Blackmagic Forum

I am running a Mac Mini M1 with 16GB RAM and 1TB SSD. And I am using DaVinci Resolve free version 17.1.1 Build 9.

On some projects, when I import footage from my iPhone, I will try to play the timeline, and the footage will play fine for about 1 second, but then start speeding up as if the clip is at maybe 130% speed, and the audio will start skipping. The iPhone footage is .MOV H.265, 4K 30FPS. The footage does not exhibit this behavior when being played back in macOS.

The video I've linked shows two projects which don't have identical footage, but are both using 4K/30FPS footage from my iPhone, and external audio. However, only one of the projects is exhibiting the playback issue, and the other is fine. The audio format is .WAV, 44.1KHz, 24-bit.

I was previously using Resolve on a Windows PC with an i5-8400, GTX-1060, and 32GB RAM. I had never experienced this on Windows before - including the same 4k iPhone footage and external audio.

I had recorded a video demonstrating the issue, but it seems as though I am not allowed to post URLs. I hope this is enough information to be helpful. Please let me know if I should provide anything else.

Hi

Maybe the problem is that your iphone records variable framerate fps !

There is a free app: Mediainfo you can use to get the full specs of your iphone footage. Get the full TREE specs of your footage and show them here !

Ole Kristiansen wrote:Hi

Maybe the problem is that your iphone records variable framerate fps !

There is a free app: Mediainfo you can use to get the full specs of your iphone footage. Get the full TREE specs of your footage and show them here !

Thank you Ole. I think you may be on to something. Below is the information for the problematic clip:
--------------------------------------------------
Mac Mini First Impressions/A ROLL .MOV
Format : MPEG-4
Format profile : QuickTime
Codec ID : qt 0000.00 (qt )
File size : 4.40 GiB
Duration : 24 min 13 s
Overall bit rate mode : Variable
Overall bit rate : 26.0 Mb/s
Encoded date : UTC 2021-04-23 21:33:04
Tagged date : UTC 2021-04-23 21:57:19
Writing library : Apple QuickTime
com.apple.quicktime.location.accuracy.ho : 9.340151
com.apple.quicktime.location.ISO6709 : +35.3028-080.7979+243.660/
com.apple.quicktime.make : Apple
com.apple.quicktime.model : iPhone SE (2nd generation)
com.apple.quicktime.software : 14.4.2
com.apple.quicktime.creationdate : 2021-04-23T17:33:04-0400

Video
ID : 1
Format : HEVC
Format/Info : High Efficiency Video Coding
Format profile : Main@L5@Main
Codec ID : hvc1
Codec ID/Info : High Efficiency Video Coding
Duration : 24 min 13 s
Bit rate : 25.7 Mb/s
Width : 3 840 pixels
Height : 2 160 pixels
Display aspect ratio : 16:9
Frame rate mode : Variable
Frame rate : 30.000 FPS
Minimum frame rate : 28.571 FPS
Maximum frame rate : 30.000 FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Bits/(Pixel*Frame) : 0.103
Stream size : 4.35 GiB (99%)
Title : Core Media Video
Encoded date : UTC 2021-04-23 21:33:04
Tagged date : UTC 2021-04-23 21:57:19
Color range : Limited
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709
Codec configuration box : hvcC

Audio
ID : 2
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Codec ID : mp4a-40-2
Duration : 24 min 13 s
Source duration : 24 min 13 s
Bit rate mode : Variable
Bit rate : 192 kb/s
Channel(s) : 2 channels
Channel layout : L R
Sampling rate : 44.1 kHz
Frame rate : 43.066 FPS (1024 SPF)
Compression mode : Lossy
Stream size : 33.5 MiB (1%)
Source stream size : 33.5 MiB (1%)
Title : Core Media Audio
Encoded date : UTC 2021-04-23 21:33:04
Tagged date : UTC 2021-04-23
----------------------------------------------------



This is the information for the clip that did not have issues:
LG 27UK670 Monitor Review/STAND.MOV
Format : MPEG-4
Format profile : QuickTime
Codec ID : qt 0000.00 (qt )
File size : 33.8 MiB
Duration : 10 s 332 ms
Overall bit rate mode : Variable
Overall bit rate : 27.4 Mb/s
Encoded date : UTC 2021-04-03 19:53:14
Tagged date : UTC 2021-04-03 19:53:25
Writing library : Apple QuickTime
com.apple.quicktime.location.accuracy.ho : 13.879337
com.apple.quicktime.location.ISO6709 : +35.3028-080.7978+243.291/
com.apple.quicktime.make : Apple
com.apple.quicktime.model : iPhone SE (2nd generation)
com.apple.quicktime.software : 14.4.2
com.apple.quicktime.creationdate : 2021-04-03T15:53:14-0400

Video
ID : 1
Format : HEVC
Format/Info : High Efficiency Video Coding
Format profile : Main@L5@Main
Codec ID : hvc1
Codec ID/Info : High Efficiency Video Coding
Duration : 10 s 332 ms
Bit rate : 27.2 Mb/s
Width : 3 840 pixels
Height : 2 160 pixels
Display aspect ratio : 16:9
Frame rate mode : Variable
Frame rate : 30.000 FPS
Minimum frame rate : 30.000 FPS
Maximum frame rate : 31.579 FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Bits/(Pixel*Frame) : 0.109
Stream size : 33.5 MiB (99%)
Title : Core Media Video
Encoded date : UTC 2021-04-03 19:53:14
Tagged date : UTC 2021-04-03 19:53:25
Color range : Limited
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709
Codec configuration box : hvcC

Audio
ID : 2
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Codec ID : mp4a-40-2
Duration : 10 s 330 ms
Source duration : 10 s 403 ms
Bit rate mode : Variable
Bit rate : 164 kb/s
Channel(s) : 2 channels
Channel layout : L R
Sampling rate : 44.1 kHz
Frame rate : 43.066 FPS (1024 SPF)
Compression mode : Lossy
Stream size : 207 KiB (1%)
Source stream size : 208 KiB (1%)
Title : Core Media Audio
Encoded date : UTC 2021-04-03 19:53:14
Tagged date : UTC 2021-04-03 19:53:25
----------------------------------------------------



Both seem to be using VFR, which is a bit confusing. I have heard that variable frame rate does not play nicely with Resolve, but I also think it's weird that I haven't yet experienced it with several projects on my Windows PC but am just now experiencing it with the M1.

Hi

Smartphones use variable frame rate for exposure... so if you want to record with your phone... it will be better with the Filmic Pro app !

Now you can try transcode your footage with DR Media Management to Prores 422 LT / Proxy.
Or use Handbrake to convert to Constant fps !

Unfortunately, neither is FiLMiC Pro recording constant frame rates.

It can, but it's hardware dependant and you need to enable the force flag. mcpro24fps is a more advanced app which gives control than filmic. Those tiny framerate varinates in modern phones are also not a problem in Resolve. I use them all the time.

I'd suggest to set the audio to 48 kHz in FiLMiC Pro.

Thank you both for your responses. I'm still confused as to why this issue has only come up with macOS and has not been something I've experienced previously with Windows? I have edited several videos on my Windows machine in Resolve using iPhone footage from the default camera up and never encountered this same playback issue.