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Overview

FLV remains a critical protocol for live streaming and video-on-demand delivery, particularly in regions where low-latency, high-concurrency streaming is essential. Gcore CDN supports both FLV Live (real-time streaming) and FLV VOD (video-on-demand from static files) with distinct implementation paths and service models. This guide provides precise configuration, protocol behavior, authentication patterns, and operational guidance for production deployments.

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Service Models

FeatureFLV VODFLV Live
Use CasePre-recorded video filesReal-time live streaming
ActivationSelf-serviceRequires support approval + sales agreement
ConfigurationGeneric CDN setupSpecialized streaming configuration
Cache ModelStandard static file cachingSliding window buffer (RAM-based)
ProtocolsHTTP/1.1, HTTP/2, HTTP/3 (QUIC)HTTP/1.1, HTTP/2, HTTP/3 (QUIC)

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FLV Live

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Opportunity

HTTP-FLV Live enables ultra-low-latency streaming with high concurrency tolerance, making it ideal for:
  • Live broadcasting with 1-3 second latency
  • High-concurrency events (100K+ simultaneous viewers per stream)

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Service Activation

IMPORTANT: FLV Live is not available for self-service activation. It requires: Sales Agreement.Contact your account manager or sales@gcore.com. Please provide the following information:
  • Domain and company name
  • Content type (e.g., sports, news, entertainment)
  • Expected concurrent viewers per stream
  • Geographic distribution of viewers
  • Sample stream URL for testing
  • Broadcasting license or content compliance policy

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Productization: HTTP-FLV Live Profile

FLV Live is delivered as a dedicated service profile with specialized CDN behavior. FLV delivery is achieved through a protocol HTTP-FLV. HTTP-FLV protocol ensures continuous delivery of frames within a single infinitely long response from the server. Inside the stream, frames are scaled across the network instantly when they are received from the origin. HTTP-FLV is a pull-based streaming method in which the player requests an FLV file over HTTP. FLV via CDN

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Configuration for FLV Live

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Origin Requirements

Your origin must provide a valid FLV stream with the following characteristics: Stream Requirements:
  • Container: FLV (Flash Video).
  • FLV Headers: Origin must prepare and return all necessary FLV headers, metadata, and data with PTS-aligned frames.
  • Timestamps: Monotonic PTS/DTS.
  • Codecs: Our CDN is codec-agnostic, providing transparent delivery of your media frames. You have the flexibility to utilize any standard or proprietary codec, including H.264 (AVC), H.265 (HEVC), and AAC.
HTTP Response Codes:
  • All statuses returned to end-user as is.
  • 200 code is cached.
  • 4xx codes are not cached.
  • 5xx codes are not cached.

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Formats and Query String Parameters

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Base URL Format

https://play.yourdomain.com/flv/{stream-id}.flv

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Query String Parameters

FLV Live supports the following query parameters for playback control:
ParameterTypeDescriptionExample
only_audiobooleanPlay only audio track?only_audio=1
only_videobooleanPlay only video track?only_video=1

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Authentication

FLV Live supports token-based authentication to prevent unauthorized access and hotlinking.
  1. Secure Token:
    • Navigate to CDN Resource → Security → Secure Token
    • More information in About Secure Token
  2. Referer-based Access Control
  3. User-Agent Filtering
  4. Geo Filtering
Get more information in About Security

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Origin Failover Configuration

FLV Live supports automatic failover to backup origins: Failover trigger examples:
  • Origin connection timeout
  • Origin returns 5xx error
  • Network unreachable to primary origin

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Observability and Monitoring

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Per-Stream KPIs

Metrics to Monitor:
  • Traffic: Traffic
  • Requests: Requests
  • Error rate: 4xx/5xx errors as % of total requests
Access via:
  • Gcore Customer Portal → CDN → Statistics
  • Grafana dashboards (if enabled)
  • Raw logs export (for custom analysis)

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Player Compatibility

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Player mpegts.js (flv.js)

Browser Support: Chrome, Firefox, Safari, Edge (via MSE) Implementation: 
<script src="https://cdn.jsdelivr.net/npm/mpegts.js/dist/mpegts.min.js"></script>
<video id="videoElement" controls></video>

