Export video with alpha channel in Davinci Resolve

A great alternative to the Adobe video editing suite is Davinci Resolve because it’s free (paid version exists, locks just a bit of features).

Exporting in Davinci Resolve

Let’s say you have a timeline with your elements places and transparency set. You will now go to the deliver tab, select Quicktime as the format and GoPro Cineform as the codec.

The most important thing is to select RGB-16 in the type and tick export Alpha.

This is the final step unless you need to publish the file as a WebM.

Convert the MOV to WEBM

When building alerts and overlays, certain services like StreamElements won’t accept the Quicktime file, you will need to convert it to a WebM with the VP9 codec to retain the transparency.

Use FFmpeg with the following command line:

ffmpeg -i inputmove.mov -c:v libvpx -pix_fmt yuva420p -b:v 2000k -auto-alt-ref 0 output.webm

Keep in my you can change the bitrate and increase it by tweaking the value following -b:v.

Conclusion

This small trick is something I spent a long time looking for and I have had mixed results with it. But lately I’ve been getting into preparing custom alerts on StreamElements for my own streams and I was hoping to add something nice.

Adding subtitles to your stream

Ever wanted to subtitle your stream in your language and add one or two other languages with automatic translation? Looks like there’s a tool for that.

Step 1: Setting up a Apps Script (Google)

Setting up the Apps Script start with creating a new script on Apps Script: https://script.google.com

In the editor you will need to paste the following code:

function doGet(e) {
  const params = e.parameter
  var translatedText = LanguageApp.translate(params.text, params.source, params.target);
  const output = ContentService.createTextOutput();
  output.setMimeType(ContentService.MimeType.JSON);
  output.setContent(translatedText);
  return output;
}

The code will need to be deployed by click on the deploy menu on the top left:

The app must be deployed as a web app:

In the form you must let anyone access it:

When it’s deployed you will be provided the app key, this is what you will need for the next steps:

Step 2: Setting up the page

This is where the fun begins. There’s a form that is totally in Japanese that will require a couple of edits to be usable. Go here to start filling the form: https://sayonari.coresv.com/ninshikiChan/20210822_config.html

In the input field for Google Script API-KEY paste the one from your Apps Script. If you didn’t copy the key in the previous step you can retrieve if by going into the editor, in the deploy menu you need to click on manage deployments and you’ll find it under deployment ID:

Change the languages you want to use lower on the page, feel free to use Google Translate to find out what is what:

On the bottom of the page you will find the URL that you can copy and paste in your web browser, Google Chrome might be the only supported browser at the time of writting.

Step 3: Setting up OBS

Now comes the less fun part. Since the web page needs to listen to your voice you will have to run the page in your own Google Chrome instance, I’m unsure if it works on other browser since I wasn’t able to make the web app perform every single time.

To set it up all you need is a window capture and some filters. If the content of the web browser doesn’t appear you might need to disable hardware acceleration.

For the filters I usually just crop the top and a bit of the bottom, then I apply a chroma key filter to remove the screen background:

Congratulations, you are know streaming while subtitling at the same time. Subs are the way to go and this is what it looks like:

Troubleshooting

Refreshing the tab might help making the web app work, but if your speech isn’t appearing on screen you should instead try closing and reopening your browser.

I kept the tab loaded before closing Google Chrome and when I opened it again it was working.

Once again this isn’t flawless and some words might appear wrong or be heard wrong, these are the limits of speech recognition. Unless we slap some machine learning over your accent.

It might also strain your performances and require relaunching Google Chrome once in a while.

Credits

This is basically a translation of a Japanese page that was shared with me: http://www.sayonari.com/trans_asr/index_asr.html

This is a very useful tool for hearing impaired viewers and to enable people to appreciate better a stream in another language.

No ShadowPlay overlay in games, no recording after install a Stream Deck

I’ve recently purchased a Stream Deck MK2 by Elgato (Corsair) after playing around with the mobile app for a while and planning out some profiles for stuff like video editing and streaming.

It’s honestly a nice piece of equipment but I’ve had it for less than 24 hours and I’ve already found some problems.

Symptoms

After running the Stream Deck software to configure the keys and browse the plugins that are available I noticed that my ShadowPlay overlay isn’t showing in the critically acclaimed Final Fantasy XIV, which is unusual.

