FFmpeg RTMP Live Streaming ? YouTube and Twitch

What You’ll Learn

• The basic RTMP push syntax in FFmpeg
• Streaming to YouTube Live and Twitch
• Encoding settings (bitrate, resolution, audio)
• Looping a video file for broadcast-style streaming
• Low-latency streaming configuration
• Common errors and fixes

Tested with: FFmpeg 7.0
Platform: Windows / macOS / Linux

What is RTMP?

RTMP (Real-Time Messaging Protocol) is a video streaming protocol originally developed by Adobe. YouTube Live, Twitch, Facebook Live, and virtually every major streaming platform accept RTMP input. FFmpeg acts as an RTMP client, encoding and pushing audio/video to the RTMP server.

Basic Syntax

ffmpeg [input] [encode options] -f flv rtmp://server-url/stream-key

Use -f flv as the output format — RTMP uses FLV as its container.

Streaming to YouTube Live

Find Your Stream Key

YouTube Studio → Go Live → Stream → Copy the stream key (e.g. xxxx-xxxx-xxxx-xxxx-xxxx)

Webcam + Microphone (Linux/macOS)

ffmpeg \
  -f v4l2 -i /dev/video0 \
  -f pulse -i default \
  -c:v libx264 -preset veryfast -b:v 3000k -maxrate 3500k -bufsize 6000k \
  -pix_fmt yuv420p -g 60 -keyint_min 60 \
  -c:a aac -b:a 128k -ar 44100 \
  -f flv rtmp://a.rtmp.youtube.com/live2/YOUR_STREAM_KEY

Webcam + Microphone (Windows, DirectShow)

ffmpeg \
  -f dshow -i video="Webcam Name":audio="Microphone Name" \
  -c:v libx264 -preset veryfast -b:v 3000k -maxrate 3500k -bufsize 6000k \
  -pix_fmt yuv420p -g 60 -keyint_min 60 \
  -c:a aac -b:a 128k -ar 44100 \
  -f flv rtmp://a.rtmp.youtube.com/live2/YOUR_STREAM_KEY

Key Parameters

YouTube Recommended Bitrates

Streaming to Twitch

Find Your Stream Key

Twitch Dashboard → Settings → Stream → Primary Stream key

ffmpeg \
  -f v4l2 -i /dev/video0 \
  -f pulse -i default \
  -c:v libx264 -preset veryfast -b:v 4500k -maxrate 5000k -bufsize 9000k \
  -pix_fmt yuv420p -g 60 -keyint_min 60 \
  -c:a aac -b:a 160k -ar 44100 \
  -f flv rtmp://live.twitch.tv/app/YOUR_STREAM_KEY

Twitch enforces a 6,000 kbps video bitrate cap. Do not exceed it.

Loop a Video File (Broadcast-Style)

Replay a pre-recorded file on loop:

ffmpeg \
  -re -stream_loop -1 -i input.mp4 \
  -c:v libx264 -preset veryfast -b:v 3000k -maxrate 3500k -bufsize 6000k \
  -pix_fmt yuv420p -g 60 \
  -c:a aac -b:a 128k \
  -f flv rtmp://a.rtmp.youtube.com/live2/YOUR_STREAM_KEY

Simultaneous Multi-Platform Streaming

Use the tee muxer to push to multiple destinations with a single encode pass:

ffmpeg \
  -f v4l2 -i /dev/video0 \
  -f pulse -i default \
  -c:v libx264 -preset veryfast -b:v 3000k -maxrate 3500k -bufsize 6000k \
  -pix_fmt yuv420p -g 60 \
  -c:a aac -b:a 128k \
  -f tee -map 0:v -map 1:a \
  "[f=flv]rtmp://a.rtmp.youtube.com/live2/YT_KEY|[f=flv]rtmp://live.twitch.tv/app/TWITCH_KEY"

