ffmpeg suddenly generating 0 byte mp4s

Development Cinematics & Media
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1

I’ve been generating movie sequences just fine up until several hours ago, then suddenly, the resultant mp4s are 0 bytes. I swear I didn’t change anything that would/could/should affect this.

  • Using movie render queue
  • Project settings for “Movie Pipline CLI Encoder” have the correct path to ffmpeg.exe, codecs (libx264, AAC) are set, output file extenstion (mp4) is set.
  • Running MovieRenderPipeline.DumpCLIEncoderCodecs from the command prompt returns the list of available codecs, confirming that UE can find the ffmpeg executable.
  • Rendering to PNG files, and they all look good.
  • After all of the PNG files have been generated, a 0 byte mp4 appears.
  • I’ve restarted UE and rebooted the computer.
  • I started a whole fresh project and re-set everything up to make absolutely sure there was nothing from the other project somehow interfering.
  • I’m not seeing any errors in either the Message Log or the Output Log. Only relevant messages are the following from the output log…
[959]LogMovieRenderPipeline: MoviePipelineLinearExecutorBase starting 1 jobs.
[959]LogMovieRenderPipeline: MoviePipelineLinearExecutorBase starting job [1/1]
[959]LogMovieRenderPipeline: [47959] Initializing overall Movie Pipeline
[959]LogMovieRenderPipeline: Applying Game Override quality settings and cvars.
[959]LogMovieRenderPipeline: Reusing existing ShotInfo for Inner: BP_BikeCamera Outer: no shot.
[959]LogMovieRenderPipeline: Registering range: [1985268000,1985888640) (InnerName: BP_BikeCamera OuterName: no shot)
[960]LogMovieRenderPipeline: Expanding Shot 1/1 (Shot: no shot Camera: BP_BikeCamera)
[960]LogMovieRenderPipeline: Finished setting up rendering for shot. Shot has 1 Passes. Total resolution: (1920x1080) Individual tile resolution: (1920x1080). Tile count: (1x1)
[960]LogMovieRenderPipeline: [47960] Initializing Camera Cut [1/1] in [no shot] BP_BikeCamera.
[960]LogMovieRenderPipeline: [47960] Initialization set state to WarmingUp due to having 1 warm up frames.
[960]LogMovieRenderPipeline: [47960] Finished initializing Camera Cut [1/1] in [no shot] BP_BikeCamera.
[583]LogMovieRenderPipeline: [48583] Finished processing Camera Cut [1/1].
[583]LogMovieRenderPipeline: [48583] Finished rendering last shot. Moving to Finalize to finish writing items to disk.
[608]LogMovieRenderPipelineIO: Generated Path 'E:/.../Saved/MovieRenders/4702D101498AEB039D7FEFA9DAFD8CBB_input.txt' for input data.
[608]LogMovieRenderPipelineIO: Final Command Line Arguments: -hide_banner -y -loglevel error   -f concat -safe 0 -i "E:/.../Saved/MovieRenders/4702D101498AEB039D7FEFA9DAFD8CBB_input.txt" -r 24.000000  -acodec AAC -vcodec libx264 -crf 28 "E:/.../Saved/MovieRenders/Scene_1_01.mp4"
[695]LogMovieRenderPipeline: PIE Ended while Movie Pipeline was still active. Stalling to do full shutdown.
[695]LogMovieRenderPipeline: Restoring Game Override quality settings and cvars.
[695]LogMovieRenderPipeline: Movie Pipeline completed. Duration: +00:00:14.250
[695]LogMovieRenderPipeline: MoviePipelinePIEExecutor: Stalling finished, pipeline has shut down.

I’ve tried using the above “Final Command Line Arguments” to run ffmpeg manually and see if I get any further information, but I can’t for the life of me figure out what to replace the -i "E:/.../Saved/MovieRenders/4702D101498AEB039D7FEFA9DAFD8CBB_input.txt" with since UE deleted that file when it “finished”. -i Scene_1_01.%07d.png seems like it should work according to what I’m reading online, but all I get is Scene_1_01.%07d.png: No such file or directory, when I files are named like Scene_1_01.1985887.png.

Anybody got any ideas? I’m totally at a loss of what to do next.

2

Well, I seem to have it working again, but something is still not right.

The “fix” for me, was to uncheck the “Skip Encode on Render Canceled” option within the Movie Render Queue Job Options.

However, the tool tip for this option says that it’s for “If a render is cancelled (via hitting escape mid render)…”, and I’m definitely not doing that. Not to mention that this just suddenly started happening about 24 hours ago, for no apparent reason.

So, I have a work around for now, but I wouldn’t say that this is really resolved. UE is rendering all of the frames to images, but then seems to think I’ve hit escape at the last nanosecond and aborting conversion to mp4.