PeerStreamer

/*

 * 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/fifo.h"

#include "libavcodec/put_bits.h"

#include "avformat.h"

#include "mpeg.h"

#define MAX_PAYLOAD_SIZE 4096

//#define DEBUG_SEEK

#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 {

    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 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;

} MpegMuxContext;

extern AVOutputFormat mpeg1vcd_muxer;

extern AVOutputFormat mpeg2dvd_muxer;

extern AVOutputFormat mpeg2svcd_muxer;

extern AVOutputFormat 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_bits(&pb, 32, 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 pbBufPtr(&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_bits(&pb, 32, 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==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 = pbBufPtr(&pb) - pb.buf;

    /* patch packet size */

    buf[4] = (size - 6) >> 8;

    buf[5] = (size - 6) & 0xff;

    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 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 == &mpeg1vcd_muxer);

    s->is_svcd =   (CONFIG_MPEG2SVCD_MUXER && ctx->oformat == &mpeg2svcd_muxer);

    s->is_mpeg2 = ((CONFIG_MPEG2VOB_MUXER  && ctx->oformat == &mpeg2vob_muxer) ||

                   (CONFIG_MPEG2DVD_MUXER  && ctx->oformat == &mpeg2dvd_muxer) ||

                   (CONFIG_MPEG2SVCD_MUXER && ctx->oformat == &mpeg2svcd_muxer));

    s->is_dvd =    (CONFIG_MPEG2DVD_MUXER  && ctx->oformat == &mpeg2dvd_muxer);

    if(ctx->packet_size)

        s->packet_size = ctx->packet_size;

    else

        s->packet_size = 2048;

    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;

        av_set_pts_info(st, 64, 1, 90000);

        switch(st->codec->codec_type) {

        case CODEC_TYPE_AUDIO:

            if        (st->codec->codec_id == CODEC_ID_AC3) {

                stream->id = ac3_id++;

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

                stream->id = dts_id++;

            } else if (st->codec->codec_id == 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 CODEC_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

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

#if 0

                /* see VCD standard, p. IV-7*/

                stream->max_buffer_size = 46 * 1024;

            else

                /* This value HAS to be used for SVCD (see SVCD standard, p. 26 V.2.3.2).

                   Right now it is also used for everything else.*/

                stream->max_buffer_size = 230 * 1024;

#endif

            s->video_bound++;

            break;

        case CODEC_TYPE_SUBTITLE:

            stream->id = mps_id++;

            stream->max_buffer_size = 16 * 1024;

            break;

        default:

            return -1;

        }

        stream->fifo= av_fifo_alloc(16);

    }

    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==AUDIO_ID)

            audio_bitrate += codec_rate;

        else if (stream->id==VIDEO_ID)

            video_bitrate += codec_rate;

    }

    if(ctx->mux_rate){

        s->mux_rate= (ctx->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*5/100;

        bitrate += 10000;

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

    }

    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 = 0;

    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(ByteIOContext *pb, int id, int64_t timestamp)

{

    put_byte(pb,

             (id << 4) |

             (((timestamp >> 30) & 0x07) << 1) |

             1);

    put_be16(pb, (uint16_t)((((timestamp >> 15) & 0x7fff) << 1) | 1));

    put_be16(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;

}

#if 0 /* unused, remove? */

/* return the exact available payload size for the next packet for

   stream 'stream_index'. 'pts' and 'dts' are only used to know if

   timestamps are needed in the packet header. */

static int get_packet_payload_size(AVFormatContext *ctx, int stream_index,

                                   int64_t pts, int64_t dts)

{

    MpegMuxContext *s = ctx->priv_data;

    int buf_index;

    StreamInfo *stream;

    stream = ctx->streams[stream_index]->priv_data;

    buf_index = 0;

    if (((s->packet_number % s->pack_header_freq) == 0)) {

        /* pack header size */

        if (s->is_mpeg2)

            buf_index += 14;

        else

            buf_index += 12;

        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)

                /* The system headers refer only to the stream they occur in,

                   so they have a constant size.*/

                buf_index += 15;

        } else {

            if ((s->packet_number % s->system_header_freq) == 0)

                buf_index += s->system_header_size;

        }

    }

    if ((s->is_vcd && stream->packet_number==0)

        || (s->is_svcd && s->packet_number==0))

