Question / Help Trimming an OBS generated mp4 output

[Toffees]

Hi all,

I've been trying to trim the .mp4 files that OBS creates. According to many sites this should be a simple task that simply requires ffmpeg and the following command :-

ffmpeg --ss 00:30:00 -i input.mp4 -c copy -t 60 trimmed.mp4

yet when I try to view the output file in Quicktime or import it into Premier CS for editing, all I see is a green screen with audio. I've also tried trimming OBS files using Avidemux which is a professional editing package and its results are the same, yet when I try other MP4/AVC files I have no problems.

Is there something strange with the way OBS encodes its mp4's? Does anyone else have trouble trimming their OBS output? I could be a problem with the codecs installed on my PC but before I wipe my computer I thought I'd better ask here for the professionals advice :-)

Cheers

 

[Toffees]

I've just tried to view an OBS mp4 file using Quicktime and it gives me a black screen with audio, so its looking like it must be my codecs that are fubar. Can anyone else confirm that they have no problems watching an OBS generated mp4 with quicktime? The strange thing is that the same un-trimmed file will import into Premier CS with no problems. its only once its trimmed that I get the green screen

 

[Y-L]

Just use vlc, it has a record option so you just record the section you want, doesn't effect quality.

 

[Toffees]

not an option. I need to know why two very well and highly respected programs are failing to be able to trim an OBS generated MP4 file. I'd rather understand the issue rather than stick a plaster on it and hope it goes away.

 

[achmetha]

Can you post a log file? I just used AviDemux to test with a stream I did yesterday and had no issues trimming the file.

Do you have any Custom X264 Encoder Settings (Advanced Tab in OBS)?

I'm assuming this can happen with an invalid bitstream or incorrect codec.
But what it could be too is that you need to download the x264vfw codec (x86 & x64 versions) from here: http://sourceforge.net/projects/x264vfw/files/

Install both the 32-bit and 64-bit codecs and see if it helps. Otherwise, post your log file and see if there are any Custom X264 settings in OBS that might have been activated.

As for Premiere Pro, I always run my footage through Handbrake first to ensure that it is CFR (to avoid audio desync) and because PP doesn't have a built-in x264 codec. Anyhow, the point is that Premiere Pro doesn't have a built in codec to read X264, so if you run it through Handbrake and encode it as H264 - you'll have no issues.

 

[Toffees]

Hi,

Just thought I'd post back as I've managed to fix my problem. It looks like I had either a corrupted codec or something not playing nice. I un-installed all my codecs and just re-installed the K-Lite Standard pack and everything is now working perfectly.

Thanks for all the replies. Sometimes the simplest solution is just to remove and re-install :-)