Usually, we employ the `pipe:` protocol to deal with the numerical file descriptors, and this answers all our needs. On Android, there is a different use case in which numerical file descriptors appear, and this is not covered well with `pipe:` protocol.
This happens when a file is opened in scoped storage (https://developer.android.com/training/data-storage#scoped-storage). Currently, there is an exception that still allows `stdio.h` - based access to the media files (https://developer.android.com/preview/privacy/storage#media-files-raw-paths), but the document says that it may be slow (we still cannot have true evidence since Android 11 is not released yet), and anyways the clean way to access media files on what is known as 'external storage' is through a document picker Intent (https://developer.android.com/reference/android/content/Intent#ACTION_OPEN_DOCUMENT and https://developer.android.com/reference/android/content/Intent#ACTION_CREATE_DOCUMENT). The Intent produces a `content://` URI from which a DocumentProvider can produce an integer file descriptor. This descriptor can be passed to ffmpeg via pipe: protocol, and almost works, except for a few glitches. 1. This fd must be closed after use. Pipe is not closeable. 2. This fd is seekable, and therefore can be used to work with `.mp4` or some other file formats that don't work through pipe protocol. 3. We can find the actual file name extension for this fd, to facilitate `av_guess_format()` both for input and for output. I have recently prepared two approaches to face this issue. One is an easy patch for the `file:` protocol that recognizes the `/proc/self/` prefix and uses the number as fd. This relies heavily on Java (or Kotlin) processing of the results of document picker. The other way adds a `content://` protocol and does all heavy lifting (calling system Java API through JNI) itself. I would like to submit my contribution to ffmpeg-devel, but I am in doubt which of the two approaches may better fit the ffmpeg development paradigm, if any. Best Regards, Alex Cohn _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
