diff --git a/dlls/mfplat/main.c b/dlls/mfplat/main.c
index 30bb808f6a8..2ef40779213 100644
--- a/dlls/mfplat/main.c
+++ b/dlls/mfplat/main.c
@@ -872,24 +872,84 @@ static HRESULT WINAPI mfattributes_GetAllocatedString(IMFAttributes *iface, REFG
 
 static HRESULT WINAPI mfattributes_GetBlobSize(IMFAttributes *iface, REFGUID key, UINT32 *size)
 {
-    FIXME("%p, %s, %p.\n", iface, debugstr_attr(key), size);
+    struct attributes *attributes = impl_from_IMFAttributes(iface);
+    struct attribute *attribute;
+    HRESULT hr = S_OK;
 
-    return E_NOTIMPL;
+    TRACE("%p, %s, %p.\n", iface, debugstr_attr(key), size);
+
+    EnterCriticalSection(&attributes->cs);
+
+    attribute = attributes_find_item(attributes, key, NULL);
+    if (attribute)
+    {
+        if (attribute->value.vt == MF_ATTRIBUTE_BLOB)
+            *size = attribute->value.u.caub.cElems;
+        else
+            hr = MF_E_INVALIDTYPE;
+    }
+    else
+        hr = MF_E_ATTRIBUTENOTFOUND;
+
+    LeaveCriticalSection(&attributes->cs);
+
+    return hr;
 }
 
 static HRESULT WINAPI mfattributes_GetBlob(IMFAttributes *iface, REFGUID key, UINT8 *buf,
                 UINT32 bufsize, UINT32 *blobsize)
 {
-    FIXME("%p, %s, %p, %d, %p.\n", iface, debugstr_attr(key), buf, bufsize, blobsize);
+    struct attributes *attributes = impl_from_IMFAttributes(iface);
+    struct attribute *attribute;
+    HRESULT hr;
 
-    return E_NOTIMPL;
+    TRACE("%p, %s, %p, %d, %p.\n", iface, debugstr_attr(key), buf, bufsize, blobsize);
+
+    EnterCriticalSection(&attributes->cs);
+
+    attribute = attributes_find_item(attributes, key, NULL);
+    if (attribute)
+    {
+        if (attribute->value.vt == MF_ATTRIBUTE_BLOB)
+        {
+            UINT32 size = attribute->value.u.caub.cElems;
+
+            if (bufsize >= size)
+                hr = PropVariantToBuffer(&attribute->value, buf, size);
+            else
+                hr = E_NOT_SUFFICIENT_BUFFER;
+
+            if (blobsize)
+                *blobsize = size;
+        }
+        else
+            hr = MF_E_INVALIDTYPE;
+    }
+    else
+        hr = MF_E_ATTRIBUTENOTFOUND;
+
+    LeaveCriticalSection(&attributes->cs);
+
+    return hr;
 }
 
 static HRESULT WINAPI mfattributes_GetAllocatedBlob(IMFAttributes *iface, REFGUID key, UINT8 **buf, UINT32 *size)
 {
-    FIXME("%p, %s, %p, %p.\n", iface, debugstr_attr(key), buf, size);
+    struct attributes *attributes = impl_from_IMFAttributes(iface);
+    PROPVARIANT attrval;
+    HRESULT hr;
 
-    return E_NOTIMPL;
+    TRACE("%p, %s, %p, %p.\n", iface, debugstr_attr(key), buf, size);
+
+    attrval.vt = VT_VECTOR | VT_UI1;
+    hr = attributes_get_item(attributes, key, &attrval);
+    if (SUCCEEDED(hr))
+    {
+        *buf = attrval.u.caub.pElems;
+        *size = attrval.u.caub.cElems;
+    }
+
+    return hr;
 }
 
 static HRESULT WINAPI mfattributes_GetUnknown(IMFAttributes *iface, REFGUID key, REFIID riid, void **ppv)
@@ -1070,9 +1130,15 @@ static HRESULT WINAPI mfattributes_SetString(IMFAttributes *iface, REFGUID key,
 
 static HRESULT WINAPI mfattributes_SetBlob(IMFAttributes *iface, REFGUID key, const UINT8 *buf, UINT32 size)
 {
-    FIXME("%p, %s, %p, %u.\n", iface, debugstr_attr(key), buf, size);
+    struct attributes *attributes = impl_from_IMFAttributes(iface);
+    PROPVARIANT attrval;
 
