I’m developing a tool for clipping streaming videos and need assistance with buffering segments.
I’ve figured out how to obtain the HLS stream URL from a live Twitch broadcast. Now, I want to create a feature where viewers can request a clip of the last 5 minutes of their stream.
The concept is straightforward: if a streamer makes an incredible play but forgets to record it, they can simply say “grab the last 5 minutes” and that clip should be saved.
public class StreamBuffer
{
private Queue<VideoSegment> highQualityBuffer = new Queue<VideoSegment>();
private Queue<VideoSegment> standardQualityBuffer = new Queue<VideoSegment>();
public void CaptureSegments(string hlsUrl)
{
// How do I differentiate between quality levels?
// How do I maintain exactly 5 minutes of data?
}
public byte[] GenerateClip(QualityLevel level)
{
// Return buffered segments as video file
return null;
}
}
My main questions are:
How can I separate the high-quality stream from the medium-quality stream while buffering?
What is the best method to ensure I maintain exactly 5 minutes of video data in memory?
Should I store the raw segments or process them prior to storage?
Any advice on working with HLS streams in C# would be greatly appreciated.
The tricky part is handling multiple downloads while keeping memory usage reasonable. Skip the separate queues per quality - use a dictionary instead. Quality IDs as keys, circular buffers as values. Way easier to scale when you add more quality levels later.
For the 5-minute buffer, run a background timer every 30 seconds to dump expired segments. HLS gives you EXT-X-TARGETDURATION which shows max segment length, so you can figure out buffer size from that.
Don’t let network hiccups kill everything - if one quality stream dies, the others should keep running. Use HttpClient with connection pooling since you’ll be hammering those requests.
When you’re building clips, double-check that segments from the same timeframe exist across all qualities before you try concatenating. Otherwise you’ll get clips with different lengths.
Built something like this last year for a sports streaming app. First, parse the master playlist to find variant streams with different bitrates. Each quality level has its own m3u8 URL you’ll need to monitor separately. For the 5-minute buffer, use a sliding window with timestamps instead of counting segments - segment durations aren’t always consistent. Store each segment with duration metadata and constantly purge anything older than 300 seconds. Keep the raw TS segments for storage. You can concatenate them directly when making clips since they use the same codec parameters within each quality stream. Only transcode if users want a different output format - saves processing power and keeps original quality. One thing that bit me: handle playlist refreshes correctly because HLS manifests update constantly during live streams.
HLS buffering in production will crush your memory fast. Don’t keep everything in RAM - I use a hybrid setup where the last 2-3 minutes stay in memory and older segments get written to temp files with aggressive cleanup. Saves you from memory bloat during long streams.
For quality separation, parse the master playlist’s bandwidth attribute to identify streams. Don’t rely on resolution tags - they’re optional and I got burned by this with audio-only streams.
Here’s something that’ll bite you: HLS streams have discontinuities marked with EXT-X-DISCONTINUITY tags. These will break segment concatenation if you don’t handle them. Your clip generation needs to account for these or you’ll get corrupted files. Also add proper error handling for network timeouts since live streams are unreliable.
ffmpeg libs are perfect for this. You can pipe HLS streams straight into memory buffers - no temp files cluttering up your disk. Handles all the segment stitching automatically when you’re making clips, plus you’ll save a ton on disk I/O.
just store the raw ts segments, they’re compressed already. use the m3u8 manifest to get different quality streams as they each have their own playlist url. for the 5-min buffer, keep track of segment durations and drop old ones after reaching 300 seconds total.