I closed the game, relaunched it, even rebooted and nothing. Time to try another game like Monster Hunter World, same. I confirmed that the main menu would show up but I had no overlay showing the replay buffer running.

Weirder was when I attempted to record it would ask me if I wanted to enable desktop recording. That’s when I started thinking that some software was grabbing ShadowPlay and keeping it to itself without ever releasing it.

I was looking for the icons on the bottom right

How to blacklist apps from ShadowPlay

The only way to fix this is to find a way to forbid ShadowPlay from hooking into it and of course Nvidia doesn’t give us tools to deal with that.
But on the bright side we have third party tools and I used the NVIDIA Profile Inspector, download a release here.

Download it, run it and the in the box on top search for Discord:

We will now add the StreamDeck.exe utility to that list by clicking on the add application to current profile button, browse to your Stream Deck installation folder and add StreamDeck.exe to it.

You might need to relaunch the Stream Deck utility, relaunch ShadowPlay through GeForce Experience or even reboot.
After that the utility will no longer trigger the overlay notification you get when you run a game and you should be able to record gameplay without enabling desktop recording.

Closing notes

I’ll make a proper post about how I use it at a later date (maybe) but for now I’m pretty much pleased with how easy it is to configure and I have started experimenting with some plugins such as Discord (mute/deafen toggle), iCUE profile changer (for my Corsair iCUE H150i RGB PRO XT) and a plugin to show CPU and GPU temps with HWiNFO.

I’ll get started with streaming a bit more often I guess and will improve my general workflow and battlestation setup.

Discord animated voice PNGs

Update 2023/05/03

Use Reactive.Fugi.Tech instead, it’s easier. You can setup your profile pictures and share a link to be integrated into OBS. It just works.

Original post

When building your streaming overlay you might want to add the other users that are in your current vocal chat but you want to customize a bit the way it’s displayed.

Discord doesn’t offer any of those options natively but with OBS Studio it’s possible to use some tricks.

CSS & web knowledge required to understand how to use CSS and how to link images.

Setting up the widget

Nothing really hard here, got to the Stream Kit page for Discord in the overlay section.

Setting up the server and the voice channel to be used will alter the URL so make sure you are using the right channel, but it’s possible to use a personal and private channel to use for PNG VTubing.

In OBS within your scene you need to create a browser source and use the provided link as such (no preview until it’s saved):

This is the basic setup. Next we will need a way to get the user ID on Discord.

Setting up Discord

To be able to get the user IDs we need to enable the developer options within Discord. Go to your settings within Discord and in the advanced tab you’ll find the developer toggle:

Getting the user’s ID is as simple as right clicking a name in the chat and clicking on the Copy ID button:

Customizing the widget

Since the widget is a web page within a web view in OBS Studio it’s easy to customize through CSS. Here’s the code to copied & pasted into the custom CSS text area in the browser source:

/*
To be used with the Voice Widget from the Discord Stream Kit
https://streamkit.discord.com/overlay

Do not hotlink images, please rehost them to avoid stealing
bandwidth and keep control over your images, Imgur is a fine
option for this.

Credits:
- Generator by kukushie: https://www.reddit.com/r/VirtualYoutubers/comments/k4q8jw/css_generator_for_discord_reactionary_images_that/
- Edited & improved by SenpaiSilver: https://twitter.com/SenpaiSilver

Please keep the credit chain when making & publishing your changes.
*/

@keyframes speak-now {
    0%  { bottom:0px; }
    15% { bottom:15px; }
    30% { bottom:0px; }
}

body {
    background-color: rgba(0, 0, 0, 0);
    margin: 0px auto;
    overflow: hidden;
}

/* Aligning everything on the same line */
.voice-state {
    display: inline-block;
}

/* Images must be square, change height for it to be scaled
back to 128px wide, or else deal with bad alignments */
.avatar {
    height: 128px !important;
    width: auto !important;
    border-radius: 0% !important;
    filter: brightness(50%);
}

.speaking {
    border-color: rgba(0,0,0,0) !important;
    position: relative;
    animation-name: speak-now;
    animation-duration: 1s;
    animation-fill-mode: forwards;
    filter: brightness(100%);
}

/* Hiding names because the discord parameter on the streamkit
doesn't seem to be taken into account correctly */
.name { display: none; }

/* Default avatar */
.avatar {
    content: url("https://link-to-image.png");
}

/* Users go here: */

.avatar[data-reactid*="new"] {
    content: url("https://link-to-image.png");
}
.speaking[data-reactid*="new"] {
    content: url("https://link-to-image.png");
}

The result is an overlay, where the images change went talking in some way:

  • Brightness is increased;
  • The image is bumped 15 pixels higher;
  • The image changes depending if an image is set for talking only.

