diff --git a/src/converters/ffmpeg.ts b/src/converters/ffmpeg.ts
index 8d5709a6..926b62d3 100644
--- a/src/converters/ffmpeg.ts
+++ b/src/converters/ffmpeg.ts
@@ -770,9 +770,9 @@ export async function convert(
   }
 
   // Parse FFMPEG_ARGS environment variable into array
-  const ffmpegArgs = process.env.FFMPEG_ARGS ? process.env.FFMPEG_ARGS.split(/\s+/) : [];
+  const ffmpegArgs = process.env.FFMPEG_ARGS ? process.env.FFMPEG_ARGS.split(/\s+/).filter(Boolean) : [];
   const ffmpegOutputArgs = process.env.FFMPEG_OUTPUT_ARGS
-    ? process.env.FFMPEG_OUTPUT_ARGS.split(/\s+/)
+    ? process.env.FFMPEG_OUTPUT_ARGS.split(/\s+/).filter(Boolean)
     : [];
 
   return new Promise((resolve, reject) => {
diff --git a/src/converters/vcf.ts b/src/converters/vcf.ts
index 2fff8ed8..d84094c0 100644
--- a/src/converters/vcf.ts
+++ b/src/converters/vcf.ts
@@ -46,12 +46,14 @@ export function parseVCF(data: string): Record<string, string>[] {
 
 export function toCSV(data: Record<string, string>[]): string {
   if (!data.length) return "";
-  const first = data[0];
-  if (!first) return "";
-  const headers = Object.keys(first);
+  const headers = new Set<string>();
+  for (const row of data) {
+    Object.keys(row).forEach((key) => headers.add(key));
+  }
+  const headerArray = Array.from(headers);
   const escape = (str: string) => `"${str.replace(/"/g, '""')}"`;
-  const rows = data.map((row) => headers.map((h) => escape(row[h] || "")).join(","));
-  return [headers.join(","), ...rows].join("\n");
+  const rows = data.map((row) => headerArray.map((h) => escape(row[h] || "")).join(","));
+  return [headerArray.join(","), ...rows].join("\n");
 }
 
 export async function convert(