io: no manually close input io

closed by avformat_close_input. results in crash in 3.1

src/QtAV/MediaIO.h

@@ -1,8 +1,8 @@
 /******************************************************************************
-    QtAV:  Media play library based on Qt and FFmpeg
-    Copyright (C) 2014-2015 Wang Bin <[email protected]>
+    QtAV:  Multimedia framework based on Qt and FFmpeg
+    Copyright (C) 2012-2016 Wang Bin <[email protected]>
 
-*   This file is part of QtAV
+*   This file is part of QtAV (from 2014)
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Lesser General Public
@@ -70,7 +70,12 @@ class Q_AV_EXPORT MediaIO : public QObject
 
     virtual ~MediaIO();
     virtual QString name() const = 0;
-    virtual void setUrl(const QString& url);
+    /*!
+     * \brief setUrl
+     * onUrlChange() will be called if url is different. onUrlChange() will close the old url and open the new url if it's not empty
+     * \param url
+     */
+    void setUrl(const QString& url = QString());
     QString url() const;
     /*!
      * \brief setAccessMode
@@ -104,7 +109,7 @@ class Q_AV_EXPORT MediaIO : public QObject
      * \param from SEEK_SET, SEEK_CUR and SEEK_END from stdio.h
      * \return true if success
      */
-    virtual bool seek(qint64 offset, int from) = 0;
+    virtual bool seek(qint64 offset, int from = SEEK_SET) = 0;
     /*!
      * \brief position
      * MUST implement this. Used in seek

src/io/MediaIO.cpp

@@ -1,9 +1,9 @@
 /******************************************************************************
-    QtAV:  Media play library based on Qt and FFmpeg
-    Copyright (C) 2014-2015 Wang Bin <[email protected]>
+    QtAV:  Multimedia framework based on Qt and FFmpeg
+    Copyright (C) 2012-2016 Wang Bin <[email protected]>
     Initial QAVIOContext.cpp code is from Stefan Ladage <[email protected]>
 
-*   This file is part of QtAV
+*   This file is part of QtAV (from 2014)
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Lesser General Public
@@ -193,10 +193,8 @@ void MediaIO::release()
     DPTR_D(MediaIO);
     if (!d.ctx)
         return;
-    d.ctx->opaque = 0; //in avio_close() opaque is URLContext* and will call ffurl_close()
-    //d.ctx->buffer = 0; //already released by ffio_rewind_with_probe_data; may be another context was freed
-    avio_close(d.ctx); //avio_closep defined since ffmpeg1.1
-    d.ctx = 0;
+    // avio_close is called by avformat_close_input. here we only allocate but no open
+    av_freep(&d.ctx->buffer);
+    av_freep(&d.ctx);
 }
-
 } //namespace QtAV