← Back to team overview

rohc team mailing list archive

Re: [Question #229419]: What protocol number should be for RTP header compression


Question #229419 on rohc changed:

    Status: Needs information => Open

Wei Wang gave more information on the question:
Hi Didier,

Looks like UDP headers can't be randomly defined. Below is how I defined.
    /* fake UDP headers, 8 bytes */
	udp_packet[0] = 0x05; /* Source address */
	udp_packet[1] = 0x06;
	udp_packet[2] = 0x05; /* Destination address */
	udp_packet[3] = 0x06;
        udp_packet_len = 36;  // 8 bytes UDP headers, 12 bytes RTP headers, and 16 bytes payload
	udp_packet[4] = (udp_packet_len >> 8) & 0xff; /* Total Length */
	udp_packet[5] = udp_packet_len & 0xff;
	udp_packet[6] = 0x00; /* fake Checksum */
	udp_packet[7] = 0x00;

In fact, the checksum will be recalculated based on RFC768 in each loop.
I occasionally gave some values to udp headers and got ideal results, 21
bytes after compression and decompression was successful as well. But
this doesn't make sense.

Yes, I used the same decompressor. I just used the compressed result as
the input of the decompressor. If the compressed packet size was 21 or
24, then decompress failed.

You received this question notification because you are a member of ROHC
Team, which is an answer contact for rohc.