Thanks to Malidoudou for the output for her streams.

Explaining some parts of the code further

It’s important to understand some parts of the properly before running this code, even though it’s just CSS.

First of all you cannot trust users, I recommend using a default image for users that are not part of the CSS to avoid displaying potentially unwanted profile pictures:

/* Default avatar */
.avatar {
    content:url("https://link-to-image.png");
}

This code will replace the img tag’s content with the provided image for everyone that connects to the voice channel. After that it will be possible to set below the specific users with their IDs:

.avatar[data-reactid*="user discord id"] {
    content:url("https://link-to-image.png");
}
.speaking[data-reactid*="user discord id"] {
    content:url("https://link-to-image.png");
}

When we override .avatar we are already setting the default image for the user, by specifying that the attribute data-reactid contains a certain string we can refine our selector and make it target a specific user ID (since they are unique).

In this case the same applies when .speaking is added to the user .avatar.

If you wish to retain round avatar you will need to tweak the border-radius within the first definition of .avatar.

Possible improvements

Since we are dealing with images, animated GIFs are an option and could be used to display an animation with transparency.

If the GIF format doesn’t provide enough colors then it’s possible to fallback to something like the animated WebP or APNG format.

Credits, warranties & notes

This code is based on a generator found on reddit, I’ve changed it to make it work better and fit my own settings. If you modify the code please keep the credit list and add yourself to it.

The code is provided as is and might break one day if the Stream Kit is updated.

This code can be used for son PNG VTubing too.

Separate your audio streams for streaming on Windows

Streaming and recording video games is something I’ve been into, casually, for years (since 2006). Recording gameplay with audio usually includes all the system audio and this can be a problem.

Recording all system audio issue

Windows, your web browser and the game’s audio will play through the default device. That default device is usually your headphones or your speakers.

OBS and ShadowPlay usually record that default device, this is something we’ll have to change.

Virtual Audio Cable

I’m using Virtual Audio Cable (VAC). You can use the trial version, buy it or use an alternative virtual cable driver, this is all up to you.

Open the Virtual Audio Control Panel as an admin (always) and setup the desired number of lines. Each line will be setup to receive audio from certain apps depending on the usage you want.

I have the main line for gameplay, my Discord line to record people I’m talking to. I also have a third line for miscellaneous things and a fourth that I’m not using.
Ideally I would’ve have set one line specifically for gaming, but Windows 10 being what it is (and standards being what they are) it ain’t going to work like that.

To complete the audio setup I also need to output those lines to something and that something is my headphones. Each output line automatically inputs the sound into a virtual input too, that way you can listen to it.

Basically this is how things go:

  • Outputs:
    1. Headphones;
    2. Line 1: Main output (default output device);
    3. Line 2: Discord output;
    4. Line 3: Misc output.
  • Inputs:
    1. USB Microphone (default input device);
    2. Line 1: Main output mirrored as input into my headphone;
    3. Line 2: Discord output mirrored as input into my headphone;
    4. Line 3: Misc output mirrored as input into my headphone.

Windows 10 doesn’t remember

Like I said previously one problem that forces me to set the line 1 as the default output device is because Windows 10 can’t exactly remember correctly which app is outputting on which device.

This issue could also be the other way around where an app will have a different output selected but still output to the default device, I’m not sure why but answers would be appreciated.

OBS recording

OBS is a great piece of software that permits me to merge lines and split some too! This is perfect for recording gameplay and streaming (at the same time).

First we need to specify that we will be recording several tracks into our ouput in OBS, for that we need to go into the settings: File, then Settings.
From there we go into the Output section and select in Streaming the first audio track as the one we will be using for streaming like so:

As a bonus you can also use a different audio track for the VOD so you can have avoid having Spotify playing in the VOD (and avoid the DMCA).

