Transcoding & Quality

Quality Presets

StreamDev provides built-in quality presets optimized for common use cases. Select a preset to automatically configure resolution, bitrate, and encoding parameters:

Preset	Resolution	Video Bitrate	Best For
360p	640 x 360	800 kbps	Low bandwidth, mobile data
480p	854 x 480	1,500 kbps	Standard definition, moderate bandwidth
720p	1280 x 720	3,000 kbps	HD streaming, general purpose
1080p	1920 x 1080	6,000 kbps	Full HD, high quality broadcasts
4K	3840 x 2160	15,000 kbps	Ultra HD, premium content

Tip: The 720p preset offers the best balance between quality and resource usage for most streaming scenarios.

Custom Settings

For fine-grained control, configure encoding parameters manually:

Resolution: Set any custom width and height (e.g., 1280x720, 1920x1080)
Video Bitrate: Specify in kbps (e.g., 4000 for 4 Mbps)
Frame Rate: Set output FPS (common values: 24, 25, 30, 60)
Audio Bitrate: Configure audio encoding quality (e.g., 128 kbps, 192 kbps)
Audio Sample Rate: Typically 44100 or 48000 Hz

# Example custom encoding settings
Resolution: 1280x720
Video Bitrate: 4000 kbps
Frame Rate: 30 fps
Audio Bitrate: 192 kbps
Audio Codec: AAC

Passthrough Mode

Passthrough mode copies the source stream directly to HLS output without re-encoding. This preserves original quality and uses minimal CPU resources.

Passthrough

No re-encoding — original quality preserved
CPU usage: ~1–2% per stream
No quality loss
Cannot change resolution or bitrate
Cannot add watermarks

Transcoding

Full re-encoding of video and audio
CPU usage: 15–100% per stream
Can change resolution, bitrate, FPS
Supports watermark overlays
Enables adaptive bitrate

Tip: Use passthrough when the source quality is already suitable for your viewers. This allows you to run significantly more concurrent streams on the same hardware.

GPU Acceleration (NVIDIA NVENC)

StreamDev supports hardware-accelerated encoding using NVIDIA GPUs with NVENC. This dramatically reduces CPU usage while maintaining excellent quality.

Requirements

NVIDIA GPU (GTX 1050 or higher recommended)
NVIDIA drivers installed on the server
CUDA toolkit (automatically detected by StreamDev)

Verify GPU Availability

# Check if NVIDIA GPU is detected
nvidia-smi

# Verify FFmpeg NVENC support
ffmpeg -encoders | grep nvenc

Important: Consumer NVIDIA GPUs (GeForce) are limited to 3–5 simultaneous NVENC sessions. For higher concurrency, use professional GPUs (Quadro/Tesla) or multiple GPUs.

CPU Usage Guidelines

Understanding CPU usage per stream helps you plan server capacity. These are approximate values per stream on a modern multi-core CPU:

Mode	CPU per Stream	Visual
Passthrough	~1–2%
720p Transcode	~15–25%
1080p Transcode	~30–50%
4K Transcode	~80–100%

Important: Keep total CPU usage below 80% to prevent frame drops and stream instability. Leave headroom for system processes.

When to Use Passthrough vs Transcoding

Use Passthrough When:

The source is already in a suitable quality and format
You need to maximize the number of concurrent streams
CPU resources are limited
No watermark or resolution change is needed
Source is already H.264 with AAC audio

Use Transcoding When:

You need to change resolution or bitrate for bandwidth optimization
Adding a watermark or logo overlay
Source codec is incompatible with HLS (e.g., H.265 to H.264 conversion)
Creating multiple quality variants (adaptive bitrate)
Normalizing frame rate or audio format across sources

Recommended Hardware per Quality Level

Use the following as a starting point for hardware planning:

Quality Level	CPU	RAM	Concurrent Streams
Passthrough Only	2+ cores	2 GB	20–50 streams
720p Transcoding	4–8 cores	4–8 GB	4–8 streams
1080p Transcoding	8–16 cores	8–16 GB	2–4 streams
4K Transcoding	16+ cores / GPU	16–32 GB	1–2 streams (CPU) / 4+ (GPU)

Tip: Adding an NVIDIA GPU can increase transcoding capacity by 3–5x compared to CPU-only encoding, making it a cost-effective upgrade for transcoding-heavy workloads.