PeerStreamer

/*

 * AVI demuxer

 * Copyright (c) 2001 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

 */

//#define DEBUG

//#define DEBUG_SEEK

#include "libavutil/intreadwrite.h"

#include "libavutil/bswap.h"

#include "avformat.h"

#include "avi.h"

#include "dv.h"

#include "riff.h"

#undef NDEBUG

#include <assert.h>

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; /* size of one sample (or packet) (in the rate/scale sense) in bytes */

    int64_t cum_len; /* temporary storage (used during seek) */

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

    int prefix_count;

    uint32_t pal[256];

    int has_pal;

} AVIStream;

typedef struct {

    int64_t  riff_end;

    int64_t  movi_end;

    int64_t  fsize;

    int64_t movi_list;

    int64_t last_pkt_pos;

    int index_loaded;

    int is_odml;

    int non_interleaved;

    int stream_index;

    DVDemuxContext* dv_demux;

    int odml_depth;

#define MAX_ODML_DEPTH 1000

} AVIContext;

static const char avi_headers[][8] = {

    { 'R', 'I', 'F', 'F',    'A', 'V', 'I', ' ' },

    { 'R', 'I', 'F', 'F',    'A', 'V', 'I', 'X' },

    { 'R', 'I', 'F', 'F',    'A', 'V', 'I', 0x19},

    { 'O', 'N', '2', ' ',    'O', 'N', '2', 'f' },

    { 'R', 'I', 'F', 'F',    'A', 'M', 'V', ' ' },

    { 0 }

};

static int avi_load_index(AVFormatContext *s);

static int guess_ni_flag(AVFormatContext *s);

#ifdef DEBUG

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

{

    dprintf(NULL, "%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 inline int get_duration(AVIStream *ast, int len){

    if(ast->sample_size){

        return len;

    }else

        return 1;

}

static int get_riff(AVFormatContext *s, ByteIOContext *pb)

{

    AVIContext *avi = s->priv_data;

    char header[8];

    int i;

    /* check RIFF header */

    get_buffer(pb, header, 4);

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

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

    get_buffer(pb, header+4, 4);

    for(i=0; avi_headers[i][0]; i++)

        if(!memcmp(header, avi_headers[i], 8))

            break;

    if(!avi_headers[i][0])

        return -1;

    if(header[7] == 0x19)

        av_log(s, AV_LOG_INFO, "This file has been generated by a totally broken muxer.\n");

    return 0;

}

static int read_braindead_odml_indx(AVFormatContext *s, int frame_num){

    AVIContext *avi = s->priv_data;

    ByteIOContext *pb = s->pb;

    int longs_pre_entry= get_le16(pb);

    int index_sub_type = get_byte(pb);

    int index_type     = get_byte(pb);

    int entries_in_use = get_le32(pb);

    int chunk_id       = get_le32(pb);

    int64_t base       = get_le64(pb);

    int stream_id= 10*((chunk_id&0xFF) - '0') + (((chunk_id>>8)&0xFF) - '0');

    AVStream *st;

    AVIStream *ast;

    int i;

    int64_t last_pos= -1;

    int64_t filesize= url_fsize(s->pb);

#ifdef DEBUG_SEEK

    av_log(s, AV_LOG_ERROR, "longs_pre_entry:%d index_type:%d entries_in_use:%d chunk_id:%X base:%16"PRIX64"\n",

        longs_pre_entry,index_type, entries_in_use, chunk_id, base);

#endif

    if(stream_id >= s->nb_streams || stream_id < 0)

        return -1;

    st= s->streams[stream_id];

    ast = st->priv_data;

    if(index_sub_type)

        return -1;

    get_le32(pb);

    if(index_type && longs_pre_entry != 2)

        return -1;

    if(index_type>1)

        return -1;

    if(filesize > 0 && base >= filesize){

        av_log(s, AV_LOG_ERROR, "ODML index invalid\n");

        if(base>>32 == (base & 0xFFFFFFFF) && (base & 0xFFFFFFFF) < filesize && filesize <= 0xFFFFFFFF)

            base &= 0xFFFFFFFF;

        else

            return -1;

