCD we fill the very first pack to increase compatibility with
            some DVD players. Not mandated by the standard.*/
         if (s->is_svcd)
             general_pack = 1;    /* the system header refers to both streams and no stream data*/
         pad_packet_bytes = packet_size - zero_trail_bytes;
     }
 
     packet_size -= pad_packet_bytes + zero_trail_bytes;
 
     if (packet_size > 0) {
 
         /* packet header size */
         packet_size -= 6;
 
         /* packet header */
         if (s->is_mpeg2) {
             header_len = 3;
             if (stream->packet_number==0)
                 header_len += 3; /* PES extension */
             header_len += 1; /* obligatory stuffing byte */
         } else {
             header_len = 0;
         }
         if (pts != AV_NOPTS_VALUE) {
             if (dts != pts)
                 header_len += 5 + 5;
             else
                 header_len += 5;
         } else {
             if (!s->is_mpeg2)
                 header_len++;
         }
 
         payload_size = packet_size - header_len;
         if (id < 0xc0) {
             startcode = PRIVATE_STREAM_1;
             payload_size -= 1;
             if (id >= 0x40) {
                 payload_size -= 3;
                 if (id >= 0xa0)
                     payload_size -= 3;
             }
         } else {
             startcode = 0x100 + id;
         }
 

         stuffing_size = payload_size - av_fifo_size(stream->fifo);

 
         // first byte does not fit -> reset pts/dts + stuffing
         if(payload_size <= trailer_size && pts != AV_NOPTS_VALUE){
             int timestamp_len=0;
             if(dts != pts)
                 timestamp_len += 5;
             if(pts != AV_NOPTS_VALUE)
                 timestamp_len += s->is_mpeg2 ? 5 : 4;
             pts=dts= AV_NOPTS_VALUE;
             header_len -= timestamp_len;
             if (s->is_dvd && stream->align_iframe) {
                 pad_packet_bytes += timestamp_len;

                 packet_size  -= timestamp_len;

             } else {
                 payload_size += timestamp_len;
             }
             stuffing_size += timestamp_len;
             if(payload_size > trailer_size)
                 stuffing_size += payload_size - trailer_size;
         }
 
         if (pad_packet_bytes > 0 && pad_packet_bytes <= 7) { // can't use padding, so use stuffing
             packet_size += pad_packet_bytes;
             payload_size += pad_packet_bytes; // undo the previous adjustment
             if (stuffing_size < 0) {

                 stuffing_size  = pad_packet_bytes;

             } else {
                 stuffing_size += pad_packet_bytes;
             }
             pad_packet_bytes = 0;
         }
 
         if (stuffing_size < 0)
             stuffing_size = 0;

 
         if (startcode == PRIVATE_STREAM_1 && id >= 0xa0) {
             if (payload_size < av_fifo_size(stream->fifo))
                 stuffing_size += payload_size % stream->lpcm_align;
         }
 

         if (stuffing_size > 16) {    /*<=16 for MPEG-1, <=32 for MPEG-2*/
             pad_packet_bytes += stuffing_size;

             packet_size      -= stuffing_size;
             payload_size     -= stuffing_size;

             stuffing_size = 0;
         }
 
         nb_frames= get_nb_frames(ctx, stream, payload_size - stuffing_size);
 

         avio_wb32(ctx->pb, startcode);

         avio_wb16(ctx->pb, packet_size);

 
         if (!s->is_mpeg2)
             for(i=0;i<stuffing_size;i++)

                 avio_w8(ctx->pb, 0xff);

 
         if (s->is_mpeg2) {

             avio_w8(ctx->pb, 0x80); /* mpeg2 id */

 
             pes_flags=0;
 
             if (pts != AV_NOPTS_VALUE) {
                 pes_flags |= 0x80;
                 if (dts != pts)
                     pes_flags |= 0x40;
             }
 
             /* Both the MPEG-2 and the SVCD standards demand that the
                P-STD_buffer_size field be included in the first packet of
                every stream. (see SVCD standard p. 26 V.2.3.1 and V.2.3.2
                and MPEG-2 standard 2.7.7) */
             if (stream->packet_number == 0)
                 pes_flags |= 0x01;
 

             avio_w8(ctx->pb, pes_flags); /* flags */
             avio_w8(ctx->pb, header_len - 3 + stuffing_size);

 
             if (pes_flags & 0x80)  /*write pts*/

                 put_timestamp(ctx->pb, (pes_flags & 0x40) ? 0x03 : 0x02, pts);

             if (pes_flags & 0x40)  /*write dts*/

                 put_timestamp(ctx->pb, 0x01, dts);

 
             if (pes_flags & 0x01) {  /*write pes extension*/

                 avio_w8(ctx->pb, 0x10); /* flags */

 
                 /* P-STD buffer info */

                 if ((id & 0xe0) == AUDIO_ID)

                     avio_wb16(ctx->pb, 0x4000 | stream->max_buffer_size/ 128);

                 else

                     avio_wb16(ctx->pb, 0x6000 | stream->max_buffer_size/1024);

