static int vp9_superframe_split_filter(AVBSFContext *ctx, AVPacket *out)

{

    VP9SFSplitContext *s = ctx->priv_data;

    AVPacket *in;

    int i, j, ret, marker;

    int is_superframe = !!s->buffer_pkt;



    if (!s->buffer_pkt) {

        ret = ff_bsf_get_packet(ctx, &s->buffer_pkt);

        if (ret < 0)

            return ret;

        in = s->buffer_pkt;



        marker = in->data[in->size - 1];

        if ((marker & 0xe0) == 0xc0) {

            int length_size = 1 + ((marker >> 3) & 0x3);

            int   nb_frames = 1 + (marker & 0x7);

            int    idx_size = 2 + nb_frames * length_size;



            if (in->size >= idx_size && in->data[in->size - idx_size] == marker) {

                GetByteContext bc;

                int total_size = 0;



                bytestream2_init(&bc, in->data + in->size + 1 - idx_size,

                                 nb_frames * length_size);



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

                    int frame_size = 0;

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

                        frame_size |= bytestream2_get_byte(&bc) << (j * 8);



                    total_size += frame_size;

                    if (total_size > in->size - idx_size) {

                        av_log(ctx, AV_LOG_ERROR,

                               "Invalid frame size in a superframe: %d\n", frame_size);

                        ret = AVERROR(EINVAL);

                        goto fail;

                    }

                    s->sizes[i] = frame_size;

                }

                s->nb_frames         = nb_frames;

                s->next_frame        = 0;

                s->next_frame_offset = 0;

                is_superframe        = 1;

            }

        }

    }



    if (is_superframe) {

        GetBitContext gb;

        int profile, invisible = 0;



        ret = av_packet_ref(out, s->buffer_pkt);

        if (ret < 0)

            goto fail;



        out->data += s->next_frame_offset;

        out->size  = s->sizes[s->next_frame];



        s->next_frame_offset += out->size;

        s->next_frame++;



        if (s->next_frame >= s->nb_frames)

            av_packet_free(&s->buffer_pkt);



        ret = init_get_bits8(&gb, out->data, out->size);

        if (ret < 0)

            goto fail;



        get_bits(&gb, 2); // frame_marker

        profile  = get_bits1(&gb);

        profile |= get_bits1(&gb) << 1;

        if (profile == 3)

            get_bits1(&gb);

        if (!get_bits1(&gb)) {

            get_bits1(&gb);

            invisible = !get_bits1(&gb);

        }



        if (invisible)

            out->pts = AV_NOPTS_VALUE;



    } else {

        av_packet_move_ref(out, s->buffer_pkt);

        av_packet_free(&s->buffer_pkt);

    }



    return 0;

fail:

    av_packet_free(&s->buffer_pkt);

    return ret;

}