<script>
if (mpegts.isSupported()) {
    var videoElement = document.getElementById('videoElement');
    var flvPlayer = mpegts.createPlayer({
        type: 'flv',
        url: 'https://play.yourdomain.com/flv/channel1.flv',
        isLive: true,
        hasAudio: true,
        hasVideo: true,
        enableStashBuffer: false,
        autoCleanupSourceBuffer: true
    });
    flvPlayer.attachMediaElement(videoElement);
    flvPlayer.load();
    flvPlayer.play();
}
</script>

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SRS Player

Use Case: Embedded player with built-in controls 
<script src="https://cdn.jsdelivr.net/npm/srs.sdk@1.2/dist/srs.sdk.min.js"></script>
<video id="srsPlayer" controls autoplay></video>

<script>
var player = new SrsPlayer('srsPlayer', {
    url: 'https://play.yourdomain.com/flv/channel1.flv',
    autoplay: true,
    live: true,
    bufferLength: 0.5  // 500ms latency target
});
player.on('error', function(err) {
    console.error('SRS Error:', err);
});
</script>

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iOS/Android Native Implementation

iOS (AVPlayer): 
// FLV not natively supported on iOS
// Recommendation: Use HLS for iOS
// Or: Implement custom FLV parser with AVAssetResourceLoader
Android (MediaPlayer): 
// Option 1: Use ExoPlayer with FLV extension
implementation 'com.google.android.exoplayer:exoplayer:2.18.0'
implementation 'com.google.android.exoplayer:extension-flv:2.18.0'

// Option 2: Use ijkplayer (Bilibili player)
implementation 'tv.danmaku.ijk.media:ijkplayer-java:0.8.8'
Browser Compatibility Matrix:
PlayerChromeFirefoxSafariEdgeMobile SafariAndroid Chrome
mpegts.js✅✅✅✅✅ (iOS 17+)✅
SRS Player✅✅✅✅✅ (iOS 17+)✅
Native✅✅✅✅✅✅

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Scale and Performance Guidance

Bandwidth Calculation: 
Total Bandwidth = Concurrent Viewers × Stream Bitrate × 1.2 (overhead)

Example:
- 50,000 concurrent viewers
- 2 Mbps stream bitrate
- Bandwidth = 50,000 × 2 Mbps × 1.2 = 120 Gbps
Capacity Planning:
  • Origin Shielding: Reduces origin load by 80-95%
  • Multi-Region Origins: Deploy origins in 2-3 regions for geographic redundancy
  • Capacity Reservation: Pre-provision edge capacity 48 hours before event!

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FLV Live response example

curl -I -X GET "https://play.domain.com/flv/stream-id.flv"

HTTP/1.1 200 OK
Server: nginx
Date: Fri, 20 Jun 2025 19:31:29 GMT
Content-Type: video/x-flv
Transfer-Encoding: chunked
Connection: keep-alive
X-Cache-Status: Hit

FLV Header: {'signature': 'FLV', 'version': 1, 'has_video': True, 'has_audio': True}
[Script] Tag: 0, Size=867, Data=onMetaData
[Video header]: 0, Size: 52 (Keyframe, H264, AVC sequence header)
[Audio header]: 0, Size: 7
[Video]: 11154298 (185:54.298), Size: 24307 (Keyframe, H264, AVC NALU)
[Audio]: 11154359 (185:54.359), Size: 458
[Video]: 11154365 (185:54.365), Size: 1375 (Inter frame, H264, AVC NALU)

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FLV VOD

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Opportunity

FLV VOD enables delivery of pre-recorded video files with standard CDN caching benefits:
  • Cost-effective: Leverages CDN edge caching (reduces origin bandwidth by 80-95%)
  • Self-service: No special activation required
  • Global reach: 210+ edge locations worldwide
  • Protocol flexibility: HTTP/1.1, HTTP/2, HTTP/3 (QUIC) support
  • Security: Full suite of CDN security features (DDoS protection, WAF, secure token)
Common Use Cases:
  • Video-on-demand platforms
  • Educational content delivery
  • Archive/replay systems
  • User-generated content hosting

