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Old 18th August 2018, 16:40   #21  |  Link
Forteen88
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Originally Posted by Asmodian View Post
Opus is higher quality than AAC, isn't that a reason to use it? Audio decode time is usually not a concern, it is really fast and can be done on another CPU/thread. HEVC takes a lot longer to decode than AVC too.
There is only a slightest quality-difference between Opus & AAC (Opus being better quality). All good GPU:s nowadays (even since Nvidia GeForce 950/960) got FULL hardware-decoding for HEVC
https://forum.doom9.org/showthread.p...84#post1846184

Even a Opus@128kbps got longer a much decoding-time than AAC@144kbps,
Opus@128kbps: "Decoding time: 0:00.832".

Last edited by Forteen88; 19th August 2018 at 06:48.
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Old 18th August 2018, 23:24   #22  |  Link
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And that equals to what? Only 300x instead of 1000x real-time?
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Old 19th August 2018, 00:59   #23  |  Link
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Originally Posted by Forteen88 View Post
Apple AAC@144kbps (using latest version with qaac_2.67, default setting),
"Decoding time: 0:00.174"

Opus@144kbps (using opus-tools-0.1.10-win64, default setting),
"Decoding time: 0:00.990"
Try that on android and the times are going to vary greatly, in windows foobar2000 in the test make opus appear 5-6 times slower while in reality is only around 0.6 times slower in the worst case, also opus is faster than HE-AAC by a good margin.
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Old 19th August 2018, 06:02   #24  |  Link
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Originally Posted by sneaker_ger View Post
And that equals to what? Only 300x instead of 1000x real-time?
That test was for only 2 channels, but I was thinking more of how much decoding time difference is for like 6channels (with 24 bits bit depth), and combine that with a high resolution (1080p or even 4k) HEVC-video with no hardware-decoding support. That's a lot of pressure on the CPU.
Although, as 'Phanton_13' wrote, maybe foobar2000 got a much slower Opus-decoder than AAC-decoder.

I did another test, source-audio was from a DD5.1 movie,
AppleAAC@320kbps (foobar2k v1.4, 8 threads in Decoding speed test):
Decoding time: 0:37.325
874.862x realtime

Opus@300kbps (foobar2k v1.4, 8 threads in Decoding speed test):
Decoding time: 2:38.280
209.636x realtime

Last edited by Forteen88; 19th August 2018 at 06:46.
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Old 19th August 2018, 11:40   #25  |  Link
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So 100% of CPU divided by 200 is 0.5% of the CPU would be used for the Opus playback. You wouldn't even be able to measure this reliably.
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Old 19th August 2018, 23:57   #26  |  Link
FranceBB
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I'm more concerned about compatibility rather than the playback speed.
Besides, Opus was created to accomplish good communications with low bandwidth when two or more people were talking.
Later on, they developed other profiles that aimed to compress other types of contents and not just speech and they did a good job, however, Opus is not widely used and is not considered as standard as AAC and AC3 are.
The large majority of players will likely accept AAC or AC3 audio files, but will probably refuse an Opus audio file.
I'm not talking about computers, I'm talking about hardware decoders like bluray players, consoles and smart tv.
I also gotta say that AC3 might be a bit old (although still valid and widely used), but AAC has a really good psychoacoustic model and its MDCT filter bank that adaptively switches between 128 and 1024 bands (length 256 and 2048 FFT windows, using 50% overlap) demonstrated to be effective through these years, that's why AAC has become the first choice when people encode lossy audio contents.
I'm not saying that you shouldn't use Opus, but is it really worth saving few megabytes at the expense of compatibility with many devices when generally AAC 192kbit/s would be sufficient, AAC 320kbit/s would be good and AAC 384 kbit/s would be crystal and all you need?
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Old 20th August 2018, 16:50   #27  |  Link
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Then why did you only mention speed and not compatibility? Some users do not care about bluray players, consoles, or smart TVs at all. Let them encode to new higher quality options if they want to to.

We would be stuck on MPEG2 with MP3 if compatibility always won out. Also, HEVC is still a bad idea if compatibility is what you are going for. There are a lot of devices out that that support AVC+AAC that do not support HEVC and AVC at a bit higher bitrate would be sufficient.

Opus is catching on, I would not be surprised to see some smart TVs supporting soon. They are usually running Android and have decent enough CPUs they could do it even without hardware decoding.
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Old 20th August 2018, 18:44   #28  |  Link
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Then why did you only mention speed and not compatibility?
'cause *I am* more concerned about compatibility, but I'm not the one who asked the question, @Arhu is, I just jumped in the topic and replied with my point of view xD

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We would be stuck on MPEG2 if compatibility always won out.
Which is the reason why I encode files in MPEG-2 interlaced 25i TFF by doing speed-ups or blending at work on a daily basis. T_T (Omneon playout ports compatibility for 1080i contents :'( )
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Old 21st August 2018, 21:58   #29  |  Link
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Personally, I think xHE-AAC is going to be used a lot more than Opus ever will, particularly for commercial use. It outperforms Opus, offers seamless bitrate switching, and is broadly available in AAC licensing. Opus is an excellent codec, seamlessly bridging between low bitrate speech coding with efficient perceptually lossless encoding.

The OEMs have many years of familiarity with Fraunhofer and Via licensing, and I expect device classes that support AAC today to support xHE-AAC in the future.
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