    }

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

        if(index_type){

            int64_t pos= get_le32(pb) + base - 8;

            int len    = get_le32(pb);

            int key= len >= 0;

            len &= 0x7FFFFFFF;

#ifdef DEBUG_SEEK

            av_log(s, AV_LOG_ERROR, "pos:%"PRId64", len:%X\n", pos, len);

#endif

            if(url_feof(pb))

                return -1;

            if(last_pos == pos || pos == base - 8)

                avi->non_interleaved= 1;

            if(last_pos != pos && (len || !ast->sample_size))

                av_add_index_entry(st, pos, ast->cum_len, len, 0, key ? AVINDEX_KEYFRAME : 0);

            ast->cum_len += get_duration(ast, len);

            last_pos= pos;

        }else{

            int64_t offset, pos;

            int duration;

            offset = get_le64(pb);

            get_le32(pb);       /* size */

            duration = get_le32(pb);

            if(url_feof(pb))

                return -1;

            pos = url_ftell(pb);

            if(avi->odml_depth > MAX_ODML_DEPTH){

                av_log(s, AV_LOG_ERROR, "Too deeply nested ODML indexes\n");

                return -1;

            }

            url_fseek(pb, offset+8, SEEK_SET);

            avi->odml_depth++;

            read_braindead_odml_indx(s, frame_num);

            avi->odml_depth--;

            frame_num += duration;

            url_fseek(pb, pos, SEEK_SET);

        }

    }

    avi->index_loaded=1;

    return 0;

}

static void clean_index(AVFormatContext *s){

    int i;

    int64_t j;

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

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

        AVIStream *ast = st->priv_data;

        int n= st->nb_index_entries;

        int max= ast->sample_size;

        int64_t pos, size, ts;

        if(n != 1 || ast->sample_size==0)

            continue;

        while(max < 1024) max+=max;

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

        size= st->index_entries[0].size;

        ts= st->index_entries[0].timestamp;

        for(j=0; j<size; j+=max){

            av_add_index_entry(st, pos+j, ts+j, FFMIN(max, size-j), 0, AVINDEX_KEYFRAME);

        }

    }

}

static int avi_read_tag(AVFormatContext *s, AVStream *st, uint32_t tag, uint32_t size)

{

    ByteIOContext *pb = s->pb;

    char key[5] = {0}, *value;

    size += (size & 1);

    if (size == UINT_MAX)

        return -1;

    value = av_malloc(size+1);

    if (!value)

        return -1;

    get_buffer(pb, value, size);

    value[size]=0;

    AV_WL32(key, tag);

    if(st)

        return av_metadata_set2(&st->metadata, key, value,

                                    AV_METADATA_DONT_STRDUP_VAL);

    else

    return av_metadata_set2(&s->metadata, key, value,

                                  AV_METADATA_DONT_STRDUP_VAL);

}

static void avi_read_info(AVFormatContext *s, uint64_t end)

{

    while (url_ftell(s->pb) < end) {

        uint32_t tag  = get_le32(s->pb);

        uint32_t size = get_le32(s->pb);

        avi_read_tag(s, NULL, tag, size);

    }

}

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

{

    AVIContext *avi = s->priv_data;

    ByteIOContext *pb = s->pb;

    unsigned int tag, tag1, handler;

    int codec_type, stream_index, frame_period, bit_rate;

    unsigned int size;

    int i;

    AVStream *st;

    AVIStream *ast = NULL;

    int avih_width=0, avih_height=0;

    int amv_file_format=0;

    uint64_t list_end = 0;

    avi->stream_index= -1;

    if (get_riff(s, pb) < 0)

        return -1;

    avi->fsize = url_fsize(pb);

    if(avi->fsize<=0)

        avi->fsize= avi->riff_end == 8 ? INT64_MAX : avi->riff_end;

    /* 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'):

            list_end = url_ftell(pb) + size;

