diff --git a/src/audio/samplebuffer.c b/src/audio/samplebuffer.c
index fa87d909e..0dac49bfb 100644
--- a/src/audio/samplebuffer.c
+++ b/src/audio/samplebuffer.c
@@ -95,7 +95,9 @@ void* samplebuffer_get(samplebuffer_t *buf, int wpos, int *wlen) {
 		if ((buf->wpos << bps) & 1) {
 			buf->wpos--; len++;
 		}
-		buf->wv_read(buf->wv_ctx, buf, buf->wpos, ROUNDUP8_BPS(len, bps), seeking);
+		if (buf->wv_read) {
+			buf->wv_read(buf->wv_ctx, buf, buf->wpos, ROUNDUP8_BPS(len, bps), seeking);
+		}
 		buf->wnext = buf->wpos + buf->widx;
 	} else {
 		// Record first sample that we still need to keep in the sample
@@ -116,12 +118,14 @@ void* samplebuffer_get(samplebuffer_t *buf, int wpos, int *wlen) {
 		if (reuse < *wlen) {
 			tracef("samplebuffer_get: read missing: reuse=%x wpos=%x wlen=%x\n", reuse, wpos, *wlen);
 			assertf(wpos+reuse == buf->wnext, "wpos:%x reuse:%x buf->wnext:%x", wpos, reuse, buf->wnext);
-			buf->wv_read(buf->wv_ctx, buf, wpos+reuse, ROUNDUP8_BPS(*wlen-reuse, bps), false);
+			if (buf->wv_read) {
+				buf->wv_read(buf->wv_ctx, buf, wpos+reuse, ROUNDUP8_BPS(*wlen-reuse, bps), false);
+			}
 			buf->wnext = buf->wpos + buf->widx;
 		}
 	}
 
-	assertf(wpos >= buf->wpos && wpos < buf->wpos+buf->widx, 
+	assertf((wpos >= buf->wpos && wpos < buf->wpos+buf->widx) || (buf->wv_read == NULL), 
 		"samplebuffer_get: logic error\n"
 		"wpos:%x buf->wpos:%x buf->widx:%x", wpos, buf->wpos, buf->widx);
 
diff --git a/src/pifile.c b/src/pifile.c
index 4b680a978..7cb5e074c 100644
--- a/src/pifile.c
+++ b/src/pifile.c
@@ -24,11 +24,6 @@ typedef struct {
 
 static void *__pifile_open(char *name, int flags)
 {
-    if (flags != O_RDONLY) {
-        errno = EACCES;
-        return NULL;
-    }
-
     // Parse the name in the foramt "ADDR:SIZE" as hexdecimal numbers
     char *end;
     uint32_t base = strtoul(name, &end, 16);
@@ -42,6 +37,13 @@ static void *__pifile_open(char *name, int flags)
         return NULL;
     }
 
+    if ((base < 0x08000000) || (base >= 0x09000000)) {
+        if (flags != O_RDONLY) {
+            errno = EACCES;
+            return NULL;
+        }
+    }
+
     pifile_t *file = malloc(sizeof(pifile_t));
     if (!file) {
         errno = ENOMEM;
@@ -123,6 +125,41 @@ static int __pifile_read(void *file, uint8_t *buf, int len)
     return len;
 }
 
+
+static int __pifile_write(void *file, uint8_t *buf, int len)
+{
+    pifile_t *f = file;
+    if (f->ptr + len > f->size)
+        len = f->size - f->ptr;
+    if (len <= 0)
+        return 0;
+
+    // Check if we can DMA directly to the output buffer
+    if ((((f->base + f->ptr) ^ (uint32_t)buf) & 1) == 0) {
+        data_cache_hit_writeback_invalidate(buf, len);
+        dma_write_raw_async(buf, f->base + f->ptr, len);
+        dma_wait();
+        f->ptr += len;
+    } else {
+        // Go through a temporary buffer
+        uint8_t *tmp = alloca(512+1);
+        if ((f->base + f->ptr) & 1) tmp++;
+
+        while (len > 0) {
+            int n = len > 512 ? 512 : len;
+            data_cache_hit_writeback_invalidate(tmp, n);
+            dma_write_raw_async(tmp, f->base + f->ptr, n);
+            dma_wait();
+            memcpy(buf, tmp, n);
+            buf += n;
+            f->ptr += n;
+            len -= n;
+        }
+    }
+
+    return len;
+}
+
 static int __pifile_close(void *file)
 {
     free(file);
@@ -135,6 +172,7 @@ static filesystem_t pifile_fs = {
 	.lseek = __pifile_lseek,
 	.read = __pifile_read,
 	.close = __pifile_close,
+	.write = __pifile_write,
 };
 
 void pifile_init(void)