[opus] Opus Tools -- low bitrates, new features in 1.5, "expect-loss"

[Petr Pařízek]

> Can you please make that sound file available?

> It is hard to tell without having anything.

> (50s of sines shouldn't be large.)

>
>> Okay, the specific sine sweep that I used was this one. Originally, I 
>> was testing the "mid" and the "side" channel, which is why the first 
>> occurrence is in mono and the second is in inverse mono. To test the 
>> low bitrates, I had to use "--downmix-mono" when running Opusenc, 
>> which obviously makes the second sweep vanish.
>>
>> In this particular example, except for the very beginning, I 
>> deliberately altered the instantaneous amplitude proportionally to 
>> sqrt(freq), which makes the overall frequency spectrum flat even 
>> though the frequency is rising exponentially (not linearly). To do 
>> that, I actually convolved two different sine sweeps, each 25 seconds 
>> long, whose combined frequency spectrum is flat (as another Farina's 
>> module can generate the corresponding inverse signal).
>>
>> This is the link (there's a Download button on the webpage):
>> https://1drv.ms/u/s!Ap_EgwEX00SDhH04THc07uQY2ojv?e=0Ab8Bf
>>
>> Petr
>>
>>
>>
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