PeerStreamer

/*

 * AVI decoder.

 * Copyright (c) 2001 Fabrice Bellard.

 *

 * This library 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 of the License, or (at your option) any later version.

 *

 * This library 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 this library; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#include "avformat.h"

#include "avi.h"

#include "dv.h"

#undef NDEBUG

#include <assert.h>

//#define DEBUG

//#define DEBUG_SEEK

typedef struct AVIStream {

    int64_t frame_offset; /* current frame (video) or byte (audio) counter

                         (used to compute the pts) */

    int remaining;

    int packet_size;

    int scale;

    int rate;

    int sample_size; /* audio only data */

    int start;

    int cum_len; /* temporary storage (used during seek) */

    int prefix;                       ///< normally 'd'<<8 + 'c' or 'w'<<8 + 'b'

    int prefix_count;

} AVIStream;

typedef struct {

    int64_t  riff_end;

    int64_t  movi_end;

    offset_t movi_list;

    int index_loaded;

    int is_odml;

    int non_interleaved;

    int stream_index;

    DVDemuxContext* dv_demux;

} AVIContext;

static int avi_load_index(AVFormatContext *s);

#ifdef DEBUG

static void print_tag(const char *str, unsigned int tag, int size)

{

    printf("%s: tag=%c%c%c%c size=0x%x\n",

           str, tag & 0xff,

           (tag >> 8) & 0xff,

           (tag >> 16) & 0xff,

           (tag >> 24) & 0xff,

           size);

}

#endif

static int get_riff(AVIContext *avi, ByteIOContext *pb)

{

    uint32_t tag;

    /* check RIFF header */

    tag = get_le32(pb);

    if (tag != MKTAG('R', 'I', 'F', 'F'))

        return -1;

    avi->riff_end = get_le32(pb);   /* RIFF chunk size */

    avi->riff_end += url_ftell(pb); /* RIFF chunk end */

    tag = get_le32(pb);

    if (tag != MKTAG('A', 'V', 'I', ' ') && tag != MKTAG('A', 'V', 'I', 'X'))

        return -1;

    return 0;

}

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

{

    AVIContext *avi = s->priv_data;

    ByteIOContext *pb = &s->pb;

    uint32_t tag, tag1, handler;

    int codec_type, stream_index, frame_period, bit_rate;

    unsigned int size, nb_frames;

    int i, n;

    AVStream *st;

    AVIStream *ast;

    int xan_video = 0;  /* hack to support Xan A/V */

    avi->stream_index= -1;

    if (get_riff(avi, pb) < 0)

        return -1;

    /* first list tag */

    stream_index = -1;

    codec_type = -1;

    frame_period = 0;

    for(;;) {

        if (url_feof(pb))

            goto fail;

        tag = get_le32(pb);

        size = get_le32(pb);

#ifdef DEBUG

        print_tag("tag", tag, size);

#endif

        switch(tag) {

        case MKTAG('L', 'I', 'S', 'T'):

            /* ignored, except when start of video packets */

            tag1 = get_le32(pb);

#ifdef DEBUG

            print_tag("list", tag1, 0);

#endif

            if (tag1 == MKTAG('m', 'o', 'v', 'i')) {

                avi->movi_list = url_ftell(pb) - 4;

                if(size) avi->movi_end = avi->movi_list + size;

                else     avi->movi_end = url_fsize(pb);

#ifdef DEBUG

                printf("movi end=%Lx\n", avi->movi_end);

#endif

                goto end_of_header;

            }

            break;

        case MKTAG('d', 'm', 'l', 'h'):

            avi->is_odml = 1;

            url_fskip(pb, size + (size & 1));

            break;

        case MKTAG('a', 'v', 'i', 'h'):

            /* avi header */

            /* using frame_period is bad idea */

            frame_period = get_le32(pb);

            bit_rate = get_le32(pb) * 8;

            url_fskip(pb, 4 * 4);

            n = get_le32(pb);

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

                AVIStream *ast;

                st = av_new_stream(s, i);

                if (!st)

                    goto fail;

                ast = av_mallocz(sizeof(AVIStream));

                if (!ast)

                    goto fail;

                st->priv_data = ast;

            }

            url_fskip(pb, size - 7 * 4);

            break;

        case MKTAG('s', 't', 'r', 'h'):

            /* stream header */

            stream_index++;

            tag1 = get_le32(pb);

            handler = get_le32(pb); /* codec tag */

#ifdef DEBUG

        print_tag("strh", tag1, -1);

#endif

            if(tag1 == MKTAG('i', 'a', 'v', 's') || tag1 == MKTAG('i', 'v', 'a', 's')){

                /*

                 * After some consideration -- I don't think we

                 * have to support anything but DV in a type1 AVIs.