            /* Ignored, except at 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 + (size & 1);

                else     avi->movi_end = url_fsize(pb);

                dprintf(NULL, "movi end=%"PRIx64"\n", avi->movi_end);

                goto end_of_header;

            }

            else if (tag1 == MKTAG('I', 'N', 'F', 'O'))

                avi_read_info(s, list_end);

            break;

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

            avi->is_odml = 1;

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

            break;

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

            amv_file_format=1;

        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;

            get_le32(pb);

            avi->non_interleaved |= get_le32(pb) & AVIF_MUSTUSEINDEX;

            url_fskip(pb, 2 * 4);

            get_le32(pb);

            get_le32(pb);

            avih_width=get_le32(pb);

            avih_height=get_le32(pb);

            url_fskip(pb, size - 10 * 4);

            break;

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

            /* stream header */

            tag1 = get_le32(pb);

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

            if(tag1 == MKTAG('p', 'a', 'd', 's')){

                url_fskip(pb, size - 8);

                break;

            }else{

                stream_index++;

                st = av_new_stream(s, stream_index);

                if (!st)

                    goto fail;

                ast = av_mallocz(sizeof(AVIStream));

                if (!ast)

                    goto fail;

                st->priv_data = ast;

            }

            if(amv_file_format)

                tag1 = stream_index ? MKTAG('a','u','d','s') : MKTAG('v','i','d','s');

#ifdef DEBUG

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

#endif

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

                int64_t dv_dur;

                /*

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

                 * have to support anything but DV in 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;

                if (CONFIG_DV_DEMUXER) {

                    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);

                url_fskip(pb, 4);  /* start time */

                dv_dur = get_le32(pb);

                if (ast->scale > 0 && ast->rate > 0 && dv_dur > 0) {

                    dv_dur *= AV_TIME_BASE;

                    s->duration = av_rescale(dv_dur, ast->scale, ast->rate);

                }

                /*

                 * else, leave duration alone; timing estimation in utils.c

                 *      will make a guess based on bitrate.

                 */

                stream_index = s->nb_streams - 1;

                url_fskip(pb, size - 9*4);

                break;

            }

            assert(stream_index < s->nb_streams);

            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)){

                av_log(s, AV_LOG_WARNING, "scale/rate is %u/%u which is invalid. (This file has been generated by broken software.)\n", ast->scale, ast->rate);

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

            st->nb_frames = get_le32(pb);

            st->start_time = 0;

            get_le32(pb); /* buffer size */

            get_le32(pb); /* quality */

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

            ast->cum_len *= FFMAX(1, ast->sample_size);

//            av_log(s, 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 = AVMEDIA_TYPE_VIDEO;

                ast->sample_size = 0;

                break;

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

                codec_type = AVMEDIA_TYPE_AUDIO;

                break;

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

                //FIXME

                codec_type = AVMEDIA_TYPE_DATA; //AVMEDIA_TYPE_SUB ?  FIXME

                break;

            case MKTAG('d', 'a', 't', 's'):

                codec_type = AVMEDIA_TYPE_DATA;

                break;

            default:

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

                goto fail;

            }

            if(ast->sample_size == 0)

                st->duration = st->nb_frames;

            ast->frame_offset= ast->cum_len;

            url_fskip(pb, size - 12 * 4);

            break;

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

            /* stream header */

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

                url_fskip(pb, size);

            } else {

                uint64_t cur_pos = url_ftell(pb);

                if (cur_pos < list_end)

                    size = FFMIN(size, list_end - cur_pos);

                st = s->streams[stream_index];

                switch(codec_type) {

                case AVMEDIA_TYPE_VIDEO:

                    if(amv_file_format){

                        st->codec->width=avih_width;

                        st->codec->height=avih_height;

                        st->codec->codec_type = AVMEDIA_TYPE_VIDEO;

                        st->codec->codec_id = CODEC_ID_AMV;

                        url_fskip(pb, size);

                        break;

                    }

                    get_le32(pb); /* size */

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

                    st->codec->height = (int32_t)get_le32(pb);

                    get_le16(pb); /* panes */

                    st->codec->bits_per_coded_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 (tag1 == MKTAG('D', 'X', 'S', 'B') || tag1 == MKTAG('D','X','S','A')) {

