static int tcp_write_packet(AVFormatContext *s, RTSPStream *rtsp_st) { RTSPState *rt = s->priv_data; AVFormatContext *rtpctx = rtsp_st->transport_priv; uint8_t *buf, *ptr; int size; uint8_t *interleave_header, *interleaved_packet; size = avio_close_dyn_buf(rtpctx->pb, &buf); ptr = buf; while (size > 4) { uint32_t packet_len = AV_RB32(ptr); int id; /* The interleaving header is exactly 4 bytes, which happens to be * the same size as the packet length header from * url_open_dyn_packet_buf. So by writing the interleaving header * over these bytes, we get a consecutive interleaved packet * that can be written in one call. */ interleaved_packet = interleave_header = ptr; ptr += 4; size -= 4; if (packet_len > size || packet_len < 2) break; if (ptr[1] >= RTCP_SR && ptr[1] <= RTCP_APP) id = rtsp_st->interleaved_max; /* RTCP */ else id = rtsp_st->interleaved_min; /* RTP */ interleave_header[0] = '$'; interleave_header[1] = id; AV_WB16(interleave_header + 2, packet_len); url_write(rt->rtsp_hd_out, interleaved_packet, 4 + packet_len); ptr += packet_len; size -= packet_len; } av_free(buf); url_open_dyn_packet_buf(&rtpctx->pb, RTSP_TCP_MAX_PACKET_SIZE); return 0; }