Package com.avpkit.core.io

Class NullProtocolHandler

  • All Implemented Interfaces:
    IURLProtocolHandler
    public class NullProtocolHandler
extends java.lang.Object
implements IURLProtocolHandler
    The NullProtocolHandler implements IURLProtocolHandler, but discards any data written and always returns 0 for reading.

    This can be useful if your operating system doesn't have the unix equivalent of /dev/null or you want to cheaply discard data.

    Author:
    aclarke

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      int close()
      A request to close() from FFMPEG
      boolean isStreamed​(java.lang.String aUrl, int aFlags)
      Special callback made by AVPKit in order to determine if your stream supports streaming.
      int open​(java.lang.String aUrl, int aFlags)
      This method gets called by FFMPEG when it opens a file.
      int read​(byte[] aBuf, int aSize)
      This method gets called by FFMPEG when it tries to read data.
      long seek​(long aOffset, int aWhence)
      A request from FFMPEG to seek to a position in the stream.
      int write​(byte[] aBuf, int aSize)
      This method gets called by FFMPEG when it tries to write data.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Method Detail

      • isStreamed

        public boolean isStreamed​(java.lang.String aUrl,
                          int aFlags)
        Description copied from interface: IURLProtocolHandler
        Special callback made by AVPKit in order to determine if your stream supports streaming.

        If this method returns true, AVPKit will assume it cannot seek backwards in this container.

        This has one main practical consequence. When writing it means certain container formats (e.g. the MOV container) will not be usable as it requires seeking back to the start of a file to write MOV required header information once the entire file has been encoded.

        But if your medium is streaming, you'll want to return true for this, and then FFMPEG will not attempt to seek back in time.

        Specified by:
        isStreamed in interface IURLProtocolHandler
        Parameters:
        aUrl - The URL that would be passed to IURLProtocolHandler.open(String, int)
        aFlags - The flags that would be passed to IURLProtocolHandler.open(String, int)
        Returns:
        true if you can stream that URL; false if not.

      • read

        public int read​(byte[] aBuf,
                int aSize)
        Description copied from interface: IURLProtocolHandler
        This method gets called by FFMPEG when it tries to read data.

        For non-blocking IO, return: IError.typeToErrorNumber(com.avpkit.core.IError.Type) pass in IError.Type.ERROR_AGAIN for the error type. This returns the platform specific number for EAGAIN on your platform signaling that callers should try again later.

        Alternately implementors may block until data is returning, but they should then respect the Thread.isInterrupted() setting.

        Specified by:
        read in interface IURLProtocolHandler
        Parameters:
        aBuf - The buffer to write your data to.
        aSize - The number of bytes in buf data available for you to write the data that FFMPEG will read.
        Returns:
        0 for end of file, else number of bytes you wrote to the buffer, or -1 if error.

      • seek

        public long seek​(long aOffset,
                 int aWhence)
        Description copied from interface: IURLProtocolHandler
        A request from FFMPEG to seek to a position in the stream.
        Specified by:
        seek in interface IURLProtocolHandler
        Parameters:
        aOffset - The offset in bytes.
        aWhence - Where that offset is relative to. Follow the C stdlib fseek() conventions EXCEPT IURLProtocolHandler.SEEK_SIZE should return back the size of the stream in bytes if known without adjusting the seek pointer.
        Returns:
        -1 if not supported, else the position relative to whence

      • write

        public int write​(byte[] aBuf,
                 int aSize)
        Description copied from interface: IURLProtocolHandler
        This method gets called by FFMPEG when it tries to write data.

        For non-blocking IO, return: IError.typeToErrorNumber(com.avpkit.core.IError.Type) pass in IError.Type.ERROR_AGAIN for the error type. This returns the platform specific number for EAGAIN on your platform signaling that callers should try again later.

        Alternately implementators may block until data is returning, but they should then respect the Thread.isInterrupted() setting.

        Specified by:
        write in interface IURLProtocolHandler
        Parameters:
        aBuf - The data you should write.
        aSize - The number of bytes in buf.
        Returns:
        0 for end of file, else number of bytes you read from buf, or -1 if error.