Blackmagic Forum

I'm talking about mechanical disc drives, waveform generation on SSD is fast but unfortunately is not always possible to use an SSD as a source drive.

I did the following test:

I have 21 clips, 1 hour long overall, I drop them in the media pool, I drag the first clip on the timeline, wait for the waveform to generate, insert the next one and so on...

It took 1:50 overall to generate all the waveforms by droping the clips one by one. The hard disk read speed on the task manager during this process was around 130 - 150 mb/s

I did the same test again but this time I dropped all the clips together.
It took 10:15 to generate all the waveforms. The hard disk read speed on the task manager was about 15 - 20mb/s this time.

I did this test multiple times with similar results.

I think Resolve tries to generate multiple waveforms at the same time and this causes slow generation speed on HDD's

Can anyone else confirm this?

I'm having the same issue. I have a 16 min timeline that I can't even playback. Hard drive speed test is 30MB/s. The HDD is spinning out of control and I can't work.

This is still a huge issue for us as well. We just opened a support ticket with Blackmagic, hoping for some answers

You mentioned HARD disk, probably Davinci is trying to load all files at the same time resulting in your hard-drive-read-head having to go back and forward to each file adding a lot of seek-time.

Might be fixable with a software update from Blackmagic, but then they would have to add a "follow playhead" rule in the code so that it loads the clip under the playhead first and then the rest one by one

Davinci reads up to 4 files in parallel, if they're on a spinning HDD then the head will seek like crazy and nothing else will work.
The only solution is to only have 1 file visible in the timeline at a time when generating waveforms.
(or, to get an SSD to make seeking a non-issue. I like the dc600m for it's write endurance)

Maybe that could help with 2-channel audio, but some of our media has up to 32 tracks and there´s no hiding from that

Mads Johansen wrote:Davinci reads up to 4 files in parallel, if they're on a spinning HDD then the head will seek like crazy and nothing else will work.
The only solution is to only have 1 file visible in the timeline at a time when generating waveforms.
(or, to get an SSD to make seeking a non-issue. I like the dc600m for it's write endurance)

Blackmagic might give us an option to read only one at a time (a toggle in the settings) but it should prioritize the clip under the playhead imo

After doing a bit more research by isolating the amount of .pfl files being output simultaneously after triggering a large waveform generation event it seems like Resolve is trying to read 32 data streams simultaneously for waveform generation. Way too many for a HDD of course

are_luke wrote:After doing a bit more research by isolating the amount of .pfl files being output simultaneously after triggering a large waveform generation event it seems like Resolve is trying to read 32 data streams simultaneously for waveform generation. Way too many for a HDD of course

This was my experience as well. Tested a lot in V16 and V17 and came the same conclusion that some codecs being read in a strange way. Each track is being processed simultaneously and Sony codecs with 8 tracks get bogged down on HDD drives massively.

It's why generating proxies helped elliviate this issue for me, sometimes. As it seems to be using the prores proxy files instead and reading those much more quickly, since they are uncompressed audio vs compressed inside mxf's.

Wrote about it a lot here:
viewtopic.php?f=21&t=90250&hilit=+waveform