MP4 Footage Does Not Update Correctly

[abpositive]

I have all kinds of problems with MP4 footage not updating properly, and I feel like it didn't used to be this bad in previous AE versions

My standard workflow is to export MP4 renders from another animation software and composite them in After Effects.

Whenever I re-render an existing shot and then switch back over to After Effects, the MP4 footage becomes all garbled / corrupt looking in the AE timeline.

"Reload Footage" does not help.

"Replace Footage" (with the same file) does not help.

Purging All Memory & Disk Cache (then reload or replace) does not help.

Most of the time, quitting out of After Effects entirely,  purging cache, re-opening the project and reloading the footage works.

But sometimes it doesn't.

Sometimes I have to change the file name of the MP4, then "Replace Footage" when After Effects reports it missing... and then change the name again every time I re-render it!

This is unacceptable.

I should be able to re-render footage in another app, tab back over to AE and see it refresh without doing anything.

[abpositive]

AE version: 23.4

macOS 13.4.1

[jenkmeister]

You might want to try updating to 23.6 to see if the situation improves. I'd also suggest seeing if turning off hardware accelerated decode (Preferences -> Import) improves the situation. It may be that your video drivers are causing hardware acceleration to fail which is resulting in the corrupt shots. 

If you have any mp4's you can share with us to see if we can repro the problem, that'd be useful too.

[abpositive]

Thanks for the suggestions.

The problem is not with the MP4 files, since they work just fine once I rename them.

It seems to obviously be some kind of persistent cache that is not user-purgable.

Turning off hardware accelerated import did not fix it (just made it slower).

I really hate updating AE mid-project, but I did update to 23.6 just now.

No improvement (with or without hardware acceleration). And it's crashing, running much slower than my previous version, stretching the preview image... a lot of general bugginess. 😞

[jenkmeister]

That's very strange and I'm not aware of those sorts of bugs existing right now from other users. Are you on Mac or Windows? 

[abpositive]

macOS 13.4.1

[nishu_kush]

Thank you for the message. Are you still having the issue? Let us know.

I am moving this thread from Bugs to Discussions for now.

Thanks,

Nishu

[j.ssuarez · Accepted solution]

found this thread almost 2 years later but I wanted to share my workflow with you in case it helps.

In order to avoid AE to corrupt mp4 files that are being re-rendered and overwritten what I've found helps is to simply move the playhead in AE to a different place in the timeline so that it is not showing said mp4 in your composition viewer.

I do this all the time between C4D and AE and it always works. Everytime I forget to move the playhead then the mp4 gets corrupted in AE.

It's a hassle and I agree with you, it's unacceptable but it is what it is

[gupon]

@nishu_kush @jenkmeister 

This issue still occurs on my end even with the latest version. Like the other user, each time I overwrite a file externally, I try Reload Footage, clearing the cache, and reloading the footage, but the behavior varies and I often end up having to restart After Effects. I can’t properly iterate rendering in an external app, updating the footage, and reviewing the comp.

As suggested, moving the playhead outside the footage’s range or hiding the layer, then clearing the cache immediately after overwriting the footage, will occasionally update successfully—but it’s very rare. Even when it looks like it worked, After Effects can freeze after a short playback.

This affects not only MP4s, but also H.264 and ProRes MOV footage. Subjectively, it’s been happening for around two years—ever since features like Smart Cache were introduced—and it’s been a nightmare.

For environment details: I have consistently been on macOS (currently Tahoe 26.2 / Apple M3 Max), and I don’t believe I’m using any special video drivers, but I will try disabling hardware accelerated decode.