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On Aug 07 00:41:52, petrparizek2000 at yahoo.com wrote: > ????#1. To test encoding at low bitrates, I encoded a sine sweep at 12 kbps > with Opusenc and then decoded the resulting file with Opusdec. What sine sweep exactly? How did you obtain it, and how exactly did you encode and decode it? Jan > The strange > thing...

On Aug 07 08:30:31, hans at stare.cz wrote: > On Aug 07 00:41:52, petrparizek2000 at yahoo.com wrote: > > ????#1. To test encoding at low bitrates, I encoded a sine sweep at 12 kbps > > with Opusenc and then decoded the resulting file with Opusdec. > 1) Opusenc --bitrate 12 --downmix-mono Sweep50.wav Sweep50.opus Why are you using a stereo file containing the sa...

> What sine sweep exactly? An exponential sweep. It started slightly below 24 Hz and ended almost at 24 kHz. And it was 50 seconds long. > How did you obtain it, I used Angelo Farina's "Aurora" modules. One of them is called "Generate sine sweep". > and how exactly did you encode and decode it? 1) Opusenc --bitrate 12 --downmix-mono Sweep50.wav

On Aug 09 11:58:33, u.windl at ukr.de wrote: > > -----Original Message----- > > From: opus <opus-bounces at xiph.org> On Behalf Of Jan Stary > > Sent: Friday, August 9, 2024 12:00 PM > > To: Petr Pa??zek <petrparizek2000 at yahoo.com> > > Cc: opus at xiph.org > > Subject: [EXT] Re: [opus] Re: Opus Tools -- low bitrates, new features in 1.5, > > "expect-loss" > > > > [Windl, Ulrich] > [...] > > > > Also if you look at the samples for (e.g.) a 20kHz sine sa...

Hello, I understand it would be better to post several messages with separate topics but I hope I don't cause too much mess if I put it all in a single message this time. To be clear, recently I've been testing Opus Tools under Windows and these are my questions/observations. ????#1. To test encoding at low bitrates, I encoded a sine sweep at 12 kbps with Opusenc and then decoded

On Aug 07 22:04:21, petrparizek2000 at yahoo.com wrote: > > The encoded opus file is 48kHz, > > so how would the output wav be resampled from 16kHz? To be clear: did you mean the opus output of opusenc or the wav output of opusdec? > > What are those "clear signs" exactly? > > The things that I ca...

> As the thing is to encode for human ears (AFAIK), I'd say that 4kHz is already "quite high", > and I wonder who can actually hear pure 20kHz sine. If you read the beginning of RFC 6716, you learn that Opus never encodes any frequencies that are higher than 20 kHz. So at some medium or high bitrates, anything above 20 kHz is filtered out, not because of the bitrate but

> Why are you using a stereo file > containing the same sweep in both channels > and then downmixing to mono? When I first tried encoding at a higher bitrate, I needed to test the different behavior of the "mid" (l+r) and "side" (l-r) channels. That's why I made the first sweep identical on both the left and the right channel (i.e. "side" is silent)

On Aug 07 10:08:43, petrparizek2000 at yahoo.com wrote: > > What sine sweep exactly? > > An exponential sweep. It started slightly below 24 Hz and ended almost at 24 > kHz. And it was 50 seconds long. > > > How did you obtain it, > > I used Angelo Farina's "Aurora" modules. One of them i...

> To be clear: did you mean the opus output of opusenc > or the wav output of opusdec? I meant during the decoding. There's one significant difference between how Opusdec deals with resampling and how, let's say, MP3 decoders usually deal with resampling. If I make an MP3 at a very low bitrate and if the encoder decides (because it's too low) to internally resample my audio