fileless input/output about ffmpeg-kit

[tanersener]

just wrap native memfd_create, it's a linux feature probably to make it before api 30 just create a jni library

This is the definition of memfd_create function in NDK's sys/mman.h header. It is in line with Android documentation. It is not available below API Level 30.

#if __ANDROID_API__ >= 30
int memfd_create(const char* __name, unsigned __flags) __INTRODUCED_IN(30);
#endif /* __ANDROID_API__ >= 30 */

another solution would be to create a pipe

FFmpegKit already supports pipes. Please have a look at Pipe Support wiki page.

[tanersener]

This was discussed on mobile-ffmpeg as well but I we couldn't find an elegant solution to implement this.

On Android, SharedMemory is one of the potential features we can use. Unfortunately, it is introduced in API Level 27. It can not be applied as a general solution.

[andrew-ld]

being that it supports storage access framework couldn't you implement a custom fileprovider?

ie open:
https://android.googlesource.com/platform/frameworks/support/+/a9ac247af2afd4115c3eb6d16c05bc92737d6305/compat/src/main/java/androidx/core/content/FileProvider.java#561

could reimplement the various methods to make it read/write in ram

[tanersener]

What do you mean by writing to RAM? I don't understand how can that FileProvider class help to implement this feature.

[andrew-ld]

The reference implementation of a fileprovider is the one of androidx, if you see when a file is requested it returns a ParcelFileDescriptor, usually it points to the filedescriptor of a file on the disk, but by extending the class you can return a filedescriptor to a anonymous file mapped to memory using memfd_create

[tanersener]

Using memfd_create is possible but it is introduced in API Level 30 according to Android documentation. We need a more general solution that we can use in earlier API levels as well.

[andrew-ld]

just wrap native memfd_create, it's a linux feature probably to make it before api 30 just create a jni library

[andrew-ld]

https://developer.android.com/reference/android/os/ParcelFileDescriptor#createPipe()

another solution would be to create a pipe

[d4rken]

Pipes do not work for output though, right?
-i pipe1 file.mp4 works, but -i pipe1 pipe2 gives an "read only filesystem" error.

[github-actions]

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