                 */

                if (s->nb_streams != 1)

                    goto fail;

                if (handler != MKTAG('d', 'v', 's', 'd') &&

                    handler != MKTAG('d', 'v', 'h', 'd') &&

                    handler != MKTAG('d', 'v', 's', 'l'))

                   goto fail;

                ast = s->streams[0]->priv_data;

                av_freep(&s->streams[0]->codec->extradata);

                av_freep(&s->streams[0]);

                s->nb_streams = 0;

                avi->dv_demux = dv_init_demux(s);

                if (!avi->dv_demux)

                    goto fail;

                s->streams[0]->priv_data = ast;

                url_fskip(pb, 3 * 4);

                ast->scale = get_le32(pb);

                ast->rate = get_le32(pb);

                stream_index = s->nb_streams - 1;

                url_fskip(pb, size - 7*4);

                break;

            }

            if (stream_index >= s->nb_streams) {

                url_fskip(pb, size - 8);

                break;

            }

            st = s->streams[stream_index];

            ast = st->priv_data;

            st->codec->stream_codec_tag= handler;

            get_le32(pb); /* flags */

            get_le16(pb); /* priority */

            get_le16(pb); /* language */

            get_le32(pb); /* initial frame */

            ast->scale = get_le32(pb);

            ast->rate = get_le32(pb);

            if(ast->scale && ast->rate){

            }else if(frame_period){

                ast->rate = 1000000;

                ast->scale = frame_period;

            }else{

                ast->rate = 25;

                ast->scale = 1;

            }

            av_set_pts_info(st, 64, ast->scale, ast->rate);

            ast->start= get_le32(pb); /* start */

            nb_frames = get_le32(pb);

            st->start_time = 0;

            st->duration = nb_frames;

            get_le32(pb); /* buffer size */

            get_le32(pb); /* quality */

            ast->sample_size = get_le32(pb); /* sample ssize */

//            av_log(NULL, AV_LOG_DEBUG, "%d %d %d %d\n", ast->rate, ast->scale, ast->start, ast->sample_size);

            switch(tag1) {

            case MKTAG('v', 'i', 'd', 's'):

                codec_type = CODEC_TYPE_VIDEO;

                ast->sample_size = 0;

                break;

            case MKTAG('a', 'u', 'd', 's'):

                codec_type = CODEC_TYPE_AUDIO;

                break;

            case MKTAG('t', 'x', 't', 's'):

                //FIXME

                codec_type = CODEC_TYPE_DATA; //CODEC_TYPE_SUB ?  FIXME

                break;

            case MKTAG('p', 'a', 'd', 's'):

                codec_type = CODEC_TYPE_UNKNOWN;

                stream_index--;

                break;

            default:

                av_log(s, AV_LOG_ERROR, "unknown stream type %X\n", tag1);

                goto fail;

            }

            url_fskip(pb, size - 12 * 4);

            break;

        case MKTAG('s', 't', 'r', 'f'):

            /* stream header */

            if (stream_index >= s->nb_streams || avi->dv_demux) {

                url_fskip(pb, size);

            } else {

                st = s->streams[stream_index];

                switch(codec_type) {

                case CODEC_TYPE_VIDEO:

                    get_le32(pb); /* size */

                    st->codec->width = get_le32(pb);

                    st->codec->height = get_le32(pb);

                    get_le16(pb); /* panes */

                    st->codec->bits_per_sample= get_le16(pb); /* depth */

                    tag1 = get_le32(pb);

                    get_le32(pb); /* ImageSize */

                    get_le32(pb); /* XPelsPerMeter */

                    get_le32(pb); /* YPelsPerMeter */

                    get_le32(pb); /* ClrUsed */

                    get_le32(pb); /* ClrImportant */

                 if(size > 10*4 && size<(1<<30)){

                    st->codec->extradata_size= size - 10*4;

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

                    get_buffer(pb, st->codec->extradata, st->codec->extradata_size);

                 }

                    if(st->codec->extradata_size & 1) //FIXME check if the encoder really did this correctly

                        get_byte(pb);

