FFmpeg Commands#

Common FFmpeg commands for publishing, subscribing, recording, and converting with go-rtmp.

Publishing#

From a File#

Re-stream a video file at its original frame rate:

ffmpeg -re -i video.mp4 -c copy -f flv rtmp://localhost:1935/live/test

• -re reads the file at its native frame rate (real-time). Without this flag, FFmpeg sends frames as fast as possible.
• -c copy copies the codec without re-encoding (fast, no quality loss).

Test Pattern (No File Needed)#

Generate a synthetic video + audio stream for testing:

ffmpeg -re \
  -f lavfi -i testsrc=size=640x480:rate=30 \
  -f lavfi -i sine=frequency=440:sample_rate=48000 \
  -c:v libx264 -preset ultrafast -tune zerolatency \
  -c:a aac -b:a 128k \
  -f flv rtmp://localhost:1935/live/test

This creates a color bar pattern with a 440Hz tone — useful for verifying the server works without any source media.

H.265 via Enhanced RTMP#

Publish H.265/HEVC video using Enhanced RTMP (requires FFmpeg 6.1+ with libx265):

ffmpeg -re -f lavfi -i testsrc=size=1280x720:rate=30 \
       -f lavfi -i sine=frequency=440:sample_rate=44100 \
       -c:v libx265 -preset ultrafast -c:a aac \
       -f flv rtmp://localhost:1935/live/test

From Webcam#

Windows:

ffmpeg -f dshow -i video="Integrated Camera":audio="Microphone" \
  -c:v libx264 -preset veryfast -c:a aac \
  -f flv rtmp://localhost:1935/live/webcam

macOS:

ffmpeg -f avfoundation -i "0:0" \
  -c:v libx264 -preset veryfast -c:a aac \
  -f flv rtmp://localhost:1935/live/webcam

Linux:

ffmpeg -f v4l2 -i /dev/video0 -f pulse -i default \
  -c:v libx264 -preset veryfast -c:a aac \
  -f flv rtmp://localhost:1935/live/webcam

Tip: List available devices with ffmpeg -list_devices true -f dshow -i dummy (Windows) or ffmpeg -f avfoundation -list_devices true -i "" (macOS).

Subscribing#

Basic Playback#

ffplay rtmp://localhost:1935/live/test

Low-Latency Playback#

Minimize buffering for the lowest possible latency:

ffplay -fflags nobuffer -flags low_delay -framedrop rtmp://localhost:1935/live/test

• -fflags nobuffer disables input buffering
• -flags low_delay enables low-delay decoding
• -framedrop drops frames if the decoder falls behind

Recording#

Record from Server to File#

ffmpeg -i rtmp://localhost:1935/live/test -c copy output.flv

This records the stream without re-encoding. Press q to stop recording.

Convert FLV to MP4#

Convert a recorded FLV file to MP4 (widely compatible):

ffmpeg -i recording.flv -c copy output.mp4

The -c copy flag remuxes without re-encoding — instant and lossless.

With Authentication#

When the server requires a token, wrap the URL in quotes to prevent shell interpretation of the ? character:

# Publish with token
ffmpeg -re -i video.mp4 -c copy -f flv "rtmp://localhost:1935/live/test?token=secret123"

# Subscribe with token
ffplay "rtmp://localhost:1935/live/test?token=secret123"

Important: The quotes are required. Without them, the shell may interpret ? as a glob pattern.

With RTMPS (TLS)#

FFmpeg does not natively support rtmps:// as an output format. To publish to an RTMPS-enabled go-rtmp server, use the plain RTMP listener or the Go client:

Publishing#

# Option 1: Use the plain RTMP listener (if dual-listener is enabled)
ffmpeg -re -i video.mp4 -c copy -f flv rtmp://localhost:1935/live/test

# Option 2: Use the Go client for true RTMPS publishing
go run ./cmd/rtmp-client -url rtmps://localhost:1936/live/test -publish video.flv

Subscribing#

# Subscribe via plain RTMP
ffplay rtmp://localhost:1935/live/test

Testing TLS Connections#

The E2E test suite validates RTMPS using the Go client:

./scripts/test-e2e.sh --test "RTMPS Publish + Capture"

Note: Even though FFmpeg connects via plain RTMP, the TLS listener can be verified independently via the Go client. All streams are shared between both listeners — a publisher on one listener is visible to subscribers on the other.

Useful Flags#