Tony
2015-Feb-24 16:30 UTC
[opus] Questions regarding OPUS_APPLICATION_AUDIO vs OPUS_BANDWIDTH_NARROWBAND
I have an audio device whose 'driver' gives me Opus encoded frames using OPUS_APPLICATION_AUDIO and max bandwidth set to OPUS_BANDWIDTH_NARROWBAND. How does Opus encoder decide the center point of the 4K bandpass filter? Is it done frame by frame? -- Tony -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.xiph.org/pipermail/opus/attachments/20150224/a72a3fde/attachment.htm
Jean-Marc Valin
2015-Feb-24 16:59 UTC
[opus] Questions regarding OPUS_APPLICATION_AUDIO vs OPUS_BANDWIDTH_NARROWBAND
Can you explain what you mean by "center point"? Jean-Marc On 24/02/15 11:30 AM, Tony wrote:> I have an audio device whose 'driver' gives me Opus encoded frames > using OPUS_APPLICATION_AUDIO and max bandwidth set to > OPUS_BANDWIDTH_NARROWBAND. How does Opus encoder decide the center > point of the 4K bandpass filter? Is it done frame by frame? > > -- > Tony > > > _______________________________________________ > opus mailing list > opus at xiph.org > http://lists.xiph.org/mailman/listinfo/opus >
Tony
2015-Feb-24 17:44 UTC
[opus] Questions regarding OPUS_APPLICATION_AUDIO vs OPUS_BANDWIDTH_NARROWBAND
Ooops! I didn't reply-all... When I look at the opus_defines.h, OPUS_BANDWIDTH_NARROWBAND, is defined as '< 4 kHz bandpass'. I assume 'bandpass' in this case refers to a 'bandpass filter'. http://en.wikipedia.org/wiki/Band-pass_filter Looking at the briefly looking at the Opus RFC, I __think__ the 'bandpass' is applied per frame. Which means the 'center' of the bandpass filter could change frame to frame. Maybe I'm wrong and I need to slapped in the face with fish, but that's what it looks like it happening. On Tue, Feb 24, 2015 at 11:59 AM, Jean-Marc Valin <jmvalin at jmvalin.ca> wrote:> Can you explain what you mean by "center point"? > > Jean-Marc > > On 24/02/15 11:30 AM, Tony wrote: > > I have an audio device whose 'driver' gives me Opus encoded frames > > using OPUS_APPLICATION_AUDIO and max bandwidth set to > > OPUS_BANDWIDTH_NARROWBAND. How does Opus encoder decide the center > > point of the 4K bandpass filter? Is it done frame by frame? > > > > -- > > Tony > > > > > > _______________________________________________ > > opus mailing list > > opus at xiph.org > > http://lists.xiph.org/mailman/listinfo/opus > > >-- Tony -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.xiph.org/pipermail/opus/attachments/20150224/8a70f063/attachment-0001.htm