                    /* Extract palette from extradata if bpp <= 8 */

                    /* This code assumes that extradata contains only palette */

                    /* This is true for all paletted codecs implemented in ffmpeg */

                    if (st->codec->extradata_size && (st->codec->bits_per_sample <= 8)) {

                        st->codec->palctrl = av_mallocz(sizeof(AVPaletteControl));

#ifdef WORDS_BIGENDIAN

                        for (i = 0; i < FFMIN(st->codec->extradata_size, AVPALETTE_SIZE)/4; i++)

                            st->codec->palctrl->palette[i] = bswap_32(((uint32_t*)st->codec->extradata)[i]);

#else

                        memcpy(st->codec->palctrl->palette, st->codec->extradata,

                               FFMIN(st->codec->extradata_size, AVPALETTE_SIZE));

#endif

                        st->codec->palctrl->palette_changed = 1;

                    }

#ifdef DEBUG

                    print_tag("video", tag1, 0);

#endif

                    st->codec->codec_type = CODEC_TYPE_VIDEO;

                    st->codec->codec_tag = tag1;

                    st->codec->codec_id = codec_get_id(codec_bmp_tags, tag1);

                    if (st->codec->codec_id == CODEC_ID_XAN_WC4)

                        xan_video = 1;

                    st->need_parsing = 2; //only parse headers dont do slower repacketization, this is needed to get the pict type which is needed for generating correct pts

//                    url_fskip(pb, size - 5 * 4);

                    break;

                case CODEC_TYPE_AUDIO:

                    get_wav_header(pb, st->codec, size);

                    if (size%2) /* 2-aligned (fix for Stargate SG-1 - 3x18 - Shades of Grey.avi) */

                        url_fskip(pb, 1);

                    /* special case time: To support Xan DPCM, hardcode

                     * the format if Xxan is the video codec */

                    st->need_parsing = 1;

                    /* force parsing as several audio frames can be in

                       one packet */

                    if (xan_video)

                        st->codec->codec_id = CODEC_ID_XAN_DPCM;

                    break;

                default:

                    st->codec->codec_type = CODEC_TYPE_DATA;

                    st->codec->codec_id= CODEC_ID_NONE;

                    st->codec->codec_tag= 0;

                    url_fskip(pb, size);

                    break;

                }

            }

            break;

        default:

            /* skip tag */

            size += (size & 1);

            url_fskip(pb, size);

            break;

        }

    }

 end_of_header:

    /* check stream number */

    if (stream_index != s->nb_streams - 1) {

    fail:

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

            av_freep(&s->streams[i]->codec->extradata);

            av_freep(&s->streams[i]);

        }

        return -1;

    }

    assert(!avi->index_loaded);

    avi_load_index(s);

    avi->index_loaded = 1;

    return 0;

}

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

{

    AVIContext *avi = s->priv_data;

    ByteIOContext *pb = &s->pb;

    int n, d[8], size;

    offset_t i, sync;

    void* dstr;

    if (avi->dv_demux) {

        size = dv_get_packet(avi->dv_demux, pkt);

        if (size >= 0)

            return size;

    }

    if(avi->non_interleaved){

        int best_stream_index = 0;

        AVStream *best_st= NULL;

        AVIStream *best_ast;

        int64_t best_ts= INT64_MAX;

        int i;

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

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

            AVIStream *ast = st->priv_data;

            int64_t ts= ast->frame_offset;

            if(ast->sample_size)

                ts /= ast->sample_size;

            ts= av_rescale(ts, AV_TIME_BASE * (int64_t)st->time_base.num, st->time_base.den);

//            av_log(NULL, AV_LOG_DEBUG, "%Ld %d/%d %Ld\n", ts, st->time_base.num, st->time_base.den, ast->frame_offset);

            if(ts < best_ts){

                best_ts= ts;

                best_st= st;

                best_stream_index= i;

            }

        }

        best_ast = best_st->priv_data;

        best_ts= av_rescale(best_ts, best_st->time_base.den, AV_TIME_BASE * (int64_t)best_st->time_base.num); //FIXME a little ugly

        if(best_ast->remaining)

            i= av_index_search_timestamp(best_st, best_ts, AVSEEK_FLAG_ANY | AVSEEK_FLAG_BACKWARD);

        else

            i= av_index_search_timestamp(best_st, best_ts, AVSEEK_FLAG_ANY);

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

        if(i>=0){

            int64_t pos= best_st->index_entries[i].pos;

            pos += avi->movi_list + best_ast->packet_size - best_ast->remaining;

            url_fseek(&s->pb, pos, SEEK_SET);

