rohc team mailing list archive

[Didier Barvaux <question229518@xxxxxxxxxxxxxxxxxxxxx>]

Question #229518 on rohc changed:
https://answers.launchpad.net/rohc/+question/229518

    Status: Open => Answered

Didier Barvaux proposed the following answer:
Friedrich,

> After using rohc_feedback_flush() to dump the feedback packet at the
> receiver side, how do we process this packet at the transmitter side?
>
> For example, I "flushed" one feedback packet to obuf which contains
> only 5 bytes. This 5-byte packet goes through PDCP, RLC, PHY...PHY, RLC,
> PDCP, and shows up as the same but only at the transmitter side. Now
> I guess that RoHC compressor needs to recognize it, and to make use
> of this feedback information. Which function can I call to fulfill it?

Use rohc_decompress() on the decompressor associated with the compressor
on the "transmitter" side.


> I noticed there were two functions doing this kind of job in the
> decompressor: d_decode_feedback_first, d_decode_feedback. But
> for this particular 5-byte feedback-only packet, we  don't need to
> decompress it since there was no compression at all. Could you please
> elaborate my concern then?

Don't use them. They are private functions. The 5-byte feedback-only
packet does not need to be decompressed but the way to parse the
feedback data is through rohc_decompress(). Parsing a feedback
+compressed-data packet and a feedback-only packet is done with the same
code. When the rohc_decompress()  function hits feedback, it decodes it
and gives it to its associated local compressor. With a feedback-only
packet, the rohc_decompress() function will return ROHC_FEEDBACK_ONLY
and the obuf buffer will be empty.

Regards,
Didier

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