[Discuss-gnuradio] Codec2 vocoder packing issue

[Sebastien Van Cauwenberghe]

Hi All,

I have been playing around with the Codec2 vocoder block. I have a working flowgraph where I put a C2 encoder and a C2 decoder back to back.

I'm puzzled with the expected stream format. In the coder, the intent seems to create a vector of 50 bits (or bytes where the LSB contains the bit value) as output. If we look closer, the output is packed, so the 7 first bytes contain actual data and the 43 others are 0.

Is there a rationale about the codec stream format (shall it be packed or unpacked) ? Is is supposed to be uniform among all codecs ?

I've seen that the GSM coder uses a single byte output for the stream.

What is the advantage of using a single byte output compared to outputting an array ?

Cheers,

Sébastien