             }
 
         } else {
             if (pts != AV_NOPTS_VALUE) {
                 if (dts != pts) {

                     put_timestamp(ctx->pb, 0x03, pts);
                     put_timestamp(ctx->pb, 0x01, dts);

                 } else {

                     put_timestamp(ctx->pb, 0x02, pts);

                 }
             } else {

                 avio_w8(ctx->pb, 0x0f);

             }
         }
 
         if (s->is_mpeg2) {
             /* special stuffing byte that is always written
                to prevent accidental generation of start codes. */

             avio_w8(ctx->pb, 0xff);

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

                 avio_w8(ctx->pb, 0xff);

         }
 
         if (startcode == PRIVATE_STREAM_1) {

             avio_w8(ctx->pb, id);

             if (id >= 0xa0) {
                 /* LPCM (XXX: check nb_frames) */

                 avio_w8(ctx->pb, 7);
                 avio_wb16(ctx->pb, 4); /* skip 3 header bytes */
                 avio_w8(ctx->pb, stream->lpcm_header[0]);
                 avio_w8(ctx->pb, stream->lpcm_header[1]);
                 avio_w8(ctx->pb, stream->lpcm_header[2]);

             } else if (id >= 0x40) {

                 /* AC-3 */

                 avio_w8(ctx->pb, nb_frames);
                 avio_wb16(ctx->pb, trailer_size+1);

             }
         }
 
         /* output data */

         assert(payload_size - stuffing_size <= av_fifo_size(stream->fifo));

         av_fifo_generic_read(stream->fifo, ctx->pb, payload_size - stuffing_size, (void*)avio_write);

         stream->bytes_to_iframe -= payload_size - stuffing_size;
     }else{
         payload_size=
         stuffing_size= 0;
     }
 
     if (pad_packet_bytes > 0)

         put_padding_packet(ctx,ctx->pb, pad_packet_bytes);

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

         avio_w8(ctx->pb, 0x00);

     avio_flush(ctx->pb);

 
     s->packet_number++;
 
     /* only increase the stream packet number if this pack actually contains
        something that is specific to this stream! I.e. a dedicated header
        or some data.*/
     if (!general_pack)
         stream->packet_number++;
 
     return payload_size - stuffing_size;
 }
 
 static void put_vcd_padding_sector(AVFormatContext *ctx)
 {
     /* There are two ways to do this padding: writing a sector/pack
        of 0 values, or writing an MPEG padding pack. Both seem to
        work with most decoders, BUT the VCD standard only allows a 0-sector
        (see standard p. IV-4, IV-5).
        So a 0-sector it is...*/
 
     MpegMuxContext *s = ctx->priv_data;
     int i;
 
     for(i=0;i<s->packet_size;i++)

         avio_w8(ctx->pb, 0);

 
     s->vcd_padding_bytes_written += s->packet_size;
 

     avio_flush(ctx->pb);

 
     /* increasing the packet number is correct. The SCR of the following packs
        is calculated from the packet_number and it has to include the padding
        sector (it represents the sector index, not the MPEG pack index)
        (see VCD standard p. IV-6)*/
     s->packet_number++;
 }
 
 static int remove_decoded_packets(AVFormatContext *ctx, int64_t scr){
 //    MpegMuxContext *s = ctx->priv_data;
     int i;
 
     for(i=0; i<ctx->nb_streams; i++){
         AVStream *st = ctx->streams[i];
         StreamInfo *stream = st->priv_data;
         PacketDesc *pkt_desc;
 
         while((pkt_desc= stream->predecode_packet)
               && scr > pkt_desc->dts){ //FIXME > vs >=
             if(stream->buffer_index < pkt_desc->size ||
                stream->predecode_packet == stream->premux_packet){
                 av_log(ctx, AV_LOG_ERROR,

