diff --git a/src/utils.ts b/src/utils.ts
index a50389c..670a8a1 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -412,7 +412,9 @@ export async function downloadUrl(
       : undefined,
     timeout,
     onDownloadProgress: event => {
-      log.debug(`downloadUrl fileUrl=${url} progress=${event}`)
+      log.debug(
+        `downloadUrl fileUrl=${url} progress=${event.progress || event.bytes}`,
+      )
     },
     httpsAgent: new Agent({
       rejectUnauthorized: false,
diff --git a/src/vmaf.ts b/src/vmaf.ts
index 42c60f5..de43304 100644
--- a/src/vmaf.ts
+++ b/src/vmaf.ts
@@ -366,8 +366,15 @@ export async function runVmaf(
   const comparisonPath = degradedPath.replace(/\.[^.]+$/, '')
   const vmafLogPath = comparisonPath + '.vmaf.json'
   const cpus = os.cpus().length
-  const referencePathMp4 = `${referencePath.replace(/\.ivf$/, '.mp4')}`
-  const degradedPathMp4 = `${degradedPath.replace(/\.ivf$/, '.mp4')}`
+
+  const dir = path.dirname(referencePath)
+  const sender = path.basename(referencePath).replace('.ivf', '')
+  const receiver = path
+    .basename(degradedPath)
+    .replace('.ivf', '')
+    .split('_recv-by_')[1]
+  const referencePathMp4 = `${dir}/${sender}_sent-to_${receiver}.mp4`
+  const degradedPathMp4 = `${dir}/${sender}_recv-by_${receiver}.mp4`
 
   const {
     width,
@@ -386,32 +393,25 @@ export async function runVmaf(
   })
 
   const textHeight = Math.ceil(height / 18) + 6
-  const referencePathMp4Exists = fs.existsSync(referencePathMp4)
   const filter = `\
 [0:v]scale=w=${width}:h=${height}:flags=bicubic:eval=frame,crop=${width}:${
     height - textHeight * 2
   }:0:${textHeight},fps=fps=${frameRate},split=3[deg1][deg2][deg3];\
 [1:v]scale=w=${width}:h=${height}:flags=bicubic:eval=frame,crop=${width}:${
     height - textHeight * 2
-  }:0:${textHeight},fps=fps=${frameRate},split=3[ref1][ref2]${
-    referencePathMp4Exists ? '' : '[ref3]'
-  };\
+  }:0:${textHeight},fps=fps=${frameRate},split=3[ref1][ref2][ref3];\
 [deg1][ref1]libvmaf=model='path=/usr/share/model/vmaf_v0.6.1.json':log_fmt=json:log_path=${vmafLogPath}:n_subsample=1:n_threads=${cpus}[vmaf]`
 
   const cmd = preview
     ? `ffmpeg -loglevel warning -y -threads ${cpus} \
--ss ${-ptsDiff / frameRate} -i ${degradedPath} \
--i ${referencePath} \
+-i ${degradedPath} \
+-ss ${ptsDiff / frameRate} -i ${referencePath} \
 -filter_complex "${filter};[ref2][deg2]hstack[stacked]" \
 -map [vmaf] -f null - \
 -map [stacked] -c:v libx264 -crf 15 -f mp4 -movflags +faststart ${
         comparisonPath + '_comparison.mp4'
       } \
-${
-  referencePathMp4Exists
-    ? ''
-    : `-map [ref3] -c:v libx264 -crf 15 -f mp4 -movflags +faststart ${referencePathMp4}`
-} \
+-map [ref3] -c:v libx264 -crf 15 -f mp4 -movflags +faststart ${referencePathMp4} \
 -map [deg3] -c:v libx264 -crf 15 -f mp4 -movflags +faststart ${degradedPathMp4} \
 `
     : `ffmpeg -loglevel warning -y -threads ${cpus} \
@@ -428,11 +428,6 @@ ${
     stdout,
     stderr,
   })
-  const sender = path.basename(referencePath).replace('.ivf', '')
-  const receiver = path
-    .basename(degradedPath)
-    .replace('.ivf', '')
-    .split('_recv-by_')[1]
   const metrics = {
     sender,
     receiver,