MythMusic: allow seeking when playing back from a storage group

mythplugins/mythmusic/mythmusic/avfdecoder.cpp

@@ -40,6 +40,7 @@ using namespace std;
 #include "metaiooggvorbis.h"
 #include "metaiomp4.h"
 #include "metaiowavpack.h"
+#include "decoderhandler.h"
 
 extern "C" {
 #include "libavformat/avio.h"
@@ -68,11 +69,39 @@ static int WriteFunc(void *opaque, uint8_t *buf, int buf_size)
 
 static int64_t SeekFunc(void *opaque, int64_t offset, int whence)
 {
-    (void)opaque;
-    (void)offset;
-    (void)whence;
-    // we dont support seeking while streaming
-    return -1;
+    QIODevice *io = (QIODevice*)opaque;
+
+    if (whence == AVSEEK_SIZE)
+    {
+        return io->size();
+    }
+    else if (whence == SEEK_SET)
+    {
+        if (offset <= io->size())
+            return io->seek(offset);
+        else
+            return -1;
+    }
+    else if (whence == SEEK_END)
+    {
+        int64_t newPos = io->size() + offset;
+        if (newPos >= 0 && newPos <= io->size())
+            return io->seek(newPos);
+        else
+            return -1;
+    }
+    else if (whence == SEEK_CUR)
+    {
+        int64_t newPos = io->pos() + offset;
+        if (newPos >= 0 && newPos < io->size())
+            return io->seek(newPos);
+        else
+            return -1;
+    }
+    else
+        return -1;
+
+     return -1;
 }
 
 static void myth_av_log(void *ptr, int level, const char* fmt, va_list vl)
@@ -213,7 +242,7 @@ bool avfDecoder::initialize()
 
     output()->PauseUntilBuffered();
 
-    m_inputIsFile = !input()->isSequential();
+    m_inputIsFile = (dynamic_cast<QFile*>(input()) != NULL);
 
     if (m_inputContext)
         avformat_free_context(m_inputContext);
@@ -236,7 +265,8 @@ bool avfDecoder::initialize()
                                              &ReadFunc, &WriteFunc, &SeekFunc);
         filename = "stream";
 
-        m_byteIOContext->seekable = 0;
+        // we can only seek in files streamed using MusicSGIODevice
+        m_byteIOContext->seekable = (dynamic_cast<MusicSGIODevice*>(input()) != NULL) ? 1 : 0;
 
         // probe the stream
         AVProbeData probe_data;
@@ -390,7 +420,7 @@ bool avfDecoder::initialize()
 
 void avfDecoder::seek(double pos)
 {
-    if (m_inputIsFile)
+    if (m_inputIsFile || (m_byteIOContext && m_byteIOContext->seekable))
         seekTime = pos;
 }