                        "buffer underflow st=%d bufi=%d size=%d\n",

                        i, stream->buffer_index, pkt_desc->size);
                 break;
             }
             stream->buffer_index -= pkt_desc->size;
 
             stream->predecode_packet= pkt_desc->next;
             av_freep(&pkt_desc);
         }
     }
 
     return 0;
 }
 
 static int output_packet(AVFormatContext *ctx, int flush){
     MpegMuxContext *s = ctx->priv_data;
     AVStream *st;
     StreamInfo *stream;

     int i, avail_space=0, es_size, trailer_size;

     int best_i= -1;
     int best_score= INT_MIN;
     int ignore_constraints=0;
     int64_t scr= s->last_scr;
     PacketDesc *timestamp_packet;
     const int64_t max_delay= av_rescale(ctx->max_delay, 90000, AV_TIME_BASE);
 
 retry:
     for(i=0; i<ctx->nb_streams; i++){
         AVStream *st = ctx->streams[i];
         StreamInfo *stream = st->priv_data;

         const int avail_data=  av_fifo_size(stream->fifo);

         const int space= stream->max_buffer_size - stream->buffer_index;

         int rel_space= 1024LL*space / stream->max_buffer_size;

         PacketDesc *next_pkt= stream->premux_packet;
 
         /* for subtitle, a single PES packet must be generated,
            so we flush after every single subtitle packet */
         if(s->packet_size > avail_data && !flush

            && st->codec->codec_type != AVMEDIA_TYPE_SUBTITLE)

             return 0;
         if(avail_data==0)
             continue;

         av_assert0(avail_data>0);

 
         if(space < s->packet_size && !ignore_constraints)
             continue;
 
         if(next_pkt && next_pkt->dts - scr > max_delay)
             continue;

         if (   stream->predecode_packet
             && stream->predecode_packet->size > stream->buffer_index)
             rel_space += 1<<28;

         if(rel_space > best_score){
             best_score= rel_space;
             best_i = i;
             avail_space= space;
         }
     }
 
     if(best_i < 0){
         int64_t best_dts= INT64_MAX;
 
         for(i=0; i<ctx->nb_streams; i++){
             AVStream *st = ctx->streams[i];
             StreamInfo *stream = st->priv_data;
             PacketDesc *pkt_desc= stream->predecode_packet;
             if(pkt_desc && pkt_desc->dts < best_dts)
                 best_dts= pkt_desc->dts;
         }
 

         av_dlog(ctx, "bumping scr, scr:%f, dts:%f\n",

                 scr / 90000.0, best_dts / 90000.0);

         if(best_dts == INT64_MAX)
             return 0;
 
         if(scr >= best_dts+1 && !ignore_constraints){
             av_log(ctx, AV_LOG_ERROR, "packet too large, ignoring buffer limits to mux it\n");
             ignore_constraints= 1;
         }
         scr= FFMAX(best_dts+1, scr);
         if(remove_decoded_packets(ctx, scr) < 0)
             return -1;
         goto retry;
     }
 
     assert(best_i >= 0);
 
     st = ctx->streams[best_i];
     stream = st->priv_data;
 

     assert(av_fifo_size(stream->fifo) > 0);

 
     assert(avail_space >= s->packet_size || ignore_constraints);
 
     timestamp_packet= stream->premux_packet;
     if(timestamp_packet->unwritten_size == timestamp_packet->size){
         trailer_size= 0;
     }else{
         trailer_size= timestamp_packet->unwritten_size;
         timestamp_packet= timestamp_packet->next;
     }
 
     if(timestamp_packet){

         av_dlog(ctx, "dts:%f pts:%f scr:%f stream:%d\n",
                 timestamp_packet->dts / 90000.0,
                 timestamp_packet->pts / 90000.0,
                 scr / 90000.0, best_i);

         es_size= flush_packet(ctx, best_i, timestamp_packet->pts, timestamp_packet->dts, scr, trailer_size);
     }else{

         assert(av_fifo_size(stream->fifo) == trailer_size);

         es_size= flush_packet(ctx, best_i, AV_NOPTS_VALUE, AV_NOPTS_VALUE, scr, trailer_size);
     }
 
     if (s->is_vcd) {
         /* Write one or more padding sectors, if necessary, to reach
            the constant overall bitrate.*/
         int vcd_pad_bytes;
 
         while((vcd_pad_bytes = get_vcd_padding_size(ctx,stream->premux_packet->pts) ) >= s->packet_size){ //FIXME pts cannot be correct here
             put_vcd_padding_sector(ctx);
             s->last_scr += s->packet_size*90000LL / (s->mux_rate*50LL); //FIXME rounding and first few bytes of each packet
         }
     }
 
     stream->buffer_index += es_size;
     s->last_scr += s->packet_size*90000LL / (s->mux_rate*50LL); //FIXME rounding and first few bytes of each packet
 
