static int mpeg4_unpack_bframes_filter(AVBSFContext *ctx, AVPacket *out) { UnpackBFramesBSFContext *s = ctx->priv_data; int pos_p = -1, nb_vop = 0, pos_vop2 = -1, ret = 0; AVPacket *in; ret = ff_bsf_get_packet(ctx, &in); if (ret < 0) return ret; scan_buffer(in->data, in->size, &pos_p, &nb_vop, &pos_vop2); av_log(ctx, AV_LOG_DEBUG, "Found %d VOP startcode(s) in this packet.\n", nb_vop); if (pos_vop2 >= 0) { if (s->b_frame_buf) { av_log(ctx, AV_LOG_WARNING, "Missing one N-VOP packet, discarding one B-frame.\n"); av_freep(&s->b_frame_buf); s->b_frame_buf_size = 0; } /* store the packed B-frame in the BSFContext */ s->b_frame_buf_size = in->size - pos_vop2; s->b_frame_buf = create_new_buffer(in->data + pos_vop2, s->b_frame_buf_size); if (!s->b_frame_buf) { s->b_frame_buf_size = 0; av_packet_free(&in); return AVERROR(ENOMEM); } } if (nb_vop > 2) { av_log(ctx, AV_LOG_WARNING, "Found %d VOP headers in one packet, only unpacking one.\n", nb_vop); } if (nb_vop == 1 && s->b_frame_buf) { /* use frame from BSFContext */ ret = av_packet_copy_props(out, in); if (ret < 0) { av_packet_free(&in); return ret; } av_packet_from_data(out, s->b_frame_buf, s->b_frame_buf_size); if (in->size <= MAX_NVOP_SIZE) { /* N-VOP */ av_log(ctx, AV_LOG_DEBUG, "Skipping N-VOP.\n"); s->b_frame_buf = NULL; s->b_frame_buf_size = 0; } else { /* copy packet into BSFContext */ s->b_frame_buf_size = in->size; s->b_frame_buf = create_new_buffer(in->data, in->size); if (!s->b_frame_buf) { s->b_frame_buf_size = 0; av_packet_unref(out); av_packet_free(&in); return AVERROR(ENOMEM); } } } else if (nb_vop >= 2) { /* use first frame of the packet */ av_packet_move_ref(out, in); out->size = pos_vop2; } else if (pos_p >= 0) { av_log(ctx, AV_LOG_DEBUG, "Updating DivX userdata (remove trailing 'p').\n"); av_packet_move_ref(out, in); /* remove 'p' (packed) from the end of the (DivX) userdata string */ out->data[pos_p] = '\0'; } else { /* copy packet */ av_packet_move_ref(out, in); } av_packet_free(&in); return 0; }