        /* the first pack of each stream contains only the pack header,

           the system header and some padding (see VCD standard p. IV-6)

           Add the padding size, so that the actual payload becomes 0.*/

        buf_index += s->packet_size - buf_index;

    else {

        /* packet header size */

        buf_index += 6;

        if (s->is_mpeg2) {

            buf_index += 3;

            if (stream->packet_number==0)

                buf_index += 3; /* PES extension */

            buf_index += 1;    /* obligatory stuffing byte */

        }

        if (pts != AV_NOPTS_VALUE) {

            if (dts != pts)

                buf_index += 5 + 5;

            else

                buf_index += 5;

        } else {

            if (!s->is_mpeg2)

                buf_index++;

        }

        if (stream->id < 0xc0) {

            /* AC-3/LPCM private data header */

            buf_index += 4;

            if (stream->id >= 0xa0) {

                int n;

                buf_index += 3;

                /* NOTE: we round the payload size to an integer number of

                   LPCM samples */

                n = (s->packet_size - buf_index) % stream->lpcm_align;

                if (n)

                    buf_index += (stream->lpcm_align - n);

            }

        }

        if (s->is_vcd && stream->id == AUDIO_ID)

            /* The VCD standard demands that 20 zero bytes follow

               each audio packet (see standard p. IV-8).*/

            buf_index+=20;

    }

    return s->packet_size - buf_index;

}

#endif

/* Write an MPEG padding packet header. */

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

{

    MpegMuxContext *s = ctx->priv_data;

    int i;

    put_be32(pb, PADDING_STREAM);

    put_be16(pb, packet_bytes - 6);

    if (!s->is_mpeg2) {

        put_byte(pb, 0x0f);

        packet_bytes -= 7;

    } else

        packet_bytes -= 6;

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

        put_byte(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;

#if 0

    printf("packet ID=%2x PTS=%0.3f\n",

           id, pts / 90000.0);

#endif

    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;

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

                    put_be32(ctx->pb, PRIVATE_STREAM_2);

                    put_be16(ctx->pb, 0x03d4);         // length

                    put_byte(ctx->pb, 0x00);           // substream ID, 00=PCI

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

                        put_byte(ctx->pb, 0x00);

                    put_be32(ctx->pb, PRIVATE_STREAM_2);

                    put_be16(ctx->pb, 0x03fa);         // length

                    put_byte(ctx->pb, 0x01);           // substream ID, 01=DSI

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

                        put_byte(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;

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

    packet_size = s->packet_size - size;

    if (s->is_vcd && id == 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 (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);

        put_be32(ctx->pb, startcode);

        put_be16(ctx->pb, packet_size);

        if (!s->is_mpeg2)

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

                put_byte(ctx->pb, 0xff);

        if (s->is_mpeg2) {

            put_byte(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;

            put_byte(ctx->pb, pes_flags); /* flags */

            put_byte(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*/

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

                /* P-STD buffer info */

                if (id == AUDIO_ID)

                    put_be16(ctx->pb, 0x4000 | stream->max_buffer_size/ 128);

                else

                    put_be16(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 {

                put_byte(ctx->pb, 0x0f);

            }

        }

        if (s->is_mpeg2) {

            /* special stuffing byte that is always written

               to prevent accidental generation of start codes. */

            put_byte(ctx->pb, 0xff);

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

                put_byte(ctx->pb, 0xff);

        }

        if (startcode == PRIVATE_STREAM_1) {

            put_byte(ctx->pb, id);

            if (id >= 0xa0) {

                /* LPCM (XXX: check nb_frames) */

                put_byte(ctx->pb, 7);

                put_be16(ctx->pb, 4); /* skip 3 header bytes */

                put_byte(ctx->pb, stream->lpcm_header[0]);

                put_byte(ctx->pb, stream->lpcm_header[1]);

                put_byte(ctx->pb, stream->lpcm_header[2]);

            } else if (id >= 0x40) {

                /* AC-3 */

                put_byte(ctx->pb, nb_frames);

                put_be16(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, &put_buffer);

        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++)

        put_byte(ctx->pb, 0x00);

    put_flush_packet(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++)

        put_byte(ctx->pb, 0);

    s->vcd_padding_bytes_written += s->packet_size;

    put_flush_packet(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++;

}

#if 0 /* unused, remove? */

static int64_t get_vcd_scr(AVFormatContext *ctx,int stream_index,int64_t pts)

{

    MpegMuxContext *s = ctx->priv_data;

    int64_t scr;

        /* Since the data delivery rate is constant, SCR is computed

           using the formula C + i * 1200 where C is the start constant

           and i is the pack index.