-    return E_NOTIMPL;
+    TRACE("%p, %s, %p, %u.\n", iface, debugstr_attr(key), buf, size);
+
+    attrval.vt = VT_VECTOR | VT_UI1;
+    attrval.u.caub.cElems = size;
+    attrval.u.caub.pElems = (UINT8 *)buf;
+    return attributes_set_item(attributes, key, &attrval);
 }
 
 static HRESULT WINAPI mfattributes_SetUnknown(IMFAttributes *iface, REFGUID key, IUnknown *unknown)
diff --git a/dlls/mfplat/tests/mfplat.c b/dlls/mfplat/tests/mfplat.c
index 73367b67ad8..edf3c6e694d 100644
--- a/dlls/mfplat/tests/mfplat.c
+++ b/dlls/mfplat/tests/mfplat.c
@@ -501,9 +501,11 @@ static void check_attr_count(IMFAttributes* obj, UINT32 expected, int line)
 static void test_MFCreateAttributes(void)
 {
     static const WCHAR stringW[] = {'W','i','n','e',0};
+    static const UINT8 blob[] = {0,1,2,3,4,5};
     IMFAttributes *attributes, *attributes1;
+    UINT8 blob_value[256], *blob_buf = NULL;
+    UINT32 value, string_length, size;
     PROPVARIANT propvar, ret_propvar;
-    UINT32 value, string_length;
     double double_value;
     IUnknown *unk_value;
     WCHAR bufferW[256];
@@ -724,6 +726,40 @@ static void test_MFCreateAttributes(void)
     ok(hr == S_OK, "Failed to copy items, hr %#x.\n", hr);
     CHECK_ATTR_COUNT(attributes, 0);
 
+    /* Blob */
+    hr = IMFAttributes_SetBlob(attributes, &DUMMY_GUID1, blob, sizeof(blob));
+    ok(hr == S_OK, "Failed to set blob attribute, hr %#x.\n", hr);
+    CHECK_ATTR_COUNT(attributes, 1);
+    hr = IMFAttributes_GetBlobSize(attributes, &DUMMY_GUID1, &size);
+    ok(hr == S_OK, "Failed to get blob size, hr %#x.\n", hr);
+    ok(size == sizeof(blob), "Unexpected blob size %u.\n", size);
+
+    hr = IMFAttributes_GetBlobSize(attributes, &DUMMY_GUID2, &size);
+    ok(hr == MF_E_ATTRIBUTENOTFOUND, "Unexpected hr %#x.\n", hr);
+
+    size = 0;
+    hr = IMFAttributes_GetBlob(attributes, &DUMMY_GUID1, blob_value, sizeof(blob_value), &size);
+    ok(hr == S_OK, "Failed to get blob, hr %#x.\n", hr);
+    ok(size == sizeof(blob), "Unexpected blob size %u.\n", size);
+    ok(!memcmp(blob_value, blob, size), "Unexpected blob.\n");
+
+    hr = IMFAttributes_GetBlob(attributes, &DUMMY_GUID2, blob_value, sizeof(blob_value), &size);
+    ok(hr == MF_E_ATTRIBUTENOTFOUND, "Unexpected hr %#x.\n", hr);
+
+    memset(blob_value, 0, sizeof(blob_value));
+    size = 0;
+    hr = IMFAttributes_GetAllocatedBlob(attributes, &DUMMY_GUID1, &blob_buf, &size);
+    ok(hr == S_OK, "Failed to get allocated blob, hr %#x.\n", hr);
+    ok(size == sizeof(blob), "Unexpected blob size %u.\n", size);
+    ok(!memcmp(blob_buf, blob, size), "Unexpected blob.\n");
+    CoTaskMemFree(blob_buf);
+
+    hr = IMFAttributes_GetAllocatedBlob(attributes, &DUMMY_GUID2, &blob_buf, &size);
+    ok(hr == MF_E_ATTRIBUTENOTFOUND, "Unexpected hr %#x.\n", hr);
+
+    hr = IMFAttributes_GetBlob(attributes, &DUMMY_GUID1, blob_value, sizeof(blob) - 1, NULL);
+    ok(hr == E_NOT_SUFFICIENT_BUFFER, "Unexpected hr %#x.\n", hr);
+
     IMFAttributes_Release(attributes);
     IMFAttributes_Release(attributes1);
 }