Why is Adobe software reading a video clip with the incorrect duration?

[Sir236896642iz6]

Let me preface this by stating that this issue applies to Premiere Pro, After Effects and Media Encoder; I have not tested it with any other Adobe software.

A bit of background information: I have a piece of stock footage that runs at a constant 23.976fps as expected. I work in a cross–platform environment, and it's not uncommon for clips to be used in multiple NLEs. Typically, when dealing with a variable frame rate clip, including stock footage, Premiere Pro will have a slightly different (shorter) length than other editing software, which I've come to expect, but I have never had this problem with a constant frame rate clip before.

If I load this clip into any other NLE, it is exactly two frames longer than it is in Premiere Pro/After Effects/Media Encoder, despite the fact that there's no reason why it should be any different in Adobe's software than in other editing tools. Does anyone know what might be causing this? I've taken this piece of stock footage and run it through multiple programs, and only Adobe is missing two frames. If I create a timeline from the clip, I cannot drag it out by two frames, so it's not as if the frames are just "hidden," the clip is simply interpreted as being two frames shorter in Adobe's software than it is in anything else, despite being a constant framerate clip.

I'm running Adobe CC 2022 on an M1 iMac, but have also tried this in Adobe CC 2021 on an M1 iMac and a Windows desktop. The specs for the iMacs are 16GB RAM, 2TB SSD and macOS Big Sur; the Windows machine has an Intel i9-7980X, 128GB RAM, GeForce GTX 1080, and runs Windows 10. Platform doesn't make a difference to this issue. Any assistance would be appreciated.

[R Neil Haugen]

Wondering if this is a drop frame/non-drop frame issue? Not an expert on that sort of thing though ...

Neil

[Warren Heaton]

For it to be a drop frame / non-drop frame issue, it would have to be running at 29.97 instead of 23.976 and the clip would be between one minute and two minutes in duration to be off 2 frames.

[Jeff Bellune]

Please post a screenshot of the text output or tree view of MediaInfo for the problem clip.

[Sir236896642iz6]

 In Premiere Pro/After Effects/Media Encoder this file displays a timecode duration of 00:00:07:12. In all other software that duration is 00:00:07:14.

[Warren Heaton]

Is Avid Media Composer where you're seeing the duration difference?

I downloaded the Shutterstock preview file "1036344554-preview.mp4" and it shows as 00:07:12 in After Effects, Premiere Pro, Final Cut Pro, and Resolve, but as 00:07:13 in Media Composer.  What's also a little strange about Media Composer is it appears to play to the same last frame of the picture in the timeline, but across 180 frames instead of 179.

 

[Sir236896642iz6]

Warren, thank you for the insight; I greatly appreciate it! The programs that I've been running this particular clip through have been Final Cut Pro, Compressor, DaVinci Resolve, FFMPEG, and Adobe Premiere Pro/After Effects/Media Encoder. FCP and Resolve both display the 7:14 duration, which matches up to the duration in ms that FFMPEG displays. One thing I wound up doing at one point was exporting the clip as a sequence of still frames from Premiere Pro/Media Encoder, Compressor and FFMPEG to see what I would get in the way of an output. Both Compressor and FFMPEG gave me the exact same number of frames, while Premiere Pro/Media Encoder were two frames short. If I threw the image sequences back into FFMPEG, Compressor, or Premiere Pro and exported a ProRes file of some sort, the files generated from the image sequences created by Compressor and FFMPEG would match up to the correct duration in ms, and to the 7:14 timecode, even when the ProRes file was exported from Premiere Pro/Media Encoder. Likewise, if I took the image sequence from Premiere Pro/Media Encoder and reassembled it in Compressor or FFMPEG, it would match up to the 7:12 timecode from Premiere Pro/Media Encoder and the time in ms would be slightly shorter than expected.

[Jeff Bellune · Accepted solution]

If you look at the MediaInfo report, the overall file duration is 7s, 603ms. The audio is also 7s, 603ms.

But if you look at the video duration, it is 7s, 508ms.

2 frames at 23.976 fps is about 84ms. Add the 14ms that it shows as last frame duration in the audio section and you get 508+84+14 = 606ms, which is really close to the 603ms reported by MediaInfo.

The discrepancy in the audio and video duration in the file itself can account for the different durations reported by different apps.

[Warren Heaton]

It's MP4 shenanigans. 

[Sir236896642iz6]

Thanks Jeff, this is very insightful. This sort of leaves me with a follow up question though. In FFMPEG, which works in ms rather than SMPTE timecode, I've exported a sequence of still frames, transcoded it into a new video file, and have a video in ms that matches up to the original. I've also stream copied the audio (no rencoding, just copying the audio stream and its duration,) and have what should at least in theory be identical in ms to the original file. If these two files are the same length in ms, why do they not create the same mismatch in Premiere Pro/After Effects/Media Encoder that the original file does?

[Jeff Bellune]

Load both files into MediaInfo and use the Compare mode to see what the difference might be. Without more information I don't even have a good guess for you beyond "MP4 shenanigans".  🙂

[Sir236896642iz6]

Thanks Jeff, I figured out what was causing the issue. My FFMPEG framerate setting was in the wrong location for the command I was attempting to run. Once I fixed that things matched up correctly and I was able to duplicate the issue. I'm marking your initial answer as correct. It's the way Adobe is interpreting the 7s, 603ms audio stream and the 7s, 508ms video stream compared to the way other apps are interpreting them. Interestingly, if I reassemble the image sequence from FFMPEG in Compressor, I get the correct 7s, 508ms video total. If I stream copy that into a new file with the audio in FFMPEG I get a file that behaves as the original did. If I try to use Premiere Pro and Media Encoder in place of Compressor and tell it to treat the sequence and timeline as 23.976fps, the duration of the video comes up consistently shorter after I reassemble it, which tells me that it's definitely a difference in the way Adobe is interpreting the difference in ms as timecode.

[Warren Heaton]

Right-click on variable frame rate clips in the Finder and choose "Encode Selected Video Files" to transcode the clip to a constant frame rate.

You're conforming everything to ProRes to take advantage of Smart Rendering in Premiere Pro and the ProRes encode and decode engines of the M1 hardware, right?

[Sir236896642iz6]

This particular clip isn't variable framerate, hence why this issue is so baffling. We're not conforming everything to ProRes, at least not at this stage. Right now my concern is with the clip being two frames off in Adobe's software vs. all other tools, not with render speeds.

[Jeff Bellune]

Are you using hardware *decoding*? The way Pr decodes the H.264 stream may cause the frame count variance.

[Sir236896642iz6]

Thanks for the suggestion Jeff. I disabled hardware accelerated decoding and restarted Premiere Pro, but it didn't make a difference. (I've since reenabled Hardware Accelerated decoding.) Premiere is adamant that this file has two fewer frames than every other tool not made by Adobe insists it has.

[Jeff Bellune]

For insight, in another NLE and comparing it to Pr, is the in point frame and/or the out point frame identical in all programs?

If not, are the two missing frames at the end, the beginning or one from each in Pr?

[Sir236896642iz6]

The in and out points are identical. I'm literally running the entire clip by itself in a timeline matched to the clip as part of attempting to figure out why the clip is behaving the way it is.