Change the read method of ffmpeg from filename to buffer to avoid

passing a filename with incorrect encoding to avformat_open_input.
Increased the size of photo thumbnails a little.

src/avdecoder.cpp

@@ -28,28 +28,70 @@
 AVDecoder::AvInit init;
 
 AVDecoder::AVDecoder() :
-    pFormatCtx(NULL)
+    pFormatCtx(NULL), file(NULL)
 {
 }
 
 AVDecoder::~AVDecoder()
 {
     if(pFormatCtx) {
+        av_free(pFormatCtx->pb->buffer);
+        av_free(pFormatCtx->pb);
         avformat_close_input(&pFormatCtx);
     }
+    if(file) {
+        file->close();
+        delete file;
+    }
+}
+
+int AVDecoder::readFunction(void* opaque, uint8_t* buf, int buf_size)
+{
+    QIODevice* stream = (QIODevice*)opaque;
+    int numBytes = stream->read((char*)buf, buf_size);
+    return numBytes;
+}
+
+int64_t AVDecoder::seekFunction(void* opaque, int64_t offset, int whence)
+{
+    if (whence == AVSEEK_SIZE) {
+        return -1;    // I don't know "size of my handle in bytes"
+    }
+    QIODevice* stream = (QIODevice*)opaque;
+    if (stream->isSequential()) {
+        return -1;    // cannot seek a sequential stream
+    }
+    if (! stream->seek(offset) ) {
+        return -1;
+    }
+    return stream->pos();
 }
 
 bool AVDecoder::open(const QString filename)
 {
-    if(avformat_open_input(&pFormatCtx, QFile::encodeName(filename).constData(), NULL, NULL) != 0) {
+    file = new QFile(filename);
+    if(!file->open(QIODevice::ReadOnly)) {
+        return false;
+    }
+    const int ioBufferSize = 32768;
+    unsigned char *ioBuffer = (unsigned char *)av_malloc(ioBufferSize + FF_INPUT_BUFFER_PADDING_SIZE);
+    AVIOContext *avioContext = avio_alloc_context(ioBuffer, ioBufferSize, 0, (void*)(file), &AVDecoder::readFunction, NULL, &AVDecoder::seekFunction);
+    pFormatCtx = avformat_alloc_context();
+    pFormatCtx->pb = avioContext;
+
+
+    if(avformat_open_input(&pFormatCtx, "dummy", NULL, NULL) != 0) {
+        av_free(avioContext->buffer);
+        av_free(avioContext);
         return false;
     }
 
     if(avformat_find_stream_info(pFormatCtx, NULL) < 0) {
+        av_free(avioContext->buffer);
+        av_free(avioContext);
         avformat_close_input(&pFormatCtx);
         return false;
     }
-
     return true;
 }
 
@@ -273,6 +315,10 @@ QByteArray AVDecoder::getVideoThumbnail(int width, int height)
 
 void AVDecoder::close()
 {
+    av_free(pFormatCtx->pb->buffer);
+    av_free(pFormatCtx->pb);
     avformat_close_input(&pFormatCtx);
     pFormatCtx = NULL;
+    file->close();
+    file = NULL;
 }