ImageResizer FFmpeg plugin failing to produce an image for a frame - asp.net-mvc-4

Question

Using a fairly simple installation of ImageResizer, integrated with our application. We're evaluating it, and so have not applied a license yet. Images are resizing as expected (with the red dot for no license), but we're trying to pull frames from videos using the FFmpeg plugin and having problems.
With a request like myvideo.mp4?ffmpeg.seconds=1 or myvideo.mp4?ffmpeg.percent=50, the browser shows The image ... cannot be displayed because it contains errors, and application log shows:
ImageResizer.ImageCorruptedException (0x80004005): File may be corrupted, empty, or may contain a PNG image with a single dimension greater than 65,535 pixels. ---> System.ArgumentException: Parameter is not valid.
at System.Drawing.Bitmap..ctor(Stream stream, Boolean useIcm)
at ImageResizer.ImageBuilder.DecodeStream(Stream s, ResizeSettings settings, String optionalPath)
at ImageResizer.ImageBuilder.LoadImage(Object source, ResizeSettings settings, Boolean restoreStreamPos)
at ImageResizer.ImageBuilder.LoadImage(Object source, ResizeSettings settings, Boolean restoreStreamPos)
at ImageResizer.ImageBuilder.BuildJob(ImageJob job)
at ImageResizer.ImageBuilder.BuildInternal(ImageJob job)
at ImageResizer.ImageBuilder.BuildInQueue(ImageJob job, Boolean useSemaphore, Int32 maxQueuingMilliseconds, CancellationToken cancel)
at ImageResizer.ImageBuilder.Build(ImageJob job)
at ImageResizer.InterceptModule.<>c__DisplayClass5_0.<handlerequest>b__1(Stream stream)
at ImageResizer.Plugins.DiskCache.CustomDiskCache.<>c__DisplayClass29_0.<trywritefile>b__0()
at ImageResizer.Plugins.DiskCache.LockProvider.TryExecute(String key, Int32 timeoutMs, LockCallback success)
at ImageResizer.Plugins.DiskCache.CustomDiskCache.GetCachedFile(String keyBasis, String extension, ResizeImageDelegate writeCallback, Int32 timeoutMs, Boolean asynchronous)
at ImageResizer.Plugins.DiskCache.DiskCache.Process(IResponseArgs e)
at ImageResizer.Plugins.DiskCache.DiskCache.Process(HttpContext context, IResponseArgs e)
at ImageResizer.InterceptModule.HandleRequest(HttpContext context, HttpModuleRequestAssistant ra, IVirtualFile vf)
at ImageResizer.InterceptModule.CheckRequest_PostAuthorizeRequest(Object sender, EventArgs e)
at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step)
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
1: Source:
ImageResizer
1: Stack Trace:
at ImageResizer.ImageBuilder.LoadImage(Object source, ResizeSettings settings, Boolean restoreStreamPos)
1: at ImageResizer.ImageBuilder.BuildJob(ImageJob job)
1: at ImageResizer.ImageBuilder.BuildInternal(ImageJob job)
1: at ImageResizer.ImageBuilder.BuildInQueue(ImageJob job, Boolean useSemaphore, Int32 maxQueuingMilliseconds, CancellationToken cancel)
1: at ImageResizer.ImageBuilder.Build(ImageJob job)
1: at ImageResizer.InterceptModule.<>c__DisplayClass5_0.<handlerequest>b__1(Stream stream)
1: at ImageResizer.Plugins.DiskCache.CustomDiskCache.<>c__DisplayClass29_0.<trywritefile>b__0()
1: at ImageResizer.Plugins.DiskCache.LockProvider.TryExecute(String key, Int32 timeoutMs, LockCallback success)
1: at ImageResizer.Plugins.DiskCache.CustomDiskCache.GetCachedFile(String keyBasis, String extension, ResizeImageDelegate writeCallback, Int32 timeoutMs, Boolean asynchronous)
1: at ImageResizer.Plugins.DiskCache.DiskCache.Process(IResponseArgs e)
1: at ImageResizer.Plugins.DiskCache.DiskCache.Process(HttpContext context, IResponseArgs e)
1: at ImageResizer.InterceptModule.HandleRequest(HttpContext context, HttpModuleRequestAssistant ra, IVirtualFile vf)
1: at ImageResizer.InterceptModule.CheckRequest_PostAuthorizeRequest(Object sender, EventArgs e)
1: at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
1: at System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step)
1: at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
UPDATE
In order to make sure that there is no issue with the underlying ffmpeg and actually pulling an image from the video in question, i used the command line to pull a frame from it manually. Full output is below, and it produced the 'test.png' image as expected.
ffmpeg.exe -i P:\path\to\media\myvideo.mp4 -vframes 1 test.png
ffmpeg version N-69258-gf994000 Copyright (c) 2000-2015 the FFmpeg developers
built on Jan 25 2015 22:21:16 with gcc 4.9.2 (GCC)
configuration: --disable-static --enable-shared --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --e
v --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm
e-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable
bvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libw
ble-lzma --enable-decklink --enable-zlib
libavutil 54. 17.100 / 54. 17.100
libavcodec 56. 20.100 / 56. 20.100
libavformat 56. 19.100 / 56. 19.100
libavdevice 56. 4.100 / 56. 4.100
libavfilter 5. 9.100 / 5. 9.100
libswscale 3. 1.101 / 3. 1.101
libswresample 1. 1.100 / 1. 1.100
libpostproc 53. 3.100 / 53. 3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'P:\path\to\media\myvideo.mp4':
Metadata:
major_brand : mp42
minor_version : 1
compatible_brands: mp41mp42isom
creation_time : 2018-02-07 00:14:12
location : +nn.nnnn-nnn.nnnn/
Duration: 00:00:13.64, start: 0.000000, bitrate: 840 kb/s
Stream #0:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 98 kb/s (default)
Metadata:
creation_time : 2018-02-07 00:14:12
handler_name : Core Media Audio
Stream #0:1(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709), 568x320, 735 kb/s, 29.98 fps, 29.97 tbr,
Metadata:
rotate : 90
creation_time : 2018-02-07 00:14:12
handler_name : Core Media Video
Side data:
displaymatrix: rotation of -90.00 degrees
Output #0, image2, to 'test.png':
Metadata:
major_brand : mp42
minor_version : 1
compatible_brands: mp41mp42isom
location : +nn.nnnn-nnn.nnnn/
encoder : Lavf56.19.100
Stream #0:0(und): Video: png, rgb24, 568x320, q=2-31, 200 kb/s, 29.97 fps, 29.97 tbn, 29.97 tbc (default)
Metadata:
rotate : 90
creation_time : 2018-02-07 00:14:12
handler_name : Core Media Video
encoder : Lavc56.20.100 png
Stream mapping:
Stream #0:1 -> #0:0 (h264 (native) -> png (native))
Press [q] to stop, [?] for help
frame= 1 fps=0.0 q=0.0 Lsize=N/A time=00:00:00.03 bitrate=N/A
video:249kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
So why can ffmpeg.exe pull the frame manually, but when i try to do it through the browser and ImageResizer, i get the error above?

Answer 1

Hoo boy, don't i feel sheepish.. it's a good thing i like humility. :-|
Turns out the comment down at the bottom of the Ffmpeg documentation page is really important: "Make sure you use <pipeline vppusage="Always"/>, or ffmpeg will not be able to participate in the request.".
Seems like that should probably be up in the Installation section.