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Testing & Validation

Methods to verify your input streams are working correctly.

Table of contents

  1. Overview
  2. Quick Verification
    1. Method 1: VLC Player (Easiest)
    2. Method 2: ffprobe (Detailed Info)
    3. Method 3: ffplay (Visual Test)
  3. Detailed Testing Procedures
    1. UDP Multicast Testing
      1. Step 1: Verify Network Connectivity
      2. Step 2: Monitor Network Traffic
      3. Step 3: Check Stream Properties
      4. Step 4: Test Playback
    2. RTMP Testing
      1. Step 1: Verify Server Reachability
      2. Step 2: Test Stream Availability
      3. Step 3: Test Playback
  4. Automated Testing
    1. Stream Health Check Script
  5. Validation Checklist
    1. Video Validation
    2. Audio Validation
    3. Network Validation
    4. Configuration Validation
  6. Performance Testing
    1. Measure Stream Bitrate
    2. Check Packet Loss
    3. Measure Latency
  7. Troubleshooting Test Failures
    1. VLC Cannot Play Stream
    2. ffprobe Shows No Streams
    3. Playback Stutters or Buffers
  8. Continuous Monitoring
    1. Set Up Monitoring
  9. Related Documentation

Overview

Testing input streams before connecting them to transcoders ensures smooth operation and helps identify issues early.

Always test input streams in a staging environment before production deployment.

Quick Verification

Method 1: VLC Player (Easiest)

VLC is the simplest way to verify your input stream is working:

Steps:

  1. Open VLC Media Player
  2. Select Media → Open Network Stream (or press Ctrl+N)
  3. Enter your Source URL
  4. Click Play

Expected Result:

  • Video plays smoothly without interruptions
  • Audio is synchronized with video
  • Quality is as expected from encoder

UDP Example:

udp://@239.1.1.1:5000

RTMP Example:

rtmp://encoder.example.com:1935/live/stream-key

Method 2: ffprobe (Detailed Info)

ffprobe provides detailed technical information about your stream:

Command:

ffprobe -v error -show_format -show_streams udp://@239.1.1.1:5000

Expected Output:

Input #0, mpegts, from 'udp://@239.1.1.1:5000':
  Duration: N/A, start: 12345.678, bitrate: 8192 kb/s
    Stream #0:0[0x100]: Video: h264, yuv420p, 1920x1080, 29.97 fps
    Stream #0:1[0x101]: Audio: aac, 48000 Hz, stereo, 128 kb/s

What to Check:

  • ✅ Video codec (should be h264 or hevc)
  • ✅ Resolution (e.g., 1920x1080)
  • ✅ Frame rate (e.g., 29.97 fps or 25 fps)
  • ✅ Audio codec (should be aac)
  • ✅ Audio sample rate (typically 48000 Hz)
  • ✅ Bitrate is reasonable

Method 3: ffplay (Visual Test)

ffplay provides playback with minimal latency for testing:

Command:

ffplay udp://@239.1.1.1:5000

Keyboard Controls:

  • Q - Quit
  • F - Toggle fullscreen
  • P or Space - Pause
  • M - Mute audio

Detailed Testing Procedures

UDP Multicast Testing

Step 1: Verify Network Connectivity

Check multicast routing:

ip route show | grep multicast

Expected output:

224.0.0.0/4 dev eth0 scope link

Step 2: Monitor Network Traffic

Capture multicast packets:

sudo tcpdump -i eth0 host 239.1.1.1 and port 5000 -c 100

What to look for:

  • Packets are arriving
  • No excessive packet loss
  • Consistent packet sizes

Step 3: Check Stream Properties

Get detailed stream information:

ffprobe -v error -show_streams udp://@239.1.1.1:5000

Step 4: Test Playback

Play stream:

ffplay -fflags nobuffer udp://@239.1.1.1:5000

RTMP Testing

Step 1: Verify Server Reachability

Test TCP connection:

telnet encoder.example.com 1935

Expected:

Trying encoder.example.com...
Connected to encoder.example.com.

Press Ctrl+] then type quit to exit.