                        st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;

                        st->codec->codec_tag = tag1;

                        st->codec->codec_id = CODEC_ID_XSUB;

                        break;

                    }

                    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);

                        if (!st->codec->extradata) {

                            st->codec->extradata_size= 0;

                            return AVERROR(ENOMEM);

                        }

                        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_coded_sample <= 8)) {

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

#if HAVE_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 = AVMEDIA_TYPE_VIDEO;

                    st->codec->codec_tag = tag1;

                    st->codec->codec_id = ff_codec_get_id(ff_codec_bmp_tags, tag1);

                    st->need_parsing = AVSTREAM_PARSE_HEADERS; // This is needed to get the pict type which is necessary for generating correct pts.

                    // Support "Resolution 1:1" for Avid AVI Codec

                    if(tag1 == MKTAG('A', 'V', 'R', 'n') &&

                       st->codec->extradata_size >= 31 &&

                       !memcmp(&st->codec->extradata[28], "1:1", 3))

                        st->codec->codec_id = CODEC_ID_RAWVIDEO;

                    if(st->codec->codec_tag==0 && st->codec->height > 0 && st->codec->extradata_size < 1U<<30){

                        st->codec->extradata_size+= 9;

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

                        if(st->codec->extradata)

                            memcpy(st->codec->extradata + st->codec->extradata_size - 9, "BottomUp", 9);

                    }

                    st->codec->height= FFABS(st->codec->height);

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

                    break;

                case AVMEDIA_TYPE_AUDIO:

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

                    if(ast->sample_size && st->codec->block_align && ast->sample_size != st->codec->block_align){

                        av_log(s, AV_LOG_WARNING, "sample size (%d) != block align (%d)\n", ast->sample_size, st->codec->block_align);

                        ast->sample_size= st->codec->block_align;

                    }

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

                        url_fskip(pb, 1);

                    /* Force parsing as several audio frames can be in

                     * one packet and timestamps refer to packet start. */

                    st->need_parsing = AVSTREAM_PARSE_TIMESTAMPS;

                    /* ADTS header is in extradata, AAC without header must be

                     * stored as exact frames. Parser not needed and it will

                     * fail. */

                    if (st->codec->codec_id == CODEC_ID_AAC && st->codec->extradata_size)

                        st->need_parsing = AVSTREAM_PARSE_NONE;

                    /* AVI files with Xan DPCM audio (wrongly) declare PCM

                     * audio in the header but have Axan as stream_code_tag. */

                    if (st->codec->stream_codec_tag == AV_RL32("Axan")){

                        st->codec->codec_id  = CODEC_ID_XAN_DPCM;

                        st->codec->codec_tag = 0;

                    }

                    if (amv_file_format)

                        st->codec->codec_id  = CODEC_ID_ADPCM_IMA_AMV;

                    break;

                default:

                    st->codec->codec_type = AVMEDIA_TYPE_DATA;

                    st->codec->codec_id= CODEC_ID_NONE;

                    st->codec->codec_tag= 0;

                    url_fskip(pb, size);

                    break;

                }

            }

            break;

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

            i= url_ftell(pb);

            if(!url_is_streamed(pb) && !(s->flags & AVFMT_FLAG_IGNIDX)){

                read_braindead_odml_indx(s, 0);

            }

            url_fseek(pb, i+size, SEEK_SET);

            break;

        case MKTAG('v', 'p', 'r', 'p'):

            if(stream_index < (unsigned)s->nb_streams && size > 9*4){

                AVRational active, active_aspect;

                st = s->streams[stream_index];

                get_le32(pb);

                get_le32(pb);

                get_le32(pb);

                get_le32(pb);

                get_le32(pb);

                active_aspect.den= get_le16(pb);

                active_aspect.num= get_le16(pb);

                active.num       = get_le32(pb);

                active.den       = get_le32(pb);

                get_le32(pb); //nbFieldsPerFrame

                if(active_aspect.num && active_aspect.den && active.num && active.den){

                    st->sample_aspect_ratio= av_div_q(active_aspect, active);

