I have a StorageFile that I want to use as input for a Media Composition (as a Media Clip). I'm hoping loading everything in memory, to speed things up. I don't know how to do this - is there any way to do it?

Hello, Welcome to our Microsoft Q&A platform! The MediaClip.CreateFromFileAsync method accepts a parameter type of IStorageFile , which means you need to pass in a variable of type StorageFile . Although we can use a MemoryStream to save a file stream in memory, MediaClip doesn't have a method of CreateFromStreamAsync , so in your case you can only load data from the file. --- If you are establishing a connection between MediaClip and Stream, you can use StorageFile.ReplaceWithStreamedFileAsync as a relay. You can first read the StorageFile as a Stream , then use this method to convert the Stream to a StorageFile when needed, and pass it to MediaClip . However, it should be noted that loading the file into memory has no effect on the speed of MediaComposition . Thanks.

Of couse, you can read StorageFile as a stream (stream is in memory)

is there a way to force loading a StorageFile in memory?

Accepted answer

Richard Zhang-MSFT 6,936 Reputation points

2020-02-25T02:12:09.333+00:00

Hello,

Welcome to our Microsoft Q&A platform!

The MediaClip.CreateFromFileAsync method accepts a parameter type of IStorageFile, which means you need to pass in a variable of type StorageFile.

Although we can use a MemoryStream to save a file stream in memory, MediaClip doesn't have a method of CreateFromStreamAsync, so in your case you can only load data from the file.

---

If you are establishing a connection between MediaClip and Stream, you can use StorageFile.ReplaceWithStreamedFileAsync as a relay.

You can first read the StorageFile as a Stream, then use this method to convert the Stream to a StorageFile when needed, and pass it to MediaClip.

However, it should be noted that loading the file into memory has no effect on the speed of MediaComposition.

Thanks.
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John Torjo 861 Reputation points

2020-02-25T08:26:08.193+00:00

So, I am well aware of the above. And basically what you're saying is: it's not possible. Yes?

Richard Zhang-MSFT 6,936 Reputation points

2020-02-26T02:55:16.173+00:00

Hi, I update my answer, please check. And I mentioned that you need to increase the loading speed, but reading the file into memory does not affect the speed of MediaComposition. What is the reason you want to do this?

John Torjo 861 Reputation points

2020-02-26T08:46:48.537+00:00

Hi Richard,

I wanted to speed the processing of the MediaComposition - but if it's not doing that, then I'll need to do something else.

Long story short, I've been suggested to use MediaOverlays and create an IVideoCompositor to speed things up - it will take some work on my part, but we'll see

Regarding StorageFile.ReplaceWithStreamedFileAsync - it may actually do what i was initially asking, even if the docs are really vague about it.

Best,
John

James Dailey - MSFT 336 Reputation points Microsoft Employee

2020-02-27T18:38:54.453+00:00

Hi John,

Why are you trying to speed up MediaComposition? Are you trying to do real time media composition? Do you understand where in the pipeline the bottleneck is that is causing the poor performance? Because of the way the file system is memory mapped by the MediaComposition engine I'm not convinced that reading everything into memory is really going to "speed" thing up.

You also mention using MediaOverlays and IVideoCompositor. That is really advanced stuff. What problem are you trying to solve by employing these technologies?

-James

John Torjo 861 Reputation points

2020-02-27T18:48:38.833+00:00

Hi James,

What I'm trying to do is more or less this: https://github.com/microsoft/microsoft-ui-xaml/issues/2015

I've been suggested to do this: https://github.com/microsoft/microsoft-ui-xaml/issues/2015#issuecomment-590611515

So long story short, I've been trying to preview a video I'm about to create, where I have lots of inner videos overlapping with one another (in other words, I'm writing a video editor). Any caching solution I've come up with simply requires a lot of memory + takes a lot of CPU/GPU.

Basically what I would prefer is to create a MediaComposition, set the videos I'm using, and let the MediaComposition take care of loading the video frames (therefore, I won't not need to do any caching at all). Does this make sense?

Best,
John
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