diff --git a/lib/pipelines.js b/lib/pipelines.js
index 8a5526c..aad950c 100644
--- a/lib/pipelines.js
+++ b/lib/pipelines.js
@@ -75,7 +75,15 @@ export const produce = async (body) => {
 
     const upload = createSpeakablesUploader(pathPrefix, storage)
 
-    const speakablesHash = getSpeakablesHash(speakables)
+    // test reducing speakables to 25 always
+    let reducedSpeakables
+    if (speakables.length >= 25) {
+      reducedSpeakables = speakables.slice(0,25)
+    } else {
+      reducedSpeakables = speakables
+    }
+
+    const speakablesHash = getSpeakablesHash(reducedSpeakables)
     debug('speakablesHash', speakablesHash)
 
     const concat = createTransloaditConcat({
@@ -85,7 +93,7 @@ export const produce = async (body) => {
       webhookUrl,
     })
 
-    await synthesize(speakables)
+    await synthesize(reducedSpeakables)
       .then(upload)
       .then(concat)
       .catch((e) => {
diff --git a/lib/transloadit.js b/lib/transloadit.js
index f7f1771..f626b80 100644
--- a/lib/transloadit.js
+++ b/lib/transloadit.js
@@ -52,6 +52,7 @@ export const createTransloaditConcat = (fields) => {
             bitrate: 48000,
             sample_rate: 24000,
             use,
+            ffmpeg_stack: "v5.0.0",
           },
         },
         ...(PUBLIC_URL && { notify_url: `${PUBLIC_URL}/webhook/transloadit` }),