//av_log(s, AV_LOG_ERROR, "vprp %d/%d %d/%d\n", active_aspect.num, active_aspect.den, active.num, active.den);

                }

                size -= 9*4;

            }

            url_fseek(pb, size, SEEK_CUR);

            break;

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

            if(s->nb_streams){

                avi_read_tag(s, s->streams[s->nb_streams-1], tag, size);

                break;

            }

        default:

            if(size > 1000000){

                av_log(s, AV_LOG_ERROR, "Something went wrong during header parsing, "

                                        "I will ignore it and try to continue anyway.\n");

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

                avi->movi_end  = url_fsize(pb);

                goto end_of_header;

            }

            /* skip tag */

            size += (size & 1);

            url_fskip(pb, size);

            break;

        }

    }

 end_of_header:

    /* check stream number */

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

    fail:

        return -1;

    }

    if(!avi->index_loaded && !url_is_streamed(pb))

        avi_load_index(s);

    avi->index_loaded = 1;

    avi->non_interleaved |= guess_ni_flag(s);

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

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

        if(st->nb_index_entries)

            break;

    }

    if(i==s->nb_streams && avi->non_interleaved) {

        av_log(s, AV_LOG_WARNING, "non-interleaved AVI without index, switching to interleaved\n");

        avi->non_interleaved=0;

    }

    if(avi->non_interleaved) {

        av_log(s, AV_LOG_INFO, "non-interleaved AVI\n");

        clean_index(s);

    }

    return 0;

}

static int get_stream_idx(int *d){

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

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

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

    }else{

        return 100; //invalid stream ID

    }

}

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

{

    AVIContext *avi = s->priv_data;

    ByteIOContext *pb = s->pb;

    int n, d[8];

    unsigned int size;

    int64_t i, sync;

    void* dstr;

    if (CONFIG_DV_DEMUXER && avi->dv_demux) {

        int 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;

            int64_t last_ts;

            if(!st->nb_index_entries)

                continue;

            last_ts = st->index_entries[st->nb_index_entries - 1].timestamp;

            if(!ast->remaining && ts > last_ts)

                continue;

            ts = av_rescale_q(ts, st->time_base, (AVRational){FFMAX(1, ast->sample_size), AV_TIME_BASE});

//            av_log(s, AV_LOG_DEBUG, "%"PRId64" %d/%d %"PRId64"\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;

            }

        }

        if(!best_st)

            return -1;

        best_ast = best_st->priv_data;

        best_ts = av_rescale_q(best_ts, (AVRational){FFMAX(1, best_ast->sample_size), AV_TIME_BASE}, best_st->time_base);

        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);

            if(i>=0)

                best_ast->frame_offset= best_st->index_entries[i].timestamp;

        }

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

        if(i>=0){

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

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

            url_fseek(s->pb, pos + 8, SEEK_SET);

//        av_log(s, AV_LOG_DEBUG, "pos=%"PRId64"\n", pos);

            assert(best_ast->remaining <= best_ast->packet_size);

            avi->stream_index= best_stream_index;

            if(!best_ast->remaining)

                best_ast->packet_size=

                best_ast->remaining= best_st->index_entries[i].size;

        }

    }

resync:

    if(avi->stream_index >= 0){

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

        AVIStream *ast= st->priv_data;

        int size, err;

        if(ast->sample_size <= 1) // minorityreport.AVI block_align=1024 sample_size=1 IMA-ADPCM

            size= INT_MAX;

        else if(ast->sample_size < 32)