In recording we need to tick all audio track to enable all audio tracksfor later:

Then of course we need to name them and change the audio bitrate if you desire:

In my case I have everything playing on track 1 since it is the default track.
Track 2 will contain the game audio or the main subject of the video/stream.
Track 3 is my voice, followed by track 4 with voices from Discord.

Having different tracks enables me to control what is output when I record and stream, this way I’m able to make audio commentary when preparing a video and after that replace that commentary with a carefully recorded one, while keeping the gameplay audio without altering it.

To select where what track plays it’s necessary to go into the Edit menu, then Advanced audio properties. Set the different inputs and outputs as you wish in the new window:

Keep the first track checked for all lines, check the other numbers as you need.

Troubleshooting: static/glitch audio

After a while if the computer is not rebooted for days it might happen that the audio fizzles, glitches or becomes static. This isn’t a good experience.

The fix consists in restarting Virtual Audio Cable or the audio service from the control panel (as an admin).

Going further with FFMpeg

This is my follow up to getting started with FFmpeg. I strongly recommend getting to know the tool better in my previous post about it.

Concatenate

Multiple clips can be merged together with the concat demuxer. The idea is to create a text file with a list of files to concatenate together (in order), the format is as follows:

# List of files in order
file './file1.mp4'
file './file2.mp4'
file './file3.mp4'

For the lazy people like me it’s possible to use shell scripting to generate this list:

for f in ./*.mp4; do
  echo "file '$f'" >> list.txt
done

Then you need to feed the file as an input and specify the format (-f) as concat:

ffmpeg -f concat -i list.txt -c copy output.mp4

The wiki page speaks more in detail about this feature.

Extracting the frames

It is quite simple to extract all the frames from a video as pictures.

ffmpeg -i input.mp4 frame_%03d.png

In this command we extract every frame from input.mp4 as PNG pictures. We use the printf format for the numbering of the frame (we pad with 0 the %d for 3 characters).

It’s possible to use the parameters for the start and length of the clip to extract part of the frames or just simply limit number of frames to extract with -vframes. We can also specify a different framerate to work with during this process with -vf fps=1.

Hardware acceleration encoding

For maximum speed it is possible to use a hardware encoder for H264, I will only cover how to do this with an NVidia GPU (NVENC).

First check that FFmpeg has not been configured with --disable-nvenc, this will appear in the banner when running FFmpeg if NVENC is disabled.

ffmpeg -ss 14:01 -i "input.mp4" \
  -c:v h264_nvenc               \
  -b:v 60000k                   \
  -t 0:30
  output.mp4

This looks exactly as encoding, except the codec on line 2 is different, it has _nvenc appended to it. This is really simple and will boost the encoding drastically.

Reading more

Please check out the following pages if you wish to know more:

Getting started with FFmpeg

The tool I use the most to clip videos and (re)encode media is FFmpeg, a command line bundle of utilities and libraries that is very powerful but not necessarily intuitive.

This is a small guide about the most useful commands.

Basic command line

The basic command is composed by an input and an output:

# Conserve the same format
ffmpeg -i "./input.mp4" "./output.mp4"

# Conserve the same exact encoding settings
ffmpeg -i "./input.mp4" -c copy "./output.mp4"

# Conserve only the sound
ffmpeg -i "./input.mp4" "./output.mp3"

In the command line we have the input parameter marked by the -i option. The output is positioned at the end of the command.

The -c argument correspond to video and audio codecs when followed by copy to conserve the same streams as they were encoded in the input.

Argument quirks

FFmpeg uses the position of the arguments, the input cannot be place elsewhere than at the start of the line and all options related to the input must be placed before the input file.

The output options can be place after the inputs.

Extracting a clip

Sometimes you are proud of the way you handled a boss in a game or you just want to clip out a part of a movie, to do that you will need to provide the start of the clip and sometimes the length of the clip you wish to extract.

ffmpeg              \
  -ss 01:37         \ 
  -i "./input.mp4"  \
  -t 01:00          \
  "./output.mp4"

Let’s break down this command line by line:

  1. We call FFmpeg;
  2. We set the start of the clip with -ss and specifying a time code;
  3. We set the input file;
  4. We set the length of the clip;
  5. We set the output.