     while(stream->premux_packet && stream->premux_packet->unwritten_size <= es_size){
         es_size -= stream->premux_packet->unwritten_size;
         stream->premux_packet= stream->premux_packet->next;
     }
     if(es_size)
         stream->premux_packet->unwritten_size -= es_size;
 
     if(remove_decoded_packets(ctx, s->last_scr) < 0)
         return -1;
 
     return 1;
 }
 
 static int mpeg_mux_write_packet(AVFormatContext *ctx, AVPacket *pkt)
 {
     MpegMuxContext *s = ctx->priv_data;
     int stream_index= pkt->stream_index;
     int size= pkt->size;
     uint8_t *buf= pkt->data;
     AVStream *st = ctx->streams[stream_index];
     StreamInfo *stream = st->priv_data;
     int64_t pts, dts;
     PacketDesc *pkt_desc;

     int preload;

     const int is_iframe = st->codec->codec_type == AVMEDIA_TYPE_VIDEO && (pkt->flags & AV_PKT_FLAG_KEY);

     preload = av_rescale(s->preload, 90000, AV_TIME_BASE);
 

     pts= pkt->pts;
     dts= pkt->dts;
 

     if (s->last_scr == AV_NOPTS_VALUE) {

         if (dts == AV_NOPTS_VALUE || (dts < preload && ctx->avoid_negative_ts) || s->is_dvd) {

             if (dts != AV_NOPTS_VALUE)
                 s->preload += av_rescale(-dts, AV_TIME_BASE, 90000);

             s->last_scr = 0;
         } else {

             s->last_scr = dts - preload;
             s->preload = 0;

         }

         preload = av_rescale(s->preload, 90000, AV_TIME_BASE);

         av_log(ctx, AV_LOG_DEBUG, "First SCR: %"PRId64" First DTS: %"PRId64"\n", s->last_scr, dts + preload);

     }

 
     if (dts != AV_NOPTS_VALUE) dts += preload;
     if (pts != AV_NOPTS_VALUE) pts += preload;

     av_dlog(ctx, "dts:%f pts:%f flags:%d stream:%d nopts:%d\n",
             dts / 90000.0, pts / 90000.0, pkt->flags,
             pkt->stream_index, pts != AV_NOPTS_VALUE);

     if (!stream->premux_packet)
         stream->next_packet = &stream->premux_packet;
     *stream->next_packet=
     pkt_desc= av_mallocz(sizeof(PacketDesc));
     pkt_desc->pts= pts;
     pkt_desc->dts= dts;
     pkt_desc->unwritten_size=
     pkt_desc->size= size;
     if(!stream->predecode_packet)
         stream->predecode_packet= pkt_desc;
     stream->next_packet= &pkt_desc->next;
 

     if (av_fifo_realloc2(stream->fifo, av_fifo_size(stream->fifo) + size) < 0)

         return -1;

 
     if (s->is_dvd){
         if (is_iframe && (s->packet_number == 0 || (pts - stream->vobu_start_pts >= 36000))) { // min VOBU length 0.4 seconds (mpucoder)

             stream->bytes_to_iframe = av_fifo_size(stream->fifo);

             stream->align_iframe = 1;
             stream->vobu_start_pts = pts;
         }
     }
 

     av_fifo_generic_write(stream->fifo, buf, size, NULL);

 
     for(;;){
         int ret= output_packet(ctx, 0);
         if(ret<=0)
             return ret;
     }
 }
 
 static int mpeg_mux_end(AVFormatContext *ctx)
 {
 //    MpegMuxContext *s = ctx->priv_data;
     StreamInfo *stream;
     int i;
 
     for(;;){
         int ret= output_packet(ctx, 1);
         if(ret<0)
             return ret;
         else if(ret==0)
             break;
     }
 
     /* End header according to MPEG1 systems standard. We do not write
        it as it is usually not needed by decoders and because it
        complicates MPEG stream concatenation. */

     //avio_wb32(ctx->pb, ISO_11172_END_CODE);

     //avio_flush(ctx->pb);

 
     for(i=0;i<ctx->nb_streams;i++) {
         stream = ctx->streams[i]->priv_data;
 

         assert(av_fifo_size(stream->fifo) == 0);
         av_fifo_free(stream->fifo);

     }
     return 0;
 }
 

 #define OFFSET(x) offsetof(MpegMuxContext, x)
 #define E AV_OPT_FLAG_ENCODING_PARAM
 static const AVOption options[] = {

     { "muxrate", NULL, OFFSET(user_mux_rate), AV_OPT_TYPE_INT, {.i64 = 0}, 0, ((1<<22) - 1) * (8 * 50), E },