            // arbitrary multiplier to avoid tiny packets for raw PCM data

            size= 1024*ast->sample_size;

        else

            size= ast->sample_size;

        if(size > ast->remaining)

            size= ast->remaining;

        avi->last_pkt_pos= url_ftell(pb);

        err= av_get_packet(pb, pkt, size);

        if(err<0)

            return err;

        if(ast->has_pal && pkt->data && pkt->size<(unsigned)INT_MAX/2){

            void *ptr= av_realloc(pkt->data, pkt->size + 4*256 + FF_INPUT_BUFFER_PADDING_SIZE);

            if(ptr){

            ast->has_pal=0;

            pkt->size += 4*256;

            pkt->data= ptr;

                memcpy(pkt->data + pkt->size - 4*256, ast->pal, 4*256);

            }else

                av_log(s, AV_LOG_ERROR, "Failed to append palette\n");

        }

        if (CONFIG_DV_DEMUXER && avi->dv_demux) {

            dstr = pkt->destruct;

            size = dv_produce_packet(avi->dv_demux, pkt,

                                    pkt->data, pkt->size);

            pkt->destruct = dstr;

            pkt->flags |= AV_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(s, AV_LOG_DEBUG, "dts:%"PRId64" offset:%"PRId64" %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, avi->stream_index, size);

            pkt->stream_index = avi->stream_index;

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

                AVIndexEntry *e;

                int index;

                assert(st->index_entries);

                index= av_index_search_timestamp(st, ast->frame_offset, 0);

                e= &st->index_entries[index];

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

                    if (e->flags & AVINDEX_KEYFRAME)

                        pkt->flags |= AV_PKT_FLAG_KEY;

                }

            } else {

                pkt->flags |= AV_PKT_FLAG_KEY;

            }

            ast->frame_offset += get_duration(ast, pkt->size);

        }

        ast->remaining -= size;

        if(!ast->remaining){

            avi->stream_index= -1;

            ast->packet_size= 0;

        }

        return size;

    }

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

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

        int j;

        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);

        n= get_stream_idx(d+2);

//av_log(s, AV_LOG_DEBUG, "%X %X %X %X %X %X %X %X %"PRId64" %d %d\n", d[0], d[1], d[2], d[3], d[4], d[5], d[6], d[7], i, size, n);

        if(i + (uint64_t)size > avi->fsize || 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')

           ||(d[0] == 'i' && d[1] == 'd' && d[2] == 'x' && d[3] == '1')){

            url_fskip(pb, size);

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

            goto resync;

        }

        //parse stray LIST

        if(d[0] == 'L' && d[1] == 'I' && d[2] == 'S' && d[3] == 'T'){

            url_fskip(pb, 4);

            goto resync;

        }

        n= get_stream_idx(d);

        if(!((i-avi->last_pkt_pos)&1) && get_stream_idx(d+1) < s->nb_streams)

            continue;

        //detect ##ix chunk and skip

        if(d[2] == 'i' && d[3] == 'x' && n < s->nb_streams){

            url_fskip(pb, size);

            goto resync;

        }

        //parse ##dc/##wb

        if(n < s->nb_streams){

            AVStream *st;

            AVIStream *ast;

            st = s->streams[n];

            ast = st->priv_data;

            if(s->nb_streams>=2){

                AVStream *st1  = s->streams[1];

                AVIStream *ast1= st1->priv_data;

                //workaround for broken small-file-bug402.avi

                if(   d[2] == 'w' && d[3] == 'b'

                   && n==0

                   && st ->codec->codec_type == AVMEDIA_TYPE_VIDEO

                   && st1->codec->codec_type == AVMEDIA_TYPE_AUDIO

                   && ast->prefix == 'd'*256+'c'

                   && (d[2]*256+d[3] == ast1->prefix || !ast1->prefix_count)

                  ){

                    n=1;

                    st = st1;

                    ast = ast1;

                    av_log(s, AV_LOG_WARNING, "Invalid stream + prefix combination, assuming audio.\n");

                }

            }

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

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

               || st->discard >= AVDISCARD_ALL){

                ast->frame_offset += get_duration(ast, size);

                url_fskip(pb, size);

                goto resync;

            }

            if (d[2] == 'p' && d[3] == 'c' && size<=4*256+4) {

                int k = get_byte(pb);

                int last = (k + get_byte(pb) - 1) & 0xFF;

                get_le16(pb); //flags