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Configuration for FLV VOD

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1. Create CDN Resource

Standard CDN resource creation process: https://gcore.com/docs/cdn/about-cdn-resources-interface-how-it-is-arranged
  1. Navigate to CDN Resources
  2. Click Create CDN Resource
  3. Configure origin:
    • Origin Type: Your server or Storage
    • Origin Address: vod.example.com or S3/Storage bucket
    • Origin Protocol: HTTP or HTTPS

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2. Enable Range Requests & Large File Optimization

FLV VOD delivery is optimized using HTTP range requests and Large File Delivery Optimization for files over 10 MB. This feature retrieves content in chunks, improves seeking performance, and reduces origin load.
  1. Navigate to CDN Resource → Content → Large files delivery optimization.
  2. Toggle Enable Large files delivery optimization.
  3. Full instructions: Optimize large file delivery

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3. Security for FLV VOD

Security settings for FLV VOD (Secure Token, Geo-restriction, RBAC, etc.) are identical to FLV Live. Refer to the Authentication section for implementation steps and token generation examples.

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4. Prefetch VOD

Use the Prefetch feature to load popular video files to the CDN cache before users request them. This ensures the first viewer gets a “HIT” status and experiences no origin-related latency.
  1. Navigate to your CDN resource and select Prefetch.
  2. Enter the paths to the files you wish to cache.
  3. Click Prefetch.
Full instructions: Load content to the CDN before users request it

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URL Format and Access

Base URL: 
https://cdn.yourdomain.com/videos/{filename}.flv

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Usage Examples

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Basic Video Delivery

HTML5 Video Player: Note: Most modern browsers do not support FLV natively. Use mpegts.js (flv.js): 
<script src="https://cdn.jsdelivr.net/npm/mpegts.js/dist/mpegts.min.js"></script>
<video id="videoElement" controls width="640" height="360"></video>

<script>
if (mpegts.isSupported()) {
    var videoElement = document.getElementById('videoElement');
    var flvPlayer = mpegts.createPlayer({
        type: 'flv',
        url: 'https://cdn.yourdomain.com/videos/sample.flv',
        isLive: false  // VOD mode
    });
    flvPlayer.attachMediaElement(videoElement);
    flvPlayer.load();
}
</script>

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Range Request Example

# Request first 1MB of video
curl -H "Range: bytes=0-1048575" \
  "https://cdn.yourdomain.com/videos/sample.flv" \
  -o sample-chunk.flv

# Expected response
HTTP/2 206 Partial Content
content-range: bytes 0-1048575/52428800
content-length: 1048576
x-cache-status: HIT

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Demo and Testing

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FLV Player Demo

Test your FLV LIVE streams and VOD files using the Gcore FLV demo video player: Demo URL: https://demo-files.gvideo.io/flv/flv-player.html Features:
  • FLV Live: Real-time stream testing
  • FLV VOD: Video file playback
  • Latency Measurement: Shows end-to-end latency
  • Diagnostics: Connection status, bitrate, dropped frames
Usage:
  1. Enter your FLV URL:
    • Live: https://play.yourdomain.com/flv/channel1.flv
    • VOD: https://cdn.yourdomain.com/videos/sample.flv
    • or use our demo FLV VOD
  2. Click Load & Play to start playback
  3. Monitor diagnostics panel for performance metrics
flv-player-demo

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Configuration Checklist

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Pre-Production Validation (FLV Live)

  • FLV Live service activated by Gcore support
  • Origin encoder configured (H.264/AAC, 1-2s keyframes)
  • CDN resource created with custom domain
  • FLV Live preset enabled (RAM buffering)
  • Secure token configured (optional)
  • Backup origin configured for failover
  • Test stream playback in demo player
  • Monitoring alerts configured (error rate, latency)
  • Capacity planning completed for expected concurrency

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Pre-Production Validation (FLV VOD)

  • CDN resource created with origin configured
  • Range requests enabled and tested
  • Secure token configured (optional)
  • Test file playback in demo player
  • Cache hit rate >80% after warmup
  • Geo-restriction or IP access control configured (optional)

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Additional Resources