LibMedia: Reduce the amount of WAV data loaded before playback starts

Apparently FFmpeg probes WAV files for 32 packets before returning the
stream info. With the default of 19200 bytes per packet, this could end
up waiting for up to 5 seconds of data to be downloaded.

Setting the max_size option only affects WAV and W64 in our build of
libavformat. No other formats we care about will be affected.

Author: Zaggy1024

Libraries/LibMedia/FFmpeg/FFmpegDemuxer.cpp

@@ -45,7 +45,15 @@ static DecoderErrorOr<void> initialize_format_context(AVFormatContext*& format_c
         return DecoderError::with_description(DecoderErrorCategory::Memory, "Failed to allocate format context"sv);
     format_context->pb = &io_context;
     format_context->flags |= AVFMT_FLAG_FAST_SEEK;
-    if (avformat_open_input(&format_context, nullptr, nullptr, nullptr) < 0)
+
+    AVDictionary* options = nullptr;
+    ScopeGuard free_options = [&] { av_dict_free(&options); };
+
+    // Reduce the maximum packet size for the WAV demuxer, so that playback begins sooner.
+    av_dict_set(&options, "max_size", "4096", 0);
+
+    auto open_result = avformat_open_input(&format_context, nullptr, nullptr, &options);
+    if (open_result < 0)
         return DecoderError::with_description(DecoderErrorCategory::Corrupted, "Failed to open input for format parsing"sv);
 
     // Read stream info; doing this is required for headerless formats like MPEG