     { "preload", "Initial demux-decode delay in microseconds.", OFFSET(preload),  AV_OPT_TYPE_INT, {.i64 = 500000}, 0, INT_MAX, E},

     { NULL },
 };
 
 #define MPEGENC_CLASS(flavor)\
 static const AVClass flavor ## _class = {\
     .class_name = #flavor " muxer",\
     .item_name  = av_default_item_name,\
     .version    = LIBAVUTIL_VERSION_INT,\
     .option     = options,\
 };
 

 #if CONFIG_MPEG1SYSTEM_MUXER

 MPEGENC_CLASS(mpeg)

 AVOutputFormat ff_mpeg1system_muxer = {

     .name              = "mpeg",

     .long_name         = NULL_IF_CONFIG_SMALL("MPEG-1 Systems / MPEG program stream"),

     .mime_type         = "video/mpeg",
     .extensions        = "mpg,mpeg",
     .priv_data_size    = sizeof(MpegMuxContext),

     .audio_codec       = AV_CODEC_ID_MP2,
     .video_codec       = AV_CODEC_ID_MPEG1VIDEO,

     .write_header      = mpeg_mux_init,
     .write_packet      = mpeg_mux_write_packet,
     .write_trailer     = mpeg_mux_end,

     .priv_class        = &mpeg_class,

 };
 #endif

 #if CONFIG_MPEG1VCD_MUXER

 MPEGENC_CLASS(vcd)

 AVOutputFormat ff_mpeg1vcd_muxer = {

     .name              = "vcd",

     .long_name         = NULL_IF_CONFIG_SMALL("MPEG-1 Systems / MPEG program stream (VCD)"),

     .mime_type         = "video/mpeg",
     .priv_data_size    = sizeof(MpegMuxContext),

     .audio_codec       = AV_CODEC_ID_MP2,
     .video_codec       = AV_CODEC_ID_MPEG1VIDEO,

     .write_header      = mpeg_mux_init,
     .write_packet      = mpeg_mux_write_packet,
     .write_trailer     = mpeg_mux_end,

     .priv_class        = &vcd_class,

 };
 #endif

 #if CONFIG_MPEG2VOB_MUXER

 MPEGENC_CLASS(vob)

 AVOutputFormat ff_mpeg2vob_muxer = {

     .name              = "vob",

     .long_name         = NULL_IF_CONFIG_SMALL("MPEG-2 PS (VOB)"),

     .mime_type         = "video/mpeg",
     .extensions        = "vob",
     .priv_data_size    = sizeof(MpegMuxContext),

     .audio_codec       = AV_CODEC_ID_MP2,
     .video_codec       = AV_CODEC_ID_MPEG2VIDEO,

     .write_header      = mpeg_mux_init,
     .write_packet      = mpeg_mux_write_packet,
     .write_trailer     = mpeg_mux_end,

     .priv_class        = &vob_class,

 };
 #endif
 
 /* Same as mpeg2vob_mux except that the pack size is 2324 */

 #if CONFIG_MPEG2SVCD_MUXER

 MPEGENC_CLASS(svcd)

 AVOutputFormat ff_mpeg2svcd_muxer = {

     .name              = "svcd",

     .long_name         = NULL_IF_CONFIG_SMALL("MPEG-2 PS (SVCD)"),

     .mime_type         = "video/mpeg",
     .extensions        = "vob",
     .priv_data_size    = sizeof(MpegMuxContext),

     .audio_codec       = AV_CODEC_ID_MP2,
     .video_codec       = AV_CODEC_ID_MPEG2VIDEO,

     .write_header      = mpeg_mux_init,
     .write_packet      = mpeg_mux_write_packet,
     .write_trailer     = mpeg_mux_end,

     .priv_class        = &svcd_class,

 };
 #endif
 
 /*  Same as mpeg2vob_mux except the 'is_dvd' flag is set to produce NAV pkts */

 #if CONFIG_MPEG2DVD_MUXER

 MPEGENC_CLASS(dvd)

 AVOutputFormat ff_mpeg2dvd_muxer = {

     .name              = "dvd",

     .long_name         = NULL_IF_CONFIG_SMALL("MPEG-2 PS (DVD VOB)"),

     .mime_type         = "video/mpeg",
     .extensions        = "dvd",
     .priv_data_size    = sizeof(MpegMuxContext),

     .audio_codec       = AV_CODEC_ID_MP2,
     .video_codec       = AV_CODEC_ID_MPEG2VIDEO,

     .write_header      = mpeg_mux_init,
     .write_packet      = mpeg_mux_write_packet,
     .write_trailer     = mpeg_mux_end,

     .priv_class        = &dvd_class,

 };
 #endif