How do I read the output.mp4 file generated by ffmpeg in my n8n Docker container?

I'm using a Docker Compose setup with PostgreSQL and n8n, and my workflow downloads videos, images, audio, and subtitles from Google Drive. Then I use ffmpeg (installed via a custom Dockerfile) to process and combine these files into a single output.mp4 stored in the mounted volume (/home/node/.n8n).

I’ve configured my environment with the following files:

YAMLCopied
services:
  postgres:
    image: postgres:latest
    container_name: postgres-demo-zenpr-net
    restart: unless-stopped
    environment:
      * POSTGRES_USER=${POSTGRES_USER}
      * POSTGRES_PASSWORD=${POSTGRES_PASSWORD}
      * POSTGRES_DB=${POSTGRES_DB}
    volumes:
      * ./postgres_data:/var/lib/postgresql/data
    ports:
      * "5456:5432"
  n8n:
    build:
      context: .
      dockerfile: Dockerfile
    container_name: demo-zenpr-net
    restart: unless-stopped
    ports:
      * "3456:5678"
    depends_on:
      * postgres
    environment:
      * N8N_HOST=${SUBDOMAIN}.${DOMAIN_NAME}
      * WEBHOOK_URL=https://${SUBDOMAIN}.${DOMAIN_NAME}/
      * DB_TYPE=postgresdb
      * DB_POSTGRESDB_HOST=postgres
      * DB_POSTGRESDB_PORT=5432
      * DB_POSTGRESDB_DATABASE=${POSTGRES_DB}
      * DB_POSTGRESDB_USER=${POSTGRES_USER}
      * DB_POSTGRESDB_PASSWORD=${POSTGRES_PASSWORD}
      * N8N_DEFAULT_BINARY_DATA_MODE=${N8N_DEFAULT_BINARY_DATA_MODE}
      * N8N_ENFORCE_SETTINGS_FILE_PERMISSIONS=${N8N_ENFORCE_SETTINGS_FILE_PERMISSIONS}
      * GENERIC_TIMEZONE=${GENERIC_TIMEZONE}
      * EXECUTIONS_DATA_PRUNE=${EXECUTIONS_DATA_PRUNE}
      * EXECUTIONS_DATA_MAX_AGE=${EXECUTIONS_DATA_MAX_AGE}
      * EXECUTIONS_DATA_PRUNE_MAX_COUNT=${EXECUTIONS_DATA_PRUNE_MAX_COUNT}
      * N8N_BASIC_AUTH_ACTIVE=true
      * N8N_BASIC_AUTH_USER=${N8N_BASIC_AUTH_USER}
      * N8N_BASIC_AUTH_PASSWORD=${N8N_BASIC_AUTH_PASSWORD}
    volumes:
      * ./n8n_data:/home/node/.n8n

The .env file contains:

DOTENVCopied
#===== Domain name information =====#
DOMAIN_NAME=zenpr.net
SUBDOMAIN=demo

And my Dockerfile is simple:

DOCKERFILECopied
FROM n8nio/n8n:latest

USER root

RUN apk update && apk add ffmpeg

USER node

In my n8n workflow, I download files from Google Drive, process them (including converting images to short video clips), merge them using a generated ffmpeg command, and then try to read the resulting file (output.mp4) using nodes like Read/Write Files from Disk and custom Node Code. For example, I attempted to convert a base64 string from the stdout of an Execute Command node with:

JAVASCRIPTCopied
// Get base64 string from node stdout Execute Command
const base64Data = items[0].json.stdout;

return [
  {
    json: { message: "File converted to binary successfully" },
    binary: {
      data: {
        data: base64Data,
        mimeType: "video/mp4",
        fileName: "output.mp4",
      }
    }
  }
];

However, I still cannot read or access the output.mp4 file from within n8n. I suspect this might be a path or permissions issue in the Docker container since my volume is mounted to /home/node/.n8n and that’s where ffmpeg writes the file.

I’ve reviewed the workflow and various configurations but haven’t resolved the problem. How can I properly read the output.mp4 file using n8n’s nodes, ensuring I’m targeting the correct container path and handling file permissions correctly?

Any guidance or troubleshooting tips would be greatly appreciated.