//        av_log(NULL, AV_LOG_DEBUG, "pos=%Ld\n", pos);

            if(best_ast->remaining)

                avi->stream_index= best_stream_index;

            else

                avi->stream_index= -1;

        }

    }

resync:

    if(avi->stream_index >= 0){

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

        AVIStream *ast= st->priv_data;

        int size;

        if(ast->sample_size == 0)

            size= INT_MAX;

        else if(ast->sample_size < 32)

            size= 64*ast->sample_size;

        else

            size= ast->sample_size;

        if(size > ast->remaining)

            size= ast->remaining;

        av_get_packet(pb, pkt, size);

        if (avi->dv_demux) {

            dstr = pkt->destruct;

            size = dv_produce_packet(avi->dv_demux, pkt,

                                    pkt->data, pkt->size);

            pkt->destruct = dstr;

            pkt->flags |= PKT_FLAG_KEY;

        } else {

            /* XXX: how to handle B frames in avi ? */

            pkt->dts = ast->frame_offset;

//                pkt->dts += ast->start;

            if(ast->sample_size)

                pkt->dts /= ast->sample_size;

//av_log(NULL, AV_LOG_DEBUG, "dts:%Ld offset:%d %d/%d smpl_siz:%d base:%d st:%d size:%d\n", pkt->dts, ast->frame_offset, ast->scale, ast->rate, ast->sample_size, AV_TIME_BASE, n, size);

            pkt->stream_index = avi->stream_index;

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

                if(st->index_entries){

                    AVIndexEntry *e;

                    int index;

                    index= av_index_search_timestamp(st, pkt->dts, 0);

                    e= &st->index_entries[index];

                    if(index >= 0 && e->timestamp == ast->frame_offset){

                        if (e->flags & AVINDEX_KEYFRAME)

                            pkt->flags |= PKT_FLAG_KEY;

                    }

                } else {

                    /* if no index, better to say that all frames

                        are key frames */

                    pkt->flags |= PKT_FLAG_KEY;

                }

            } else {

                pkt->flags |= PKT_FLAG_KEY;

            }

            if(ast->sample_size)

                ast->frame_offset += pkt->size;

            else

                ast->frame_offset++;

        }

        ast->remaining -= size;

        if(!ast->remaining){

            avi->stream_index= -1;

            ast->packet_size= 0;

            if (size & 1) {

                get_byte(pb);

                size++;

            }

        }

        return size;

    }

    memset(d, -1, sizeof(int)*8);

    for(i=sync=url_ftell(pb); !url_feof(pb); i++) {

        int j;

        if (i >= avi->movi_end) {

            if (avi->is_odml) {

                url_fskip(pb, avi->riff_end - i);

                avi->riff_end = avi->movi_end = url_fsize(pb);

            } else

                break;

        }

        for(j=0; j<7; j++)

            d[j]= d[j+1];

        d[7]= get_byte(pb);

        size= d[4] + (d[5]<<8) + (d[6]<<16) + (d[7]<<24);

        if(    d[2] >= '0' && d[2] <= '9'

            && d[3] >= '0' && d[3] <= '9'){

            n= (d[2] - '0') * 10 + (d[3] - '0');

        }else{

            n= 100; //invalid stream id

        }

//av_log(NULL, AV_LOG_DEBUG, "%X %X %X %X %X %X %X %X %lld %d %d\n", d[0], d[1], d[2], d[3], d[4], d[5], d[6], d[7], i, size, n);

        if(i + size > avi->movi_end || d[0]<0)

            continue;

        //parse ix##

        if(  (d[0] == 'i' && d[1] == 'x' && n < s->nb_streams)

        //parse JUNK

           ||(d[0] == 'J' && d[1] == 'U' && d[2] == 'N' && d[3] == 'K')){

            url_fskip(pb, size);

//av_log(NULL, AV_LOG_DEBUG, "SKIP\n");

            goto resync;

        }

        if(    d[0] >= '0' && d[0] <= '9'

            && d[1] >= '0' && d[1] <= '9'){

            n= (d[0] - '0') * 10 + (d[1] - '0');

        }else{

            n= 100; //invalid stream id

        }

        //parse ##dc/##wb

        if(n < s->nb_streams){

          AVStream *st;

          AVIStream *ast;

          st = s->streams[n];

          ast = st->priv_data;

          if(   (st->discard >= AVDISCARD_DEFAULT && size==0)

