bandpass, 2bdecided, saratoga and John Siau will hopefully find this interesting.4th post here http://www.hydrogenaudio.org/forums/index....st&p=820447has a .CSV with the raw data from a scan.
Are you seeing what I'm seeing? i.e. do an X-Y plot of column B against column D.
bandpass, 2bdecided, saratoga and John Siau will hopefully find this interesting.The 3.71% in the +1 to +2 range and the 0.79% in the +2 to +3 range is very worrying, but a DAC like that mentioned by John Siau should handle this fine.Where it really gets creepy is the >3dBFS ISPs, 3.62% total in the +3 to >+9 dBFS range. Hopefully you guys find the .csv interesting, 5824 tracks is a rather large sample of data and thus hopefully useful.
The "+11 dB" test signal (that started this thread) is proving very useful for testing the overload characteristics of DSP code. If the DSP process is working properly, the inter-sample peak should pass at full amplitude (when there is sufficient headroom), or should be clipped when there is insufficient headroom. The ES9018 D/A conversion IC seems to invert the inter-sample peak in some modes of operation.
I'm coming at this from the other direction - I suspect that, in the context of EBU R128, consideration of intersample peak is irrelevant for content that reaches the consumer. Any consumer-targeted audio track that is loudness matched to -23LUFS is very unlikely to have any content near clipping, and as long as the actual samples sit below 0dB FS I bet the intersample peaks are safe too (except on a track intentionally created to disprove this statement!).For pop CDs, which are often 10-15dB louder than EBU R128 requires, and often smashed/clipressed to be as loud as possible, then of course intersample overs are a real issue.
That upper "series" (Y=X+8dB) must be wrong, and is contaminating your results for the number of intersample overs above 0dB FS.
if that anomaly rears it's head again, I'll make sure I track the filepaths so I can check the offenders if it's either damaged files/bad encodings or something else.
I could probably code something similar to sox's "upsample 4 sinc -a 40 -t 8k -24k" if I got some pointers/help though.
Quote from: 2Bdecided on 14 January, 2013, 07:00:15 AMAre you seeing what I'm seeing? i.e. do an X-Y plot of column B against column D.No! I Do not have MatLAB or whatever. (can't afford to pay thousands).
Since inter-sample overshoot is a problem for the analog stage of a DAC...
...what would happen at the corresponding stage in an ADC, assuming the same analog/digital waveform?
It seems that inter-sample over values are quoted with great accuracy and confidence, even though the exact reconstruction filter is not specified.
Quote from: knutinh on 04 February, 2013, 03:20:56 AMSince inter-sample overshoot is a problem for the analog stage of a DAC...It's also a problem for the digital section, i.e. the over sampling + reconstruction filter.
After reading about that topic a bit i found that iZotope offers a feature build into their limiter that has intersample detection for "True Peaks"Since Alexey Lukin is member here and to my understanding is part of the iZotope team he may give us some idea how they reached their conclusion of the peaks in music hitting above 3dB. Interesting is their limiter now seems to be able to prevent this directly while mixing it hot.http://www.izotope.com/support/help/ozone/...s_maximizer.htm
Quote from: knutinh on 04 February, 2013, 03:20:56 AMIt seems that inter-sample over values are quoted with great accuracy and confidence, even though the exact reconstruction filter is not specified.The EBU R128 definition is pretty strict, though it doesn't necessarily give the absolute highest possible true peak.Cheers,David.
I vaguely remember something about "phase scrabling" peaks in radio transmission - i.e. messing with the phase so as to minimize peaks while keeping the average levels (or, effectively maximizing the average levels with minimal audible distortion).Could this be done in a DAC/SRC application? If complexity/delay was of no concern, one could choose between a set of prototype filters that sounded equally good, selecting the filter that minimized intersample overs? Is not this a neater (although certainly overkill) solution than throwing away a few dB of SNR for all material?
I vaguely remember something about "phase scrabling" peaks in radio transmission
- i.e. messing with the phase so as to minimize peaks while keeping the average levels (or, effectively maximizing the average levels with minimal audible distortion).Could this be done in a DAC/SRC application? If complexity/delay was of no concern, one could choose between a set of prototype filters that sounded equally good, selecting the filter that minimized intersample overs? Is not this a neater (although certainly overkill) solution than throwing away a few dB of SNR for all material?
