10bd01 wrote:plexuss wrote:Another confirmation that RoundTrip adheres to the ITU spec. Whether its sub-optimal or not is a matter of opinion.
Is it? Or is it a matter of testing?
I think it's also worth asking at this point: are you hearing the clipping or just seeing it on your meter? Because if the meter is using a sub-optimal specification you could be viewing clipping with your eyes that isn't actually happening to you ears.
Pretty much everyone I've consulted that has tested and uses RoundTripAAC has confirmed it is legit and useful. This include professional mastering engineers through the mastering engineers and loudness facebook groups. For example Ian Shepard and Bob Katz are on those pages. As well as numerous other professionals.
Remember that the whole issue is trying to determine what will happen in the analogue domain. This isn't an issue if your peaks are lower than 0dBFS. Not AT 0 dBFS but lower than it. But in order to get the loudness that still many people crave, the gain of the whole track has to rise pushing the peaks at or over 0 dBFS. this is where clipping occurs and why we want truly true peak meters, a good sounding approach to managing those clips and some way to estimate if there will still be any clipping in the analogue domain.
It's almost rocket science.
Since its an estimation of the risk of clipping in analogue and there are so many DAC approaches, there won't be one way to do it.
I think RoundTripAAC is the best tool for the job for the reasons I cited: it appears to be based on the ITU spec for peak and clip detection and it measures clip velocity. No other meter I know of does these two things. But if a better meter comes out I will use it if I can. What would make it better: confirming that it uses the ITU spec at the very least and if it uses a "better" algorythm, then a description of the rationale for why it's better. Maybe a better GUI. Not much else. RoundTripAAC does the right stuff if you are trying to reducing clipping in the analogue domain.
In terms of subjective evaluation: this is why clip velocity is so important because one single clip is not going to be (very) audible (I always have to make room for people who believe they can hear one sample of clipping - that's the nature of audio). A stream of clips in a short duration become more audible. The problem with subjective evaluation is that audbile clipping imparts a kind of broadband "haze" to the audio and it can difficult to hear it as a problem. Until you AB with one without clipping. Just because a track may SOUND good without comparing it to a version that sounds better, doesn't mean its the best version. Audio is subjective and our brains often react in the opposite way we expect so AB'ing and metering for problems is the way to do it.
And, as has been discussed here, you don't HAVE TO eliminate ISP clipping: some genres actually sound good with some clipping. Clipping causes yet another kind of distortion. There are plugins just to create good sounding clipping. Just do what you think sounds best.
For my work I prefer not to have clipping like that. I do not like the sound of it in my music and audio work. So this topic and these tools and considerations are imporant to me. That's why I've spent so much time to learn about all this. YMMV