[PBE-5141] Enhance RTMP public docs (#690)

docusaurus/video/docusaurus/docs/api/streaming/rtmp.mdx

@@ -7,11 +7,21 @@ title: RTMP input
 
 import RTMP from '../_common_/rtmp.mdx';
 
-## RTMP input support overview
+## RTMP input service overview
 
-Almost all livestream software and hardware supports RTMP. Our API supports using third-party software for streaming using RTMP.
+RTMP input is a service designed to bridge the gap between RTMP (Real-Time Messaging Protocol) and WebRTC (Web Real-Time Communication). 
+It enables users to stream content using an RTMP client, such as OBS (Open Broadcaster Software), and have that content published to participants in a [Call](../basics/calls.mdx). 
+The service will transcode the received media to ensure compatibility with WebRTC. It will also publish multiple qualities of it with [Simulcast](https://getstream.io/resources/projects/webrtc/architectures/simulcast/).
 
-_Please not that this page is about publishing video/audio using RTMP, **NOT** watching livestreams using RTMP._
+_Please note that this page is about publishing video/audio using RTMP, **NOT** watching livestreams using RTMP._
+
+### About RTMP
+
+[RTMP](https://rtmp.veriskope.com/docs/spec/) is a real-time streaming protocol created by Adobe, as media container format it uses Flash Video [FLV](https://rtmp.veriskope.com/pdf/video_file_format_spec_v10.pdf)
+also developed by Adobe.
+
+There's also an enhanced RTMP protocol, created to support a [wider range of newer video codecs](https://veovera.org/docs/enhanced/enhanced-rtmp-v2)
+like AV1, HEVC and VP8. OBS for example supports AV1 and HEVC. **RTMP input service doesn’t support them**.
 
 ## RTMP publishing
 
@@ -35,6 +45,31 @@ You can see an example in the [Quickstart](../../streaming/overview/#test-sendin
   style={{ width: '100%' }}
 />
 
+#### Optimal OBS Video Encoding Settings
+
+To ensure optimal quality and performance when transcoding media from RTMP, follow these recommended H.264 encoding settings:
+
+Go to `Settings`:
+
+**Video**:
+- Base Resolution: 1920x1080
+- Output Resolution: 1920x1080 (Same as input resolution)
+
+**Output**:
+- Encoder: `x264`
+- Rate Control: `CBR` (Constant Bit Rate)
+- Bitrate: 3,000-6,000 kbps (adjust based on your network and type of media being streamed, higher movement will require higher bitrate)
+- Keyframe Interval: 2 seconds
+- CPU Usage Preset: `veryfast` (balance between quality and encoding speed)
+- Tune: `zerolatency`
+
+<img
+  src={require('../assets/rtmp_in_obs_output_settings.png').default}
+  style={{ width: '50%' }}
+/>
+
+_The example is for OBS, but any other RTMP client should support adding the same settings_
+
 ### Streaming into a call with restream.io
 
 1. Go to [restream.io](https://restream.io/) and create an account.
@@ -47,3 +82,37 @@ You can see an example in the [Quickstart](../../streaming/overview/#test-sendin
   src={require('../assets/rtmp_restream_settings.png').default}
   style={{ width: '50%' }}
 />
+
+
+### Streaming a file into a call with FFmpeg
+
+With your call's RTMP url `$CALL_RTMP_URL` and your token streamKey `$STREAM_KEY` from [publishing](#rtmp-publishing). 
+Run:
+
+```bash
+ffmpeg -re -stream_loop 400 -i YourVideoFile1080p30fps.mp4 \
+  -c:v libx264 -preset veryfast -tune zerolatency \
+  -pix_fmt yuv420p -g 50 -c:a aac -b:a 160k \
+  -ac 2 -f flv "$CALL_RTMP_URL/$STREAM_KEY"
+```
+
+### FAQ
+
+#### What is the typical latency introduced by RTMP?
+
+RTMP input typically introduces a latency of 2-5 seconds. This can vary based on the network conditions, encoder settings (as the stream will be transcoded), and the performance of the RTMP server. 
+Optimizing [encoding settings](#optimal-obs-video-encoding-settings) and ensuring a stable network connection can help minimize this latency.
+
+#### What are the best practices for setting up OBS for RTMP streaming?
+
+Refer to [Optimal OBS Video Encoding Settings](#optimal-obs-video-encoding-settings).
+
+#### Do we support both RTMP and RTMPS?
+
+RTMP input service supports exclusively RTMPS. RTMPS is the recommended for secure streaming as it uses SSL/TLS to encrypt the data, providing an additional layer of security over RTMP.
+
+#### What are the recommended internet connection settings for optimal streaming performance?
+
+- **Upload Speed**: At least double the target bitrate of your stream. For example, if streaming at 5,000 kbps, ensure an upload speed of at least 10 Mbps.
+- **Connection Type**: Wired Ethernet connection is preferred over Wi-Fi for stability.
+- **Network Quality**: Ensure low packet loss (<1%) and low jitter (<30ms).