Or, one could have a two-path filtering, switching to a cruder interpolation in those few segments where intersample overs are an issue (linear interpolation?)
6528 tracks.Avg. Peak -1.24 dBFS (Min -24.55, Max 0.00)Avg. ISP -0.56 dBFS (Min -25.71, Max 9.54)ISP/Peak Delta -1.79 dB (Min -49.06, Max 9.54)RMS -16.79 dBFS (Min -42.05, Max 0.00)24.08% (1572) ISP <-1 dBFS75.92% (4956) ISP >-1 dBFS18.57% (1212) ISP -1 to 0 dBFS43.49% (2839) ISP 0 to 1 dBFS8.70% (568) ISP 1 to 2 dBFS1.53% (100) ISP 2 to 3 dBFS0.57% (37) ISP 3 to 4 dBFS0.17% (11) ISP 4 to 5 dBFS0.23% (15) ISP 5 to 6 dBFS0.46% (30) ISP 6 to 7 dBFS1.44% (94) ISP 7 to 8 dBFS0.75% (49) ISP 8 to 9 dBFS0.02% (1) ISP 9 to 10 dBFS0.00% (0) ISP 10> dBFS
The only track that had a True Peak above +9 dBFS:Jayce and the Wheeled Warriors, opening theme (mp3) +9.54 dBFS, -11.88 RMSI can't recall where it's from, I think I ripped this from from a Youtube video. I watched this show when I was young, so it's in my collection for nostalgia reasons. Can't share the track for legal reasons, sorry. But it should be searchable on Youtube so try there first (you'll also be treated to a cheesy 80s animated intro as well).
Quite a few tracks have surprisingly high intersample peaks that are above +8 dBFS.Legendary standup comedian George Carlin's performances/recordings/albums "Back in Town", "Complaints And Grievances", "Playin With Your Head" all have true peaks at/above +8.0 dBFS, the RMS varies from -17 dBFS to -21 dBFS, so even if EBU R128 or ReplayGain was used the true peaks would still be above 0 dBFS afterwards.Michael Land's Monkey Island III OST and RockStar Games Grand Theft Auto Liberty City Stories OST also have very high true peaks, their RMS is higher than George Carlin's stuff for various reasons (talking vs music being one, but also the years they where mastered, and the way they where mastered).Liberty City Stories OST should be somewhat available (check WIMP, Spotify, iTunes, Google Play, Amazon etc) but I'm unsure if they match the game audio rip or not. (the in-game radio channels are sometimes mastered differently from the individual tracks).Frank Klepacki's Blade Runner The Game soundtrack also show similar high true peaks.His website is at http://www.frankklepacki.com/ you can find some tracks in the flash player on the page http://www.frankklepacki.com/portfolio/game-BR.htmlYou'll have to rip the tracks from there (or use a live True Peak meter), the rest of the tracks you'll have to rip/convert from Blade Runner The Game itself.
A few other collections are above +3 dBFS though.A few tracks from the "Trilogy" album by "Carpenter Brut" (mp3) for example (check the various outlets or bandcamp or Youtube https://carpenterbrut.bandcamp.com/album/trilogy )A few tracks from Yuki Kajiura's "Noir" soundtrack OST2 disc (mp3). Eminem's album "Relapse" (mp3). Savant's album "ISM" (FLAC)
Tracks with True Peaks in the +2 dBFS to +3 dBFS range.Eminem's album "Relapse", Type O Negative's "World Coming Down" album, Pendulum's album "Immersion", Savant's "ISM" album, Vader's "XXV" album, Ramin Djawadi 's season 1 "Game of Thrones" soundtrack). Some of this stuff is more mainstream so tests should hopefully be more easily reproducible by others.
6486 tracks.Avg. ISP -0.78 dBFS (Min -24.55, Max 5.75)RMS -16.87 dBFS (Min -42.05, Max -5.88)27.03% (1753) ISP <-1 dBFS72.97% (4733) ISP >-1 dBFS20.35% (1320) ISP -1 to 0 dBFS34.84% (2260) ISP 0 to 1 dBFS13.61% (883) ISP 1 to 2 dBFS3.25% (211) ISP 2 to 3 dBFS0.62% (40) ISP 3 to 4 dBFS0.25% (16) ISP 4 to 5 dBFS0.05% (3) ISP 5 to 6 dBFS