Three settings decide the picture quality of a stream and the load on the computer: the encoder, the output size and the bitrate. This page also explains the total bitrate, which is often misunderstood.
Encoder
This setting is under Settings → Outputs → Encoder.
| Option | |
|---|---|
| x264 (software) | Encodes on the processor. It is available on every computer and gives the best quality at a given bitrate, but it is also the heaviest load on the computer. |
| Hardware encoders | The encoders of the graphics card: NVIDIA, Intel or AMD. They appear in the list automatically. |
Use the hardware encoder if the computer has one. The processor is already busy rendering your playouts, and the hardware encoder takes the encoding away from it. On a computer with two playouts, this can prevent dropped frames.
Use x264 on a computer without a suitable graphics card, or when quality at a low bitrate is more important than the load on the processor.
Output size
The output size is the size of the stream: the size of the canvas, or a smaller size with the same proportions. It is normal to build at full size and scale down for the stream, for example with a canvas of 1920×1080 and a stream of 1280×720.
A smaller size needs less bitrate and less encoding. Do not send a size that is too large for your bitrate, because the picture then becomes blurred when there is movement.
Total bitrate
The total bitrate is the video and the audio together, and it is the figure that your server allows. The audio is part of the total and is not added to it.
The program sends the value that you enter, so a server that allows 4000 kbit/s receives 4000. The line below the field shows how the total is divided: → video 3840 + audio 160 = 4000 kbit/s.
A higher audio bitrate therefore leaves less for the picture. For a service with music that is usually worth it; for speech it is not.
Suggested values
| Situation | Size | Total |
|---|---|---|
| Speech, limited upload | 1280 × 720 | 2500 kbit/s |
| General use | 1280 × 720 | 4000 kbit/s |
| Music, plenty of upload | 1920 × 1080 | 6000 kbit/s |
Set the total to a value that your upload can carry all the time, and not to its peak. A stream that runs reliably is better than a stream that looks excellent for twenty minutes and then fails.
You can check this during a stream: the status block shows dropped frames, which are frames that the network could not carry. If they appear, the bitrate is too high for the connection, whatever a speed test shows.