             /*|| (st->discard >= AVDISCARD_NONKEY && !(pkt->flags & PKT_FLAG_KEY))*/ //FIXME needs a little reordering

             || st->discard >= AVDISCARD_ALL){

                if(ast->sample_size) ast->frame_offset += pkt->size;

                else                 ast->frame_offset++;

                url_fskip(pb, size);

                goto resync;

          }

          if(   ((ast->prefix_count<5 || sync+9 > i) && d[2]<128 && d[3]<128) ||

                d[2]*256+d[3] == ast->prefix /*||

                (d[2] == 'd' && d[3] == 'c') ||

                (d[2] == 'w' && d[3] == 'b')*/) {

//av_log(NULL, AV_LOG_DEBUG, "OK\n");

            if(d[2]*256+d[3] == ast->prefix)

                ast->prefix_count++;

            else{

                ast->prefix= d[2]*256+d[3];

                ast->prefix_count= 0;

            }

            avi->stream_index= n;

            ast->packet_size= size + 8;

            ast->remaining= size;

            goto resync;

          }

        }

        /* palette changed chunk */

        if (   d[0] >= '0' && d[0] <= '9'

            && d[1] >= '0' && d[1] <= '9'

            && ((d[2] == 'p' && d[3] == 'c'))

            && n < s->nb_streams && i + size <= avi->movi_end) {

            AVStream *st;

            int first, clr, flags, k, p;

            st = s->streams[n];

            first = get_byte(pb);

            clr = get_byte(pb);

            if(!clr) /* all 256 colors used */

                clr = 256;

            flags = get_le16(pb);

            p = 4;

            for (k = first; k < clr + first; k++) {

                int r, g, b;

                r = get_byte(pb);

                g = get_byte(pb);

                b = get_byte(pb);

                    get_byte(pb);

                st->codec->palctrl->palette[k] = b + (g << 8) + (r << 16);

            }

            st->codec->palctrl->palette_changed = 1;

            goto resync;

        }

    }

    return -1;

}

/* XXX: we make the implicit supposition that the position are sorted

   for each stream */

static int avi_read_idx1(AVFormatContext *s, int size)

{

    AVIContext *avi = s->priv_data;

    ByteIOContext *pb = &s->pb;

    int nb_index_entries, i;

    AVStream *st;

    AVIStream *ast;

    unsigned int index, tag, flags, pos, len;

    unsigned last_pos= -1;

    nb_index_entries = size / 16;

    if (nb_index_entries <= 0)

        return -1;

    /* read the entries and sort them in each stream component */

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

        tag = get_le32(pb);

        flags = get_le32(pb);

        pos = get_le32(pb);

        len = get_le32(pb);

#if defined(DEBUG_SEEK)

        av_log(NULL, AV_LOG_DEBUG, "%d: tag=0x%x flags=0x%x pos=0x%x len=%d/",

               i, tag, flags, pos, len);

#endif

        if(i==0 && pos > avi->movi_list)

            avi->movi_list= 0; //FIXME better check

        index = ((tag & 0xff) - '0') * 10;

        index += ((tag >> 8) & 0xff) - '0';

        if (index >= s->nb_streams)

            continue;

        st = s->streams[index];

        ast = st->priv_data;

#if defined(DEBUG_SEEK)

        av_log(NULL, AV_LOG_DEBUG, "%d cum_len=%d\n", len, ast->cum_len);

#endif

        if(last_pos == pos)

            avi->non_interleaved= 1;

        else

            av_add_index_entry(st, pos, ast->cum_len, 0, (flags&AVIIF_INDEX) ? AVINDEX_KEYFRAME : 0);

        if(ast->sample_size)

            ast->cum_len += len / ast->sample_size;

        else

            ast->cum_len ++;

        last_pos= pos;

    }

    return 0;

}

static int guess_ni_flag(AVFormatContext *s){

    int i;

    int64_t last_start=0;

    int64_t first_end= INT64_MAX;

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

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

        int n= st->nb_index_entries;

        if(n <= 0)

            continue;

        if(st->index_entries[0].pos > last_start)

            last_start= st->index_entries[0].pos;

        if(st->index_entries[n-1].pos < first_end)

            first_end= st->index_entries[n-1].pos;

    }

    return last_start > first_end;

}

static int avi_load_index(AVFormatContext *s)

{

    AVIContext *avi = s->priv_data;

