mfreadwrite: Set url hint from stream content.

dlls/mfreadwrite/main.c

@@ -576,6 +576,71 @@ failed:
     return hr;
 }
 
+static HRESULT bytestream_get_url_hint(IMFByteStream *stream, WCHAR const **url)
+{
+    static const UINT8 asfmagic[] = {0x30,0x26,0xb2,0x75,0x8e,0x66,0xcf,0x11,0xa6,0xd9,0x00,0xaa,0x00,0x62,0xce,0x6c};
+    static const WCHAR asfW[] = {'.','a','s','f',0};
+    static const struct stream_content_url_hint
+    {
+        const UINT8 *magic;
+        UINT32 magic_len;
+        const WCHAR *url;
+    }
+    url_hints[] =
+    {
+        { asfmagic, sizeof(asfmagic), asfW },
+    };
+    IMFAttributes *attributes;
+    UINT32 length = 0;
+    UINT8 buffer[16];
+    DWORD caps = 0;
+    QWORD position;
+    unsigned int i;
+    HRESULT hr;
+
+    *url = NULL;
+
+    if (SUCCEEDED(IMFByteStream_QueryInterface(stream, &IID_IMFAttributes, (void **)&attributes)))
+    {
+        IMFAttributes_GetStringLength(attributes, &MF_BYTESTREAM_CONTENT_TYPE, &length);
+        IMFAttributes_Release(attributes);
+    }
+
+    if (length)
+        return S_OK;
+
+    if (FAILED(hr = IMFByteStream_GetCapabilities(stream, &caps)))
+        return hr;
+
+    if (!(caps & MFBYTESTREAM_IS_SEEKABLE))
+        return S_OK;
+
+    if (FAILED(hr = IMFByteStream_GetCurrentPosition(stream, &position)))
+        return hr;
+
+    hr = IMFByteStream_Read(stream, buffer, sizeof(buffer), &length);
+    IMFByteStream_SetCurrentPosition(stream, position);
+    if (FAILED(hr))
+        return hr;
+
+    if (length < sizeof(buffer))
+        return S_OK;
+
+    for (i = 0; i < ARRAY_SIZE(url_hints); ++i)
+    {
+        if (!memcmp(buffer, url_hints[i].magic, min(url_hints[i].magic_len, length)))
+        {
+            *url = url_hints[i].url;
+            break;
+        }
+    }
+
+    if (!*url)
+        WARN("Unrecognized content type %s.\n", debugstr_an((char *)buffer, length));
+
+    return S_OK;
+}
+
 static HRESULT create_source_reader_from_stream(IMFByteStream *stream, IMFAttributes *attributes,
         REFIID riid, void **out)
 {
@@ -583,8 +648,13 @@ static HRESULT create_source_reader_from_stream(IMFByteStream *stream, IMFAttrib
     IMFSourceResolver *resolver;
     MF_OBJECT_TYPE obj_type;
     IMFMediaSource *source;
+    const WCHAR *url;
     HRESULT hr;
 
+    /* If stream does not have content type set, try to guess from starting byte sequence. */
+    if (FAILED(hr = bytestream_get_url_hint(stream, &url)))
+        return hr;
+
     if (FAILED(hr = MFCreateSourceResolver(&resolver)))
         return hr;
 
@@ -592,7 +662,7 @@ static HRESULT create_source_reader_from_stream(IMFByteStream *stream, IMFAttrib
         IMFAttributes_GetUnknown(attributes, &MF_SOURCE_READER_MEDIASOURCE_CONFIG, &IID_IPropertyStore,
                 (void **)&props);
 
-    hr = IMFSourceResolver_CreateObjectFromByteStream(resolver, stream, NULL, MF_RESOLUTION_MEDIASOURCE, props,
+    hr = IMFSourceResolver_CreateObjectFromByteStream(resolver, stream, url, MF_RESOLUTION_MEDIASOURCE, props,
             &obj_type, (IUnknown **)&source);
     IMFSourceResolver_Release(resolver);
     if (props)