With an enjoyable retro feel, this accessible video on understanding how analogue video works is useful for those who have to work with SDI rasters, interlaced video, black and burst, subtitles and more. It’ll remind those of us who once knew, a few things since forgotten and is an enjoyable primer on the topic for anyone coming in fresh.
Displaced Gamers is a YouTube channel and their focus on video games is an enjoyable addition to this video which starts by explaining why analogue 525-line video is the same as 480i. Using a slow-motion video of a CRT (Cathode Ray Tube) TV, the video explains the interlacing technique and why consoles/computers would often use 240p.
We then move on to timing looking at the time spent drawing a line of video, 52.7 microseconds, and the need for horizontal and vertical blanking. Blanking periods, the video explains are there to cover the time that the CRT TV would spend moving the electron beam from one side of the TV to the other. As this was achieved by electromagnets, while these were changing their magnetic level, and hence the position of the beam, the beam would need to be turned off – blanked.
The importance of these housekeeping manoeuvres for older computers was that this was time they could use to perform calculations, free from the task of writing data in to the video buffer. But this was not just useful for computers, broadcasters could use some of the blanking to insert data – and they still do. We see in this video a VHS video played with the blanking clearly visible and the data lines flashing away.
For those who work with this technology still, for those who like history, for those who are intellectually curious and for those who like reminiscing, this is an enjoyable video and ideal for sharing with colleagues.
The ST 2110-40 standard specifies the real-time, RTP transport of SMPTE ST 291-1 Ancillary Data packets. It allows to create IP essence flow carrying VANC data known from SDI (like AFD, closed captions or triggering), complementing the existing video and audio portions of the SMPTE ST 2110 suite.
In this video, Bill McLaughlin introduces 2110-40 and shows its advantages for closed captioning. With video, audio and ancillary data broken into separate essence flows, you no longer need full SDI bandwidth to process closed captioning and transcription can be done by subscribing to a single audio stream which bandwith is less than 1 Mbps. That allows for a very high processing density, with up to 100 channels of closed captioning in 1 RU server.
Another benefit is that a single ST 2110-40 multicast containing closed captioning can be associated with multiple videos (e.g. for two different networks or dirty and clean feeds), typically using NMOS connection management. This translates into additional bandwidth savings and lower cost, as you don’t need separate CC/Subtitling encoders working in SDI domain.
Test and measurment equipment for ST 2110-40 is still under developmnent. However, with date rates of 50-100 kbps per flow monitoring is very managable and you can use COTS equipment and generic packet analyser like Wireshark with dissector available on Github.
VP Product Development
This webinar will provide an overview of the recent revision of bitmap subtitles and the recent specs for UHD Subtitles.
The DVB specification for TTML-based Subtitling Systems, approved in July 2017, has now been complemented by a revision of the existing specification for bitmap subtitles, creating a comprehensive suite of subtitling specifications from DVB. This approval also marks the completion of the current generation of specifications for Ultra High Definition Television – DVB UHD-1.
The agenda for the webinar is:
•Bitmap subtitle specification (EN 300 743) Update (DVB Bluebook A009)
•New DVB TTML specification (Bluebook A174)
•Deployment considerations DVB Subtitling
Experts conducting the webinar include:
Dr. Peter Cherriman, Senior R&D Engineer, BBC Research & Development and Chair of the TM-SUB
Paul Szucs, Senior Manager, Technology Standards, Sony Europe
Stefan Pöschel, Engineer, Production Technologies, IRT
As much as video and audio are an essential part of watching a video, increasingly so is Timed Text (AKA Subtitles or Closed Captions). Legally required in some countries, its practical use beyond the hard of hearing is increasingly acknowledged. Whether for a sound-less TV in a reception or to help your follow the programme over the noise, Timed Text is here to stay online and in traditional broadcast. With the FCC declaring SMPTE-TT a ‘Safe Harbor’ format it has become a default format for subtitles interchange in the professional world.
In this webinar:
Why did we need a language for Timed Text?
An overview of TTML (Timed Text Markup Language from the WC3)
Examples of TTML
How SMPTE-TT extends TTML
How SMPTE-TT ends up as Closed Captions/CEA-608