[opus] Strange behavior with OGG packets?

Drew Allen bitllama at google.com
Thu May 18 19:23:29 UTC 2017

I should also say the the ogg_packet.packet[] char array is zero-filled for
packet mentioned.

On Thu, May 18, 2017 at 12:19 PM Drew Allen <bitllama at google.com> wrote:

> Hello all,
> I'm currently in the process of implementing a mixing matrix into the
> header of OPUS files for the proposed channel mapping 3 seen here:
> https://tools.ietf.org/html/draft-ietf-codec-ambisonics-03#section-3.2
> My implementation simply replaces writing the stream mapping char array
> with the Q15 col-wise matrix vals described in the above document.
> I'm able to write/read matrices of 4x4 and 9x9 and encode->decode first
> and second order just fine, but writing larger matrices causes what seems
> to be some sort of packet corruption. The OpusHead packet is never found,
> but in it's place we have a packet at b_o_s=256 (which is where OpusHead
> usually lives), but the byte size is reported to be 0 and e_o_s=0 as well.
> (This is generated by parsing the packets via ogg's *ogg_stream_packetout* function.
> It appears a matrix larger than 7x16 causes this issue. (The matrix values
> are all signed short vals, so >224 bytes seems to fail.
> I'm not very familiar with ogg internals so any advice would be greatly
> appreciated! Thanks so much! :)
> Cheers,
> Drew
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