RTMP Ingest on Android. RTMP H264 to SRT H265 (aka HEVC)

The goal is to send RTMP stream from an action camera (or any RTMP feed really) to the server running on Android phone and use that as a source for a video encoder (running on the same Android phone) to stream it as SRT HEVC.

To achieve this we need a server that can run on Android and a video encoder.

We'll be using MediaMTX as a server (running in Termux).

IRL Pro is a great video encoder app. It can stream SRT HEVC with dynamic bitrate and bonding. Unfortunately, it cannot use audio from an RTMP stream, but it can use audio from a phone audio input or a Bluetooth mic connected to the phone.

Another option is to use ffmpeg in Termux. It can do SRT HEVC with no dynamic bitrate and no bonding. It uses audio from RTMP stream.

Termux

MediaMTX will be running in Termux. Install Termux on your phone. Do not use Google Play version.

Start Termux and copy-paste or type the commands below.

To copy commands open this page in the browser of your the phone and tap on commands.

To paste into Termux long tap anywhere on Termux terminal view to bring up context menu and choose Paste.

If at any time you need a new terminal swipe from the left edge of screen and select New session button.

MediaMTX

Install wget to allow downloading MediaMTX.

pkg install wget

We need to grab linux_arm64v8 version from one of MediaMTX releases. (Your phone can have a different architecture, but try this first.)

wget https://github.com/bluenviron/mediamtx/releases/download/v1.11.3/mediamtx_v1.11.3_linux_arm64v8.tar.gz

Unarchive it.

tar -xvzf mediamtx_v1.11.3_linux_arm64v8.tar.gz

Run MediaMTX.

./mediamtx

To stop MediaMTX tap CTRL button in Termux and type c.

Test

Hotspot

Create a hotspot with your phone. Your camera will need to connect to your phone's hotspot (be on the same network).

New Termux terminal session

Keep MediaMTX running. Open new Termux terminal by swiping right from the left edge of the screen and tapping New session button.

Phone's IP address

Find out your phone's IP address.

ifconfig

Look for IP under swlan0 > inet.

Get ready to stream RTMP to your phone

Configure your camera or video encoder to push to RTMP ingest of your phone.

(Replace IP_OF_YOUR_PHONE with an actual IP of your phone.)

rtmp://IP_OF_YOUR_PHONE:1935/mystream

Start the stream

Start streaming your camera to MediaMTX server. If it works it works.

(Optional) Configure MediaMTX to auto start

There are different ways to do this. Creating a service is a little a bit involved. The lazy way is to add MediaMTX to .bashrc file. The server will start on new Termux terminal session and will be killed when you exit terminal.

nano .bashrc

Add the following line to the content of .bashrc file.

./mediamtx

In Nano:

• CTRL + O, Enter to write file.
• CTRL + X to quit.

Restart Termux app or create a new terminal session to see it work.

IRL Pro

Intro

As of March 2025 IRL Pro doesn't have RTMP ingest feature, so this is a workaround.

Big thanks to Supairyacht user from IRL Pro Discord server for this idea.

We'll be pushing into RTMP ingest of MediaMTX and pulling HLS from MediaMTX. MediaMTX can do this without any extra setup.

HLS is essentially an HTML page with a video in it.

We'll create an overlay to display HLS page in IRL Pro. It can cover the whole view area if you like.

Audio

The issue with this idea is that overlays have no audio. IRL Pro lets you use audio via phone's audio input or Bluetooth mic connected to the phone.

There will be a delay of about 3 seconds between HLS video and phone audio, so you'll have to fix that in OBS (that has SRT media source).

Setup IRL Pro

• Add an overlay in IRL Pro. Use HLS feed from MediaMTX as an overlay source URL:

  http://localhost:8888/mystream
  

• Setup your IRL Pro to stream SRT HEVC.
• Start your stream in IRL Pro.
• In OBS add audio delay of about 3000 ms. (Note when you test it in OBS delay is not applied to audio monitoring, only to recording or stream.)
• Done!

ffmpeg

Keep MediaMTX running. Open a new Termux terminal and run ffmpeg in it.

Install ffmpeg.

pkg install ffmpeg

To encode HEVC with hardware accelation use Mediacodec options. This works on my Samsung S20 FE for example.

Try this first (w/o -codec_name option):

ffmpeg -i srt://localhost:8890?streamid=read:mystream \
-c:v hevc_mediacodec \
-bitrate_mode 2 \
-b:v 3000K \
-g 250 \
-pix_fmt nv12 \
-c:a copy \
-f mpegts \
srt://YOUR_SRT_URL

Different phones can have different codecs, so if that doesn't work try setting -codec_name explicitly. You need to look it up for your phone. Install Codec Info app and use it to find a codec name on your phone that can do hardware accelation.

Here is what I use. -codec_name set to OMX.qcom.video.encoder.hevc:

ffmpeg -i srt://localhost:8890?streamid=read:mystream \
-c:v hevc_mediacodec \
-codec_name OMX.qcom.video.encoder.hevc \
-bitrate_mode 2 \
-b:v 3000K \
-g 250 \
-pix_fmt nv12 \
-c:a copy \
-f mpegts \
srt://YOUR_SRT_URL

Tweak other ffmpeg options to your liking.

(Optional) Get more details on Mediacodec options:

ffmpeg -help encoder=hevc_mediacodec

(Optional) Script that can restart ffmpeg if it exits or errors out

For convenience you can create a script and manually run it.

nano ffmpeg.sh

Paste script.

while true; do
ffmpeg -i srt://localhost:8890?streamid=read:mystream \
-c:v hevc_mediacodec \
-bitrate_mode 2 \
-b:v 3000K \
-g 250 \
-pix_fmt nv12 \
-c:a copy \
-f mpegts \
srt://YOUR_SRT_URL
echo "FFmpeg exited. Restarting in 5 seconds."
sleep 5
done

In Nano:

• CTRL + O, Enter to write file.
• CTRL + X to quit.

Give executable permissions.

chmod +x ffmpeg.sh

Run script.

./ffmpeg.sh

To stop running CTRL + C a couple of times.

Test results (March 2025)

IRL Pro

Tested HLS overlay in IRL Pro idea a bit more. Overall, it works fine. The issue I've noticed is that it's skipping frames randomly here and there for me. The same frame is rendered twice, so it has these micro stutters. I had to step through frame by frame in YouTube player to see it. Untrained eyes might not notice it. I tried to fix it by changing resolutions and bitrate in both IRL Pro and ingest stream - no luck. I suspect that's just how overlays work, so I don't think it can be fixed.

ffmpeg HEVC

As for hardware acceleration for encoding HEVC when ffmpeg and Medicodec - tested that thoroughly too. It has issues with playback of stream in OBS and SRT players. It's a little flaky. It sometimes works alright for 1080p, but needs a bunch restarts. Weird. With libx265 -crf 23 I can get somewhat stable 480p stream, that at least is reliably playable in OBS.

This sums state of HEVC with ffmpeg in Termux on Android so far for me.

References

• IRL Pro Discord threads
  • RTMP Ingest
  • Built-in RTMP Server that can be used as a source
• This is sort of a continuation of this page that I wrote https://github.com/dimadesu/termux-nginx-rtmp (it's missing a bit with hardware accelarate options though, I'll update it someday).
• I got Mediacodec ideas from https://wiki.x266.mov/docs/encoders_hw/mediacodec