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/*******************************************************************************
* Copyright (c) 2013, Art Clarke. All rights reserved.
*
* This file is part of Humble-Video.
*
* Humble-Video is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Humble-Video is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with Humble-Video. If not, see
* You must implement this interface if you want to register a
* new type of URLProtocolHandler with the {@link URLProtocolManager}.
*
*
* If you throw an exception in your implementation of this handler during
* a callback from within Humble Video, we will assume your method returned -1 while
* still in native code. Once the stack unwinds back into Java we will
* re-raise your exception.
*
* @see FileProtocolHandler
* @see NullProtocolHandler
*
* @author aclarke
*
*/
public interface IURLProtocolHandler
{
// These are the flags that can be passed to open
// IMPORTANT: These values must match the corresponding
// flags in the avio.h header file in libavformat
/**
* A flag for {@link #seek(long, int)}. Denotes positions relative to start of file.
*/
public static final int SEEK_SET = 0;
/**
* A flag for {@link #seek(long, int)}. Denotes positions relative to where the current file pointer is.
*/
public static final int SEEK_CUR = 1;
/**
* A flag for {@link #seek(long, int)}. Denotes positions relative to the end of file.
*/
public static final int SEEK_END = 2;
/**
* A flag for {@link #seek(long, int)}.
* A special hack of FFMPEG, denotes you want to find the total size of the file.
*/
public static final int SEEK_SIZE = 0x10000;
/**
* Open the file in Read Only mode.
*/
public static final int URL_RDONLY_MODE = 0;
/**
* Open the file in Write Only mode.
*/
public static final int URL_WRONLY_MODE = 1;
/**
* Implement the file in Read/Write mode.
*/
public static final int URL_RDWR = 2;
/**
* This method gets called by FFMPEG when it opens a file.
*
* @param url The URL to open
* @param flags The flags (e.g. {@link #URL_RDONLY_MODE})
* @return >= 0 for success; -1 for error.
*
*/
public int open(String url, int flags);
/**
* This method gets called by FFMPEG when it tries to read data.
*
* For non-blocking IO, return:
* {@link io.humble.video.Error#typeToErrorNumber(io.humble.video.Error.Type)}
* pass in {@link io.humble.video.Error.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 {@link Thread#isInterrupted()} setting.
*
*
* @param buf The buffer to write your data to.
* @param size The number of bytes in buf data available for you to write the data that FFMPEG will read.
* @return 0 for end of file, else number of bytes you wrote to the buffer, or -1 if error.
*/
public int read(byte[] buf, int size);
/**
* This method gets called by FFMPEG when it tries to write data.
*
* For non-blocking IO, return:
* {@link io.humble.video.Error#typeToErrorNumber(io.humble.video.Error.Type)}
* pass in {@link io.humble.video.Error.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 {@link Thread#isInterrupted()} setting.
*
*
* @param buf The data you should write.
* @param size The number of bytes in buf.
* @return 0 for end of file, else number of bytes you read from buf, or -1 if error.
*/
public int write(byte[] buf, int size);
/**
* A request from FFMPEG to seek to a position in the stream.
*
* @param offset The offset in bytes.
* @param whence Where that offset is relative to. Follow the C stdlib fseek() conventions EXCEPT
* {@link #SEEK_SIZE} should return back the size of the stream in bytes if known without adjusting
* the seek pointer.
* @return -1 if not supported, else the position relative to whence
*/
public long seek(long offset, int whence);
/**
* A request to close() from FFMPEG
*
* @return -1 on error; else >= 0
*/
public int close();
/**
* Special callback made by Humble Video in order to determine if your
* stream supports streaming.
*
*
*
* If this method returns true, Humble Video 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.
*
*
*
* @param url The URL that would be passed to {@link #open(String, int)}
* @param flags The flags that would be passed to {@link #open(String, int)}
* @return true if you can stream that URL; false if not.
*/
public boolean isStreamed(String url, int flags);
}