url_fskip(pb, size - 5 * 4);
static int avi_read_header(AVFormatContext *s, AVFormatParameters *ap){    AVIContext *avi = s->priv_data;    ByteIOContext *pb = &s->pb;    uint32_t tag, tag1;    int codec_type, stream_index, frame_period, bit_rate;    unsigned int size;    int i;    AVStream *st;    /* check RIFF header */    tag = get_le32(pb);    if (tag != MKTAG('R', 'I', 'F', 'F'))        return -1;    get_le32(pb); /* file size */    tag = get_le32(pb);    if (tag != MKTAG('A', 'V', 'I', ' '))        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_end = url_ftell(pb) + size - 4;#ifdef DEBUG                printf("movi end=%Lx\n", avi->movi_end);#endif                goto end_of_header;            }            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);            s->nb_streams = get_le32(pb);            for(i=0;i<s->nb_streams;i++) {                AVStream *st = av_mallocz(sizeof(AVStream));                if (!st)                    goto fail;                avcodec_get_context_defaults(&st->codec);                s->streams[i] = st;	    }            url_fskip(pb, size - 7 * 4);            break;        case MKTAG('s', 't', 'r', 'h'):            /* stream header */            stream_index++;            tag1 = get_le32(pb);            switch(tag1) {            case MKTAG('v', 'i', 'd', 's'):                codec_type = CODEC_TYPE_VIDEO;                get_le32(pb); /* codec tag */                get_le32(pb); /* flags */                get_le16(pb); /* priority */                get_le16(pb); /* language */                get_le32(pb); /* XXX: initial frame ? */                get_le32(pb); /* scale */                get_le32(pb); /* rate */                url_fskip(pb, size - 7 * 4);                break;            case MKTAG('a', 'u', 'd', 's'):                codec_type = CODEC_TYPE_AUDIO;                /* nothing really useful */                url_fskip(pb, size - 4);                break;            default:                goto fail;            }            break;        case MKTAG('s', 't', 'r', 'f'):            /* stream header */            if (stream_index >= s->nb_streams) {                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);                    if (frame_period)                        st->codec.frame_rate = (int64_t_C(1000000) * FRAME_RATE_BASE) / frame_period;                    else                        st->codec.frame_rate = 25 * FRAME_RATE_BASE;                    get_le16(pb); /* panes */                    get_le16(pb); /* depth */                    tag1 = get_le32(pb);#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);                    url_fskip(pb, size - 5 * 4);                    break;                case CODEC_TYPE_AUDIO:                    get_wav_header(pb, &st->codec, (size >= 18));                    if (size%2) /* 2-aligned (fix for Stargate SG-1 - 3x18 - Shades of Grey.avi) */                        url_fskip(pb, 1);                    break;                default:                    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]);        }        return -1;    }    return 0;}