    ByteIOContext *pb = &s->pb;

    uint32_t tag, size;

    offset_t pos= url_ftell(pb);

    url_fseek(pb, avi->movi_end, SEEK_SET);

#ifdef DEBUG_SEEK

    printf("movi_end=0x%llx\n", avi->movi_end);

#endif

    for(;;) {

        if (url_feof(pb))

            break;

        tag = get_le32(pb);

        size = get_le32(pb);

#ifdef DEBUG_SEEK

        printf("tag=%c%c%c%c size=0x%x\n",

               tag & 0xff,

               (tag >> 8) & 0xff,

               (tag >> 16) & 0xff,

               (tag >> 24) & 0xff,

               size);

#endif

        switch(tag) {

        case MKTAG('i', 'd', 'x', '1'):

            if (avi_read_idx1(s, size) < 0)

                goto skip;

            else

                goto the_end;

            break;

        default:

        skip:

            size += (size & 1);

            url_fskip(pb, size);

            break;

        }

    }

 the_end:

    avi->non_interleaved |= guess_ni_flag(s);

    url_fseek(pb, pos, SEEK_SET);

    return 0;

}

static int avi_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)

{

    AVIContext *avi = s->priv_data;

    AVStream *st;

    int i, index;

    int64_t pos;

    if (!avi->index_loaded) {

        /* we only load the index on demand */

        avi_load_index(s);

        avi->index_loaded = 1;

    }

    assert(stream_index>= 0);

    st = s->streams[stream_index];

    index= av_index_search_timestamp(st, timestamp, flags);

    if(index<0)

        return -1;

    /* find the position */

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

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

//    av_log(NULL, AV_LOG_DEBUG, "XX %Ld %d %Ld\n", timestamp, index, st->index_entries[index].timestamp);

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

        AVStream *st2 = s->streams[i];

        AVIStream *ast2 = st2->priv_data;

        ast2->packet_size=

        ast2->remaining= 0;

        if (st2->nb_index_entries <= 0)

            continue;

//        assert(st2->codec.block_align);

        assert(st2->time_base.den == ast2->rate);

        assert(st2->time_base.num == ast2->scale);

        index = av_index_search_timestamp(

                st2,

                av_rescale(timestamp, st2->time_base.den*(int64_t)st->time_base.num, st->time_base.den * (int64_t)st2->time_base.num),

                flags | AVSEEK_FLAG_BACKWARD);

        if(index<0)

            index=0;

        if(!avi->non_interleaved){

            while(index>0 && st2->index_entries[index].pos > pos)

                index--;

            while(index+1 < st2->nb_index_entries && st2->index_entries[index].pos < pos)

                index++;

        }

//        av_log(NULL, AV_LOG_DEBUG, "%Ld %d %Ld\n", timestamp, index, st2->index_entries[index].timestamp);

        /* extract the current frame number */

        ast2->frame_offset = st2->index_entries[index].timestamp;

        if(ast2->sample_size)

            ast2->frame_offset *=ast2->sample_size;

    }

    if (avi->dv_demux)

        dv_flush_audio_packets(avi->dv_demux);

    /* do the seek */

    pos += avi->movi_list;

    url_fseek(&s->pb, pos, SEEK_SET);

    avi->stream_index= -1;

    return 0;

}

static int avi_read_close(AVFormatContext *s)

{

    int i;

    AVIContext *avi = s->priv_data;

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

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

        AVIStream *ast = st->priv_data;

        av_free(ast);

        av_free(st->codec->extradata);

        av_free(st->codec->palctrl);

    }

    if (avi->dv_demux)

        av_free(avi->dv_demux);

    return 0;

}

static int avi_probe(AVProbeData *p)

{

    /* check file header */

    if (p->buf_size <= 32)

        return 0;

    if (p->buf[0] == 'R' && p->buf[1] == 'I' &&

        p->buf[2] == 'F' && p->buf[3] == 'F' &&

        p->buf[8] == 'A' && p->buf[9] == 'V' &&

        p->buf[10] == 'I' && p->buf[11] == ' ')

        return AVPROBE_SCORE_MAX;

    else

        return 0;

}

static AVInputFormat avi_iformat = {

    "avi",

    "avi format",

    sizeof(AVIContext),

    avi_probe,

    avi_read_header,

    avi_read_packet,

    avi_read_close,

    avi_read_seek,

};

int avidec_init(void)

{

    av_register_input_format(&avi_iformat);

    return 0;

}