Desktop Capture Streaming

Linux (X11)

ffmpeg \
  -f x11grab -s 1920x1080 -r 30 -i :0.0+0,0 \
  -f pulse -i default \
  -c:v libx264 -preset veryfast -b:v 4000k -maxrate 4500k -bufsize 8000k \
  -pix_fmt yuv420p -g 60 \
  -c:a aac -b:a 128k \
  -f flv rtmp://a.rtmp.youtube.com/live2/YOUR_STREAM_KEY

macOS (AVFoundation)

ffmpeg \
  -f avfoundation -capture_cursor 1 -i "1:0" \
  -c:v libx264 -preset veryfast -b:v 4000k -maxrate 4500k -bufsize 8000k \
  -pix_fmt yuv420p -g 60 \
  -c:a aac -b:a 128k \
  -f flv rtmp://a.rtmp.youtube.com/live2/YOUR_STREAM_KEY

Low-Latency Settings

ffmpeg \
  -f v4l2 -i /dev/video0 \
  -f pulse -i default \
  -c:v libx264 -preset ultrafast -tune zerolatency \
  -b:v 2000k -maxrate 2000k -bufsize 2000k \
  -pix_fmt yuv420p -g 30 -keyint_min 30 \
  -c:a aac -b:a 128k \
  -f flv rtmp://a.rtmp.youtube.com/live2/YOUR_STREAM_KEY

-tune zerolatency combined with -preset ultrafast minimizes encoding delay at the cost of some compression efficiency.

GPU Encoding (Reduce CPU Load)

NVIDIA (NVENC)

ffmpeg \
  -f v4l2 -i /dev/video0 \
  -f pulse -i default \
  -c:v h264_nvenc -preset p4 -b:v 4000k -maxrate 4500k -bufsize 8000k \
  -pix_fmt yuv420p -g 60 \
  -c:a aac -b:a 128k \
  -f flv rtmp://a.rtmp.youtube.com/live2/YOUR_STREAM_KEY

Apple VideoToolbox (macOS)

ffmpeg \
  -f avfoundation -i "1:0" \
  -c:v h264_videotoolbox -b:v 4000k \
  -pix_fmt yuv420p -g 60 \
  -c:a aac -b:a 128k \
  -f flv rtmp://a.rtmp.youtube.com/live2/YOUR_STREAM_KEY

Troubleshooting

Connection refused / Server error

• Your stream key is wrong — re-copy it from the dashboard
• YouTube Live requires you to schedule or enable a stream before pushing

Video drops / choppy stream

Reduce bitrate or switch to a faster preset:

-preset ultrafast -b:v 2000k

Audio/video out of sync

-async 1

avformat_write_header: Connection timed out

Verify the RTMP URL. YouTube’s RTMP endpoint is rtmp://a.rtmp.youtube.com/live2/.

Frequently Asked Questions

What bitrate should I push to YouTube Live?

4500–6000 kbps for 1080p 30 fps; 9000 kbps for 1080p 60 fps. Audio at 128–192 kbps. YouTube’s Live Encoder Settings page lists current targets.

Why does my stream buffer at the viewer end?

Either upload bandwidth is insufficient (check with iperf3) or the keyframe interval is too long. Set keyframes every 2 s with -g 60 -keyint_min 60 at 30 fps.

RTMP vs RTMPS vs SRT — which should I use?

RTMPS (TLS-wrapped RTMP) is the modern default for YouTube and Twitch. SRT is better for unreliable networks but requires the receiver to support it.

How do I monitor stream health?

Watch the bitrate= and dup= fields in FFmpeg’s status line. Sustained dup > 0 means the encoder is dropping frames to keep up.

Can I stream the same input to two services?

Yes — use tee muxer: -map 0 -f tee "[f=flv]rtmp://a|[f=flv]rtmp://b". Both endpoints receive identical bytes.

Related Articles

• HLS Segmenting
• YouTube Encoding Settings
• Two-Pass Encoding

Tested with ffmpeg 7.0 / Ubuntu 24.04
Primary source: ffmpeg.org/ffmpeg-protocols.html#rtmp