[opus] OPUS Packet Size

Abdulaziz Alghosh aziz647 at gmail.com
Fri Oct 18 14:00:23 UTC 2019

Hi Everbody,

i am not so good with codecs and a lot of terms in RFC 6716 of OPUS are not
so familiar for me.
I work in VoIP domain (Internet telephony) and try to support OPUS codec
throughout our network.
Therefore, I am trying actully to calculate or estimate the biggest
possible size of the RTP OPUS Packet in case of WB or FB.

Unfortunately, The "Frame Length Coding" paragraph of RFC 6716 (
https://tools.ietf.org/html/rfc6716#section-3.2.1)  is not clear enough for
me to understand why  "" The maximum representable length is 255*4+255=1275
bytes ""

is the Frame length useful only to calculate the bitrate but not the packet
size ?
the OPUS coded data is compressed. Is it not possible because of this to
estimate the packet size ?

according to https://tools.ietf.org/html/rfc6716#section-2.1.4 (Frame
Duration)  :

it (OPUS) can also combine multiple frames into packets of up to 120 ms.
(for me this means 6 Frames. Each is 20 ms)

so if I the VoIP Device support FB OPUS the and Sampling Rate is 48000
Sample per a Second (1000 ms), then that means the Frame has 9600 samples.

9600 samples * 16 bit (bit-depth) = 153600 bit per a Frame => 19200 Byte
per a Frame
19200 Byte per a Frame  * 6 Frames in a Packet (longest Packet) = 115200
Byte per a Packet.

are  the 15200 Bytes normally compressed ?

once again, I am trying to find out how could the packet size of OPUS be

thanks in advance for your help
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