static int decode_pic_hdr(IVI45DecContext *ctx, AVCodecContext *avctx)
{
    int             pic_size_indx, i, p;
    IVIPicConfig    pic_conf;

    if (get_bits(&ctx->gb, 18) != 0x3FFF8) {
        av_log(avctx, AV_LOG_ERROR, "Invalid picture start code!\n");
        return AVERROR_INVALIDDATA;
    }

    ctx->prev_frame_type = ctx->frame_type;
    ctx->frame_type      = get_bits(&ctx->gb, 3);
    if (ctx->frame_type == 7) {
        av_log(avctx, AV_LOG_ERROR, "Invalid frame type: %d\n", ctx->frame_type);
        return AVERROR_INVALIDDATA;
    }

#if IVI4_STREAM_ANALYSER
    if (ctx->frame_type == FRAMETYPE_BIDIR)
        ctx->has_b_frames = 1;
#endif

    ctx->transp_status = get_bits1(&ctx->gb);
#if IVI4_STREAM_ANALYSER
    if (ctx->transp_status) {
        ctx->has_transp = 1;
    }
#endif

    /* unknown bit: Mac decoder ignores this bit, XANIM returns error */
    if (get_bits1(&ctx->gb)) {
        av_log(avctx, AV_LOG_ERROR, "Sync bit is set!\n");
        return AVERROR_INVALIDDATA;
    }

    ctx->data_size = get_bits1(&ctx->gb) ? get_bits(&ctx->gb, 24) : 0;

    /* null frames don't contain anything else so we just return */
    if (ctx->frame_type >= FRAMETYPE_NULL_FIRST) {
        av_dlog(avctx, "Null frame encountered!\n");
        return 0;
    }

    /* Check key lock status. If enabled - ignore lock word.         */
    /* Usually we have to prompt the user for the password, but      */
    /* we don't do that because Indeo 4 videos can be decoded anyway */
    if (get_bits1(&ctx->gb)) {
        skip_bits_long(&ctx->gb, 32);
        av_dlog(avctx, "Password-protected clip!\n");
    }

    pic_size_indx = get_bits(&ctx->gb, 3);
    if (pic_size_indx == IVI4_PIC_SIZE_ESC) {
        pic_conf.pic_height = get_bits(&ctx->gb, 16);
        pic_conf.pic_width  = get_bits(&ctx->gb, 16);
    } else {
        pic_conf.pic_height = ivi4_common_pic_sizes[pic_size_indx * 2 + 1];
        pic_conf.pic_width  = ivi4_common_pic_sizes[pic_size_indx * 2    ];
    }

    /* Decode tile dimensions. */
    if (get_bits1(&ctx->gb)) {
        pic_conf.tile_height = scale_tile_size(pic_conf.pic_height, get_bits(&ctx->gb, 4));
        pic_conf.tile_width  = scale_tile_size(pic_conf.pic_width,  get_bits(&ctx->gb, 4));
#if IVI4_STREAM_ANALYSER
        ctx->uses_tiling = 1;
#endif
    } else {
        pic_conf.tile_height = pic_conf.pic_height;
        pic_conf.tile_width  = pic_conf.pic_width;
    }

    /* Decode chroma subsampling. We support only 4:4 aka YVU9. */
    if (get_bits(&ctx->gb, 2)) {
        av_log(avctx, AV_LOG_ERROR, "Only YVU9 picture format is supported!\n");
        return AVERROR_INVALIDDATA;
    }
    pic_conf.chroma_height = (pic_conf.pic_height + 3) >> 2;
    pic_conf.chroma_width  = (pic_conf.pic_width  + 3) >> 2;

    /* decode subdivision of the planes */
    pic_conf.luma_bands = decode_plane_subdivision(&ctx->gb);
    pic_conf.chroma_bands = 0;
    if (pic_conf.luma_bands)
        pic_conf.chroma_bands = decode_plane_subdivision(&ctx->gb);
    ctx->is_scalable = pic_conf.luma_bands != 1 || pic_conf.chroma_bands != 1;
    if (ctx->is_scalable && (pic_conf.luma_bands != 4 || pic_conf.chroma_bands != 1)) {
        av_log(avctx, AV_LOG_ERROR, "Scalability: unsupported subdivision! Luma bands: %d, chroma bands: %d\n",
               pic_conf.luma_bands, pic_conf.chroma_bands);
        return AVERROR_INVALIDDATA;
    }

    /* check if picture layout was changed and reallocate buffers */
    if (ivi_pic_config_cmp(&pic_conf, &ctx->pic_conf)) {
        if (ff_ivi_init_planes(ctx->planes, &pic_conf)) {
            av_log(avctx, AV_LOG_ERROR, "Couldn't reallocate color planes!\n");
            return AVERROR(ENOMEM);
        }

        ctx->pic_conf = pic_conf;

        /* set default macroblock/block dimensions */
        for (p = 0; p <= 2; p++) {
            for (i = 0; i < (!p ? pic_conf.luma_bands : pic_conf.chroma_bands); i++) {
                ctx->planes[p].bands[i].mb_size  = !p ? (!ctx->is_scalable ? 16 : 8) : 4;
                ctx->planes[p].bands[i].blk_size = !p ? 8 : 4;
            }
        }

        if (ff_ivi_init_tiles(ctx->planes, ctx->pic_conf.tile_width,
                              ctx->pic_conf.tile_height)) {
            av_log(avctx, AV_LOG_ERROR,
                   "Couldn't reallocate internal structures!\n");
            return AVERROR(ENOMEM);
        }
    }

    ctx->frame_num = get_bits1(&ctx->gb) ? get_bits(&ctx->gb, 20) : 0;

    /* skip decTimeEst field if present */
    if (get_bits1(&ctx->gb))
        skip_bits(&ctx->gb, 8);

    /* decode macroblock and block huffman codebooks */
    if (ff_ivi_dec_huff_desc(&ctx->gb, get_bits1(&ctx->gb), IVI_MB_HUFF,  &ctx->mb_vlc,  avctx) ||
        ff_ivi_dec_huff_desc(&ctx->gb, get_bits1(&ctx->gb), IVI_BLK_HUFF, &ctx->blk_vlc, avctx))
        return AVERROR_INVALIDDATA;

    ctx->rvmap_sel = get_bits1(&ctx->gb) ? get_bits(&ctx->gb, 3) : 8;

    ctx->in_imf = get_bits1(&ctx->gb);
    ctx->in_q   = get_bits1(&ctx->gb);

    ctx->pic_glob_quant = get_bits(&ctx->gb, 5);

    /* TODO: ignore this parameter if unused */
    ctx->unknown1 = get_bits1(&ctx->gb) ? get_bits(&ctx->gb, 3) : 0;

    ctx->checksum = get_bits1(&ctx->gb) ? get_bits(&ctx->gb, 16) : 0;

    /* skip picture header extension if any */
    while (get_bits1(&ctx->gb)) {
        av_dlog(avctx, "Pic hdr extension encountered!\n");
        skip_bits(&ctx->gb, 8);
    }

    if (get_bits1(&ctx->gb)) {
        av_log(avctx, AV_LOG_ERROR, "Bad blocks bits encountered!\n");
    }

    align_get_bits(&ctx->gb);

    return 0;
}