Step 2: Test Stream Availability

Check if stream is live:

ffprobe rtmp://encoder.example.com:1935/live/stream-key

Step 3: Test Playback

Play RTMP stream:

ffplay rtmp://encoder.example.com:1935/live/stream-key

Automated Testing

Stream Health Check Script

Create a simple health check script:

#!/bin/bash
# stream-check.sh

STREAM_URL="$1"
TIMEOUT=10

echo "Testing stream: $STREAM_URL"

# Test with ffprobe
if timeout $TIMEOUT ffprobe -v error -show_streams "$STREAM_URL" > /dev/null 2>&1; then
    echo "✅ Stream is accessible"
    
    # Get stream details
    ffprobe -v error -show_entries stream=codec_type,width,height,codec_name "$STREAM_URL"
else
    echo "❌ Stream is not accessible"
    exit 1
fi

Usage:

chmod +x stream-check.sh
./stream-check.sh "udp://@239.1.1.1:5000"

Validation Checklist

Before marking an input stream as production-ready, verify:

Video Validation

  • Video codec is H.264 or HEVC
  • Resolution matches expected (e.g., 1920x1080)
  • Frame rate is consistent (29.97 fps or 25 fps)
  • Bitrate is appropriate for content (5-15 Mbps for HD)
  • No visible artifacts or corruption
  • Color space is correct
  • Aspect ratio is correct

Audio Validation

  • Audio codec is AAC or MPEG Audio
  • Sample rate is 48000 Hz (or 44100 Hz)
  • Audio channels are correct (stereo or multi-channel)
  • Audio bitrate is appropriate (128-256 kbps)
  • Audio is synchronized with video
  • No audio dropouts or glitches
  • Volume levels are appropriate

Network Validation

  • Stream is consistently accessible
  • No packet loss or minimal loss (< 0.1%)
  • Latency is acceptable
  • Bandwidth is sufficient
  • Firewall allows traffic
  • No network routing issues

Configuration Validation

  • Content ID is unique
  • Content ID is case-consistent
  • Source URL is correct
  • Server assignment is appropriate
  • Documentation is complete

Performance Testing

Measure Stream Bitrate

Using ffprobe:

ffprobe -v error -select_streams v:0 -show_entries \
  stream=bit_rate -of default=nokey=1:noprint_wrappers=1 \
  udp://@239.1.1.1:5000

Check Packet Loss

Monitor with tcpdump:

sudo tcpdump -i eth0 host 239.1.1.1 -c 1000 | \
  awk '{print $1}' | uniq -c

Measure Latency

Test end-to-end latency:

  1. Display timecode on encoder output
  2. Play stream with VLC or ffplay
  3. Compare displayed timecode with reference
  4. Calculate latency difference

Troubleshooting Test Failures

VLC Cannot Play Stream

Possible Causes:

  • Stream URL is incorrect
  • Network connectivity issue
  • Encoder not transmitting
  • Firewall blocking traffic

Solutions:

  1. Verify URL format is correct
  2. Test network connectivity with ping/telnet
  3. Check encoder status and output
  4. Review firewall rules

ffprobe Shows No Streams

Possible Causes:

  • Stream not available at that moment
  • Wrong URL or port
  • Codec not supported
  • Network routing issue

Solutions:

  1. Verify encoder is streaming
  2. Check URL and port are correct
  3. Test with different tool (VLC)
  4. Check network configuration

Playback Stutters or Buffers

Possible Causes:

  • Insufficient bandwidth
  • Packet loss on network
  • Encoder output unstable
  • Server resource constraints

Solutions:

  1. Check available bandwidth
  2. Monitor packet loss with tcpdump
  3. Verify encoder settings and stability
  4. Check server CPU and network utilization

Continuous Monitoring

Set Up Monitoring

For production streams, implement continuous monitoring:

Monitor script example:

#!/bin/bash
# monitor-stream.sh

STREAM_URL="$1"
INTERVAL=60  # Check every 60 seconds

while true; do
    if timeout 10 ffprobe -v error "$STREAM_URL" > /dev/null 2>&1; then
        echo "[$(date)] ✅ Stream OK"
    else
        echo "[$(date)] ❌ Stream FAILED"
        # Alert logic here (email, SMS, etc.)
    fi
    sleep $INTERVAL
done