The start and length are expressed as a time code:

Hours Minutes Secondes Milliseconds
00 : 01 : 37 . 000

In our case we are working with minutes and seconds, but we can go as low a milliseconds. Keep in mind that if you do not re-encode you might end up with a couple of unwanted frames.

Encoding

More often than not encoding will be necessary if you want to publish online, reduce the file size or edit the media file. Here are a couple of snippets for different formats.

Implicitly convert

For the programmer lazy people like me it’s possible to quickly extract the sound or convert a video as a gif:

# Convert a video to an audio only file
ffmpeg             \
  -i "./input.mp4" \
  "./output.mp3"

# Convert to a gif
ffmpeg             \
  -i "./input.mp4" \
  "./output.gif"

This will use default settings, you can tweak the settings by going in-depth depending on the output format you choose (Encode/MP3).

Same codec, different bitrate

Changing the bitrate is possible, for a loss in quality.

# Convert to h264 with a bitrate of 
ffmpeg             \
  -i "./input.mp4" \
  "./output.mp4"

It’s also possible to run two passes by adding the parameter -pass with the argument 1 or 2 for the first and second pass.

# Convert to h264 with a bitrate of 
ffmpeg -i "./input.mp4" -c:v libx264 -b:v 2600k -pass 1 -an -f mp4 /dev/null
ffmpeg -i "./input.mp4" -c:v libx264 -b:v 2600k -pass 2 -c:a aac -b:a 128k "./output.mp4"

As you see on line 2 we use the argument -an to not treat the audio but during the second pass we specify a codec with -c:a and the audio bitrate -b:a, this is because the first pass only treats the video stream.
If you wish you can add the audio the the first pass, nothing is stopping you from doing so.

We still supply the video codec for both passes with -c:v and the bitrate -b:v.
Please note that bitrates can also be expressed in other units such as M for megabits.

We also don’t output the video stream to a file on line 2 because we are having FFmpeg generate a log file for the second pass. We also need to specify the output format to the encode with -f so that the second pass is not lost.

You can read more on h264 encode on the FFmpeg wiki.

What about the WebM format? Well it’s a bit the same but with different codecs:

# Convert to a webm (VP9)
ffmpeg             \
  -i "./input.mp4" \
  -c:v libvpx-vp9  \
  -crf 10          \
  -b:v 0           \
  -c:a libvorbis   \
  "./output.webm"

A new option on line 5 is the constant quality mode and this is the reason we have set the video bitrate to 0. Instead of imposing a fixed bitrate we will instead of have a variable bitrate used to target the quality we want.
It is possible to omit -crf and specify a video bitrate instead.

If you wish to target a lossless quality you can do so by setting the argument -lossless to 1.

VP9 does support two pass encoding and will work the same as h264.

Read more about VP9.

Editing

It’s also possible to reduce the frame rate and the resolution.

ffmpeg             \
  -i "./input.mp4" \
  -r 25            \
  -vf scale=160x90 \
  -c:v libvpx-vp9  \
  -b:v 2M          \
  -c:a libvorbis   \
  "./output.webm"

Here we reduce the frame rate to 25 with the option -r. The resolution is lowered with option -vf scale= to 160 by 90. It’s possible to keep the aspect ratio by specifying -1 in the scaling such as scale=1280x-1 to scale down to 720p from 1080p (assuming the aspect ratio was 16:9).

Conclusion

FFmpeg is a great tool that can basically do anything when working with media files. It’s very popular and used everywhere because of how powerful it is.

Remap Ansel hotkey

Ansel is Nvidia’s tool that is used for making high resolution, 360° and stereoscopic screenshots. You can move around freely in a paused scene to capture your character’s best side.

Sadly during action ALT+F2 is quite hard to hit. Let’s remap the key.

Launching the configuration utility

To launch the utility hit Windows+R and paste this path:

%PROGRAMFILES%\NVIDIA Corporation\Ansel\Tools\NvCameraConfiguration.exe

You should be greeted with this window:

The input hotkey is used to remap, hit the key or the combination you wish to use then confirm and save.

I have tested this on Windows 10 with the Witcher 3.

Source: https://forums.geforce.com/default/topic/957949/ansel/any-way-to-rebind-keys-/