           It is recommended that SCR 0 is at the beginning of the VCD front

           margin (a sequence of empty Form 2 sectors on the CD).

           It is recommended that the front margin is 30 sectors long, so

           we use C = 30*1200 = 36000

           (Note that even if the front margin is not 30 sectors the file

           will still be correct according to the standard. It just won't have

           the "recommended" value).*/

        scr = 36000 + s->packet_number * 1200;

    return scr;

}

#endif

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 i=%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= 1024*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 != CODEC_TYPE_SUBTITLE)

            return 0;

        if(avail_data==0)

            continue;

        assert(avail_data>0);

        if(space < s->packet_size && !ignore_constraints)

            continue;

        if(next_pkt && next_pkt->dts - scr > max_delay)

            continue;

        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;

        }

#if 0

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

               scr/90000.0, best_dts/90000.0);

#endif

        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_log(ctx, AV_LOG_DEBUG, "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;

    const int preload= av_rescale(ctx->preload, 90000, AV_TIME_BASE);

    const int is_iframe = st->codec->codec_type == CODEC_TYPE_VIDEO && (pkt->flags & PKT_FLAG_KEY);

    pts= pkt->pts;

    dts= pkt->dts;

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

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

//av_log(ctx, AV_LOG_DEBUG, "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. */

    //put_be32(ctx->pb, ISO_11172_END_CODE);

    //put_flush_packet(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;

}

#if CONFIG_MPEG1SYSTEM_MUXER

AVOutputFormat mpeg1system_muxer = {

    "mpeg",

    NULL_IF_CONFIG_SMALL("MPEG-1 System format"),

    "video/mpeg",

    "mpg,mpeg",

    sizeof(MpegMuxContext),

    CODEC_ID_MP2,

    CODEC_ID_MPEG1VIDEO,

    mpeg_mux_init,

    mpeg_mux_write_packet,

    mpeg_mux_end,

};

#endif

#if CONFIG_MPEG1VCD_MUXER

AVOutputFormat mpeg1vcd_muxer = {

    "vcd",

    NULL_IF_CONFIG_SMALL("MPEG-1 System format (VCD)"),

    "video/mpeg",

    NULL,

    sizeof(MpegMuxContext),

    CODEC_ID_MP2,

    CODEC_ID_MPEG1VIDEO,

    mpeg_mux_init,

    mpeg_mux_write_packet,

    mpeg_mux_end,

};

#endif

#if CONFIG_MPEG2VOB_MUXER

AVOutputFormat mpeg2vob_muxer = {

    "vob",

    NULL_IF_CONFIG_SMALL("MPEG-2 PS format (VOB)"),

    "video/mpeg",

    "vob",

    sizeof(MpegMuxContext),

    CODEC_ID_MP2,

    CODEC_ID_MPEG2VIDEO,

    mpeg_mux_init,

    mpeg_mux_write_packet,

    mpeg_mux_end,

};

#endif

/* Same as mpeg2vob_mux except that the pack size is 2324 */

#if CONFIG_MPEG2SVCD_MUXER

AVOutputFormat mpeg2svcd_muxer = {

    "svcd",

    NULL_IF_CONFIG_SMALL("MPEG-2 PS format (VOB)"),

    "video/mpeg",

    "vob",

    sizeof(MpegMuxContext),

    CODEC_ID_MP2,

    CODEC_ID_MPEG2VIDEO,

    mpeg_mux_init,

    mpeg_mux_write_packet,

    mpeg_mux_end,

};

#endif

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

#if CONFIG_MPEG2DVD_MUXER

AVOutputFormat mpeg2dvd_muxer = {

    "dvd",

    NULL_IF_CONFIG_SMALL("MPEG-2 PS format (DVD VOB)"),

    "video/mpeg",

    "dvd",

    sizeof(MpegMuxContext),

    CODEC_ID_MP2,

    CODEC_ID_MPEG2VIDEO,

    mpeg_mux_init,

    mpeg_mux_write_packet,

    mpeg_mux_end,

};

#endif