Sign Language Books- Technical Considerations
This document serves as a working document to compile collective wisdom from various organizations that have already developed several Sign Language books for Bloom.
It is expected that each organization will take this wisdom and adapt it to the specific needs and constraints of its local situation.
We hope to add to this work-in-progress as we gather information from various stakeholders around the world who have already demonstrated adeptness in making Sign Language Books.
What follows are some thoughts shared by some creators of SL books.
Basic Recording Studio & Equipment
Camera
“A key feature we look for in the camera we use is the frame rate. A minimum is 60 fps. Anything less than this, and the sign movements are choppy. If you get something higher, you will obviously get a smoother video, but it will also be a heavier video file. If you find your file too heavy for the book, upload it to a streaming platform like YouTube since they have an in-built and decent enough way to reduce the size without reducing quality too much.”
“Record the videos in 4K HD or higher resolution to be able to make edits with clarity.”
Lighting
“You will have to play with your available lights to have the interpreter evenly lit to avoid shadows on the wall behind them. The shadows will make green screen removal harder and will result in inferior representation of the interpreter.”
“For the setup itself, good lighting is an essential consideration. Make sure the light is even, that there are no shadows and that there is nothing reflective or shiny. Pay attention to the visibility of the face - expressions are key and you don't want shadows or shiny spots causing confusion.”
“Simple tube lights work and are probably the cheapest solution.”
“For a decent output of a signed video, we recommend a dark room with 5-point lighting of 1000W with a green screen background 5 feet away from the signer and an SLR camera at least 7 feet away from the signer. This is to ensure that the signer’s head-to-hip area is captured while recording. Ensure that the room is completely dark and devoid of any reflections other than the focus lights.”
Green Screens
“The EFL team in Papua New Guinea uses a green screen for their Sign language recordings. They simply painted a piece of 10mm masonite (hardboard) in a lime green color and placed it on two wooden stands. A piece of plywood might work as well, but is normally not as smooth as masonite. … The green screen allows you to take out the distracting background in the video-editing software and replace it with a plain white or any color to match your book. In this way, your Sign language video will be more integrated with the rest of the book.”
“A typical suggestion is to wear black and have a green screen background. What we found was the color of the shirt had to be picked based on the best contrast with the skin tone and then a suitable background that highlighted the person and the background was most helpful. A common mistake is to pick a background the same or similar shade as the person's shirt, thinking that it helps "pop" the hands and face. However, this disembodied look is really not helpful, since the position of the sign vis-à-vis the body is a grammatical marker in sign.”
Positioning of the Camera
“Pay attention to how far away the camera should be from the person who is signing. You want to give a good signing space so that movements are not cut or cramped, so move back until the trunk is visible.”
Preparation for the Shoot
“What we learnt was the importance of really taking time before the shoot to make sure you have thought through how you want to tell the story, what you want emphasised and so on. Keeping the images simple and clear was another important thing we learnt helped kids learning to sign quickly and easily get the support they needed to understand or to reinforce the main idea of that page.”
Video Editing Software
“An inexpensive video editing option is Camtasia. It is easy to use. Easy to change background and allows for a lot of flexibility should you want to redesign it. It's simple enough that you can use it on your phone.”
“Since we were making stories for little kids, we tried really hard to get people to sign slower but this led to an odd awkward ISL. What we found worked better was to simply slow the playback [of the video] rate a little [when rendering].
“You will need professional software like Adobe Photoshop, Illustrator, Premiere, and After Effects to make a decent edit of your video. Save files under 500Mb with 1080 resolution. The bit rate can be set to automatic, or if you prefer a manual setting, ensure it is a minimum of 24 bits (for both audio & video). Ensure the bit rate is the same for audio & video, else you will have sync issues.”
“Make sure that you can apply effects to the whole video track. If you have 10 sign language videos on one track, one video effect (i.e., curves, to brighten up the interpreter’s face) will affect all the clips at once.”
Video Rendering
“For videos being used in a Bloom e-book, 480 x 320 is fine. Choosing a more square frame ratio gives you more room for text and/or pictures. You will have to crop the video from your camera.” See this book example.
“Exporting to an average bitrate of ~ 300Kbps is probably good enough quality.”
“Important questions to think about: How are the Bloom Reader books going to be used? Projector? Phone? Tablet? The bigger the device, the higher resolution/quality you will likely need. Check a book on the preferred devices and evaluate.”
“Use timeline markers to mark the beginning and end of each clip. This saves a lot of time when exporting.”
Authenticity
“Always use a deaf signer to convey information. Avoid using interpreters as signers in pre-scheduled videos. Interpreters can be used as a last priority in a video if the event is live. Create scripts, convert scripts into concept videos, and then record the concept videos for editing. Include multiple levels of quality checks for both signs and messaging. The design of the script varies for each category of content created. News videos will have a distinct look and feel compared to children’s educational videos. Ensure you have the right instructional designer on the team to create the video effectively. Special education teachers may not be familiar with instructional design for digital consumption. This will mean you will need two people to do that.”